Session: SYMP 4-8: Shape Memory Alloy Applications

Paper Number: 148300

148300 - Shape Memory Alloys for Variable Frequency Wind Chimes 

For decades shape memory alloys (SMA) and other active materials have been considered for a wide range of practical applications including medical devices, compact actuators, multifunctional materials, and morphing structures. However, only a handful of projects have utilized the unique properties of SMAs for aesthetic purposes such as sculptures or art installations that interact with the changing ambient environment. In 2022 an undergraduate team of Materials Science and Engineering (MSEN) students at Texas A&M were tasked with designing a wind chime that would change pitch and tone as a function of temperature. Wind chimes are a popular garden ornament. Most are composed of two primary elements, a clapper that is driven by the wind and one or more chimes that resonate when struck by the clapper producing a pleasing tone. The most common wind chime design has a single clapper surrounded by vertically hanging tubes of varying geometries that are designed to resonate at complimentary frequencies. The students developed two concepts. The first used the shape memory effect of SMA springs to either move the clapper or modify the overall assembly so the clapper would strike different chimes depending on the ambient temperature. The second concept utilized tubular chimes made from SMA. Rather than shape change, the second concept exploits the change in bulk modulus that the SMA tubes experience as they go through thermally induced transformation. The thermally induced change in modulus modifies the resonant frequency of the tubes and the pitch and tone of the wind chime. In this presentation we will briefly review the student’s design concepts and then discuss in detail the most promising approach of using SMA as the base material for tubular chimes. The effect of the SMA’s thermally induced phase transformation on its bulk modulus and therefore the chime’s resonant frequency will be discussed and data on tubular chimes made from commercially available NiTi tubes will be presented. The effect of geometry and temperature on the SMA tube’s resonant pitch and tone will be shown and the data will be compared to the theory for wind chime design. Additionally, the resonant frequency of SMA sheet and bar elements as a function of temperature will be shown as an alternative to tubular chime components.  The practicality of SMA based wind chimes will be evaluated including a discussion of the range of worldwide ambient temperatures and potential alloy compositions best suited to respond to the specific temperature ranges in a given region.  

Presenting Author: James Mabe MabeCo Productions LLC

Presenting Author Biography: James Mabe retired from Boeing as a Technical Fellow (TF) in 2022, after 36 years of research focused on adaptive systems and smart materials. Projects involved a range of advanced adaptive system demonstrations including component and system modeling, benchtop tests, wind tunnel models, and full-scale flight tests. Mr. Mabe was the Boeing Subject Matter Expert (SME) in the field of advanced actuators, system level design, and testing of emerging technologies. His research experience at Boeing regularly included significant collaboration with universities, DoD, NASA, and government research labs. He led numerous teams of industry, government, and academic experts to develop approved standards for shape memory alloys (SMA) that support development and certification of SMA materials and applications, resulting in the publication of two ASTM Test Methods with additional test methods in development. Following retirement from Boeing, Mr. Mabe joined the faculty at Texas A&M as a Professor of Practice and Principal Research Engineer in the Aerospace and Material Science and Engineering Departments. At Texas A&M Mr. Mabe taught senior design courses, authored research proposal, and supported government and industry funded research. Mr. Mabe holds over 25 patents related to active materials and advanced actuator technology. He graduated Summa Cum Laude with a BSEE in Electrical Engineering from Seattle Pacific University in 1995.

Authors:

James Mabe
Ibrahim Karaman
Kadri Atli