Speaker: Jennifer E. Michaels, Associate Professor
School of Electrical & Computer Engineering
Georgia Institute of Technology

Title: Processing of Diffuse Ultrasonic Signals for Structural Health Monitoring

Date: November 7, 2003

Time: 3:00 pm

Location: GCATT Room 325

Abstract:
The use of permanently mounted sensors to monitor the health of critical structures such as airplanes, bridges and buildings is quickly becoming a reality as sensors for measuring such physical quantities as temperature, moisture and strain become smaller and more robust. However, these devices are limited to point, or local, measurements and thus do not truly interrogate the volumetric state of the structure. Sparse arrays of permanently mounted ultrasonic sensors, acting as both sources and receivers, can send ultrasonic energy throughout the entire structural volume and thus have the potential to detect critical changes. Necessary for implementation are the development of methods for processing the received ultrasonic signals so that structural changes that may lead to catastrophic failure can be reliably detected with an acceptably low false alarm rate. A significant complication is that benign environmental effects such as changes in temperature and surface conditions can cause larger changes in the ultrasonic signals than actual flaws. Diffuse ultrasonic signals, which result from waves generated by point-like sources after many reverberations in a structure, are of particular interest due to their ease of generation and sensitivity to change, although they are very difficult to interpret. This seminar presents recent work at Georgia Tech in detecting and classifying changes in diffuse ultrasonic signals in structures subjected to both environmental changes and introduction of artificial defects.

Biography:

Jennifer Michaels came from industry to join the faculty in the School of Electrical and Computer Engineering at Georgia Tech in 2002. She received her Bachelor’s degree in Electrical Engineering from Georgia Tech in 1976, and her Master’s and Ph.D. degrees in Theoretical and Applied Mechanics from Cornell University in 1982 and 1984, respectively. She subsequently worked in industry, first as co-founder of a startup company, and later as Manager of Systems Development at Panametrics, Inc., a world leader in custom automated ultrasonic inspection systems. Since her arrival at Georgia Tech, she has jointly established the ECE Ultrasonic Measurements Laboratory with her husband, Thomas E. Michaels, who is also on the ECE faculty. Her current research is concentrated on the development of ultrasonic sensors and methods for health monitoring of civil and aerospace structures, and developing ultrasonic nondestructive evaluation methods for high-speed, large area imaging.

Slides: sem11_07_2003_Jennifer_Michaels.pdf

Speaker:	Jennifer E. Michaels, Associate Professor School of Electrical & Computer Engineering Georgia Institute of Technology
Title:	Processing of Diffuse Ultrasonic Signals for Structural Health Monitoring
Date:	November 7, 2003
Time:	3:00 pm
Location:	GCATT Room 325
Abstract:	The use of permanently mounted sensors to monitor the health of critical structures such as airplanes, bridges and buildings is quickly becoming a reality as sensors for measuring such physical quantities as temperature, moisture and strain become smaller and more robust. However, these devices are limited to point, or local, measurements and thus do not truly interrogate the volumetric state of the structure. Sparse arrays of permanently mounted ultrasonic sensors, acting as both sources and receivers, can send ultrasonic energy throughout the entire structural volume and thus have the potential to detect critical changes. Necessary for implementation are the development of methods for processing the received ultrasonic signals so that structural changes that may lead to catastrophic failure can be reliably detected with an acceptably low false alarm rate. A significant complication is that benign environmental effects such as changes in temperature and surface conditions can cause larger changes in the ultrasonic signals than actual flaws. Diffuse ultrasonic signals, which result from waves generated by point-like sources after many reverberations in a structure, are of particular interest due to their ease of generation and sensitivity to change, although they are very difficult to interpret. This seminar presents recent work at Georgia Tech in detecting and classifying changes in diffuse ultrasonic signals in structures subjected to both environmental changes and introduction of artificial defects.
Biography:	Jennifer Michaels came from industry to join the faculty in the School of Electrical and Computer Engineering at Georgia Tech in 2002. She received her Bachelor’s degree in Electrical Engineering from Georgia Tech in 1976, and her Master’s and Ph.D. degrees in Theoretical and Applied Mechanics from Cornell University in 1982 and 1984, respectively. She subsequently worked in industry, first as co-founder of a startup company, and later as Manager of Systems Development at Panametrics, Inc., a world leader in custom automated ultrasonic inspection systems. Since her arrival at Georgia Tech, she has jointly established the ECE Ultrasonic Measurements Laboratory with her husband, Thomas E. Michaels, who is also on the ECE faculty. Her current research is concentrated on the development of ultrasonic sensors and methods for health monitoring of civil and aerospace structures, and developing ultrasonic nondestructive evaluation methods for high-speed, large area imaging.
Slides:	sem11_07_2003_Jennifer_Michaels.pdf