RECENT DEVELOPMENTS IN SONIC IR IMAGING

摘要

We describe recent developments in sonic infrared (IR) imaging. The sonic IR imaging NDE technique uses a single short pulse of sound to cause cracks to heat up and become visible in the infrared. Results of recent experiments on metal aircraft structures and composite test samples with natural and simulated defects are presented in this paper. Examples of defects in metals include cracks originating under fasteners and cracks in mechanical parts. Examples of defects in composites include fatigue cracks, pillow inserts, pull-tab disbonds, skin-to-core disbonds, etc. Both 20kHz and 40kHz ultrasonic excitation sources were used for studying the frequency effect. Vibrational behavior of surfaces near the defects was monitored and correlated with the IR signals.