DYNAMICS OF FLEXIBLE MECHANICAL SYSTEMS WITH CONTACT-IMPACT AND PLASTIC-DEFORMATIONS

A computer based formulation for the analysis of mechanical systems is investigated as a feasible method to predict the impact response of c omplex structural systems. A general methodology for the dynamic analy sis of rigid-flexible multibody systems using a number of redundant Ca rtesian coordinates and the method of the Lagrange multipliers is pres ented. The component mode synthesis is then used to reduce the number of flexible degrees of freedom. In many impact situations, the individ ual structural members are overloaded giving rise to plastic deformati ons in highly localized regions, called plastic hinges. This concept i s used by associating revolute nonlinear actuators with constitutive r elations corresponding to the collapse behavior of the structural comp onents. The contact of the system components is described using a cont inuous force model based on the Hertz contact law with hysteresis damp ing. The effect and importance of structural damping schemes in flexib le bodies are also addressed here. Finally, the validity of this metho dology is assessed by comparing the results of the proposed models wit h those obtained in different experimental tests where: a beam collide s transversally with a rigid block; a torque box impacts a rigid barri er.