Abstract: Topological design of compliant mechanisms may be prone to generate de facto hinges which results in stress concentration and poor fatigue performance. In order to suppress the hinges, a method for topology optimization of compliant mechanisms with maximum stress constraint is proposed. The modified solid isotropic material with penalization approach is adopted. The maximization of mutual strain energy of compliant mechanisms is applied as the objective function. The stress constraints for all elements are aggregated into a global stress constraint using the P-norm method. The adaptive constraint scaling method is adopted to transforms the P-norm stress to approximate the maximum stress. The maximum stress and structural volume are used as the constraints. The model for topological design of compliant mechanisms with maximum stress constraint is established. The globally convergent version of the method of moving asymptotes is applied to solve the optimization problem. The results of numerical examples show that the appearance of de facto hinges can be suppressed effectively using the proposed method. As the stress limit is decreased, the obtained mechanisms is gradually transformed from the lumped compliant mechanism to the distributed compliant mechanism. At the same time the stress is more uniformly distributed, the mutual strain energy of the mechanism decreases.

Key words: compliant mechanisms, maximum stress constraints, P-norm approach, topology optimization