Wine and alcoholic fermentations are complex and fascinating ecosystems. Wine aroma is shaped by the wine’s chemical compositions, in which both microbes and grape constituents play crucial roles. Activities of the microbial community impact the sensory properties of the final product, therefore, the characterisation of microbial diversity is essential in understanding and predicting sensory properties of wine. Characterisation has been challenging with traditional approaches, where microbes are isolated and therefore analyzed outside from their natural environment. This causes a bias in the observed microbial composition structure. In addition, true community interactions cannot be studied using isolates. Furthermore, the multiplex ties between wine chemical and sensory compositions remain evasive due to their multivariate and nonlinear nature. Therefore, the sensorial outcome arising from different microbial communities has remained inconclusive. In this thesis, microbial diversity during Riesling wine fermentations is investigated with the aim to understand the roles of microbial communities during fermentations and their links to sensory properties. With the advancement of high-throughput tools based ‘omic methods, such as next-generation sequencing (NGS) technologies, it is now possible to study microbial communities and their functions without isolation by culturing. This developing field and its potential to wine community is reviewed in Chapter 1. The standardisation of methods remains challenging in the field. DNA extraction is a key step in capturing the microbial diversity in samples for generating NGS data, therefore, DNA extraction methods are evaluated in Chapter 2. In Chapter 3, machine learning is utilized in guiding raw data mining generated by the untargeted GC-MS analysis. This step is crucial in order to take full advantages of the large scope of data generated by ‘omic methods. These lay a solid foundation for Chapters 4 and 5 where microbial community structures and their outputs - chemical and sensory compositions are studied by using approaches and tools based on multiple ‘omics methods. The results of this thesis show first that by using novel statistical approaches, it is possible to extract meaningful information from heterogeneous biological, chemical and sensorial data. Secondly, results suggest that the variation in wine aroma, might be related to microbial interactions taking place not only inside a single community, but also the IV interactions between communities, such as vineyard and winery communities. Therefore, the true sensory expression of terroir might be masked by the interaction between two microbial communities, although more work is needed to uncover this potential relationship. Such potential interaction mechanisms were uncovered between non- Saccharomyces yeast and bacteria in this work and unexpected novel bacterial growth was observed during alcohol fermentation. This suggests new layers in understanding of wine fermentations. In the future, multi-omic approaches could be applied to identify biological pathways leading to specific wine aroma as well as investigate the effects upon specific winemaking conditions. These results are relevant not just for the wine industry, but also to other industries where complex microbial networks are important. As such, the approaches presented in this thesis might find widely use in the food industry. 


MsmS is a heme-based redox sensor kinase in Methanosarcina acetivorans consisting of alternating PAS and GAF domains connected to a C-terminal kinase domain. In addition to MsmS, M. acetivorans possesses a second kinase, MA0863 with high sequence similarity. Interestingly, MA0863 possesses an amber codon in its second GAF domain, encoding for the amino acid pyrrolysine. Thus far, no function of this residue has been resolved. In order to examine the heme iron coordination in both proteins, an improved method for the production of heme proteins was established using the Escherichia coli strain Nissle 1917. This method enables the complete reconstitution of a recombinant hemoprotein during protein production, thereby resulting in a native heme coordination. Analysis of the full-length MsmS and MA0863 confirmed a covalently bound heme cofactor, which is connected to one conserved cysteine residue in each protein. In order to identify the coordinating amino acid residues of the heme iron, UV/vis spectra of different variants were measured. These studies revealed His702 in MsmS and the corresponding His666 in MA0863 as the proximal heme ligands. MsmS has previously been described as a heme-based redox sensor. In order to examine whether the same is true for MA0863, redox dependent kinase assays were performed. MA0863 indeed displays redox dependent autophosphorylation activity, which is independent of heme ligands and only observed under oxidizing conditions. Interestingly, autophosphorylation was shown to be independent of the heme cofactor but rather relies on thiol oxidation. Therefore, MA0863 was renamed in RdmS (redox dependent methyltransferase-associated sensor). In order to identify the phosphorylation site of RdmS, thin layer chromatography was performed identifying a tyrosine as the putative phosphorylation site. This observation is in agreement with the lack of a so-called H-box in typical histidine kinases. Due to their genomic localization, MsmS and RdmS were postulated to form two-component systems (TCS) with vicinal encoded regulator proteins MsrG and MsrF. Therefore, protein-protein interaction studies using the bacterial adenylate two hybrid system were performed suggesting an interaction of RdmS and MsmS with the three regulators MsrG/F/C. Due to these multiple interactions these signal transduction pathways should rather be considered multicomponent system instead of two component systems.

Endless fibre reinforced thermoplastic sheets (organic sheets) are significantly gaining in importance due to their outstanding characteristics. In comparison to common thermoplastic press moulding composites with random reinforcement like GMT and LFRT they offer remarkably better specific mechanical properties (stiffness, strength). And different from endless fibre reinforced thermosets, they also possess high toughness and show good impact behaviour. Furthermore, they enable welding and have an appreciable recycling potential. The manufacturing steps, beginning from impregnation and consolidation of the semi-finished sheets up to thermoforming and welding to obtain the final part, represent a closed processing chain. This results in short cycle times and the potential for mass production. However, this material class is rarely used because of its cost and surface quality problems. Therefore, only a few applications exist as demanding functional or structural parts. High costs emerge in consequence of either expensive raw materials (carbon fibres, technical thermoplastics) or the sophisticated processing technique concerning the impregnation and consolidation step (double belt press). The surface quality problem is mainly caused by the print-through of reinforcing fibres, which therefore precludes applications in visible regions, especially in the field of automotive exterior panels. The aim of the thesis was to enhance the chances of application by improving the surface quality of endless fibre reinforced thermoplastics. Thus the surface characteristics and possibilities for reproducible quantitative measuring were identified. Surface roughness, gloss rate, profile amplitude and wavelength as well as short (sw) and long term (lw) waviness were chosen as appropriate values. By varying the type of fibre, matrix, fabric and coating the influence of material parameters on the surface appearance could then be investigated. It became obvious that the fibre print-through is a result of the significantly higher volume shrinkage of the thermoplastic resin (higher coefficient of linear thermal expansion) in comparison to that of the reinforcement during the cooling process, combined with an uneven distribution of resin and fibres. Thus, amorphous matrices that have no shrinkage due to crystallisation and a preferably small thermal induced density growth lead to significantly better surface qualities (from lw = 60 to lw = 20). Qualitatively the texture is dominated by the reinforcing architecture. The kind of textile weaving and fineness of the fibre bundles determine the wavelength of the profile deflection. It was found that the coating has the largest influence on the surface appearance. A common varnish layer with a thickness of only 40 μm enhances the gloss of the substrate which makes the surface waviness even more clearly visible. However, optimising the varnish system with additional base coat or filling layers drastically reduced the waviness but did not raze it completely (lw = 10). Only the application of a thermoplastic varnish layer could diminish the waviness to the desired range below 10 (lw = 4). Besides the experimental work a theoretical analysis of the consolidation and solidification step was carried out. A finite element model has been created representing a semi-finished sheet with four layers of a 2/2 twill textile reinforcement. Based on this geometry various matrix characteristics as well as alterations of the global reinforcement structure (more or less horizontal ply off-set) have been analysed. The simulations supported the experimental results. They indicated the strong influence of the matrix and showed that the off-set of the reinforcing layers plays an important role concerning the resulting surface profile. Because the off-set of the plies can not be controlled in the real material and therefore is at random, the profile depths show a remarkable standard deviation (30 %). In the example considering a 2/2-twill reinforcement the optimum off-set could reduce the profile depth up to 40 %. Furthermore, the influence of the process parameters (pressure and cooling rate)during the consolidation process was experimentally and theoretically investigated. In addition to the non-isotropic characteristics of the textile, the time and temperature dependent mechanical behaviour of the thermoplastic matrix had to be ascertained and transferred into the model. A rapid cooling rate was identified to reduce the surface profile of the substrate. The profile depth of the simulated GF-PC could be decreased from 5 - 3 μm. However, experimental tests concerning temperature changes and weathering showed that this advantageous effect decreases with time due to the viscoelastic behaviour of the polymer and resetting forces of the reinforcement. The pressure can influence the texture phenomenon only by affecting the fibre volume content of the sample. In case of static isobaric press processing a certain matrix flow across the margins of the tool can not be totally averted. With a rising pressure the outflow becomes stronger and leads to a growing fibre volume content and stronger surface waviness. By carrying out several simulations with systematically varying material data a nomogram could be created that represents a tool to predict the surface profile of comparable composites (2/2 twill reinforcement, FVC around 50 %) just in dependence of the matrix. It takes into account the specific matrix volume shrinkage and the pitch from its solidification to usage temperature. Thus, the possibilities but also limitations of a certain material combination concerning surface waviness can easily be estimated. In order to reduce the heterogeneity of the fibre matrix distribution common textile fabrics were substituted by unidirectional (UD) non-crimped structures and UD fabrics. A newly established processing method was used to manufacture a noncrimped and non-sewed endless fibre reinforced thermoplastic sheet by direct combination of a multiaxial weft insertion machine and a continuous rotocure press. The resulting product proved the potential for an improved surface quality. Despite the use of relatively heavy rovings and not yet optimised fibre placement the surface profile of this new kind of organic sheets is comparable with the one of those samples having the fine 8-H-satin fabric reinforcement (lw = 20). Finally it could be shown that the method of thermoplastic varnish layer lamination which has successfully been used for semi-finished parts can also be integrated in a thermoforming step to create three-dimensional components. The best results of this trial (lw = 10, sw = 14) do not reach the level of the flat sheets but almost meet the requirements of the automotive “Class A” standard. With regard to economical and weight saving aspects this material option can be considered a competitive alternative to common car body panels. In conclusion the investigations showed a notable feasibility to improve the surface quality of endless fibre reinforced thermoplastic sheets. Therefore, this thesis represents a contribution to amplify the application potential of this material class, particularly in the fields of leisure and sports goods, and in the range of commercial vehicles.

Die Einmischung von Altgummipartikeln aus zerkleinerten Altreifen in Thermoplast-, Elastomer- und Duromer-Matrizes im Sinne einer stofflichen Wiederverwertung führt zu erheblichen Eigenschaftsverschlechterungen der altgummipartikelmodifizierten Polymerblends. Vor diesem Hintergrund gewinnt die Modifizierung der Altgummipartikel für eine Verbesserung der Verträglichkeit mit den Matrixmaterialien zunehmend an Bedeutung. Zur Modifizierung der Altgummipartikel wurden photochemische Pfropfungsreaktionen mit Glycidylmethacrylat (GMA) und Methacrylsäure (MAA) nach einem radikalischen Polymerisationsmechanismus durchgeführt. Um Altgummipartikel erfolgreich chemisch modifizieren zu können, ist ein fundiertes Wissen über die entscheidenden Parameter des Pfropfungsprozesses erforderlich. So haben beispielsweise die Art und Konzentration der Pfropfungschemikalien wie Monomer und Photoinitiator, die Art des Spülgases, die Temperatur sowie die Bestrahlungszeit einen entscheidenden Einfluss auf das Pfropfungsergebnis. Der Nachweis der Oberflächenmodifizierung erfolgte mit Hilfe chemischer Analytikmethoden sowie mittels Kontaktwinkelmessungen. Ein weiterer Schwerpunkt dieser Arbeit lag auf der Herstellung von altgummipartikelmodifizierten Thermoplast-, Duromer- und Elastomer-Blends. Polyamid-6 (PA-6) und Polybutylenterephthalat (PBT) wurden als thermoplastische Matrixmaterialien ausgewählt. Als Vertreter der Duromere wurde beispielhaft ein Vinylester-Urethan-Hybridharz (VEUH) angewendet und als elastomeres Matrixmaterial kam ein Polyurethan-Gießelastomer (PUR) zur Anwendung. Bei höheren Gummipartikel-Konzentrationen zeigte sich, dass durch die Pfropfung die Verträglichkeit zwischen Gummipartikeln und den o. g. Matrixmaterialien verbessert wurde. Die Modifizierung von PA-6 und VEUH mit feinverteilten Gummipartikeln bewirkte bei geringfügigen Einbußen an Festigkeit und Steifigkeit deutliche Zähigkeitssteigerungen. Dieser Effekt war bei den GMA modifizierten Gummipartikeln stärker ausgeprägt. Bei der Anwendung von 10 Gew.% MAA gepfropften Gummipartikeln in PURElastomeren konnten sehr gute mechanische Kennwerte erzielt werden. Damit stellen altgummipartikelmodifizierte PUR-Blends eine interessante Recyclingoption für Altreifen und Altgummiabfälle dar.

