Multi-objective topology optimization of piezoelectric stick-slip actuators for design and performance analysis

The conflicting requirements of stiffness and flexibility present a key design challenge for compliant mechanisms in piezoelectric stick-slip actuators. To overcome this, we introduce a multi-objective topology optimization scheme that employs a combined objective function, simultaneously minimizing strain energy and maximizing the displacement amplification ratio. The multi-objective function addresses two key aspects, the strain energy minimization term serves to improve the stiffness of the flexible hinges, whereas the displacement amplification ratio maximization term is designed to increase their deformation, thus achieving greater flexibility in the compliant mechanism. To address the disparity in the magnitude of the objective function, a normalization technique is utilized. The sensitivities are determined using the adjoint method, and the optimization challenge is tackled through the Method of Moving Asymptotes (MMA). The stiffness and flexibility of the compliant mechanism are verified by finite element analysis (FEA), then the prototype is fabricated. The results from the experiments indicate a load capacity of 170 g and an actuator velocity of 16.57 mm/s. The findings validate the efficiency of the proposed multi-objective topology optimization approach.