Topology optimization of compliant mechanisms with desired structural stiffness

• A new and simple BESO method is proposed for designing compliant mechanisms.
• Various 2D and 3D mechanism designs with or without hinge regions are obtained.
• The study reveals the formation of hinges associated with structural stiffness.
• The detail recommends are given for the design of compliant mechanisms.

This paper develops a bi-directional evolutionary structural optimization (BESO) method for topological design of compliant mechanisms. The design problem is reformulated as maximizing the flexibility of the compliant mechanism subject to the mean compliance and volume constraints. Based on the finite element analysis, a new BESO algorithm is established for solving such an optimization problem by gradually updating design variables until a convergent solution is obtained. Several 2D and 3D examples are presented to demonstrate the effectiveness of the proposed BESO method. A series of optimized mechanism designs with or without hinge regions are obtained. Numerical results also indicate that the flexibility and hinge-related property of the optimized compliant mechanisms can be controlled by the desired structural stiffness.