Gao Fei, Hua Jiadong, Zeng Liang, Lin Jing
Shaanxi Key Laboratory of Mechanical Product Quality Assurance and Diagnostics, School of Mechanical Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi Province 710049, China.
School of Reliability and Systems Engineering, Beihang University, Xueyuan Road No. 37, Haidian District, Beijing, China.
Ultrasonics. 2019 Mar;93:122-129. doi: 10.1016/j.ultras.2018.10.008. Epub 2018 Oct 21.
Composite structure is increasingly used in civil and aerospace applications due to its high mechanical performance. Lamb wave based sparse reconstruction imaging for damage localization is promising for structural health monitoring (SHM) and nondestructive evaluation (NDE) by using few measurements. However, this dictionary based method requires accurate atoms to represent Lamb wave propagating features in structure very well. Besides dispersion, signal changes caused by amplitude modulation should be considered for waveform distortion when constructing the dictionary for sparse imaging method. In this paper, a non-contact laser is used for Lamb wave excitation which exhibits a strong amplitude modulation in low frequency. Additionally, the strong attenuation resulting from material damping would also presents a distance-dependent amplitude modulation. To reconstruct an amplitude model of Lamb wave, the decomposition method of system response and attenuation is proposed. Then, the influence of amplitude modulation on signal representation is analyzed, which shows the restriction of dictionary without considering amplitude modulation. On this basis, the amplitude considered dictionary is built together with the phase considered dictionary for sparse imaging in terms of damage detection. Furthermore, according to Lamb wave reflection model, the solution for sparse reconstruction imaging is given. Finally, the performance of sparse imaging method is discussed by experimental investigation with different parameters. The results show the efficiency of the proposed method with improved imaging performance and give comparisons for better parameter choice.
由于其高机械性能，复合材料结构在土木和航空航天应用中越来越多地被使用。基于兰姆波的稀疏重建成像用于损伤定位，通过少量测量对结构健康监测（SHM）和无损评估（NDE）具有前景。然而，这种基于字典的方法需要精确的原子来很好地表示结构中兰姆波的传播特征。除了色散之外，在为稀疏成像方法构建字典时，当考虑波形失真时，应考虑由幅度调制引起的信号变化。在本文中，使用非接触激光来激发兰姆波，其在低频中表现出强烈的幅度调制。此外，材料阻尼导致的强衰减也会呈现出与距离相关的幅度调制。为了重建兰姆波的幅度模型，提出了系统响应和衰减的分解方法。然后，分析了幅度调制对信号表示的影响，这显示了不考虑幅度调制的字典的局限性。在此基础上，为了损伤检测，将考虑幅度的字典与考虑相位的字典一起构建用于稀疏成像。此外，根据兰姆波反射模型，给出了稀疏重建成像的解决方案。最后，通过不同参数的实验研究讨论了稀疏成像方法的性能。结果显示了所提方法的有效性，具有改进的成像性能，并为更好的参数选择给出了比较。
