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Proceedings Paper

Stiffness measurement and defect detection in laminated composites by dry-coupled plate waves
Author(s): W. Huang; Steve M. Ziola; John F. Dorighi; Michael R. Gorman
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Paper Abstract

This paper presents a novel non-destruction technique for stiffness measurement and defect detection in laminated composite plates using dry-coupled ultrasonic plate waves. The technique involves using a pari of wide-band transducers normally-placed on the plate surface to generate and receive the lowest order flexural mode (A0 mode) at low frequencies. The stiffness measurement first experimentally determines the phase velocity of the A0 mode, then reconstructs the stiffness matrix components D11, D22, A44, and A55 utilizing the higher order plate wave solution for laminated composites and a nonlinear least-square optimization method. Such stiffness measurements can be used for quality control/quality assurance of in-service composite structures or composite manufacturing process, and for verification of composite design. As well as the stiffness measurements, the time-of- flight and amplitude measurements are achieved by keeping the pulser-receiver distance and pulsing frequency constant, and scanning the transducers over the plate surface. Since the plate wave measurements are based on the direct first arrival of the flexural mode, they are not limited by the thinness of the specimen as the conventional c-scan. Examples of stiffness measurement and defect detection are given, including cases of impact damage, delamination and debonding in composite structures. Finally the main hardware and software features of a recently-developed F-Scan system are also described.

Paper Details

Date Published: 15 March 1998
PDF: 11 pages
Proc. SPIE 3399, Process Control and Sensors for Manufacturing, (15 March 1998); doi: 10.1117/12.302538
Show Author Affiliations
W. Huang, Digital Wave Corp. (United States)
Steve M. Ziola, Digital Wave Corp. (United States)
John F. Dorighi, Digital Wave Corp. (United States)
Michael R. Gorman, Digital Wave Corp. (United States)

Published in SPIE Proceedings Vol. 3399:
Process Control and Sensors for Manufacturing
Richard H. Bossi; David M. Pepper, Editor(s)

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