FATIGUE BASED TOPOLOGY OPTIMIZATION OF LARGE AND FLEXIBLE MULTIBODY DYNAMIC SYSTEMS

In topology optimization (TO), a mass distribution in a given design space and for known loads is computed, so that a prior defined criteria is minimized. TO of dynamically loaded elastic structures is still a challenge. A relevant example of such a situation would be a multibody dynamic system with integrated Finite Element (FE) structures. Related publications in the literature have in common that they are quite inefficient for an application to large FE models. The latter, however, is necessary in case of complex design spaces with given edges, bores and the like. This paper describes an algorithm derived from the ‘equivalent static load’ – approach, where quasistatic TO and mode based time integration are performed in a loop. In contrast to many existing methods, damage is used as termination criteria for the iterative optimization procedure. Instead of a global optimum search, the FE model is systematically reinforced until the desired damage level is reached. Due to the consideration of dynamic effects and the integration of damage analysis in the presented optimization algorithm the lifetime of the generated structure is ensured for the given loading condition. Three standard examples from literature and an industrial application with a large number of degrees of freedom (600,000) demonstrate the computational efficiency of the proposed method.