Geometric Stiffness Influence in Linearized Flexible Multibody Systems.

Abstract

For simulations of flexible multibody systems (MBS) the theory of elasticity and the Rayleigh-Ritz assumption are used. In case of vehicle system dynamics the total body motion can be subdivided into a known large reference motion and a small deviation. The deviation will be described by a linearized rigid body motiuon and a linearized elastic deformation. For a correct development of the equations of motion the nominal state of the MBS must be in equilibrium. Nominal forces, torques and stresses result in geometric stiffness terms of the system equations. The paper discusses various alternatives for incorporating these terms; it is suggested to derive the geometric stiffness terms by using the equilibrium of the forces and stresses of the deflected and deformed bodies. The method is demonstrated by a flexible beam example.