TREATMENT OF MATERIAL CREEP AND NONLINEARITIES IN FLEXIBLE MULTIBODY DYNAMICS

This paper addresses the modeling of the generalized active forces res ulting from deformable bodies when subjected to high temperature condi tions, elastic-plastic deformations, creep effects, and material nonli nearities. The effects of elastic plastic deformations are studied mak ing use of the nonlinear stress-strain relationship and the geometrica l stiffness concepts. Creep conditions resulting from high temperature are studied through several proposed models. Material nonlinearities for isotropic and composites are accounted for by their tangential ela sticity matrix. A general procedure used in the study of multibody sys tems dynamics with elastic-plastic bodies depicting the characteristic s mentioned is developed. This includes an explicit formulation of the equations of motion using Kane's equations, finite element method, co ntinuum mechanics, and modal coordinate reduction techniques. A numeri cal simulation of a flexible robotic arm with a prescribed angular vel ocity subject to high temperature conditions is analyzed. The effects of creep are discussed.