NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Detection of Delamination in Composite Beams Using Broadband Acoustic Emission SignaturesDelamination in composite structure may be caused by imperfections introduced during the manufacturing process or by impact loads by foreign objects during the operational life. There are some nondestructive evaluation methods to detect delamination in composite structures such as x-radiography, ultrasonic testing, and thermal/infrared inspection. These methods are expensive and hard to use for on line detection. Acoustic emission testing can monitor the material under test even under the presence of noise generated under load. It has been used extensively in proof-testing of fiberglass pressure vessels and beams. In the present work, experimental studies are conducted to investigate the use of broadband acoustic emission signatures to detect delaminations in composite beams. Glass/epoxy beam specimens with full width, prescribed delamination sizes of 2 inches and 4 inches are investigated. The prescribed delamination is produced by inserting Teflon film between laminae during the fabrication of composite laminate. The objectives of this research is to develop a method for predicting delamination size and location in laminated composite beams by combining smart materials concept and broadband AE analysis techniques. More specifically, a piezoceramic (PZT) patch is bonded on the surface of composite beams and used as a pulser. The piezoceramic patch simulates the AE wave source as a 3 cycles, 50KHz, burst sine wave. One broadband AE sensor is fixed near the PZT patch to measure the AE wave near the AE source. A second broadband AE sensor, which is used as a receiver, is scanned along the composite beams at 0.25 inch step to measure propagation of AE wave along the composite beams. The acquired AE waveform is digitized and processed. Signal strength, signal energy, cross-correlation of AE waveforms, and tracking of specific cycle of AE waveforms are used to detect delamination size and location.
Document ID
19960047694
Acquisition Source
Langley Research Center
Document Type
Conference Paper
Authors
Okafor, A. C.
(Missouri Univ. Rolla, MO United States)
Chandrashekhara, K.
(Missouri Univ. Rolla, MO United States)
Jiang, Y. P.
(Missouri Univ. Rolla, MO United States)
Date Acquired
August 17, 2013
Publication Date
March 1, 1996
Publication Information
Publication: Proceedings of the 4th Annual Workshop: Advances in Smart Materials for Aerospace Applications
Subject Category
Composite Materials
Accession Number
96N33304
Funding Number(s)
CONTRACT_GRANT: N00014-94-1-1200
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
Document Inquiry

Available Downloads

There are no available downloads for this record.
No Preview Available