Kohlenstofffaserverstärkte Kunststoffe (CFK) sind Hochleistungsverbundwerkstoffe, die sich durch ihre thermischen und gewichtsspezifischen mechanischen Eigenschaften auszeichnen. Eine glasige, hochvernetzte Epoxidharzmatrix verleiht dem Material einen hohen thermischen Widerstand, macht den Verbundwerkstoff jedoch auch spröde und anfällig für Risse und schlagartige Beanspruchungen. Eine Möglichkeit, diese Schlüsseleigenschaft, die Zähigkeit von Epoxidharzmatrixsystemen, zu erhöhen, ist die Modifikation der zugrundeliegenden Morphologie; das Einbringen zusätzlicher Substrukturen erhöht den Widerstand des Materials gegen Rissbildung und -fortschritt. Diese Arbeit liefert einen Beitrag zum Verständnis des Einflusses von Substruktur-bildenden, selbstorganisierenden Block-Copolymern (BCP) und vorgeformten Kern-Schale-Partikeln (KSP) auf die Zähigkeit und die Schadenstoleranz von dünnen CFK-Strukturen und deren Epoxidharzmatrizes. Mittels einer neuen, thermooptischen Messmethode wird gezeigt, dass die Bildung von BCP-reichen Substrukturen alleine vom chemischen Umsatz der Vernetzungsreaktion der Epoxidharzmatrix abhängt. Zudem wird die Substrukturbildung im CFK stark durch die Anwesenheit der Kohlenstofffasern beeinflusst. Bereits geringe BCP-Konzentrationen (7 Gew.-%) führen zu einer drastischen Erhöhung (250 %) des interlaminaren Risswiderstands des Faserverbunds (Mode I). Eine Modifikation mittels KSP wiederrum steigert den benötigten Energieeintrag zur Initiierung von Delaminationen (160 %, Mode II). Durch eine Hybridisierung beider Modifikatoren ist es so möglich, das Schädigungsvolumen unter Schlagbeanspruchung, wenn beide Lastfälle kombiniert auftreten, um mehr als 67% zu verringern. Die generierten Materialsysteme und das erarbeitete Verständnis erlauben es, zukünftig noch dünnere CFK-Strukturen herzustellen, ohne deren Strukturintegrität bei Schlagbeanspruchung zu reduzieren. Carbon fibre reinforced epoxies (CFRE) are a class of high performance, light-weight composites that show outstanding, weight-specific (thermo-)mechanical properties. A glassy and highly cross-linked epoxy matrix provides the composite with a high thermal resistance, but makes the CFRE also inherently brittle and susceptible to cracks and impacts. One strategy to overcome this drawback and to improve fracture toughness of epoxy matrices is to modify the underlying morphology with additional substructures (domains in the nano and/or micron size range). This allows increasing the energy that is required to initiate or propagate a crack within the material. The present work contributes to a better understanding of the effect of substructure-forming, self-assembling block copolymers (BCP) and pre-formed core-shell rubber particles (CSR) on the toughness and impact behaviour of thin CFREs and their epoxy matrices. Using a new thermo-optical measurement technique, it is shown that the phaseseparation process of BCP-rich domains is solely driven by the degree of cure of the epoxy matrix. Also, it is found that the process of BCP phase-separation, e.g. the BCP-rich domain size, changes strongly in the presence of carbon fibres. Low concentrations of BCPs (7wt.-%) yield a 2.5-fold enhancement of the resistance to interlaminar fracture of the CFRE (Mode), already. Using CSR particles, on the other hand, the energy required to initiate delamination (Mode II) within the CFRE increases by 160 %. Subsequently, by a hybridization of BCP and CSR modifiers, after low energy impacts, when both load cases occur in combination, a synergistic damage volume reduction by more than 67% is achieved. Hence, the generated material systems and the acquired understanding allow future CFRE based structures to be even thinner than current design solutions, without affecting their structural integrity under impact loads.

