Lamb Wave Generation Based on Laser Ablation with Damage Prevention

Abstract

This paper proposes a method of Lamb wave generation based on laser ablation with damage prevention chip for non-contact damage detection for huge objects such as aircraft structures. In recent years, a damage detection method using Lamb waves has been studied. In many cases, contact devices such as a piezoelectric transducer and an ultrasonic probe are used to generate Lamb waves. However, these methods take a lot of measurement time to inspect damage. Although Lamb waves generation using laser ultrasonic as non-contact method has been studied to improve the disadvantage, generated Lamb waves are measured with low signal-to-noise ratio. Therefore, laser ultrasonic is difficult to be applied to detect damage in wide area. We have realized a Lamb wave generation using a laser ablation excitation force. On the other hand, laser ablation causes submillimeter damage on target structures. In this paper, we propose a method of Lamb wave generation with damage prevention chip on the duralumin plate. Lamb waves were generated by Nd: YAG pulse laser and detected by scanning laser Doppler vibrometer. We evaluated the characteristics of broadband Lamb wave generation by laser ablation with damage prevention chip.