Shape Memory Alloy Films for Increasing Amplitude of Photoacoustic Signals
Open Access
Author:
Bozek, Andrew
Graduate Program:
Engineering Science and Mechanics
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
March 21, 2022
Committee Members:
Albert Segall, Program Head/Chair Clifford Jesse Lissenden, III, Thesis Advisor/Co-Advisor Mark William Horn, Committee Member Reginald F Hamilton, Committee Member
Keywords:
Ultrasound Thin Films Shape Memory Alloy
Abstract:
Laser based ultrasound is a noncontact method of generating ultrasound for detecting flaws in parts. One of the main drawbacks of this method is the poor signal quality and difficulty of detecting the wave. Previous work has shown that a thin film of a shape memory alloy increases the ultrasonic wave amplitude by having a favorable photoacoustic effect. This material was proposed to increase signal amplitude due to a unique coefficient of thermal expansion associated with the shape memory phase transformation. A series of tests were conducted to investigate how material properties affect the photoacoustic signal amplitude. The shape memory alloy showed an increase in signal amplitude when heated above the phase transformation before absorbing the laser energy. The results do not support the hypothesis that the unique coefficient of thermal expansion is the cause for the increase in signal amplitude.
