Performance Modeling of a Smart Material Hydraulic Actuator

Smart Material Hydraulic Actuators (SMEHAs) allow high-energy-density materials, such as piezoelectrics and magnetostrictives, to be used to develop compact, high-power actuators. Hydraulic rectification using check valves converts the high-frequency, small-displacement motion of a smart material to large displacements of a hydraulic actuator. In this paper, the performance of a magnetostrictive actuator is evaluated over a range of input frequencies and loading conditions and compared to model results of the overall system. The system’s dynamic performance is found to depend highly on the response of both the check valves used to rectify the motion of the smart material driver and the fluid system, including the passages connecting the smart material pump to the output hydraulic cylinder. Using AMESim, a model is developed for the response of the system and compared to experimental results.

Smart Material Electrohydrostatic Actuator for Intelligent Transportation Systems

Future intelligent transportation systems require actuation systems that are lightweight, compact and have a large power density. Due to their solid-state operation, fast frequency response, and high power-to-weight ratio, electrohydrostatic actuators based on smart materials are attractive as a replacement for conventional hydraulic actuators. This paper is focused on the development of a smart material pump for EHAs in which mechanical vibrations produced by a magnetostrictive terbiumiron-dysprosium alloy are rectified by means of diode-type mechanical reed valves. A maximum blocked pressure differential of 1100 psi is achieved with a power consumption of 84 W. A linear dynamic system model of the magnetostrictive pump is presented. The linear model quantifies the maximum pressure and electromechanical coupling of the magnetostrictive pump and facilitates the determination of system parameters from simple experimental measurements.