Numerical aspects in the dynamic simulation of geometrically exact rods

  • Classical geometrically exact Kirchhoff and Cosserat models are used to study the nonlinear deformation of rods. Extension, bending and torsion of the rod may be represented by the Kirchhoff model. The Cosserat model additionally takes into account shearing effects. Second order finite differences on a staggered grid define discrete viscoelastic versions of these classical models. Since the rotations are parametrised by unit quaternions, the space discretisation results in differential-algebraic equations that are solved numerically by standard techniques like index reduction and projection methods. Using absolute coordinates, the mass and constraint matrices are sparse and this sparsity may be exploited to speed-up time integration. Further improvements are possible in the Cosserat model, because the constraints are just the normalisation conditions for unit quaternions such that the null space of the constraint matrix can be given analytically. The results of the theoretical investigations are illustrated by numerical tests.

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Metadaten
Author:H. Lang, M. Arnold
URN:urn:nbn:de:hbz:386-kluedo-16443
Series (Serial Number):Berichte des Fraunhofer-Instituts für Techno- und Wirtschaftsmathematik (ITWM Report) (179)
Document Type:Report
Language of publication:English
Year of Completion:2009
Year of first Publication:2009
Publishing Institution:Fraunhofer-Institut für Techno- und Wirtschaftsmathematik
Date of the Publication (Server):2010/07/21
Tag:Kirchhoff and Cosserat rods; artial differential algebraic equations; deformable bodies; geometrically exact rods; multibody dynamics
Faculties / Organisational entities:Fraunhofer (ITWM)
DDC-Cassification:5 Naturwissenschaften und Mathematik / 510 Mathematik
Licence (German):Standard gemäß KLUEDO-Leitlinien vor dem 27.05.2011