ABSTRACT Finite element models with explicitly modelled mesoscale heterogeneity in material are introduced to numerically investigate the correlation between the ultrasonic higher harmonics and plastic deformation. The model predicts the changes of the second- and third-harmonics due to the plastic deformation in materials without the microstructural information and state variables at each loading step. The numerical predictions of ultrasonic higher harmonics change agree with the experimental data on Aluminium 1100. The numerical model is extended to study the effect of heterogeneity characteristics, including volume fraction, size and strength deviation, on the higher harmonics. The numerical studies consistently show that the third-harmonics is more sensitive than the second-harmonics to the level of plastic deformation for all heterogeneity characteristics. Moreover, among the heterogeneity characteristics considered, the material strength deviation of heterogeneity from the bulk affects the changes of higher harmonics the most. The numerical observations are discussed and compared with experimental results provided in the literature.

中文翻译：

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异质性对超声高次谐波产生影响的数值研究

摘要引入了具有明确建模的材料中尺度异质性的有限元模型，以数值研究超声波高次谐波与塑性变形之间的相关性。该模型预测由于材料的塑性变形而导致的二次和三次谐波的变化，而无需每个加载步骤的微观结构信息和状态变量。超声高次谐波变化的数值预测与铝1100的实验数据一致。扩展数值模型以研究高次谐波的不均匀特性，包括体积分数、尺寸和强度偏差的影响。数值研究一致表明，对于所有非均质性特征，三次谐波对塑性变形水平比二次谐波更敏感。此外，在考虑的异质性特征中，异质性与体相的材料强度偏差对高次谐波的变化影响最大。讨论了数值观察结果，并与文献中提供的实验结果进行了比较。