In this thesis, we deal with the worst-case portfolio optimization problem occuring in discrete-time markets. First, we consider the discrete-time market model in the presence of crash threats. We construct the discrete worst-case optimal portfolio strategy by the indifference principle in the case of the logarithmic utility. After that we extend this problem to general utility functions and derive the discrete worst-case optimal portfolio processes, which are characterized by a dynamic programming equation. Furthermore, the convergence of the discrete worst-case optimal portfolio processes are investigated when we deal with the explicit utility functions. In order to further study the relation of the worst-case optimal value function in discrete-time models to continuous-time models we establish the finite-difference approach. By deriving the discrete HJB equation we verify the worst-case optimal value function in discrete-time models, which satisfies a system of dynamic programming inequalities. With increasing degree of fineness of the time discretization, the convergence of the worst-case value function in discrete-time models to that in continuous-time models are proved by using a viscosity solution method.

The tape placement technique is of particular importance for the production of large and weight optimized structural components especially in the aeronautic industry. The components are produced independently of size and load directions by placing single unidirectional fiber reinforced tapes automatically. Moreover, very large component dimensions enable a reduction of joining processes. In comparison to the thermoset tape placement, additional potentials can be set up through the usage of thermoplastic semi-finished materials, as beside the high degree of integration und the defined laminate construction less material specific problems and a non-autoclave production can be realized. This thesis follows an allembracing analyses and development of the thermoplastic tape placement process to provide knowledge to overcome the deficits concerning semi-finished materials, systems engineering and available models for the process description. First, the process is described and differentiated. Within the scope of a strategic process analyses, the potentials and strength of this process are worked out. Through a succeeding operational process analyses, the process is pictured in detail and further developments of the process and the control are made possible. All aspects of the process in terms of quality of the semi-finished material, systems engineering, process control, and quality assurance are considered for the process development. Innovative concepts to solve the first layer problem and a new tape placement head are worked out. A new model is developed to support strategic decisions on basis of component specific cycle times. A measure for the component shape complexity is derived and integrated into a continuous approach. The model is based on the process physics and can be applied to any component without a need for empiric data. Finally, new process potentials are presented through a combination of thermoforming and thermoplastic tape placement.

Die effektive Nutzung der attraktiven Materialeigenschaften von Verbundwerkstoffen, insbesondere die der langfaserverstärkten Polymere in Großserienbauteilen, macht nicht nur die Entwicklung entsprechender Fertigungsverfahren sondern einhergehend prognosefähige Berechnungsmethoden für Werkstoff und Bauweise notwendig. Praxistaugliche Berechnungsmodelle beschränken sich in der Regel auf bewusst einfach gehaltene analytische Modelle zur Grobdimensionierung oder auf Finite-Elemente- Analysen. Letztere erlauben, lokale Konstruktionsaspekte darzustellen und detaillierte Einsicht in das Strukturverhalten zu nehmen. Am Beispiel von mit der Wickeltechnik hergestellter zylindrischer Vollkunststoff- Druckbehälter wurden Auslegungsmethoden für unidirektional verstärkte FKV-Strukturen erörtert, experimentell validiert und zusammen mit analytisch formulierten Randbedingungen bzw. Modellen zu Geometrie, Werkstoff und Fertigung in ein vollparamtrisches, dreidimensionales FE-Auslegungsmodul implementiert. Durch die Auflösung der tragenden Tankstruktur in die einzelnen Wickellagen und der parametrischen Variation von Lagenaufbau und Domgeometrie gestattet dieses eine effektive Bauweisenoptimierung hinsichtlich Gewicht und Werkstoffausnutzung. Insbesondere die neuartige, experimentell verifizierte Beschreibung der einzelnen Wickellagendicken im Behälterdom erlaubt eine der Fertigung entsprechende, im jeweiligen Wicklungslagenende wulstfreie Behältermodellgenerierung. Gewebeverstärkte thermoplastische Halbzeuge können oberhalb ihrer Verformungstemperatur wiederholt mittels Stempelumformprozess in aufeinander abgestimmten Werkzeughälften umgeformt werden. Für eine effektivere Auslegung solcher Bauweisen durch Verbesserung der Werkstoffmodellierung wird erstmalig die Prozesssimulation mit der Strukturanalyse gekoppelt. Die hierfür entwickelte Schnittstelle vollzieht neben der Datenübersetzung die automatisierte Aufbereitung des Simulationsschalennetzes zum voluminösen Strukturmodell nebst Modellbeschneidung und beinhaltet erste Ansätze zur Abschätzung der Werkstoffkennwerte des infolge der Drapierung nicht mehr orthogonal gewebeverstärkten FKV. Die Berücksichtigung von Fadenorientierung, Dickenverteilung und auftretenden Falten durch Übertragung des Simulationsnetzes erlaubt eine im Vergleich zum Stand der Technik realitätsnähere, durch Bauteilprüfungen validierte Abbildung des mechanischen Strukturverhaltens. The effective use of the attractive material properties of fiber reinforced plastics (FRP), especially of long fiber reinforced polymers in mass production, requires an advanced development of suitable manufacturing processes and prognostic design and analysis methods for the material and structural behavior. This paper resulted out of two research projects, accompanied by industrial, close to series development tasks. The objective was to increase the efficiency of the material, structure and manufacturing aspects of the prototype development through improved modeling methods in analysis and simulation in close relationship with the design, material development and testing facilities. Mass production capability of thermoforming processing in combination with weight saving potentials on the one hand and thermal and electrical insulation advantages of thermoplastics in comparison to steel on the other hand was the motivation for the development of a safety toe cap for safety shoes made of canvas reinforced thermoplastics. An innovative analysis method for structures made of canvas reinforced plastics which was initiated by this development program focus on a realistic reproduction of the non-orthogonal fiber reinforcement of the woven fabric after the thermoforming process. Canvas reinforced thermoplastics can be simplified as an alignment of small unidirectional fiber reinforced sections in weft and warp direction. The underlying design theories for unidirectional FRP were rehashed and advanced in the framework of a full plastic high pressure vessel development program. To improve the effectiveness of the pressure vessel design work, the mentioned design theories and further specific manufacturing models were implemented in an innovative, full-parametric design module validated by burst pressure vessel tests. Of importance for the dimensioning and wide application of FRP-structures is the ability to forecast the material behavior, particularly with regard to the frequent lack of measured material properties in practical design work. The conceptual formulation was augmented for the quality assessment of the accomplished design work with a systematic evaluation of the most well known estimations in regards to stiffness and strength properties of unidirectional and canvas reinforced plastics. For non-orthogonal canvas reinforced FRP, as in case of thermoformed components, no appropriate material model is available. A relative easy handling material model for orthogonal canvas reinforced FRP known in literature was augmented to non-orthogonal. This paper is not dealing with lightweight construction methods but in fact with the objective to improve the praxis relevant design methods of unidirectional and bidirectional fiber reinforced plastics; i.e. including estimations for material properties and manufacturing influences. The fundamentals of the presented analyses are the consideration of fiber orientation and ply thickness close to reality by analytical models implemented in the FEA like the description of the fiber deposition in a filament winding process. A significant improvement of the design and analyses methods for unidirectional FRP exemplarity in the case of high pressure vessels made of full plastic has been done by the comprehension of relevant manufacturing parameters, especially through the improved description of the ply thickness in the vessel domes. This was achieved by combining two models, each separately known in literature, to level the bulges at the end of each ply due to increasing fiber coverage and their mathematical description. This leveling meets the practical corrections that also have to be done in a filament winding program in the manufacturing process. Validating measurements on pressure vessel prototypes were performed and showed excellent accordance. Beyond it, the developed parametric FE analysis tool for cylindrical pressure vessels produced with the filament winding technique enables a time efficient design optimization vessels in the analysis tool were set back to future work due to the unsufficient amount of vessel tests and for the benefit of a challenging design analysis concept for canvas reinforced FRP. For thermoformed canvas reinforced FRP the fiber orientation and play thickness can be determined by process simulation. Interfaces to the structural analysis that particularly include the theoretical estimation of material properties and the material modeling are not available in the commercial market. Hence, even the structural analysis of such constructions can not be assumed to be state of the art. Previous analyses of thermoformed constructions depend on material isotropy or neglect the canvas shearing during draping; i.e. the thermoformed woven fabric material is modeled with orthogonal fiber orientation and constant ply thickness. The objective of this paper is to combine forming simulation and structural analysis in a way, that beside the pure data translation, the interface performs an automated transformation of the shell based process simulation FE net to a volumetric structure model including the model trimming and the estimation of the non-orthogonal material properties. The consideration of fiber orientation, thickness distribution and eventually occurring crinkles transferred with the FE net of the process simulation into the structural analysis allows a much more reliable reproduction of the mechanical structure behavior as in comparison to the traditional state of the art analysis which has been validated by extensive prototype tests. The static, non-linear analysis of the toe cap made of canvas reinforced thermoplastic is accompanied by very successful prototype tests, which in turn pushed this toe cap design ahead. This series are closely linked to material development, as well as new manufacturing technology. and analysis because of it's automated model generation. The analysis or evaluation of variants of the load bearing FRP lay-up, the influence of different valve geometry and dome contours necessitates now solely the modification of the input parameters. For a specific forecast of the achievable burst pressure of a pressure vessel design additional work has to be done. A degradation model has to be implemented in the analysis tool to evaluate the increasing local ply failures until the vessel burst. The main objective for the unidirectional FRP essay of the paper was to improve the model generation and to increase the time effectiveness of the design analysis, which has been achieved. The originally planed implementation of a strength evaluation of pressure

Ever since establishment of portfolio selection theory by Markowitz (1952), the use of Standard deviation as a measure of risk has heavily been criticized. The aim of this thesis is to refine classical portfolio selection and asset pricing theory by using a downside deviation risk measure. It is defined as below-target semideviation and referred to as downside risk. Downside efficient portfolios maximize expected payoff given a prescribed upper bound for downside risk and, thus, are analogs to mean-variance efficient portfolios in the sense of Markowitz. The present thesis provides an alternative proof of existence of downside efficient portfolios and identifies a sufficient criterion for their uniqueness. A specific representation of their form brings structural similarity to mean-variance efficient portfolios to light. Eventually, a separation theorem for the existence and uniqueness of portfolios that maximize the trade-off between downside risk and return is established. The notion of a downside risk asset market equilibrium (DRAME) in an asset market with finitely many investors is introduced. This thesis addresses the existence and uniqueness Problem of such equilibria and specifies a DRAME pricing formula. In contrast to prices obtained from the mean-variance CAPM pricing formula, DRAME prices are arbitrage-free and strictly positive. The final part of this thesis addresses practical issues. An algorithm that allows for an effective computation of downside efficient portfolios from simulated or historical financial data is outlined. In a simulation study, it is revealed in which scenarios downside efficient portfolios outperform mean-variance efficient portfolios.

