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Proceedings Paper

Detection of layup errors in prepreg laminates using shear ultrasonic waves
Author(s): David K. Hsu; Brent A. Fischer
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Paper Abstract

The highly anisotropic elastic properties of the plies in a composite laminate manufactured from unidirectional prepregs interact strongly with the polarization direction of shear ultrasonic waves propagating through its thickness. The received signals in a 'crossed polarizer' transmission configuration are particularly sensitive to ply orientation and layup sequence in a laminate. Such measurements can therefore serve as an NDE tool for detecting layup errors. For example, it was shown experimentally recently that the sensitivity for detecting the presence of misoriented plies is better than one ply out of a 48-ply laminate of graphite epoxy. A physical model based on the decomposition and recombination of the shear polarization vector has been constructed and used in the interpretation and prediction of test results. Since errors should be detected early in the manufacturing process, this work also addresses the inspection of 'green' composite laminates using electromagnetic acoustic transducers (EMAT). Preliminary results for ply error detection obtained with EMAT probes are described.

Paper Details

Date Published: 15 November 1996
PDF: 8 pages
Proc. SPIE 2948, Nondestructive Evaluation for Process Control in Manufacturing, (15 November 1996); doi: 10.1117/12.259209
Show Author Affiliations
David K. Hsu, Iowa State Univ. (United States)
Brent A. Fischer, Iowa State Univ. (United States)

Published in SPIE Proceedings Vol. 2948:
Nondestructive Evaluation for Process Control in Manufacturing
Richard H. Bossi; Tom Moran, Editor(s)

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