基于非线性临界折射纵波的金属材料塑性损伤评估

Plastic damage evaluation of metal materials based on the nonlinear critical refraction longitudinal wave

本文利用临界折射纵波的非线性特性对金属构件的塑性损伤进行评估。首先,分别对两组试件进行在线和离线应力加载,使试件具有不同的应力状态;再对试件进行基于临界折射纵波的非线性超声实验,计算不同应力下的相对非线性系数。实验结果表明,相对非线性系数和试件变形均随着试件应力水平的增加而单调递增,且相对非线性系数和试件宏观变形的皮尔逊关联系数分别为0.9884和0.9876,说明这两组参数之间具有较强的关联性。此外,基于实验数据建立了相对非线性系数和试件变形的幂指数函数关系,该关系可以定量说明试件宏观变形量和相对非线性系数之间的内在联系。在不清楚材料微观结构的情况下,利用幂指数关系可以从宏观角度根据材料变形预测相对非线性系数,这在实际的工程应用中对金属材料进行塑性损伤评估是十分方便的。

In this paper the nonlinear property of critical refraction longitudinal wave was applied to evaluate the plastic damage of metallic materials in actual engineering application.Firstly,the two groups of specimens were subjected to on-line and off-line stress loading respectively,so that the specimens have different stress states.Then the nonlinear ultrasonic experiments based on critical refraction longitudinal wave were conducted on two kinds of specimens and the relative nonlinear coefficient was calculated.The experimental results indicate that the relative nonlinear coefficient and deformation increase monotonically with stress,both on-line and off-line experiments have similar variation trend.Furthermore,the Pearson correlation coefficient between the relative nonlinear coefficient and deformation are 0.9884 and 0.9876,respectively,which indicates the relative nonlinear coefficient and deformation has strong correlation.The power exponential function is established,which can be used to quantitatively explain the internal relationship between the macroscopic deformation of specimens and the relative nonlinear coefficient.Without knowing the microstructure of material,the power exponential relation can be applied to predict the relative nonlinear coefficient according to the deformation of material,which is very convenient to evaluate the plastic damage in practical engineering application.