Continuous fibre reinforced thermoplastics are a high competitive material class for diversified applications because of their inherent properties like light-weight construction potential, integral design, corrosion resistance and high energy absorption level. Using these materials, one approach towards a large volume scaled part production rate is covered by an automated process line, consisting of a pressing process for semi-finised sheet material production, a thermoforming step and some additional joining technologies. To allow short cycle times in the thermoforming step, the utilised semi-finished sheet materials, which are often referred to as “organic sheets”, have to be fully impregnated and consolidated. Nowadays even this combination of outstanding physical and chemical material properties combined with the economic processing technology are no guarantee for the break-through of continuous fibre reinforced thermoplastics, mainly because of the high material costs for the semi-finished sheet materials. These costs can be attributed to a non adapted material selection or choice of process parameters, as well as by unfavourable pressing process type itself. Therefore the aim of the present investigations was to generate some alternatives regarding the choice of raw materials, the set-up or the selection of the pressing process line and to provide some theoretical tools for the determination of process parameters and dimensions. Concerning raw material aspects, the use of the blending technology is one promising approach towards cost reduction for the matrix component. Novel characteristics related to the fibre structure are CF-yarns with high filament numbers (e.g. 6K or 12K instead of 3K) or multiaxial fibre orientations. These two approaches were both conducted for sheet materials with carbon fibre reinforcement and high temperature thermoplastics. Two new developed ternary blend matrices consisting of PEEK and PEI as the main ingredients were tested in comparison with neat PEEK. PES and PSU were used as the third blend component, which provides a cost reduction potential of approximately 30 % compared to the basis PEEK polymer. The results of the static pressing experiments pointed out that the processing behaviour of the new blends is similar to the neat PEEK matrix. A maximum process temperature of 410 °C should not be surpassed, otherwise thermal degradation will occur and will have a negative influence on mechanical laminat properties. To accelerate the impregnation progress a process pressure of 25 bar in combination with a sidewise opened tooling concept is helpful. No differences were identified if film-stacking technique was substituted by powder-prepreg-technology or vice versa. By increasing the yarn filament number from 3K over 6K to 12K, which is equal to an increase in bundle diameter and therefore transverse flow distance, the impregnation time has to be extended. If unspread yarns are used, the risk of void entrapment rises tremendously, especially with 12K and UD-structures. To reach full impregnation with a woven 6K-fabric, an increase of process time of 20 to 30 % compared to a 3K textile structure is required. Furthermore, it was shown that if only transverse flow is used for the impregnation of a UDstructure, a maximum area weight of 300-400 g/m² should not be exceeded. Additionally, the transport of air is strictly affected by the fibre orientation, because the main amount of displaced air runs in longitudinal fibre direction. These facts play an important role in the design of a multaxial laminat or an impregnation process for such a structure and have to be taken into account. Apart from these static pressing experiments the semi-continuous (stepwise compression moulding) and continuous (double belt press processing) processing technology were investigated and compared to each other. The first basic processing trails on the stepwise compression moulding equipment were carried out with the material system GF/PA66. Whereas the processing behaviour of this material combination in a double belt press is known quite well, there is only little information about semi-continuous processing. The performed trials pointed out that the resulting laminate quality for both technologies only differs in the achievable local surface quality. Mechanical laminate properties like three point bending stiffness and strength are directly comparable. Due to the fact that there is only small experience with the stepwise compression moulding process, potential improvements regarding surface Quality are feasible by adapting the step procedure and the temperature distribution within the tooling concept. If laminates, produced by semi-continuous processing, are deployed in a thermoforming process or in a non visible structural application, the surface appearance only plays an inferior role. The present results with high temperature thermoplastic matrices and CF do confirm the positive assessment for the stepwise compression moulding technology, even though the mechanical laminate values have only reached 90 % of the data received by static press processing. In comparison to the data from literature, 90 % is already a high mechanical performance level. The results are quite promising for the use of the semi-continuous technology, despite the process set-up and processing parameters not being optimised. Furthermore there are tremendous advantages in processing equipment costs. Finally a process model was developed based on the experimental data pool. This model can be characterised as a tool, which provides useful boundary conditions and dimension values for the selection of a certain pressing process depending on the desired material combination, laminate thickness and production output. The applicability and accuracy of the model was proofed by a direct comparison between experimental and calculated data. First of all the temperature profile of the pressing process was generalised by a very common structure. This profile reflects the main characteristics for the processing of a thermoplastic composite material. Depending on the material combination, the laminate thickness and the occurring heat transfers, several process- and processing- portfolios were calculated. For a defined combination of the aforementioned parameters, these portfolios directly provide the periods of time for heating and cooling of the laminate structure. The last step is to convert these information into an equipment dimension and to decide which machinery configuration fulfils these requirements.

Liquid composite moulding (LCM) is an efficient process for manufacturing polymer composite structures. During LCM a liquid thermoset resin is injected into the mould cavity containing a pre-placed dry fabric preform. In the last step of the process the resin cures and afterwards the part can be removed from the mould. Due to relative low injection pressure applied in processing this technique is expected to offer potential for cost reduction in the fabrication of large parts of complex shape. However, in practice, much time is spent for optimising processing parameters and properly designing the mould in order to avoid problems such as void formation and dry spots. The common trial and error tactic to determine optimised parameters increases time and costs for an optimal process configuration. Thus simulation will help to speed up the development process saving cost and time. When producing double curved parts the angles between warp and weft fibres of the fabrics change and influence the permeability of the fabric as well as the preferred direction of flow through the fabric during the injection phase. Further on these shearing effects increase the fibre volume fractions and therefore less resin is available in the correspondent areas. This leads to different results of the curing process in the sheared areas compared to the curing process in the unsheared areas. Opposite to the current LCM simulation technique where only the injection process is simulated, this work presents the simulation of the three single processes and combines them in an appropriate way to improve the simulation results. First draping simulations are performed. Therefore, the shear behaviour is investigated. These results are used in the draping simulation in order to obtain the fibre orientations of the warp and weft fibres. The draping results are verified by comparing them with the corresponding parameters of parts formed. In order to use the results of the draping simulation in the flow simulation an interface is developed that transforms the result files obtained from the draping simulation into a file format suitable for the flow simulation. The mode of operation of this interface is illustrated. First a standard file format is generated to combine the shearing angles and the node locations delivered by PamForm™. A programme is developed that reads the node locations, the shear angles and the fibre orientations at the end of the draping simulation and creates a new file usable for the flow simulations. Further on several features are implemented in the new model as for example the automatic generation of a circular inlet with a defined diameter and the adjustment of the draping model to the model for the flow simulation concerning the fitting of the geometry model. In order to consider the changes of permeability and fibre volume fraction in sheared areas, zones are defined which represent areas of the same fibre volume fractions and the same permeability. Flow experiments on sheared fabrics are performed to get information about the flow behaviour. The permeability values of the sheared fabric are calculated by observing the position of the flow front over time and the application of Darcy’s law. This material behaviour is implemented into a commercially available LCM-simulation software which is verified first using a simple plate with a sheared fabric, then using a double curved structure (hemisphere) with draped fabric. After the verification based on the hemisphere another part is chosen to show the ability of the interface to deal with more complicated geometries. To obtain the input parameters for the cure kinetic model of Kamal-Sourour an epoxy resin is characterised using DSC. The validity of this model is verified by comparing the cure process of a flat sheet with a rib with the corresponding simulation results. To determine the influence of the fibre volume fraction on the maximum temperature, a cure simulation of the hemisphere with the zone distribution is performed. Cure Simulation on a flat plate are done to quantify the influence of the thickness of the part on the maximum temperature in the part. In der vorliegenden Arbeit wird eine Simulation der Prozesskette der Harzinjektionsverfahren vorgestellt. Dazu wird der Gesamtprozess in drei unterschiedliche Einzelprozesse unterteilt: Drapierung, Injektion und Aushärtung. Die für die gesamte Prozesskette grundlegende Simulation stellt die Drapiersimulation dar. Diese liefert die Faserorientierungen des drapierten Bauteils, die für die im Anschluss durchzuführende Injektionssimulation entscheidend sind. Um die Ergebnisse der Drapiersimulation zur Simulation der Fließvorgänge zu nutzen, wird eine Schnittstelle entwickelt. Diese wandelt die Ergebnisse der Drapiersimulation in ein für die Injektionssimulation nutzbares Format um und berücksichtigt deren spezielle Anforderungen an das Simulationsmodell. Zur möglichst effizienten Durchführung der Harzinjektionssimulation wird das Modell in einzelne Zonen mit gleichen Permeabilitätswerten und Faservolumengehalten unterteilt. Um den Einfluss der Gewebescherung auf das Fließverhalten von Fluiden zu ermitteln, werden Fließversuche mit gescherten Geweben durchgeführt und verifiziert. Die Funktionsweise der Schnittstelle und die Anwendbarkeit der gemessenen Materialkennwerte werden an einer Kugelhalbschale demonstriert und durch Versuche verifiziert. Anhand einer Armaturentafel wird der Nutzen der Schnittstelle für die Fließsimulation komplexer Bauteile gezeigt. Die Prozesskette wird mit der Simulation der Aushärtevorgänge abgeschlossen. Dazu wird ein reaktionskinetisches Modell nach Kamal-Sourour für ein ausgewähltes Epoxidharz erstellt. Anhand einer Rippenstruktur wird die Aushärtesimulation verifiziert. Durch die Aushärtesimulationen kann der Einfluss des Faservolumengehalts sowie der Bauteildicke auf die während des Aushärtevorgangs erreichbaren Maximaltemperaturen ermittelt werden.

Carotenoids are organic lipophilic tetraterpenes ubiquitously present in Nature and found across the three domains of life (Archaea, Bacteria and Eukaryotes). Their structure is characterized by an extensive conjugated double-bond system, which serves as a light-absorbing chromophore, hence determining its colour, and enables carotenoids to absorb energy from other molecules and to act as antioxidant agents. Humans obtain carotenoids mainly via the consumption of fruits and vegetables, and to a smaller extent from other food sources such as fish and eggs. The concentration of carotenoids in the human plasma and tissues has been positively associated with a lower incidence of several chronic diseases including, cancer, diabetes, macular degeneration and cardiovascular conditions, likely due to their antioxidant properties. However, an important aspect of carotenoids, namely β- and α-carotene and β-cryptoxanthin, in human health and development, is their potential to be converted by the body into Vitamin A. Yet, bioavailability of carotenoids is relatively low (< 30%) and dependent, among others, on dietary factors, such as amount and type of dietary lipids and the presence of dietary fibres. One dietary factor that has been found to negatively impact carotenoid bioaccessibility and cellular uptake in vitro is high concentrations of divalent cations during simulated gastro-intestinal digestion. Nevertheless, the mechanism of action of divalent cations remains unclear. The goal of this thesis was to better understand how divalent cations act during digestion and modulate carotenoid bioavailability. In vitro trials of simulated gastro-intestinal digestion and cellular uptake were run to investigate how varying concentrations of calcium, magnesium and zinc affected the bioaccessibility of both pure carotenoids and carotenoids from food matrices. In order to validate or refute results obtained in vitro, a randomized and double blinded placebo controlled cross-over postprandial trial (24 male participants) was carried out, testing the effect of 3 supplementary calcium doses (0 mg, 500 mg and 1000 mg) on the bioavailability of carotenoids from a spinach based meal. In vitro trials showed that addition of the divalent cations significantly decreased the bioaccessibility of both pure carotenoids (P < 0.001) and those from food matrices (P < 0.01). This effect was dependent on the type of mineral and its concentration. Strongest effects were seen for increasing concentrations of calcium followed by magnesium and zinc. The addition of divalent cations also altered the physico-chemical properties, i.e. viscosity and surface tension, of the digestas. However, the extent of this effect varied according to the type of matrix. The effects on bioaccessibility and physico-chemical properties were accompanied by variations of the zeta-potential of the particles in solution. Taken together, results from the in vitro trials strongly suggested that divalent cations were able to bind bile salts and other surfactant agents, affecting their solubility. The observed i) decrease in macroviscosity, ii) increase in surface tension, and the iii) reduction of the zeta-potential of the digesta, confirmed the removal of surfactant agents from the system, most likely due to precipitation as a result of the lower solubility of the mineral-surfactant complexes. As such, micellarization of carotenoids was hindered, explaining their reduced bioaccessibility. As for the human trial, results showed that there was no significant influence of supplementation with either 500 or 1000 mg of supplemental calcium (in form of carbonate) on the bioavailability of a spinach based meal, as measured by the area-under curve of carotenoid concentrations in the plasma-triacylglycerol rich fraction, suggesting that the in vitro results are not supported in such an in vivo scenario, which may be explained by the initial low bioaccessibility of spinach carotenoids and the dissolution kinetics of the calcium pills. Further investigations are necessary to understand how divalent cations act during in vivo digestion and potentially interact with lipophilic nutrients and food constituents.

