Modeling of acoustoelastic effects based on anharmonic atomic interaction

Abstract

The acoustoelastic effects have been widely applied in the fields of nondestructive characterization and optimal design of nanomaterial. However, the traditional acoustoelastic constitutive model is established at the macro scale, which is incompatible with nanomaterials, and the micro mechanism of acoustoelastic effect is neglected. In this work, the acoustoelastic constitutive model is reestablished based on the elastic constitutive relation and the motion equation of elastic wave at the atomic scale. The derivation demonstrates that the acoustoelastic effect is caused by the anharmonic interatomic potential. Furthermore, as the interatomic distance increases and decreases, different elastic constitutive relations are exhibited. As a result, an acoustoelastic constitutive model taking into account different elastic constitutive relations is proposed, and the theoretical acoustoelastic effect of single crystal aluminum with anisotropic characteristics is calculated. To verify the proposed constitutive model, the acoustoelastic effect at the atomic scale is simulated based on molecular dynamics (MD). The outcomes demonstrate the consistency between the simulated and theoretical acoustoelastic effects. That is, even though the magnitude of the tensile and compressive stresses is the same, the material exhibits different acoustoelastic effect. This work presents a fairly comprehensive theoretical model for the acoustoelastic effect at the atomic scale.