In order to exploit the full lightweight potential of fibre-reinforced plastics (FRP), a detailed knowledge of their progressive failure behaviour under load is required. In this context, acoustic emission analysis offers a method to characterize the underlying mechanisms in more detail. By detecting and analszing acoustic waves emitted during crack initiation and growth, the location and type of damage can be described over the course of the test. A major challenge thereby is the differentiation between FRP specific damaging events, such as fibre and matrix fractures, on the basis of their acoustic emissions. The present work deals with the influence of two parameters which can have a significant impact on the acoustic characteristics of damaging events. These include the depth in which the damaging event occurs (source depth) and the lateral distance the acoustic wave has to travel from the source to the sensor (source-to-sensor distance). In order to gain an understanding of the effects of both parameters, the work highlights the properties of guided waves in fibre- reinforced plastics as crucial. By analysing artificial acoustic emission sources as well as acoustic emissions from real damaging events, the work demonstrates that changes in source depth and source-to-sensor distance can be accompanied by strong changes in the modal and frequency content of the acoustic emissions. These changes can even lead to a fibre break being mistakenly classified as a matrix break and vice versa. Consequently, for more reliable results in source identification, the influence of source depth and source-to-sensor distance must be considered. In this context, the use of modal acoustic emission analysis can be of great benefit in understanding the underlying phenomena and developing more robust evaluation methods.

This work deals with the simulation of the micro-cutting process of titanium. For this purpose, a suitable crystal-plastic material model is developed and efficient implemen- tations are investigated to simulate the micro-cutting process. Several challenges arise for the material model. On the one hand, the low symmetry hexagonal close-packed crystal structure of titanium has to be considered. On the other hand, large defor- mations and strains occur during the machining process. Another important part is the algorithm for the determination of the active slip systems, which has a significant influence on the stability of the simulation. In order to obtain a robust implemen- tation, different aspects, such as the algorithm for the determination of the active slip systems, the method for mesh separation between chip and workpiece as well as the hardening process are investigated, and different approaches are compared. The developed crystal-plastic material model and the selected implementations are first validated and investigated using illustrative examples. The presented simulations of the micro-cutting process show the influence of different machining parameters on the process. Finally, the influence of a real microstructure on the plastic deformation and the cutting force during the process is shown.

This paper presents a method for classifying traffic participants based on high-resolution automotive radar sensors for autonomous driving applications. The major classes of traffic participants addressed in this work are pedestrians, bicyclists and passenger cars. The preprocessed radar detections are first segmented into distinct clusters using density-based spatial clustering of applications with noise (DBSCAN) algorithm. Each cluster of detections would typically have different properties based on the respective characteristics of the object that they originated from. Therefore, sixteen distinct features based on radar detections, that are suitable for separating pedestrians, bicyclists and passenger car categories are selected and extracted for each of the cluster. A support vector machine (SVM) classifier is constructed, trained and parametrised for distinguishing the road users based on the extracted features. Experiments are conducted to analyse the classification performance of the proposed method on real data.

Mixed-mode chromatography (MMC), which combines features of ion exchange chromatography (IEC) and hydrophobic interaction chromatography (HIC), is an interesting method for protein separation and purification. The design of MMC processes is challenging as adsorption equilibria are influenced by many parameters, including ionic strength and the presence of different salts in solution. Systematic studies on the influence of those parameters in MMC are rare. Therefore, in the present work, the influence of four salts, namely, sodium chloride, sodium sulfate, ammonium chloride, and ammonium sulfate, on the adsorption of lysozyme on the mixed-mode resin Toyopearl MX-Trp-650M at pH 7.0 and 25°C was studied systematically in equilibrium adsorption experiments for ionic strengths between 0 mM and 3000 mM. For all salts, a noticeable adsorption strength was observed over the entire range of studied ionic strengths. An exponential decay of the loading of the resin with increasing ionic strength was found until approx. 1000 mM. For higher ionic strengths, the loading was found to be practically independent of the ionic strength. At constant ionic strength, the highest lysozyme loadings were observed for ammonium sulfate, the lowest for sodium chloride. A mathematical model was developed that correctly describes the influence of the ionic strength as well as the influence of the studied salts. The model is the first that enables the prediction of adsorption isotherms of proteins on mixed-mode resins in a wide range of technically interesting conditions, accounting for the influence of the ionic strength and four salts of practical relevance.