Design and optimization of a clamping mechanism for piezoelectric inchworm actuator

Abstract

This paper presents the structure design and optimization of a clamping mechanism for an inchworm-type piezoelectric actuator. Since the performance of clamping mechanism will decide the feasibility of inchworm-type actuator, design and fabrication of better clamping mechanism will continuously be part of the focus in inchworm-type piezoelectric actuator design. Currently the driving force of piezoelectric inchworm actuator is usually not high enough. In order to more efficiently design the clamping mechanism, numerical simulation is performed to select the geometry parameters that can improve the performance. As a kind of numerical simulation method, ANSYS Optimization Design Method is used to analyze and optimize the performance of the clamping mechanism. In this design, a special kind of piezoelectric ceramic and 65Mn are chosen as the main materials; the dimensions of clamping mechanism and a pre-load force are chosen as design variables; the maximum von Misses stress and the holding forces are chosen as state vectors. When clamping the holding force should reach the maximum and when releasing the holding force should arrive at the minimum. In accordance with this requirement, an objective function is constructed. When the objective function reaches the minimum value, the best design set will be attained. The results of simulation experiments and optimization analysis show that the clamping mechanism can reach the desired performance and has an adequate self-locking force when power off. A prototype of the clamping mechanism has been fabricated and tested to validate the simulation results.