DETECTING PLASTIC STRAIN DISTRIBUTION BY A NONLINEAR WAVE MIXING METHOD

A nonlinear wave mixing method is used to measure the plastic strain distribution in polycrystalline materials. A pair of collinear longitudinal and shear waves is generated. Under the phase matching condition, a resonant shear wave with a difference frequency is generated and propagates towards the shear wave transducer. The amplitude of this resonant shear wave is proportional to the acoustic nonlinearity parameter beta, which is known to be related to plastic deformation. By adjusting the two primary waves so that they mix at different locations, the distribution of beta can be obtained. This study demonstrates the feasibility of detecting plastic strain distribution in polycrystalline materials by the nonlinear wave mixing technique.