Accession Number : ADA115566

Title :   Time-Domain First Born Approximations to Elastodynamic Backscatter with Applications to Non-Destructive Evaluation of Composites.

Descriptive Note : Master's thesis,

Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING

Personal Author(s) : Warhola,Gregory T

PDF Url : ADA115566

Report Date : Dec 1981

Pagination or Media Count : 79

Abstract : The first Born approximations to solutions of a time-domain integral equation were used to obtain the backscattered dilatation wave response from spherical and cylindrical inclusions of arbitrary homogeneous anisotropic elastic material embedded within a homogeneous isotropic host. For large ka, where the validity of the first Born approximation is questioned, the time waveform responses from cylinders and spheres are markedly different; for ka approaches limit of 0, they have identical time form with amplitudes dependent upon the volume of the scatterer. Excellent agreement with an experimental result for scattering from a cylindrical void was obtained for a value of ka = 0.32. A 'transparency condition' was obtained, allowing that for certain combinations of both density and stiffness of the scatterer and host, the scatterer appears transparent to the incoming wave in the first Born approximation.

Descriptors :   *Fiber reinforced composites, *Approximation(Mathematics), Elastic waves, Elastic scattering, Nondestructive testing, Waveforms, Failure(Mechanics), Time domain, Porosity, Cylindrical bodies, Spheres, Anisotropy, Homogeneity, Transparencies, Plane waves, Amplitude, Solutions(General), Integral equations, Approximation(Mathematics), Theses

Subject Categories : Laminates and Composite Materials
      Numerical Mathematics
      Test Facilities, Equipment and Methods

Distribution Statement : APPROVED FOR PUBLIC RELEASE