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Input-output characterization of fiber composites by SH wavesInput-output characterization of fiber composites is studied theoretically by tracing SH waves in the media. A fiberglass epoxy composite is modeled as a homogeneous transversely isotropic continuum plate. The reflection of an SH wave at a stress-free plane boundary in a semi-infinite transversely isotropic medium is considered first. It is found that an incident SH wave reflects only a similar SH wave back into the medium. It is also established that the angle of reflection of the reflected wave is equal to the angle of incidence of the incident wave. The phase velocity of the SH waves and the delay time of the SH waves in reaching the receiving transducer are computed as functions of a reflection index, defined as the number of reflections of the SH waves from the bottom face of the continuum plate. The directivity function corresponding to the shear stress associated with the SH waves in the continuum plate is also derived as a function of the reflection index. A theoretical output voltage from the receiving transducer is calculated for a tone burst (a periodic input voltage of finite duration). The output voltage is shown for tone bursts of duration 60 microseconds and center frequencies of 0.75, 1.00, and 1.25 MHz. The study enhances the quantitative and qualitative understanding of the nondestructive evaluation (NDE) of fiber composites which can be modeled as transversely isotropic media.
Document ID
19880014602
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Renneisen, John D. (Massachusetts Inst. of Tech. Cambridge, MA, United States)
Williams, James H., Jr. (Massachusetts Inst. of Tech. Cambridge, MA, United States)
Date Acquired
September 5, 2013
Publication Date
June 1, 1988
Publication Information
Publisher: NASA
Subject Category
Quality Assurance And Reliability
Report/Patent Number
E-4043
NASA-CR-4153
NAS 1.26:4153
Accession Number
88N23986
Funding Number(s)
PROJECT: RTOP 506-43-11
CONTRACT_GRANT: NAG3-328
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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