Topology optimization of compliant mechanisms

Abstract

A compliant mechanism (CM) is a special kind of mechanism which has seen an increase in use in various high-tech applications. A CM is a structure designed with the intention to deform: motion is achieved by deformation of flexible members of its body. CMs are designed by topology optimization (TO) algorithms, which use boundary conditions as an input and give a design as an output. Additive manufacturing (AM) is used to fabricate the designed CMs, as geometric complexity is much less of a problem compared to conventional methods. One issue with AM is that local overheating during printing can cause defects in the design, specifically for metal designs, as the temperature is very high during printing. In this thesis, a CM is designed using TO and fabricated using AM. The design is then printed and analysed for overheating defects to determine if any defects due to overheating are present. Also, a computationally inexpensive AM model is integrated into the TO for CM, which can detect zones prone to local overheating. Next to that, the robust optimization method is used to obtain a design which needs much less post-processing. The obtained designs are compared to existing TO methods and it is found that the added constraint can reduce overheating by a large amount while maintaining a relatively high CM performance.