Modeling and control of shape memory alloy actuators to reduce vibration in a building model
Abstract
The objective of this work is to find an alternative actuator for controlling the vibration of a structure based on shape memory alloys. The approach is to first find the bandwidth of these actuators and suggest ways of increasing the bandwidth. Next, the thermomechanical response of these actuators attached to one bay of a multi-story building in a criss-cross manner was analytically investigated using a detailed thermomechanical model of the SMA derived from basic laws of thermodynamics and a constitutive equation developed by Brinson relating stress, strain, temperature, and martensite volume fraction of these materials. To make control studies easier, the thermomechanical equations were put in a state space format. To validate this model, thermomechanical responses of SMA actuators, obtained in a particular experimental implementation, have been compared with results derived from the analytical model using a simple set up. Finally, a local robust controller was designed so that these actuators could track the desired force dictated by the structural controller and reject disturbances due to stretching rate of the actuators. This controller was designed based on Quantitative Feedback Theory. It has been shown that using semiconductor "heat pump" modules for heating and cooling these materials can result in higher bandwidths. It was also shown that using these actuators in a particular implementation can reduce the vibration by factors of 16 when used passively and 55 when used actively. Experimental validation of the analytical model indicates similar trends but the magnitudes differ by close to 15%. Applied force response of the actuators was shown to satisfy the desired specifications in simulation. Based on the work presented here, shape memory alloy actuators represent a viable method to reduce vibration in structures.
Degree
Ph.D.
Advisors
Jones, Purdue University.
Subject Area
Mechanical engineering|Civil engineering
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