Design of compliant constant-output-force mechanisms using topology optimization

ABSTRACT

Compliant constant-force mechanisms (CCFMs) are compliant mechanisms that provide nearly constant forces over prescribed deflection ranges. This study proposes a topology optimization method for designing hinge-free compliant constant-output-force mechanisms. Bifurcation cause the objective function to oscillate, leading to convergence failure. Therefore, a constraint for preventing bifurcation in constant-output-force mechanisms is proposed. Moreover, a minimum scale constraint method that extends the design domain is utilized in the proposed optimization algorithm. The relationship between the minimum length scale and the force variation in the optimized CCFM is obtained and discussed, and an optimized CCFM is fabricated and tested. The optimized CCFM exhibits a force variation of 0.7% over a constant-force stroke of 26% of the CCFM length and is thus competitive among recently proposed CCFMs.

KEYWORDS:

• Topology optimization
• compliant mechanism
• constant force mechanism
• minimum length scale
• bifurcation

Acknowledgements

This work was supported by Guangzhou Basic and Applied Basic Research Foundation, research start-up funding from Guangdong Polytechnic Normal University (grant number 99/991620450) and the Research Fund of the Guangdong Key Laboratory of Precision Equipment and Manufacturing Technique (grant number 1745801).

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Additional information

Funding

This work was supported by Guangdong Polytechnic Normal University [grant number 99/991620450]; Guangdong Key Laboratory of Precision Equipment and Manufacturing Technique [grant number 1745801].