Magnetoelastic coupling describes the mutual dependence of the elastic and magnetic fields and can be observed in certain types of materials, among which are the so-called "magnetostrictive materials". They belong to the large class of "smart materials", which change their shape, dimensions or material properties under the influence of an external field. The mechanical strain or deformation a material experiences due to an externally applied magnetic field is referred to as magnetostriction; the reciprocal effect, i.e. the change of the magnetization of a body subjected to mechanical stress is called inverse magnetostriction. The coupling of mechanical and electromagnetic fields is particularly observed in "giant magnetostrictive materials", alloys of ferromagnetic materials that can exhibit several thousand times greater magnitudes of magnetostriction (measured as the ratio of the change in length of the material to its original length) than the common magnetostrictive materials. These materials have wide applications areas: They are used as variable-stiffness devices, as sensors and actuators in mechanical systems or as artificial muscles. Possible application fields also include robotics, vibration control, hydraulics and sonar systems. Although the computational treatment of coupled problems has seen great advances over the last decade, the underlying problem structure is often not fully understood nor taken into account when using black box simulation codes. A thorough analysis of the properties of coupled systems is thus an important task. The thesis focuses on the mathematical modeling and analysis of the coupling effects in magnetostrictive materials. Under the assumption of linear and reversible material behavior with no magnetic hysteresis effects, a coupled magnetoelastic problem is set up using two different approaches: the magnetic scalar potential and vector potential formulations. On the basis of a minimum energy principle, a system of partial differential equations is derived and analyzed for both approaches. While the scalar potential model involves only stationary elastic and magnetic fields, the model using the magnetic vector potential accounts for different settings such as the eddy current approximation or the full Maxwell system in the frequency domain. The distinctive feature of this work is the analysis of the obtained coupled magnetoelastic problems with regard to their structure, strong and weak formulations, the corresponding function spaces and the existence and uniqueness of the solutions. We show that the model based on the magnetic scalar potential constitutes a coupled saddle point problem with a penalty term. The main focus in proving the unique solvability of this problem lies on the verification of an inf-sup condition in the continuous and discrete cases. Furthermore, we discuss the impact of the reformulation of the coupled constitutive equations on the structure of the coupled problem and show that in contrast to the scalar potential approach, the vector potential formulation yields a symmetric system of PDEs. The dependence of the problem structure on the chosen formulation of the constitutive equations arises from the distinction of the energy and coenergy terms in the Lagrangian of the system. While certain combinations of the elastic and magnetic variables lead to a coupled magnetoelastic energy function yielding a symmetric problem, the use of their dual variables results in a coupled coenergy function for which a mixed problem is obtained. The presented models are supplemented with numerical simulations carried out with MATLAB for different examples including a 1D Euler-Bernoulli beam under magnetic influence and a 2D magnetostrictive plate in the state of plane stress. The simulations are based on material data of Terfenol-D, a giant magnetostrictive materials used in many industrial applications.

Materials in general can be divided into insulators, semiconductors and conductors, depending on their degree of electrical conductivity. Polymers are classified as electrically insulating materials, having electrical conductivity values lower than 10-12 S/cm. Due to their favourable characteristics, e.g. their good physical characteristics, their low density, which results in weight reduction, etc., polymers are also considered for applications where a certain degree of conductivity is required. The main aim of this study was to develop electrically conductive composite materials based on epoxy (EP) matrix, and to study their thermal, electrical, and mechanical properties. The target values of electrical conductivity were mainly in the range of electrostatic discharge protection (ESD, 10-9-10-6 S/cm). Carbon fibres (CF) were the first type of conductive filler used. It was established that there is a significant influence of the fibre aspect ratio on the electrical properties of the fabricated composite materials. With longer CF the percolation threshold value could be achieved at lower concentrations. Additional to the homogeneous CF/EP composites, graded samples were also developed. By the use of a centrifugation method, the CF created a graded distribution along one dimension of the samples. The effect of the different processing parameters on the resulting graded structures and consequently on their gradients in the electrical and mechanical properties were systematically studied. An intrinsically conductive polyaniline (PANI) salt was also used for enhancing the electrical properties of the EP. In this case, a much lower percolation threshold was observed compared to that of CF. PANI was found out to have, up to a particular concentration, a minimal influence on the thermal and mechanical properties of the EP system. Furthermore, the two above-mentioned conductive fillers were jointly added to the EP matrix. Improved electrical and mechanical properties were observed by this incorporation. A synergy effect between the two fillers took place regarding the electrical conductivity of the composites. The last part of this work was engaged in the application of existing theoretical models for the prediction of the electrical conductivity of the developed polymer composites. A good correlation between the simulation and the experiments was observed. Allgemein werden Materialien in Bezug auf ihre elektrische Leitfähigkeit in Isolatoren, Halbleiter oder Leiter unterteilt. Polymere gehören mit einer elektrischen Leitfähigkeit niedriger als 10-12 S/cm in die Gruppe der Isolatoren. Aufgrund vorteilhafter Eigenschaften der Polymere, wie z.B. ihren guten physikalischen Eigenschaften, ihrer geringen Dichte, welche zur Gewichtsreduktion beiträgt, usw., werden Polymere auch für Anwendungen in Betracht gezogen, bei denen ein gewisser Grad an Leitfähigkeit gefordert wird. Das Hauptziel dieser Studie war, elektrisch leitende Verbundwerkstoffe auf der Basis von Epoxidharz (EP) zu entwickeln und deren elektrische, mechanische und thermische Eigenschaften zu studieren. Die Zielwerte der elektrischen Leitfähigkeit lagen hauptsächlich im Bereich der Vermeidung elektrostatischer Aufladungen (ESD, 10-9-10-6 S/cm). Bei der Herstellung elektrisch leitender Kunststoffen wurden als erstes Kohlenstofffasern (CF) als leitfähige Füllstoffe benutzt. Bei den durchgeführten Experimenten konnte man beobachten, dass das Faserlängenverhältnis einen bedeutenden Einfluss auf die elektrischen Eigenschaften der fabrizierten Verbundwerkstoffe hat. Mit längeren CF wurde die Perkolationsschwelle bereits bei einer niedrigeren Konzentration erreicht. Zusätzlich zu den homogenen CF/EP Verbundwerkstoffen, wurden auch Gradientenwerkstoffe entwickelt. Mit Hilfe einer Zentrifugation konnte eine gradierte Verteilung der CF entlang der Probenlängeachse erreicht werden. Die Effekte der unterschiedlichen Zentrifugationsparameter auf die resultierenden Gradientenwerkstoffe und die daraus resultierenden, gradierten elektrischen und mechanischen Eigenschaften wurden systematisch studiert. Ein intrinsisch leitendes Polyanilin-Salz (PANI) wurde auch für das Erhöhen der elektrischen Eigenschaften des EP benutzt. In diesem Fall wurde eine viel niedrigere Perkolationsschwelle verglichen mit der von CF beobachtet. Der Einsatz von PANI hat bis zu einer bestimmten Konzentration nur einen minimalen Einfluß auf die thermischen und mechanischen Eigenschaften des EP Systems. In einem dritte Schritt wurden die zwei oben erwähnten, leitenden Füllstoffe gemeinsam der EP Matrix hinzugefügt. Erhöhte elektrische und mechanische Eigenschaften wurden in diesem Fall beobachtet, wobei sich ein Synergie-Effekt zwischen den zwei Füllstoffen bezogen auf die elektrische Leitfähigkeit der Verbundwerkstoffe ergab. Im letzten Teil dieser Arbeit fand die Anwendung von theoretischen Modelle zur Vorhersage der elektrischen Leitfähigkeit der entwickelten Verbundwerkstoffe statt. Dabei konnte eine gute Übereinstimmung mit den experimentellen Ergebnissen festgestellt werden .

Die Versorgungsaufgaben für Niederspannungsnetze werden sich in den kommenden Jahrzehnten durch die weitere Verbreitung von Photovoltaikanlagen, Wärmepumpenheizungen und Elektroautomobilen gegenüber denen des Jahres 2018 voraussichtlich stark ändern. In der Praxis verbreitete Planungsgrundsätze für den Neubau von Niederspannungsnetzen sind veraltet, denn sie stammen vielfach in ihren Grundzügen aus Zeiten, in denen die neuen Lasten und Einspeisungen nicht erwartet und dementsprechend nicht berücksichtigt wurden. Der Bedarf für neue Planungsgrundsätze fällt zeitlich mit der Verfügbarkeit regelbarer Ortsnetztransformatoren (rONT) zusammen, die zur Verbesserung der Spannungsverhältnisse im Netz eingesetzt werden können. Die hier entwickelten neuen Planungsgrundsätze erfordern für ländliche und vorstädtische Versorgungsaufgaben (nicht jedoch für städtische Versorgungsaufgaben) den rONT-Einsatz, um die hohen erwarteten Leistungen des Jahres 2040 zu geringen Kosten beherrschen zu können. Eine geeignete rONT-Standardregelkennlinie wird angegeben. In allen Fällen werden abschnittsweise parallelverlegte Kabel mit dem Querschnitt 240 mm² empfohlen.

