Evolutionary topology optimization of hinge-free compliant mechanisms

• This paper develops a new bi-directional evolutionary structural optimization (BESO) method for the design of compliant mechanisms.
• A new objective function is proposed to maximize the desirable displacement and preclude the formation of hinges.
• Numerical examples show optimized designs for various hinge-free compliant mechanisms.
• Compared with other topology optimization methods, the proposed BESO algorithm provides clear solid–void topologies of compliant mechanisms without any “gray” area.

This paper develops a bi-directional evolutionary structural optimization (BESO) method for the design of hinge-free compliant mechanisms. A new objective function is proposed to maximize the desirable displacement and preclude the formation of hinges simultaneously. Sensitivity numbers are derived according to the variation of the objective function with respect to the design variables. Based on the resulting sensitivity numbers, the BESO procedure is established by gradually removing and adding elements until an optimal topology is achieved. Several 2D and 3D examples are given to demonstrate the effectiveness of the proposed BESO method for the design of various hinge-free compliant mechanisms.

How to design an optimal topology of an inverter mechanism without any hinge? The top picture shows the design domain and boundary conditions. The desired output displacement is opposed to the direction of the applied force. This paper proposed an optimization algorithm to find the optimal topology of the invert mechanism as shown in the below picture. The deformed shape shows that the desired output displacement is successfully obtained through elastic deformation of the hinge-free compliant mechanism.Figure optionsDownload as PowerPoint slide