Lie group generalized-α time integration of constrained flexible multibody systems

2012 ◽  
Vol 48 ◽  
pp. 121-137 ◽  
Author(s):  
Olivier Brüls ◽  
Alberto Cardona ◽  
Martin Arnold
Author(s):  
Olivier A. Bauchau ◽  
Jesus Rodriguez

Abstract This paper is concerned with the modeling of joints with clearance within the framework of finite element based dynamic analysis of nonlinear, flexible multi-body systems. For actual joints, clearance, lubrication and friction phenomena can significantly affect the dynamic response of the system. In this work, the effects of clearance and lubrication are studied for revolute and spherical joints. The formulation is developed within the framework of energy preserving and decaying time integration schemes that provide unconditional stability for nonlinear, flexible multibody systems. Numerical examples are presented that demonstrate the efficiency and accuracy of the proposed approach. The importance of modeling structural damping and limited driving power are discussed.


2015 ◽  
Vol 723 ◽  
pp. 215-223
Author(s):  
Wen Jie Yu ◽  
Zhen Kuan Pan

A new type of dynamic equations of flexible multibody systems is derived via virtual work principle together with floating frame approach. The absolute Cartesian coordinates are used to describe positions of floating frames’ origins of deformable bodies; The orientation transform matrices as special orthogonal groups are used to describe rotation motions; The modal coordinates are used to express small deflections of deformable bodies with respect to the corresponding floating frames. The resulting equations are mixed classic Euler-Lagrange equations of translational motion of bodies and deformation and Euler-Poinaré equations of rotation in Lie groups and Lie algebras, the Lie-Poisson equations as reconstruction equations obtaining Lie Groups from Lie algebras, constraint equations Lie groups and Lie algebras. In order to simplify the implementation, we separate the constant coefficient matrices in generalized mass matrices and generalized forces in detail. The results can be easily used to design geometric integrators of Lie group structure preserving.


Author(s):  
Andreas Müller

The exponential and Cayley maps on SE(3) are the prevailing coordinate maps used in Lie group integration schemes for rigid body and flexible body systems. Such geometric integrators are the Munthe–Kaas and generalized- α schemes, which involve the differential and its directional derivative of the respective coordinate map. Relevant closed form expressions, which were reported over the last two decades, are scattered in the literature, and some are reported without proof. This paper provides a reference summarizing all relevant closed-form relations along with the relevant proofs, including the right-trivialized differential of the exponential and Cayley map and their directional derivatives (resembling the Hessian). The latter gives rise to an implicit generalized- α scheme for rigid/flexible multibody systems in terms of the Cayley map with improved computational efficiency.


2013 ◽  
Vol 30 (1) ◽  
pp. 13-35 ◽  
Author(s):  
Maria Augusta Neto ◽  
Jorge A. C. Ambrósio ◽  
Luis M. Roseiro ◽  
A. Amaro ◽  
C. M. A. Vasques

1999 ◽  
Vol 122 (4) ◽  
pp. 498-507 ◽  
Author(s):  
Marcello Campanelli ◽  
Marcello Berzeri ◽  
Ahmed A. Shabana

Many flexible multibody applications are characterized by high inertia forces and motion discontinuities. Because of these characteristics, problems can be encountered when large displacement finite element formulations are used in the simulation of flexible multibody systems. In this investigation, the performance of two different large displacement finite element formulations in the analysis of flexible multibody systems is investigated. These are the incremental corotational procedure proposed in an earlier article (Rankin, C. C., and Brogan, F. A., 1986, ASME J. Pressure Vessel Technol., 108, pp. 165–174) and the non-incremental absolute nodal coordinate formulation recently proposed (Shabana, A. A., 1998, Dynamics of Multibody Systems, 2nd ed., Cambridge University Press, Cambridge). It is demonstrated in this investigation that the limitation resulting from the use of the infinitesmal nodal rotations in the incremental corotational procedure can lead to simulation problems even when simple flexible multibody applications are considered. The absolute nodal coordinate formulation, on the other hand, does not employ infinitesimal or finite rotation coordinates and leads to a constant mass matrix. Despite the fact that the absolute nodal coordinate formulation leads to a non-linear expression for the elastic forces, the results presented in this study, surprisingly, demonstrate that such a formulation is efficient in static problems as compared to the incremental corotational procedure. The excellent performance of the absolute nodal coordinate formulation in static and dynamic problems can be attributed to the fact that such a formulation does not employ rotations and leads to exact representation of the rigid body motion of the finite element. [S1050-0472(00)00604-8]


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