Experimental Evaluation of Smart Composite Device with Shape Memory Alloy and Piezoelectric Materials for Energy Dissipation

Abstract

Based on the superelasticity of shape memory alloy (SMA) and the electrodeformation of a piezoelectric transition (PZT) ceramic, a novel SMA/PZT composite control device (SPCCD) was designed and its energy dissipation performance and neural network constitutive model investigated. The composite control device is composed of a variable friction unit that contains four rectangular PZT actuators and an SMA unit that includes energy-dissipation and resettable wires. The friction force can be adjusted in real time by applying the voltage to the PZT actuators and the SMA wires can dissipate energy via hysteresis and provide a reset force. This composite control device’s different components participate in energy dissipation at different seismic intensities. Electro-mechanical tests are conducted to evaluate the performance of the SPCCD with different displacement amplitudes, loading/unloading frequencies, and excitation voltages. Correspondingly, the force-displacement curves are acquired, and the influences of the lap hysteretic energy dissipation, equivalent stiffness, and equivalent damping ratio on the energy dissipation capacity of the SPCCD are analyzed. Then, the excitation voltage and loading history are considered as neuronal input to establish a back-propagation (BP) neural network model of the SPCCD. The experimental results show that the hysteresis curves of the SPCCD are approximately symmetrical and the loading/unloading frequency has little effect on the mechanical properties. The maximum control force of the SPCCD linearly increases with an increase in the excitation voltage, and its semiactive PZT unit has a large adjustable range for energy dissipation. Thus, the SPCCD is reasonably designed. Moreover, the BP network constitutive model is able to accurately track the output of the SPCCD, providing an effective means for the establishment and application of the constitutive model to SMA-based composite control devices.