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Wave propagation in anisotropic medium due to an oscillatory point source with application to unidirectional compositesThe far-field displacements in an infinite transversely isotropic elastic medium subjected to an oscillatory concentrated force are derived. The concepts of velocity surface, slowness surface and wave surface are used to describe the geometry of the wave propagation process. It is shown that the decay of the wave amplitudes depends not only on the distance from the source (as in isotropic media) but also depends on the direction of the point of interest from the source. As an example, the displacement field is computed for a laboratory fabricated unidirectional fiberglass epoxy composite. The solution for the displacements is expressed as an amplitude distribution and is presented in polar diagrams. This analysis has potential usefulness in the acoustic emission (AE) and ultrasonic nondestructive evaluation of composite materials. For example, the transient localized disturbances which are generally associated with AE sources can be modeled via this analysis. In which case, knowledge of the displacement field which arrives at a receiving transducer allows inferences regarding the strength and orientation of the source, and consequently perhaps the degree of damage within the composite.
Document ID
19860018194
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Williams, J. H., Jr. (Massachusetts Inst. of Tech. Cambridge, MA, United States)
Marques, E. R. C. (Massachusetts Inst. of Tech. Cambridge, MA, United States)
Lee, S. S. (Massachusetts Inst. of Tech. Cambridge, MA, United States)
Date Acquired
September 5, 2013
Publication Date
July 1, 1986
Publication Information
Publisher: NASA
Subject Category
Quality Assurance And Reliability
Report/Patent Number
E-3093
NAS 1.26:4001
NASA-CR-4001
Accession Number
86N27666
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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