Location

Seattle, WA

Start Date

1-1-1996 12:00 AM

Description

Ultrasonic method has become a very popular nondestructive characterizing technique because of its versatility and ease of operation. It can usually detect internal cracks and inclusion type defects in homogeneous or layered materials without any difficulty. However, it has its own shortcomings. It is not very effective in detecting cracks which are vertical to the plate surface. This is because the ultrasonic signal is not reflected by the crack when the signal propagation direction is parallel to the crack surface. The back scattering technique and acoustic microscopy technique are used for detecting such vertical defects. However, when these defects are not located very close to the surface these techniques also encounter difficulties. Use of Lamb waves to detect such defects may be a viable alternative to the currently practiced methods. Theoretical studies by Kundu and Blodgett [1], Yang and Kundu [2,3] and Yang [4] have shown that different Lamb wave modes produce different levels of excitation in various layers in a multilayered solid plate. This phenomenon is exploited here to experimentally generate C-scan images of different layers of a composite plate by propagating Lamb waves of different modes through the plate. The C-scan image generated by receiving the leaky Lamb waves is denoted as the “L-scan” image in this paper.

Volume

15A

Chapter

Chapter 1: Standard Techniques

Section

UT Guided Wave Propagation

Pages

231-238

DOI

10.1007/978-1-4613-0383-1_29

Language

en

File Format

application/pdf

Share

COinS
 
Jan 1st, 12:00 AM

Lamb Wave Mode Sensitivity to Detect Various Material Defects in Multilayered Composite Plates

Seattle, WA

Ultrasonic method has become a very popular nondestructive characterizing technique because of its versatility and ease of operation. It can usually detect internal cracks and inclusion type defects in homogeneous or layered materials without any difficulty. However, it has its own shortcomings. It is not very effective in detecting cracks which are vertical to the plate surface. This is because the ultrasonic signal is not reflected by the crack when the signal propagation direction is parallel to the crack surface. The back scattering technique and acoustic microscopy technique are used for detecting such vertical defects. However, when these defects are not located very close to the surface these techniques also encounter difficulties. Use of Lamb waves to detect such defects may be a viable alternative to the currently practiced methods. Theoretical studies by Kundu and Blodgett [1], Yang and Kundu [2,3] and Yang [4] have shown that different Lamb wave modes produce different levels of excitation in various layers in a multilayered solid plate. This phenomenon is exploited here to experimentally generate C-scan images of different layers of a composite plate by propagating Lamb waves of different modes through the plate. The C-scan image generated by receiving the leaky Lamb waves is denoted as the “L-scan” image in this paper.