The work presented here supports the industrial use of natural fibre reinforced composite materials under mass production circumstances. Potentials for optimising the materials’ properties are offered and evaluated with regard to their effect on the process chain material – coupling agent – processing. The possibility to use these materials in mass production applications are improved by optimising each partial stage. Throughout the world there exists a great variety of suitable applications for this group of composites affecting the raw materials choice. The Europe’s market is stamped by the requirements of the automotive industry, the important markets of Japan and the USA are dominated by civil engineering and landscaping applications. A yearly increase of 18 % in Europe, 25 % in Japan and 14 % in the US is expected. The US market offers the largest market volume of more than 480000 t exceeding the European Market for nearly five times. To enhance the fields of application for natural fibre reinforced thermoplastics the common techniques of the film-stacking and the compression moulding process are used to manufacture optimised composites based on polypropylene and bast (hemp, flax) as well as leaf (sisal) and wood (spruce) fibres. Therefore new semi finished parts for the compression moulding process had to be developed. Within the manufacturing of natural fibre reinforced polypropylene using the filmstacking process material and process parameters were identified to transfer the gathered knowledge to the compression moulding process. It has been seen that most problems are caused by the organic origin of the fibres. Especially the addiction of the fibres to decompose when treated with higher temperatures under pressure hampers their use in thermoplastic composites. By investigating wood fibres as reinforcements, which differ from bast fibres in their chemical composition the influence of the process parameters temperature and pressure on the composite properties were evaluated and verified for hemp fibre reinforced polypropylene. The minimum process time was observed and in order to enhance the fibre-matrix-adhesion by using coupling agents the diffusion of the coupling agent molecules was determined theoretically. Therefore a model was evaluated dealing with the maximum mass flow of coupling agent being transferred in the fibre-matrix-interface because of mass transfer mechanisms. In order to optimise the wetting of the fibres with the matrix different possibilities to modify the fibres were investigated. Drying the fibres prior to the manufacturing of the composite is an easy and effective way to improve the fibre-matrix-adhesion. The tensile strength of all composites rose conspicuously. The removal of dust and water soluble substances by washing led to a higher tensile strength only with the sisal fibre reinforced composite. Washing the other fibres led to decreasing fibre wetting. Fibre substances like lignin and pectin were removed using the mercerisation technique. Composites made from these chemically retted fibres show the more disintegrated fibre structure and a worse wet ability of the fibre surface with the polypropylene. Hence the tensile and bending strength was not enhanced. The Charpy impact strength of the composite raised distinctly. The use of coupling agents based on maleic acid crafted polypropylene led to an increasing tensile strength up to 58 % compared to the composite manufactured with pre-dried fibres. The bending strength raised about 109 %. The Charpy decreased about 60 to 80 %. Flax fibre reinforced composites showed the highest tensile strength, sisal fibre reinforced composites offered the highest Charpy. No differences between copolymeric and homopolymeric polypropylene when using PP-MAH as coupling agents were determined. The kind of application of the coupling agent in the compound has an major effect on the amount of coupling agent to be added. The closer the coupling agent is brought to the fibres surface at the beginning of the impregnation step the less amount has to be used. If using an aqueous suspension the least amount had to be added as the coupling agent remains directly on the fibre surface after drying. Mixing the coupling agent with the polypropylene hinders the well dispersed PP-MAH to act in the fibrematrix- interface effectively, so the amount of coupling agent has to be increased. The comparison of coupling agent containing compounds which differ in the amount of coupling agent and the molar mass distribution showed the amount of coupling agent related to the mass of fibres to be the important parameter to dose the PPMAH. The mean molar mass distribution had no effect on the compounds’ properties.Transferring the knowledge gained from the film-stacked composites to the compression moulding process offered the possibility to use jute long fibre reinforced granules (LFT) under optimised processing conditions. The composites gained from the molten and pressed granules showed the highly dependency of the mechanical properties to the fibre direction in the part. If the fibres are able to flow along the cavity and direct themselves into parallelism the tensile and bending strength increases in the main flow direction and decreases perpendicular to this direction. The impact strength decreases with raising orientation of the fibres. The jute fibre surface presents a better adhesion to the polypropylene as the surfaces of the hemp, flax and sisal fibres, which could be improved by adding PP-MAH as coupling agent. A newly developed pelletised semi finished part with sisal fibre reinforcement and the development of a direct impregnation process using solely a horizontal plasticating unit completes the work. Using an established plasticating extruder offers the possibility for the compression moulding industry to process natural fibre reinforced polypropylene with less investment. The compression moulded sisal fibre reinforced polypropylene showed varying fibre directions and disproportionate fibre-matrixadhesion. As a result of the plasticating process in some parts bended fibres are still visible after compression moulding. Hence the used single-screw plasticator is not able to equalize the molten material. Increasing the compaction pressure was not possible as some parts showed beginning fibre degradation. Adding PP-MAH improved the fibre-matrix-adhesion but the positive effect of the materials’ strength was not as clear as found for the film-stacked composites. Regarding the additional expenditures for compounding and the coupling agent costs the use of PP-MAH in compression moulded parts seems not to be useful. Compared to the compression moulded glass fibre reinforced polypropylene from GMT and LFT-materials the natural fibre reinforced composites cannot reach the high level of material properties. Optimising the fibre-matrix-interface increases the properties but they are still lower than the properties of the glass fibre reinforced composites. Therefore the natural fibre reinforced materials are not able to substitute the traditional GMT and LFT, they rather should be used in new applications with lower demands.

Die Nähtechnik in Verbindung mit Harzinfusions- und -injektionstechniken eröffnet ein erhebliches Gewichts- und Kosteneinsparpotential primär belasteter Strukturbauteile aus Faser-Kunststoff-Verbundwerkstoffen. Dabei ist es unter bestimmten Voraussetzungen möglich, durch Vernähungen gezielte Steigerungen mechanischer Eigenschaften zu erreichen. Ein genaues Verständnis wirksamer Zusammenhänge bezüglich der Änderung mechanischer Kennwerte verglichen mit dem unvernähten Verbund ist unverzichtbar, um einen Einsatz dieser Technologie im zivilen Flugzeugbau voranzubringen. Im Rahmen dieser Arbeit wird eine breit angelegte experimentelle Parameterstudie zum Einfluss verschiedener Nähparameter auf Scheiben-Elastizitäts- und Festigkeitseigenschaften von kohlenstofffaserverstärkten Epoxidharzverbunden unter Zug- und Druckbelastung durchgeführt. Neben der Stichrichtung, der Garnfeinheit, dem Nahtabstand und der Stichlänge wurde auch die Belastungsrichtung variiert. Bei einigen Parametereinstellungen konnten keine Änderungen des Elastizitätsmoduls oder der Festigkeit in der Laminatebene festgestellt werden, wohingegen in anderen Fällen Reduktionen oder Steigerungen um bis zu einem Drittel des Kennwerts des unvernähten Laminats beobachtet wurden. Dabei ist vor allem der Einfluss der Garnfeinheit dominierend. Die Fehlstellenausbildung infolge eines Stichs in Abhängigkeit der gewählten Parameter und der Orientierung der Einzelschicht wurde anhand von Schliffbildern in der Laminatebene untersucht. Ein erheblicher Einfluss der einzelnen Parameter auf die Fehlstellenausbildung ist festzustellen, wobei wiederum die Garnfeinheit dominiert. Anhand der Ergebnisse der Auswertung der Fehlstellenausbildung in den Einzelschichten wurde ein empirisches Modell generiert, womit charakteristische Fehlstellengröße n wie die Querschnittsfläche, die Breite und die Länge in Abhängigkeit der genannten Parameter berechnet werden können. Darauf aufbauend wurde ein Finite-Elemente-Elementarzellenmodell generiert, mit welchem Scheiben-Elastizitätsgrößen vernähter Laminate abgeschätzt werden können. Neben der Berücksichtigung der genannten Nähparameter ist der zentrale Aspekt hierbei die Beschreibung eines Stichs in Form von Reinharzgebiet und Faserumlenkungsbereich in jeder Einzelschicht. Stitching technology in combination with Liquid Composite Molding techniques offers a possibility to reduce significantly weight and costs of primarily loaded structural parts made of Fiber Reinforced Polymers. Thereby, it is possible to enhance mechanical properties simultaneously. It is essential to understand effective correlations of all important parameters concerning changes in mechanical characteristics due to additional stitching if stitching technologies have to be established in the civil aircraft industry. In this thesis, a broad experimental study on the influence of varying stitching parameters on the membrane tensile and compressive modulus and strength of carbon fiber reinforced epoxy laminates is presented. The direction of stitching, thread diameter, spacing and pitch length as well as the direction of testing had been varied. In some cases, no changes in modulus and strength could be found due to the chosen parameters, whereas in other cases reductions or enhancements of up to 30 % compared to the unstitched laminate were observed. Thereby, the thread diameter shows significant influence on these changes in mechanical properties. In addition, the stitch and void formation in the thickness direction due to the stitching parameters was investigated by evaluating micrographs in each layer of the laminate. Again, the thread diameter showed an outstanding influence on the characteristics of matrix pure area (void) and fiber disorientation. A mathematical model was evaluated in order to predict in-plane characteristics of stitches and voids, from which the cross sectional area, the width and the length of a void due to the chosen stitching parameters can be derived. Finally, a Finite Element based unit cell model was established to calculate elastic constants of stitched FRP laminates. With this model it is possible to consider a stitch as a matrix pure region and additionally an area of in-plane fiber disorientation depending on the stitching parameters as introduced above. The model was validated using the experimental data for tensile and compressive loading. The outstanding flexibility of this FE unit cell approach is shown in a parametric study, where different void formations as well as stitching parameters were varied in a stitched, unidirectional laminate. It was found that three different aspects influence significantly the in-plane elastic constants of stitched laminates. First of all, the stitching parameters as well as the laminate characteristics define the shape of the unit cell including the areas of the stitch and the fiber disorientation. Secondly, stitching changes the fiber volume fraction in all layers, which causes changes in elastic properties as well. Thirdly, the type and the direction of loading has to be considered, because each change in the architecture of the laminate results in different effects on the in-plane elastic constants namely tensile, compressive or shear moduli as well as the Poisson´s ratios.

