title: Numerical simulation of damage detection using laser-generated ultrasound.
abstract: Laser ultrasonic techniques have been widely investigated due to its high spatial resolution and capacity for remote and noncontact measurement. In this study, the laser induced ultrasonic wave on an aluminum plate is simulated, and a nonlinear feature is used to detect a micro crack introduced in the plate model. A multi-physics simulation is conducted and optimized considering the effect of thermal diffusion. A nonlinear feature, called Bhattacharyya Distance (BD), is calculated to show the crack-induced geometric difference among the state space attractors obtained from closely spaced measurement points near the crack. First, a 3D model is built, and its simulation result is compared with an experiment performed using a noncontact laser ultrasonic measurement system. Then, by creating a micro crack in the model, BD is extracted and the crack is successfully detected and visualized. Finally, the effects of BD parameters, such as embedding dimension and frequency band, on damage visualization are investigated.
authors.affiliation: Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-338, Republic of Korea.
authors.forename: Peipei
authors.initials: P
authors.lastname: Liu
authors.affiliation: Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-338, Republic of Korea.
authors.forename: Ab Wahab
authors.initials: AW
authors.lastname: Nazirah
authors.affiliation: Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-338, Republic of Korea. Electronic address: hoonsohn@kaist.ac.kr.
authors.forename: Hoon
authors.initials: H
authors.lastname: Sohn
keywords: Damage visualization; Laser ultrasonics; Numerical simulation; State space; Thermal diffusion