Location

La Jolla, CA

Start Date

1-1-1993 12:00 AM

Description

In this paper, the dispersion of surface acoustic waves (SAW) in case carborized steel samples was calculated. The calculations were based on the Thomsen-Haskill matrix formalism. This method has the advantage that it treats a given profile as a stack of several layers, each with arbitrary thickness, density and elastic moduli. This treatment allows for a realistic representation of real material effects by allowing, for example, fluctuations in these parameters with depth, either from material variability or measurement error. In order to demonstrate the capability of the formalism we measured hardness, density and bulk velocity in homogeneously carbonized specimens. We then used these data to synthesize several different hardness profiles, such as might be encountered in actual industrial applications. For these profiles the SAW dispersion curves were then calculated. The results provided valuable insight into such questions as the range of SAW velocity extremal values and the frequency bandwidth over which the velocity changes are maximum. Thus the Thomson- Haskill matrix method is shown to provide a useful tool for simulating the effect of hardness on SAW velocity with potential applications for a wide variety of physical property gradients.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

12B

Chapter

Chapter 6: Material Properties

Section

Metals

Pages

1639-1644

DOI

10.1007/978-1-4615-2848-7_209

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Surface Acoustic Wave Determination of Hardness: Forward Problem

La Jolla, CA

In this paper, the dispersion of surface acoustic waves (SAW) in case carborized steel samples was calculated. The calculations were based on the Thomsen-Haskill matrix formalism. This method has the advantage that it treats a given profile as a stack of several layers, each with arbitrary thickness, density and elastic moduli. This treatment allows for a realistic representation of real material effects by allowing, for example, fluctuations in these parameters with depth, either from material variability or measurement error. In order to demonstrate the capability of the formalism we measured hardness, density and bulk velocity in homogeneously carbonized specimens. We then used these data to synthesize several different hardness profiles, such as might be encountered in actual industrial applications. For these profiles the SAW dispersion curves were then calculated. The results provided valuable insight into such questions as the range of SAW velocity extremal values and the frequency bandwidth over which the velocity changes are maximum. Thus the Thomson- Haskill matrix method is shown to provide a useful tool for simulating the effect of hardness on SAW velocity with potential applications for a wide variety of physical property gradients.