In der modernen Hubschrauberfertigung werden neben Rotorblättern auch tragende Strukturteile aus kohlenstofffaserverstärkten Kunststoffen eingesetzt. Um dabei einen möglichst hohen Leichtbaugrad zu erreichen, werden immer neue Design- Konzepte entwickelt. Innovative Design-Lösungen sind aber nur dann in der Fertigung umsetzbar, wenn sie effizient, kostengünstig und fehlerfrei gefertigt werden können. Ein wichtiger Baustein für die Produktion sind die Fertigungsvorrichtungen, auf denen die Bauteile laminiert und ausgehärtet werden. Diese Vorrichtungen sind ein maßgeblicher Faktor zum Erreichen der geforderten Bauteilqualität. Das Augenmerk liegt hierbei auf der sogenannten tool-part-interaction, also der Interaktion zwischen Fertigungsvorrichtung und Faserverbundmaterial. Diese hat einen großen Einfluss auf das Aufheiz- und Verpressungsverhalten der Prepreg-Materialien und somit auch direkt auf fertigungsinduzierte Schädigungen wie Faltenbildung und Verzug. Aktuell kann der Vorrichtungsentwickler lediglich auf Erfahrungswerte zurückgreifen, um ein gutes Aufheiz- und Verpressungsverhalten der Vorrichtung zu erreichen. Zur Minimierung von Falten fehlt jedoch häufig sogar das nötige Hintergrundwissen über die grundlegenden Mechanismen der Faltenbildung. Nur ein langwieriger trial-and-error Prozess nach Produktion der Vorrichtung kann helfen, Faltenbildung zu eliminieren oder zumindest zu reduzieren. Zukünftig muss es ein primäres Ziel für den Vorrichtungsbau sein, Fertigungsmittel gezielt auslegen und bereits im Rahmen der Konzeptentwicklung Aussagen über die zu erwartende Bauteilgüte und das Fertigungsergebnis machen zu können. Einen möglichen Weg stellt die Einführung einer Herstellprozesssimulation dar, da sie bereits in einer frühen Entwicklungsphase das Aufheiz- und Verpressungsverhalten eines Bauteils sowie den Einfluss der Fertigungsvorrichtung auf die Bauteilqualität einschätzen kann. Fertigungsinduzierte Schädigungen, wie der prozessinduzierte Verzug, lassen sich bereits mit Hilfe von kommerziell erhältlichen Software-Tools vorhersagen. Um zukünftig auch die Faltenbildung bei der Prepreg-Autoklavfertigung vorhersagbar zu machen, müssen zwei übergeordnete Fragestellungen bearbeitet werden:Faltenbildung: Wie läuft die Faltenbildung in der Autoklavfertigung ab und welche Mechanismen bzw. Einflussfaktoren müssen besonders beachtet werden?  Simulation: Wie muss eine Herstellprozesssimulation geartet sein, um den Einfluss der Fertigungsvorrichtung auf die Faltenbildung vorhersagen zu können und Vorrichtungen auf diese Weise zukünftig auslegbar zu machen? Experimentelle Untersuchungen an Omega- und C-Profilen helfen, die Faltenbildung, ihren primären Mechanismus und vor allem die verschiedenen Einflussfaktoren zu verstehen und zu bewerten. Im Falle der vorliegenden Arbeit wurde besonders die Kompaktierung des Laminates über einem Außenradius und die daraus entstehende überschüssige Faser- bzw. Rovinglänge als primärer Faltenauslöser betrachtet. Es konnte aus den Experimenten abgeleitet werden, dass besonders der Verpressungsweg, die Bauteilgeometrie, das verwendete Faserhalbzeug (unidirektional oder Gewebe), die tool-part-interaction und das interlaminare Reibverhalten für den untersuchten Mechanismus von Bedeutung sind. Daraus lassen sich die Mindestanforderungen an eine Herstellprozesssimulation zusammenstellen. Eine umfassende Materialcharakterisierung inklusive der interlaminaren Reibung, der Reibinteraktionen zwischen Bauteil und Fertigungsvorrichtung sowie des Verpressungsverhaltens des Faserbettes sind der erste Schritt in der Entwicklung einer industriell einsetzbaren Simulation. Die Simulation selbst setzt sich aus einem thermo-chemischen und einem Kompaktiermodul zusammen. Ersteres ermittelt das Aufheizverhalten der Vorrichtung und des Bauteils im Autoklaven und stellt darüber hinaus Aushärtegrad und Glasübergangstemperatur als Parameter für das zweite Simulationsmodul zur Verfügung. Zur korrekten Bestimmung des Wärmeübergangs im Autoklaven wurde ein semi-empirisches Verfahren entwickelt, das in der Lage ist, Strömungseffekte und Beladungszustände des Autoklaven zu berücksichtigen. Das Kompaktiermodul umfasst das Verpressungsverhalten des Faserbettes inklusive des Harzflusses, der toolpart- interaction und der Relativverschiebung der Laminatlagen zueinander. Besonders das Erfassen der Durchtränkung des Fasermaterials mittels eines phänomenologischen Ansatzes und das Einbringen der Reibinteraktionen in die Simulation muss als Neuerung im Vergleich zu bisherigen Simulationskonzepten gesehen werden. Auf diese Weise ist die Simulation in der Lage, alle wichtigen Einflussfaktoren der Faltenbildung zu erfassen. Der aus der Simulation auslesbare Spannungszustand kann Aufschluss über die Faltenbildung geben. Mit Hilfe eines im Rahmen dieser Arbeit entwickelten (Spannungs-)Kriteriums lässt sich eine Aussage über das zu erwartende Faltenrisiko treffen. Außerdem ermöglicht die Simulation eine genaue Identifikation der Haupttreiber der Faltenbildung für das jeweilige Bauteil bzw. Fertigungskonzept. Parameter- und Sensitivitätsstudien können dann den experimentellen Aufwand zur Behebung der Faltenbildung deutlich reduzieren. Die hier vorliegende Arbeit erweitert damit nicht nur das Wissen über die Faltenbildung in der Prepreg-Autoklavfertigung und deren Einflussfaktoren, sondern gibt dem Vorrichtungsentwickler auch eine Simulationsmethodik an die Hand, die ihn in die Lage versetzt, Fertigungsvorrichtungen gezielt auszulegen und zu optimieren. In addition to rotor blades, primary structural parts are also manufactured from carbon fiber reinforced plastics in modern helicopter production. New design concepts are constantly developed in order to reach a maximum degree of lightweight design. However, innovative design solutions are only realizable, if they can be manufactured efficiently, economically, and free from defects. Molds for laminating and curing of composite parts are of particular importance. They are a relevant factor for achieving the required part quality. The attention is directed at the so-called tool-part-interaction, i.e. the interaction between tools and fiber composite materials, which has a great influence on the heating and compaction behavior of the prepreg materials and therefore also directly on manufacturing induced damage such as wrinkling and warping. At present, the tooling designer can only resort to his/her experience to achieve a good heating and compaction behavior of the molds. However, the necessary background knowledge about the fundamental mechanisms of wrinkling is often lacking and only a tedious trial-and-error process after the production of the mold can help eliminate or at least reduce wrinkling. In the future, the primary goal for tooling production must be to specifically design the manufacturing equipment and to be able to already make a statement about the expected part quality and production result during the conceptual stage. A possible solution is the introduction of a manufacturing process simulation, because at an early development stage it can estimate the heating and compaction behavior of a part as well as the influence of the manufacturing equipment on part quality. Commercially available software tools are already able to predict damage during production, as e.g. process induced deformation. In order to make wrinkling predictable also, two primary issues need to be dealt with: Wrinkling: How does wrinkling develop in autoclave manufacturing and which mechanisms or influencing factors need to be particularly considered?  Simulation: What must be integrated into a manufacturing process simulation, if it is to predict the influence of the mold on wrinkling and to ensure future tooling improvement? Experimental examinations of omega and c-profiles help to understand and evaluate wrinkling, its primary mechanism, and particularly the various influencing factors. In the case of the present paper, the compaction of the laminate over a convex radius and the resulting surplus roving length was especially examined as primary cause for wrinkling. From the experiments could be deduced that the compaction, the part geometry, the utilized semi-finished fabrics (unidirectional and woven), the tool-part-interaction and the interlaminar friction are of importance for the examined mechanism. These factors determine the minimum requirements for a manufacturing process simulation. A comprehensive material characterization including interlaminar friction, friction interaction between part and tool as well as the compaction behavior of the fiber bed are the first step toward the development of a simulation on an industrial scale. The simulation consists of a thermochemical and a compaction module. The former determines the heating behavior of the mold and the part in the autoclave and additionally provides the degree of cure and the glass transition temperature as parameters for the second simulation module. A semi-empirical method that is able to consider flow effects and loading conditions of the autoclave was developed for the correct determination of the heat transfer within the autoclave. The compaction module comprises the compaction behavior of the fiber bed including resin flow, tool-partinteraction and relative displacement of the layers. Especially the integration of the saturation phase by means of a phenomenological approach and the inclusion of friction interaction in the simulation must be seen as innovation in comparison to other simulation concepts. The simulation is thus able to capture all the important influencing factors of wrinkling. The state of stress that is retrieved from the simulation can provide information about the formation of wrinkles. Furthermore, the simulation enables an exact identification of the main drivers for the development of wrinkles in the respective part or manufacturing concept. Parameters and sensitivity analyses can then significantly reduce the experimental effort for the elimination of wrinkling. The present study does therefore not only expand the knowledge about wrinkling and its influencing factors in prepreg autoclave manufacturing, but also presents the tooling designer with a simulation methodology that enables him/her to systematically develop and optimize manufacturing equipment.

The focus of this work is to provide and evaluate a novel method for multifield topology-based analysis and visualization. Through this concept, called Pareto sets, one is capable to identify critical regions in a multifield with arbitrary many individual fields. It uses ideas found in graph optimization to find common behavior and areas of divergence between multiple optimization objectives. The connections between the latter areas can be reduced into a graph structure allowing for an abstract visualization of the multifield to support data exploration and understanding. The research question that is answered in this dissertation is about the general capability and expandability of the Pareto set concept in context of visualization and application. Furthermore, the study of its relations, drawbacks and advantages towards other topological-based approaches. This questions is answered in several steps, including consideration and comparison with related work, a thorough introduction of the Pareto set itself as well as a framework for efficient implementation and an attached discussion regarding limitations of the concept and their implications for run time, suitable data, and possible improvements. Furthermore, this work considers possible simplification approaches like integrated single-field simplification methods but also using common structures identified through the Pareto set concept to smooth all individual fields at once. These considerations are especially important for real-world scenarios to visualize highly complex data by removing small local structures without destroying information about larger, global trends. To further emphasize possible improvements and expandability of the Pareto set concept, the thesis studies a variety of different real world applications. For each scenario, this work shows how the definition and visualization of the Pareto set is used and improved for data exploration and analysis based on the scenarios. In summary, this dissertation provides a complete and sound summary of the Pareto set concept as ground work for future application of multifield data analysis. The possible scenarios include those presented in the application section, but are found in a wide range of research and industrial areas relying on uncertainty analysis, time-varying data, and ensembles of data sets in general.

Novel image processing techniques have been in development for decades, but most of these techniques are barely used in real world applications. This results in a gap between image processing research and real-world applications; this thesis aims to close this gap. In an initial study, the quantification, propagation, and communication of uncertainty were determined to be key features in gaining acceptance for new image processing techniques in applications. This thesis presents a holistic approach based on a novel image processing pipeline, capable of quantifying, propagating, and communicating image uncertainty. This work provides an improved image data transformation paradigm, extending image data using a flexible, high-dimensional uncertainty model. Based on this, a completely redesigned image processing pipeline is presented. In this pipeline, each step respects and preserves the underlying image uncertainty, allowing image uncertainty quantification, image pre-processing, image segmentation, and geometry extraction. This is communicated by utilizing meaningful visualization methodologies throughout each computational step. The presented methods are examined qualitatively by comparing to the Stateof- the-Art, in addition to user evaluation in different domains. To show the applicability of the presented approach to real world scenarios, this thesis demonstrates domain-specific problems and the successful implementation of the presented techniques in these domains.

