ANALYSIS OF FLEXIBLE MULTIBODY SYSTEMS WITH SPATIAL BEAMS USING MIXEDVARIATIONAL-PRINCIPLES

A general finite element formulation is presented for dynamic analysis of spatial elastic beams, for small strains, in a multi-body configur ation The tangent maps associated to the finite rotation vector are us ed to compute the tangent matrices used to integrate implicitly the eq uations of motion in descriptor form. A corotational method and a mixe d variational method are used to compute the tangent stiffness matrix. The tangent constraint matrices are obtained using consistent lineari zation of the constraint equations. The tangent inertia matrices, incl uding the gyroscopic and centrifugal terms, are also obtained by using the tangent maps of rotation. The numerical examples analyzed in this paper include: dynamic analysis of flexible beam structures and multi -flexible body systems with open and closed kinematic loops. A compari son with the previous results in the literature shows a very good perf ormance in terms of lime integration step and number of elements used. (C) 1998 John Wiley & Sons, Ltd.