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Application of a peak-valley detector for secant stiffness measurementsA technique for monitoring the change in secant stiffness of composite specimens during cyclic-fatigue loading computes the secant modulus every five seconds. A resettable peak-valley detector, which captures and holds the maximum and minimum values of an input analog signal, is used in conjunction with a multichannel data acquisition unit. This detector is also used in conjunction with an analog switch to halt the cycling of the specimen after a certain degradation of stiffness develops for the application of NDE techniques. Results for a T300/5208 graphite-epoxy specimen are presented in the form of a stiffness vs number of cycles curve.
Document ID
19840037587
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Stiffler, R. (Virginia Polytechnic Institute and State University Blacksburg, VA, United States)
Date Acquired
August 12, 2013
Publication Date
January 1, 1984
Publication Information
Publication: Experimental Techniques
Volume: 8
ISSN: 0732-8818
Subject Category
Instrumentation And Photography
Accession Number
84A20374
Funding Number(s)
CONTRACT_GRANT: NAG1-232
Distribution Limits
Public
Copyright
Other

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