基于非线性声学技术的微裂纹扩展特性研究

Study on the micro-crack propagation characteristics based on Nonlinear Acoustic Techniques

摘要:

本文旨在研究非线性声学手段在检测材料损伤中微裂纹扩展的应用，并进一步探讨非线性尾波干涉技术（NCWI）在非均质复杂材料微裂纹损伤检测中的灵敏度和适用性。根据多重散射理论和微裂纹状散射体的有效散射截面特征研究，在多重散射介质中，尾波传播速率的变化与裂纹长度的变化具有有效的关联。通过使用谱有限元（SEM）数值仿真方法，本文开展了基于NCWI方法的裂纹长度变化的参数敏感性分析，并获得了尾波传播速率相对变化值与材料损伤区域裂纹密度和长度变化之间的线性比例关系。研究结果表明，NCWI方法既能对非均质材料中声传播微小变化具有敏感性，又能利用材料微裂纹引起的强非线性声学效应，因此，在复杂材料中对微裂纹的检测具有良好的效果。

Abstract:

The purpose of this article is to study the application of nonlinear acoustic techniques in detecting micro-crack propagation in material damage, and to further explore the sensitivity and applicability of Nonlinear Coda Wave Interferometry (NCWI) in the detection of micro-cracks in heterogeneous complex materials. Based on the multi-scattering theory and the effective scattering cross-section characteristics of micro-crack-shaped scatterers, the variation of the coda wave propagation velocity in multi-scattering media has an effective correlation with the variation of crack length. Using the Spectral finite Element Method (SEM) numerical simulation, this article carries out parameter sensitivity analysis of the crack length change based on the NCWI method and obtains a linear proportional relationship between the relative change value of coda wave propagation velocity and the crack density and length change in the material damage area. The research results show that the NCWI method has both sensitivity to small changes in acoustic propagation in heterogeneous materials and utilizes the strong nonlinear acoustic effects caused by material micro-cracks, making it effective in detecting micro-cracks in complex materials.