基于非线性声学技术的微裂纹扩展特性研究

Study on Micro-Crack Propagation Characteristics Based on Nonlinear Acoustic Techniques

摘要:

为评估非线性声学手段在检测材料损伤中微裂纹扩展的应用潜力，并检验非线性尾波干涉技术 （Nonlinear Coda Wave Interferometry，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。基于多重散射理论与裂纹状散射体有效散射截面，建立尾波传播速率与裂纹参数的关联模型。采用谱有限元 （Spectral Element Method，SEM）法构建含随机裂纹的介质并开展仿真与敏感性分析，结果显示尾波传播速率相对变化值与损伤区域的裂纹密度和长度变化呈线性比例关系，在低幅度微损伤工况下相关性稳定，对裂纹取向与空间分布具有良好鲁棒性。研究结果进一步表明，NCWI 对传播介质的微小变化高度敏感，能有效利用微裂纹引起的非线性效应，实现复杂材料微裂纹的早期识别与定量表征。

Abstract:

This study evaluates the application potential of nonlinear acoustics for detecting micro-crack growth in damaged materials and examines the sensitivity and applicability of nonlinear coda wave interferometry （NCWI）for micro-crack detection in heterogeneous，complex media. Based on multiple-scattering theory and the effective scattering cross-section of crack-like scatters，a linkage model between coda-wave propagation velocity and crack parameters is established. A spectral element method（SEM）framework is used to construct media with random crack fields，and simulations and sensitivity analyses are carried out. The results show that the relative coda-wave velocity change（Δv/v）exhibits an approximately linear proportional relationship with both crack density and crack-length variation within the damaged region. This correlation remains stable under low-amplitude micro-damage conditions and shows strong robustness to variations in crack orientation and spatial distribution. The research results further demonstrate that NCWI is highly sensitive to minute changes in propagation media and effectively utilizes nonlinear acoustic effects induced by micro-cracks，enabling early identification and quantitative characterization of micro-crack evolution in complex materials.