On the equations of motion in multibody dynamics

The equations of motion for a multibody system are derived from a continuum mechanical point of view. This will allow for the presence of rigid, as well as deformable, parts in the multibody system. The approach, using the principle of virtual power, leads to the classical Lagrange equations of motion. The generalized forces appearing in the equations are given as expressions involving contact, internal and body forces in the sense of continuum mechanics. A detailed analysis of the interaction between parts and their implication for the equations of motion is presented. Transformation properties, covariance and invariance under changes of configuration coordinates, are elucidated and a power theorem for the multibody system is proved. The equivalence between the standard balance equations for momentum and moment of momentum and the principle of virtual power is demonstrated.