OPTIMUM DESIGN OF FLEXIBLE MULTIBODY SYSTEMS WITH DYNAMIC BEHAVIOR CONSTRAINTS

A methodology is presented for the optimum design of high-speed multib ody systems under time-dependent stress and displacement constraints b y mathematical programming. Finite elements are used in the modeling o f the flexible links. The design variables are the sectional propertie s of the elements. The time dependence of the constraints is removed t hrough the use oi equivalent constraints based on the most critical co nstraints. It is shown that this approach yields a better design than using equivalent constraints obtained by the Kresselmeier-Steinhauser function. An optimizer based on sequential quadratic programming is us ed and the design sensitivities are evaluated by overall finite differ ences. The dynamical equations contain the nonlinear interactions betw een the rigid and elastic degrees-of-freedom. To illustrate the proced ure, a Peaucellier-Lipkin mechanism is optimized by using different eq uivalent constraints.