In der vorliegenden Arbeit wurde ein glasfaserverstärkter Rotor für einen Elektromotor entwickelt, welcher bei elektrisch angetriebenen Fahrzeugen verwendet werden soll. Ziel ist eine kostengünstige Serienversion des Motors auf Basis eines bereits bestehenden Baumusters. Im Wesentlichen waren dabei zwei Anforderungsfelder zu erfüllen. Als erstes mussten Verformungsrestriktionen unter Betriebslast eingehalten werden. Es wurde ein Finite-Elemente-(FE-) Modell erstellt, wobei eine Schnittstelle zwischen der Prozesssimulation der Fertigung und dem FE-Modell geschrieben wurde, um die Informationen zum Lagenaufbau zu transferieren. Sowohl in der Analytik als auch in der numerischen Simulation hat sich gezeigt, dass bei der im Betrieb auftretenden Fliehkraft die gewünschte Verformung nur mit Hilfe der zu verwendenden Glasfaser nicht eingehalten werden kann. Daraufhin wurde ein Konzept entwickelt, um die Verformung mittels einer adaptiven Steuerung mit Formgedächtnislegierungen zu begrenzen. Zunächst wurden Konzepte entwickelt, wie die Formgedächtnislegierung in Drahtform an den Rotor angebunden werden kann. Die Konzepte wurden experimentell überprüft, wobei gleichzeitig das Verhalten der Formgedächtnislegierung ermittelt wurde, um daraus ein numerisches Simulationsmodell zu entwickeln, welches mit dem Modell des Rotors verknüpft wurde. Dabei zeigte sich, dass dieses Konzept das Verformungsverhalten positiv beeinflusst und in Abhängigkeit von der verwendeten Menge die Verformungsrestriktion eingehalten werden kann. Als zweites Anforderungsfeld wurde die Lasteinleitung zwischen dem Rotor und der Abtriebswelle ausgelegt. Dafür wurde ein Konzept für eine Verschraubung als Sonderform einer Bolzenverbindung erarbeitet, bei denen ein Gewinde in der dickwandigen glasfaserverstärkten Kunststoff (GFK-) Struktur des Rotors mittels insitu- Herstellung eingebracht wird. Um die Vor- und Nachteile eines solchen geformten Gewindes gegenüber einer geschnittenen Variante zu ermitteln, wurden umfangreiche quasistatische Versuche und zyklische Lebensdauerversuche an zwei verschiedenen Laminaten und zwei verschiedenen Gewindetypen durchgeführt. Gemessen wurde jeweils die (Ermüdungs-) Festigkeit bei axialer Kraft und bei Scherkraft. Dabei zeigte sich, dass bei quasistatischer axialer Belastung die geformten Gewinde im Mittel eine geringere Festigkeit aufweisen als die geschnittene Variante.Bei der für den Anwendungsfall relevanteren Scherbelastung konnten im Mittel jedoch Festigkeitssteigerungen gemessen werden. Bei der Ermüdungsfestigkeit waren die Vorteile abhängig von dem geprüften Lastniveau. Die Wöhlerlinien bei den geformten Gewinden haben im Mittel einen deutlich flacheren Verlauf. Für die meisten Vergleichspaare bedeutet dies, dass die geschnittene Variante bei sehr hohen Lastniveaus beim Einstufenversuch eine größere Versagensschwingspielzahl erreicht als die geformte Variante. Bei Verringerung der Last haben ab einem individuellen Kreuzungspunkt jedoch die geformten Gewinde eine größere Schwingspielzahl erreicht. Abschließend wurde ein voll parametrisches numerisches Einheitszellen-Modell erstellt, welches sowohl die geformten als auch die geschnittenen Gewinde abbilden kann. Hierbei wurden auch Degradationsmodelle integriert, die ein verändertes Werkstoffverhalten nach dem Auftreten insbesondere von Zwischenfaserbrüchen und Delaminationen abbilden sollen. Validiert wurden die Modelle, indem die quasistatischen Versuche nachgebildet wurden und die globale Verformung mit den optischen Messungen aus den Versuchsreihen verglichen wurden. Dabei zeigte sich eine gute Übereinstimmung bis relativ nah an die Schraube heran. In diesem Bereich war die Simulation minimal zu steif, was auf eine noch nicht ausreichende Degradation in der Simulation hindeutet. In this study a GFRP rotor of an electric engine is developed. The engine shall be used in electric drive trains in cars. Major aim of the study is to develop a low-cost version of an existing prototype for serial production with a relatively high output of at least 50.000 units per annum. Two main aims must be achieved. First of all, the structural deformation must be limited under operating load. To predict the deformation, a finite element model was set up. To import the lay-up information from a filament winding process simulation software into the FE-model, a compilertool was written. The numerical simulation and an analytical calculation have shown that the GFRP-laminate alone is not able to limit the radial deformation caused by centrifugal force under rotation. So a different approach was developed, using an adaptive control with shape memory alloys. For this, a concept was investigated, how the shape memory alloy wires can be attached on the GFRP structure. The strengths of the different concepts were measured experimentally and simultaneously the force-temperature behavior of the wire was investigated. Out of these empirical studies, a material model of the shape memory alloys for the numerical simulation was developed and combined with the existing simulation model of the rotor. The simulation showed that the shape memory alloys can be used to decrease the radial deformation below the given limits. The second main requirement was to develop a proper load transfer from the metallic output shaft into the GFRP rotor. For serial rotor production with a high output, the direct forming of threads in the thick-walled GFRP was investigated. The direct forming of threads reduces the manufacturing costs by avoiding wear of drilling and cutting tools, although with a slight increase of tooling costs which are less relevant due to the economies of scale of high output manufacturing processes as the filament winding process. In this study the mechanical behavior of directly formed threads was compared to conventionally tapped threads. Two different GFRP laminate layups were investigated, a cross-ply-laminate and a quasi-isotropic laminate, both with a thickness of approximately 12 mm, impregnated with epoxy resin. A standard metrical thread and a more coarse thread were also compared, both with an outer diameter of 8 mm. Two different tests were investigated: a pullout test of the screw perpendicular to the laminate and a bearing-pull-through-test in the laminate plane. The quasi static test results show differences in fracture behavior, but in general very good strength and stiffness behavior compared to conventionally cut threads in thickwalled GFRP. The deformations of the surface of the GFRP laminates during the tests were measured with a three dimensional digital image correlation system. The measured deformations were used to validate the numerical simulations of the tests. These simulations were parametrical built up in order to adapt them easily to other application cases. They use a degradation mechanism to simulate the connection behavior very close to the total fraction and show a very good correlation to the experimental results. As a second step, the fatigue behavior of the connection was also investigated. To compare the cyclic performance of the formed and cut threads for both kinds of tests, for both laminates and both threads - the metric and the coarse ones -, Woehler diagrams with a load aspect ratio of R=0.1 were measured. Especially the high cycle fatigue behavior with a relatively low maximum load, as commonly used in a real structure, improves a lot when forming the threads. At last a full parametrical numerical model of the laminate with both the formed and the cut thread was generated. Also algorithms for material degradation were integrated. They can represent the behavior of the material after the appearance of inter fiber failures or delamination. The validation of the numerical model was achieved by remodeling the experimental tests and comparing the global deformation of the model with the optical measurement of the quasi static tests. The deformation of the simulation was very congruent to the tests, only very close to the screw the simulation shows a slightly more stiff behavior. This indicates a not sufficient degradation of the simulation due to damage effects in the material.

Faser-Kunststoff-Verbunde (FKV) sind in der Luftfahrt etabliert, wohingegen andere Branchen diese aufgrund der hohen Kosten nur zögerlich einsetzen. Die hohen Betriebskosten von Flugzeugen, die sich vorrangig durch Leichtbau reduzieren lassen, erlauben kostenintensivere Lösungen als die Kostenstrukturen in anderen Branchen. Die Mehrkosten sind neben dem Leichtbau der entscheidende Faktor für den Einsatz von FKV-Strukturen außerhalb der Luftfahrtbranche. Während in der Luftfahrtbranche üblicherweise Niete zur Krafteinleitung eingesetzt werden und diese nur eine Demontage eines Bauteils durch Aufbohren zulassen, genügen Niete den Ansprüchen anderer Branchen nicht, da ein hoher Demontageaufwand durch das Aufbohren hohe Kosten mit sich zieht. Aus diesem Grund erfordert es preisgünstige und qualitative Lösungen, die eine lösbare Verbindung ermöglichen. In den meisten Branchen werden daher, im Gegensatz zur Luftfahrt, traditionell reibschlüssige Schraubenverbindungen für metallische Bauteile verwendet. Für reibschlüssige Schraubenverbindungen, die zur Krafteinleitung in FKV-Strukturen genutzt werden, sind dem Stand der Forschung nach kaum Erkenntnisse vorhanden. Daher ist es Gegenstand dieser Arbeit aufzuzeigen, wie durch eine Erhöhung des Reibwerts bei reibschlüssigen Krafteinleitungen in FKV-Bauteilen eine Verbesserung der statischen und zyklischen Verbindungsfestigkeit erreicht werden kann. Um den zuverlässigen Einsatz von reibschlüssigen Schraubenverbindungen zu ermöglichen, werden außerdem die maximal zulässige Flächenpressung und der Vorspannkraftverlust an FKV-Proben ermittelt. Dabei bilden experimentelle Ergebnisse eine Basis, anhand derer aufgezeigt wird, inwieweit analytische Modelle genutzt werden können,um die reibschlüssige Krafteinleitung in FKV abzubilden. Zunächst wird der Haftreibwert zwischen Stahl und FKV experimentell untersucht, um Konzepte zur Steigerung des Reibwerts zu quantifizieren. Durch die experimentelle Ermittlung einer maximal zulässigen Flächenpressung für die verwendeten FKVMaterialien werden Schädigungen infolge zu hoher Vorspannkräfte vermieden. Dazu werden FKV- Proben mit einem Stempel belastet und mit Hilfe der Schallemissionsmethode Schädigungen detektiert, zu dem Zweck eine Belastungsgrenze zu definieren. Versuche zur Bestimmung des Vorspannkraftverlusts an FKV-Proben zeigen, dass die Vorspannkraft durch Setzen und Kriechen zwar reduziert wird, dies aber in vertretbarem Maße. Darüber hinaus lässt sich in den Versuchen beobachten, dass das Setzen deutlich von der Oberflächenbeschaffenheit bestimmt wird. Um die Einflüsse des Matrixwerkstoffs, des Reibwerts, der Passung und der Vorspannkraft auf die Kraftübertragung in der Schraubverbindung zu prüfen, werden außerdem doppellaschige Zugscherversuche durchgeführt. An geklemmten FKV-Bauteilen im Fahrradbau lassen sich Defizite bei der Auslegung dieser Bauteile und ihrer Anbindungstechnologie feststellen. Da der Verbindung zwischen Vorbau und Gabelschaft besondere sicherheitsrelevante Bedeutung zukommt, wird eine marktübliche Gabelschaft-Vorbau-Klemmung im Rahmen dieser Arbeit experimentell und numerisch auf die Belastungen durch die Montage sowie im Betrieb untersucht. Es kann dargelegt werden, dass ein komplexer Belastungszustand in der genannten Klemmverbindung vorliegt, der numerisch abgebildet werden kann. Auf Basis des validierten Finite-Element-Modells kann gezeigt werden, dass die Steigerung des Reibwerts ein deutliches Potential aufweist um die Werkstoffanstrengung zu reduzieren. Zur experimentellen Absicherung dieser Beobachtung, werden quasistatische und zyklische Untersuchungen an Vorbau-Gabelschaft-Baugruppen durchgeführt, bei denen der Reibwert durch die Applikation von Schmierfett und Carbonmontagepaste variiert wird. Durch die Verwendung von Carbonmontagepaste bzw. bei einem höheren Reibwert steigt sowohl die quasi-statische Festigkeit als auch die Lebensdauer im Vergleich zum Einsatz von Schmierfett deutlich an. Fiber reinforced plastics (FRP) are well established materials in the aviation industry, whereas in other industries these materials are not yet this commonly used due to the comparatively high costs. The high operating costs of aircrafts can be reduced primarily through lightweight design, which allows the choice of more expensive solutions than in other industries. The additional costs are beside the weight savings the deciding factor for the use of FRP structures beyond the aviation sector. Since normally rivets are used in the aviation industry to join components, the dismantling of these riveted structures needs drilling. Hence rivets are insufficient for the demands of other sectors due to the high disassembly costs caused by the high disassembly effort. For this reason affordable solutions that permit an easy disassembly procedure are essential for a wider application of FRP structures. Therefore – in most sectors – preloaded bolted joints are used for the assembly of metallic components, in contrast to aviation. For preloaded bolted joints in combination with FRP structures almost no information is available by the current state of scientific knowledge Therefore in this work it is investigated how an improvement of the static and cyclic connection strength can be achieved by increasing the coefficient of friction at preloaded bolted joints on FRP components. To enable a reliable application of preloaded bolted joints the maximum allowable surface pressure and the loss of the preload force of FRP specimens are determined. Therefore experimental results provide the basis to study if analytical computation can be used to describe bolted joints on FRP structures. The coefficient of friction between steel and FRP is experimentally investigated in order to quantify concepts that aim to increase the coefficient of friction. An experimental determination of the maximum permissible surface pressure of the used FRP materials avoids damage by excessive bolt preload. Therefore FRP specimens are tested and a simultaneous detection of damage is performed by using the acoustic emission method. An experimentalinvestigation of the loss of bolt preload shows that the preload is reduced by embedding and material relaxation but in an acceptable manner. In addition it can be observed that the embedding of the contact surfaces is significantly dependent on the surface condition of the specimens. To analyze the influence of the matrix material, the coefficient of friction, the clearance and the bolt preload to a bolted joint, double lap tensile shear tests are performed. Clamped FRP components used on bicycles show shortcomings in the design of these components and their connection technology. Since the connection between stem and steerer has a significant impact on safety, a standard stem/steerer connection is investigated both experimentally and numerically considering the stresses during the assembling as well as during operation. It can be demonstrated that this connection has a complex load condition and a finite element analysis can describe this connection sufficiently. Based on the validated finite element model it can be shown that an increasing coefficient of friction has a significant potential for the reduction of the material effort of the FRP steerer. To validate these theoretical observations, quasi-static and cyclic tests on stem/steerer assemblies are carried out. Thereby the coefficient of friction is varied by the application of grease and carbon assembly paste. By the use of carbon assembly paste (high coefficient of friction) both the quasi-static strength as well as the operating life increases in comparison to the use of grease (low coefficient of friction).

