Detection of interfacial debonding in epoxy resin-bonded lead-steel structure using laser ultrasonics

Abstract

The epoxy resin-bonded lead-steel structures are widely used in nuclear industry for the protection of intense radiation, and the accurate detection of the interfacial debonding is very important. This paper studies the detection of interfacial debonding in the epoxy resin-bonded lead-steel structure using laser ultrasonic method. Two-dimensional finite element method is used to simulate the propagation of laser generated ultrasonic waves in lead-steel bonded structure and the interaction with interfacial debonding. The wave reflection and the attenuation occurred at the good bonding interface and the debonding interface are clearly shown. The reflection and attenuation of laser ultrasonic induced by the interfacial debonding are analyzed theoretically and experimentally, and the feature signals for the characterization of interfacial debonding are extracted. The appropriate wave frequency and measurement position are analyzed. The C-scan image of the specimen is obtained using the laser ultrasonic method. The results show that the laser ultrasonic method is effective for the noncontact detection of interfacial debonding in epoxy resin-bonded lead-steel structure, and the interfacial debonding with a diameter larger than 4 mm can be imaged clearly with laser ultrasonic C-scan method.