An implementation method for constrained flexible multibody dynamics usinga virtual body and joint

A convenient implementation method for constrained flexible multibody dynam ics is presented by introducing a virtual rigid body and joint. The general purpose program for rigid and flexible multibody dynamics consists of thre e major parts of a set of inertia modules, a set of force modules, and a se t of joint modules. Whenever a new force or joint module is added to the ge neral purpose program, the modules for the rigid body dynamics are not reus able for the flexible body dynamics. Consequently, the corresponding module s for the flexible body dynamics must be formulated and programmed again. S ince the flexible body dynamics handles more degrees of freedom than the ri gid body dynamics does, implementation of the module is generally complicat ed and prone to coding mistakes. In order to overcome these difficulties, a virtual rigid body is introduced at every joint and force reference frames . New kinematic admissibility conditions are imposed on two-body reference frames of virtual and original bodies by introducing a virtual flexible bod y joint. There are some computational overheads due to the additional bodie s and joints. However, since computation time is mainly dependent on the fr equency of flexible body dynamics, the computational overhead of the presen ted method is not a critical problem, while implementation convenience is d ramatically improved.