材料塑性损伤的共轴异向波束混频定位及表征方法

Localizing the Plastic Deformation Zone Using the Collinear Two-Way Mixing Method

共线波束混频方法是一种有效的非线性超声检测方法.当满足共振条件时,一对频率为f1的剪切波和频率为f2的纵波发生共振,产生频率为f2-f1(假设f2大于f1)的共振波.共振波的幅值与超声非线性参数βT成正比.通过调整两激励主波的时延,使得它们在试样中的不同位置混合,可以获得超声非线性参数βT在试样中的分布.试样的塑性变形会引起材料内部三阶弹性常数的变化,而由上述方法得到的超声非线性参数βT恰恰对三阶弹性常数的变化比较敏感.因此,本文利用上述特性实现了对试样塑性变形的定位与表征.

The distribution of the plastic deformation zone in the metal component is very important.The collinear wave mixing method is an effective nonlinear ultrasonic detection method.Under the phase matching condition,a transverse wave with frequency f1 and a longitudinal wave with frequency f2 resonate to generate a resonant wave with frequency f2-f1(assuming f 2 is greater than f1).The amplitude of the resonant wave is proportional to the ultrasonic nonlinear parameterβT.By adjusting the delay of the two excitation main waves so that they are mixed in different positions in the sample,the distribution of ultrasonic nonlinear parameterβT in the sample can be obtained.Plastic deformation may result in the variation of the third-order elastic constants,the acoustic non-linearity parameters obtained by the above method are just sensitive to the variation.Thus,localizing the plastic deformation zone and express the distribution of it can be achieved by the above relationship.