Using Rayleigh Wave Dispersion to Characterize Residual Stresses
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Abstract
Acoustoelasticity has been the subject of a great deal of research over the past thirty years. However, most of this work involved bulk waves. For surface waves’ activity has been limited. Rayleigh wave acoustoelasicity was first studied by Hayes and Riviin [1]. Subsequently, Iwashimizu and Kobori [2] analyzed Rayleigh wave propagation in a finitely deformed isotropic elastic material. Martin [3] investigated the relative effects of stress and preferred grain orientation. Adler [4] measured the residual stress of circumferential welds in pipe. Recently, Lee et al [5] utilized line-focus acoustic microscopy to determine local near surface stress in an isotropic material. However as a uniform strain distribution is assumed, the analysis is insensitive to variations in the stress through the thickness of the material. In 1981, M. Hirao et al [6] theoretically and experimentally studied the dispersion of Rayleigh waves for a plate in pure bending. They found that the dispersion of Rayleigh waves was prominent for relatively low frequencies and diminished as the frequency increases. In this paper, the research goal is to develop a more general technique to characterize the through thickness stress distribution. Assuming the strain to be distributed quadratically with depth, the formulas for the velocity change versus the initial static stress are derived based on the first order perturbation approach. This information can be used to reconstruct synthetic residual stress distributions from frequency dependent Rayleigh wave velocity data.