Wavelet Analysis of Laser-Generated Surface Waves in a Layered Structure With Unbond Regions

Author:

Wu T.-T.1,Chen Y.-Y.1

Affiliation:

1. Institute of Applied Mechanics, National Taiwan University, Taipei, Taiwan

Abstract

This paper presents the results on the utilization of a wavelet transform to study the dispersion of laser-generated surface waves in an epoxy-bonded copper-aluminum layered specimen with and without unbond areas. Laser ultrasonic experiments based on the point-source/point-receiver (PS/PR) technique were undertaken to measure surface wave signals in a layered specimen. The wavelet transform with a Morlet wavelet function was adopted to analyze the group velocity dispersion of the surface wave signals. A novel hybrid formula for group velocity dispersion is proposed for measurements across unbond regions. Results and data obtained are in good agreement with calculated and experimental dispersion curves. The general behavior of the group velocity dispersion for different measurement, configurations can be utilized to differentiate the unbond regions in a layered structure.

Publisher

ASME International

Subject

Mechanical Engineering,Mechanics of Materials,Condensed Matter Physics

Reference26 articles.

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3. Determinations of Anisotropic Elastic Constants Using Laser Generated Surface Waves;Chai;J. Acoustic Soc. Am,1994

4. Chen Y-C 1994 Dispersion of Surface Waves in an Anisotropic Layered Medium M.S. thesis National Taiwan University

5. Noncontact Laser Ultrasonics for Detecting Subsurface Lateral Defects;Cho;NDT&E International,1996

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