Thermal control of a shape memory alloy for actuation in the Sommerfeld effect of a non-ideal system

Abstract

The studies of mechanical vibration and the behavior of a dynamic system are characterized as essential activities in engineering projects. In addition to the mechanical vibration, electromechanical systems can present another type of behavior, where occur an energy exchange between the mechanical structure and the source(s) of excitation. These systems are classified as non-system systems. In this type of system, at the same time that the power supply directly influences the dynamics of the mechanical structure, the excitation source suffers a reciprocal influence, altering his behavior and causing a loss of energy that would be used by the motor(s). Nowadays, the interest in the use of the so-called smart materials for the attenuation and control of the effects that can appear in these complexes systems are increasing. The smart materials have the ability to change some specific property in the presence of a certain impulse, changing physical characteristics when necessary and thus, being able to serve as sensors and/or actuators. This master's thesis contributes to the study of the smart materials area proposing the control of the vibration and Sommerfeld effect in a non-ideal system through the use of a Shape Memory Alloy (SMA) actuator - material that has the ability to change the physical form when undergoing a change in his temperature. Initially, the characterization of the SMA actuator is done through a practical experiment, where several electric voltages are applied to the material. These voltages are subsequently related to the physical recovery, electric current consumed and to the surface temperatures of the actuator. To obtain the temperatures of the SMA material were used Fiber Bragg Grating (FBG) sensors, specific for this application. To demonstrate the functionality of the shape memory actuator, an equivalent prototype of the nonideal type system was constructed and instrumented. After analyzing the behavior of the system, it was proposed the installation of an SMA actuator that will be activated through a projected ON/OFF controller.