An Automatic Crack Detection Algorithm for Vibrothermography Sequence-of-Images Data

• Activity Number: 352
• Type: Contributed
• Date/Time: Tuesday, August 3, 2010 : 10:30 AM to 12:20 PM
• Sponsor: Section on Physical and Engineering Sciences
• Author(s): William Q. Meeker*+ and Ming Li and Steve Holland
• Companies: Iowa State University and Iowa State University and Iowa State University
• Keywords: Matched Filter ; Probability of Detection ; Thermal Acoustics

Abstract

Vibrothermography (VTG) is a technique for finding cracks through frictional heat given off in response to vibration. VTG provides a sequence of infrared images as output of the inspection process. A fast and accurate automatic crack-detection algorithm for the VTG data will increase the productivity of VTG inspections. A matched filter is the optimal linear filter to maximize the signal-to-noise ratio in the presence of additive uncorrelated noise. Based on key features from images of known cracks, we can construct a three-dimensional matched filter to detect cracks from the VTG data. In this paper, we evaluate a matched filter developed from VTG inspection data. We compare the probability of detection for the matched filter detection algorithm and a simpler detection algorithm that is based on a scalar measure of the amount of heat generated in an inspection. Our results show the match