Destructive diseases of the lung like lung cancer or fibrosis are still often lethal. Also in case of fibrosis in the liver, the only possible cure is transplantation. In this thesis, we investigate 3D micro computed synchrotron radiation (SR\( \mu \)CT) images of capillary blood vessels in mouse lungs and livers. The specimen show so-called compensatory lung growth as well as different states of pulmonary and hepatic fibrosis. During compensatory lung growth, after resecting part of the lung, the remaining part compensates for this loss by extending into the empty space. This process is accompanied by an active vessel growing. In general, the human lung can not compensate for such a loss. Thus, understanding this process in mice is important to improve treatment options in case of diseases like lung cancer. In case of fibrosis, the formation of scars within the organ's tissue forces the capillary vessels to grow to ensure blood supply. Thus, the process of fibrosis as well as compensatory lung growth can be accessed by considering the capillary architecture. As preparation of 2D microscopic images is faster, easier, and cheaper compared to SR\( \mu \)CT images, they currently form the basis of medical investigation. Yet, characteristics like direction and shape of objects can only properly be analyzed using 3D imaging techniques. Hence, analyzing SR\( \mu \)CT data provides valuable additional information. For the fibrotic specimen, we apply image analysis methods well-known from material science. We measure the vessel diameter using the granulometry distribution function and describe the inter-vessel distance by the spherical contact distribution. Moreover, we estimate the directional distribution of the capillary structure. All features turn out to be useful to characterize fibrosis based on the deformation of capillary vessels. It is already known that the most efficient mechanism of vessel growing forms small torus-shaped holes within the capillary structure, so-called intussusceptive pillars. Analyzing their location and number strongly contributes to the characterization of vessel growing. Hence, for all three applications, this is of great interest. This thesis provides the first algorithm to detect intussusceptive pillars in SR\( \mu \)CT images. After segmentation of raw image data, our algorithm works automatically and allows for a quantitative evaluation of a large amount of data. The analysis of SR\( \mu \)CT data using our pillar algorithm as well as the granulometry, spherical contact distribution, and directional analysis extends the current state-of-the-art in medical studies. Although it is not possible to replace certain 3D features by 2D features without losing information, our results could be used to examine 2D features approximating the 3D findings reasonably well.

The growing computational power enables the establishment of the Population Balance Equation (PBE) to model the steady state and dynamic behavior of multiphase flow unit operations. Accordingly, the twophase flow behavior inside liquid-liquid extraction equipment is characterized by different factors. These factors include: interactions among droplets (breakage and coalescence), different time scales due to the size distribution of the dispersed phase, and micro time scales of the interphase diffusional mass transfer process. As a result of this, the general PBE has no well known analytical solution and therefore robust numerical solution methods with low computational cost are highly admired. In this work, the Sectional Quadrature Method of Moments (SQMOM) (Attarakih, M. M., Drumm, C., Bart, H.-J. (2009). Solution of the population balance equation using the Sectional Quadrature Method of Moments (SQMOM). Chem. Eng. Sci. 64, 742-752) is extended to take into account the continuous flow systems in spatial domain. In this regard, the SQMOM is extended to solve the spatially distributed nonhomogeneous bivariate PBE to model the hydrodynamics and physical/reactive mass transfer behavior of liquid-liquid extraction equipment. Based on the extended SQMOM, two different steady state and dynamic simulation algorithms for hydrodynamics and mass transfer behavior of liquid-liquid extraction equipment are developed and efficiently implemented. At the steady state modeling level, a Spatially-Mixed SQMOM (SM-SQMOM) algorithm is developed and successfully implemented in a onedimensional physical spatial domain. The integral spatial numerical flux is closed using the mean mass droplet diameter based on the One Primary and One Secondary Particle Method (OPOSPM which is the simplest case of the SQMOM). On the other hand the hydrodynamics integral source terms are closed using the analytical Two-Equal Weight Quadrature (TEqWQ). To avoid the numerical solution of the droplet rise velocity, an analytical solution based on the algebraic velocity model is derived for the particular case of unit velocity exponent appearing in the droplet swarm model. In addition to this, the source term due to mass transport is closed using OPOSPM. The resulting system of ordinary differential equations with respect to space is solved using the MATLAB adaptive Runge–Kutta method (ODE45). At the dynamic modeling level, the SQMOM is extended to a one-dimensional physical spatial domain and resolved using the finite volume method. To close the mathematical model, the required quadrature nodes and weights are calculated using the analytical solution based on the Two Unequal Weights Quadrature (TUEWQ) formula. By applying the finite volume method to the spatial domain, a semi-discreet ordinary differential equation system is obtained and solved. Both steady state and dynamic algorithms are extensively validated at analytical, numerical, and experimental levels. At the numerical level, the predictions of both algorithms are validated using the extended fixed pivot technique as implemented in PPBLab software (Attarakih, M., Alzyod, S., Abu-Khader, M., Bart, H.-J. (2012). PPBLAB: A new multivariate population balance environment for particulate system modeling and simulation. Procedia Eng. 42, pp. 144-562). At the experimental validation level, the extended SQMOM is successfully used to model the steady state hydrodynamics and physical and reactive mass transfer behavior of agitated liquid-liquid extraction columns under different operating conditions. In this regard, both models are found efficient and able to follow liquid extraction column behavior during column scale-up, where three column diameters were investigated (DN32, DN80, and DN150). To shed more light on the local interactions among the contacted phases, a reduced coupled PBE and CFD framework is used to model the hydrodynamic behavior of pulsed sieve plate columns. In this regard, OPOSPM is utilized and implemented in FLUENT 18.2 commercial software as a special case of the SQMOM. The dropletdroplet interactions (breakage and coalescence) are taken into account using OPOSPM, while the required information about the velocity field and energy dissipation is calculated by the CFD model. In addition to this, the proposed coupled OPOSPM-CFD framework is extended to include the mass transfer. The proposed framework is numerically tested and the results are compared with the published experimental data. The required breakage and coalescence parameters to perform the 2D-CFD simulation are estimated using PPBLab software, where a 1D-CFD simulation using a multi-sectional gird is performed. A very good agreement is obtained at the experimental and the numerical validation levels.

Der Einstieg in ein kommunales Starkregenrisikomanagement muss über eine fundierte Risikoanalyse erfolgen, die mögliche Gefährdungen, Objektbetroffenheiten und Schadenspotenziale identifiziert und bewertet. GIS-basierte Verfahren stellen hierfür vergleichsweise einfache, effiziente Werkzeuge dar, deren Ergebnisse jedoch erheblich von subjektiven Festlegungen, der Qualität der Eingangsdaten und methodischen Einzelaspekten abhängen. Im Gegensatz zur vergleichsweise zuverlässig quantifizierbaren Gefährdung entzieht sich die Objektvulnerabilität bislang mangels Daten noch einer gebietsweiten Beurteilung. Auch die Ersatzgröße Schadenspotenzial lässt sich nur schwer auf mikroskaliger Ebene erfassen. Das im Rahmen dieser Arbeit entwickelte Gesamtkonzept einer GIS-basierten Risikoanalyse widmet sich zum einen einer methodischen Vertiefung der einzelnen Arbeitsschritte und analysiert die Auswirkungen unterschiedlicher Festlegungen auf die generierten Ergebnisse. Ein Hauptaugenmerk liegt dabei auf dem Einfluss der Eingangsdaten und deren optimaler Verwertung. Parallel dazu werden die Abbildungsdefizite der Vulnerabilität näher untersucht und Vorschläge für eine methodische Verbesserung der gebietsweiten Schadenspotenzialanalyse ausgearbeitet. Beide Schritte münden in Empfehlungen zur Anwendung sowie zur Ergebnisverwertung im Zuge der weiterführenden Risikokommunikation. Die Untersuchungen zeigen, dass vor allem die Vorglättung des Oberflächenmodells (DOM) das Gefährdungsergebnis prägt und dass für Senken und Fließwege unterschiedliche DOM-Aufbereitungen erforderlich sind. Ferner darf die methodische Berücksichtigung weiterer gefährdungsrelevanter Parameter nicht die Effizienz und Handhabungsvorteile beeinträchtigen. Die Abbildung von Vulnerabilitäten auf Objektebene scheitert vorrangig an mangelnden Angaben zur Objektanfälligkeit und zur Bewältigungskapazität, während sich Schadenspotenziale sehr grob anhand von Nutzungsdaten abschätzen lassen. Eine bessere Objektivierung der Schadenspotenzialanalyse lässt sich erreichen, wenn dieses getrennt nach Vulnerabilitätsdimensionen bewertet wird und wenn dazu charakteristische Schadenstypen als Hilfsgrößen der Bewertung verwendet werden. Risikobewertungen sind vorrangig vulnerabilitätsbezogen, d. h. mit Fokus auf möglichen Schadensausmaße und Präventionsmaßnahmen durchzuführen. Dies kann jedoch nur auf Objektebene, konkret durch bzw. mit dem potenziell Betroffenen erfolgen. Damit wird die Risikoanalyse zwangsläufig zu einem gemeinsamen Prozess und Dialog zwischen kommunaler Verantwortung zu Information und Aufklärung auf der einen Seite und individueller Eigenverantwortung und Risikoakzeptanz auf der anderen Seite.

Though environmental inequality research has gained extensive interest in the United States, it has received far less attention in Europe and Germany. The main objective of this book is to extend the research on environmental inequality in Germany. This book aims to shed more light on the question of whether minorities in Germany are affected by a disproportionately high burden of environmental pollution, and to increase the general knowledge about the causal mechanisms, which contribute to the unequal distribution of environmental hazards across the population. To improve our knowledge about environmental inequality in Germany, this book extends previous research in several ways. First, to evaluate the extent of environmental inequality, this book relies on two different data sources. On the on hand, it uses household-level survey data and self-reports about the impairment through air pollution. On the other hand, it combines aggregated census data and objective register-based measures of industrial air pollution by using geographic information systems (GIS). Consequently, this book offers the first analysis of environmental inequality on the national level that uses objective measures of air pollution in Germany. Second, to evaluate the causes of environmental inequality, this book applies a panel data analysis on the household level, thereby offering the first longitudinal analysis of selective migration processes outside the United States. Third, it compares the level of environmental inequality between German metropolitan areas and evaluates to which extent the theoretical arguments of environmental inequality can explain differing levels of environmental inequality across the country. By doing so, this book not only investigates the impact of indicators derived by the standard strand of theoretical reasoning but also includes structural characteristics of the urban space. All studies presented in this book confirm the disproportionate exposure of minorities to environmental pollution. Minorities live in more polluted areas in Germany but also in more polluted parts of the communities, and this disadvantage is most severe in metropolitan regions. Though this book finds evidence for selective migration processes contributing to the disproportionate exposure of minorities to environmental pollution, it also stresses the importance of urban conditions. Especially cities with centrally located industrial facilities yield a high level of environmental inequality. This poses the question of whether environmental inequality might be the result of two independent processes: 1) urban infrastructure confines residential choices of minorities to the urban core, and 2) urban infrastructure facilitates centrally located industries. In combination, both processes lead to a disproportionate burden of minority households.