Papers by Author: Shi Zhu Wen

Abstract: A theoretical model of the displacement-heating response of the differential shape memory alloy (SMA) actuator was developed. The model was constructed by using the constitutive equation and considering the force equilibrium and the energy balance on the SMA. The output displacement was predicted as a function of the heating power by the model and the simulations of the output displacement and temperature of the SMA actuator were also obtained. To evaluate the model, a prototype actuator which was made up of two SMA coil springs placed opposite each other was briefly described and an experimental setup of the SMA actuator was developed to study the relations among the heating power, the temperature and the output displacement of the SMA actuator. The similarity between the simulated and experimental results verified the proposed model, which indicated that the proposed model could express the thermo-mechanical behavior of the differential Ni-Ti SMA actuators.

Abstract: The influence of electro-mechanical operation conditions on the actuation capabilities of the piezoelectric bimorph is investigated in this paper. The objective is to compare the performance of the piezoelectric bimorph in different operation conditions and to determine the optimum operating conditions. An experimental set-up is built, and a series of experiments are presented to investigate the static and dynamic characteristics of the bimorph, including tip displacements of the bimorph under different preloads, dynamic response at different drive frequencies, step response and creep. Some properties such as displacement output, force output and hysteresis of the piezoelectric bimorph under different operating conditions are evaluated. Experimental results indicate strong dependence of both elastic and piezoelectric properties of the bimorph on the operating conditions.