Optimal design of the loading mechanism in a tester for micro-mechanical properties

The loading mechanism is one of the most important parts of a tester for micromechanical properties, by which specimens can be loaded and deformed on both the microscopic scale and one millimetre scale with a monolithic two-stage flexure- hinged structure. The mechanical characteristics of the two-stage loading mechanism are analyzed separately. On the basis of this analysis, the problems in the optimal structure design about the first and second stages are discussed, and the optimal models are presented respectively according to the mechanism's practical application requirements. The genetic algorithm and fuzzy optimization methods were used to solve the optimization problems in the design of the mechanism. Based on the optimal solutions, a finite element model of the mechanism was established and a prototype of the loading mechanism was also made. The comparative results of finite element simulations and experiments showed that the optimization procedure is effective and that the optimal results could satisfy the needs of the mechanism's application requirements.