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Nondestructive Evaluation of Adhesive Bonds via Ultrasonic Phase MeasurementsThe use of advanced composites utilizing adhesively bonded structures offers advantages in weight and cost for both the aerospace and automotive industries. Conventional nondestructive evaluation (NDE) has proved unable to reliably detect weak bonds or bond deterioration during service life conditions. A new nondestructive technique for quantitatively measuring adhesive bond strength is demonstrated. In this paper, an ultrasonic technique employing constant frequency pulsed phased-locked loop (CFPPLL) circuitry to monitor the phase response of a bonded structure from change in thermal stress is discussed. Theoretical research suggests that the thermal response of a bonded interface relates well with the quality of the adhesive bond. In particular, the effective stiffness of the adhesive-adherent interface may be extracted from the thermal phase response of the structure. The sensitivity of the CFPPLL instrument allows detection of bond pathologies that have been previously difficult-to-detect. Theoretical results with this ultrasonic technique on single epoxy lap joint (SLJ) specimens are presented and discussed. This technique has the potential to advance the use of adhesive bonds - and by association, advanced composite structures - by providing a reliable method to measure adhesive bond strength, thus permitting more complex, lightweight, and safe designs.
Document ID
20160014859
Document Type
Conference Paper
Authors
Haldren, Harold A.
(Virginia Univ. Hampton, VA, United States)
Perey, Daniel F.
(NASA Langley Research Center Hampton, VA, United States)
Yost, William T.
(NASA Langley Research Center Hampton, VA, United States)
Cramer, K. Elliott
(NASA Langley Research Center Hampton, VA, United States)
Gupta, Mool C.
(Virginia Univ. Charlottesville, VA, United States)
Date Acquired
December 22, 2016
Publication Date
September 19, 2016
Subject Category
Composite Materials
Report/Patent Number
Paper No. 2909
NF1676L-23495
Meeting Information
American Society for Composites Technical Conference(Williamsburg, VA)
Funding Number(s)
WBS: WBS 826611.04.07.02
Distribution Limits
Public
Copyright
Public Use Permitted.

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