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Modeling Dislocation Mechanisms of the Acoustic Nonlinearity in Metallic Crystals

W. D. CASH, W. CAI

Abstract


The acoustic nonlinearity of dislocations in metallic crystals predicted by recently developed analytic models and discrete dislocation dynamics (DD) simulations are compared with past experiments over a range of externally applied stresses. The variation in the acoustic nonlinearity parameter, β, with glide stress on the dislocations is shown to qualitatively agree with the trends seen in experiments on FCC single crystals. Samples that were subjected to a single plastic load are found to have an initial decrease in β, which is consistent with the prediction of an isolated edge monopole. Fatigued samples aligned well with the behavior of two-dimensional multipolar structures as long β from microcracks is negligible.

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