Research On Strength Failure Design For Compliant Mechanisms With Topology Optimization

Compliant mechanism is a kind of new mechanisms which could transfer movement and force through the elastic deformation of its components. Compared with the traditional rigid-body mechanism, compliant mechanism has less components, uses less assembly time, has no frictional wear and kinematic pair gaps, so it becomes a hot spot of mechanism research. At present, there are two ways to design compliant mechanisms, one is based on pseudo-rigid-body mode, and the other is achieved through topological optimization theory. When designing compliant mechanism through topological optimization theory, the design domain and the location of input and output are only need, an existing mechanism is unnecessary. And the final mechanism with optimal input-output relationships of force and displacement is given as a result.Topology optimization design for compliant mechanism is a new research field, it developed rapidly and there are many unsolved problems in this field, one of them is the strength failure design for compliant mechanisms. Due to the external load on the compliant mechanism, stress will appear in it, and failure appears if the local stress is too high. Now compliant mechanisms are widely used in aerospace, MEMS, precision mechanics, etc. It is necessary to do research on strength design for compliant mechanisms. Based on topology optimization and finite element theory, this paper focus on strength design for compliant mechanism with topology optimization. The main contributions are as follows:(1) Through numerical examples, the influence such as the elastic modulus, the effects of elastic modulus, thickness of design domain, external load and volume ratio on the maximal equivalent stress is studied.(2) Based on the relationship between volume ratio and maximum equivalent stress, an approach of meeting the intensity requirements via searching the optimal volume ratio is proposed, and numerical examples verify the correctness and effectiveness of this method.(3) Based on full stress design criteria, taking the thickness of elements as design variables, an approach of meeting the intensity requirements via controlling the thickness of elements is proposed. Then, it is improved according to engineering facts. Finally numerical examples verify the correctness and effectiveness of this method.