Seno Aldyandra Hami, Aliabadi M H Ferri
Department of Aeronautics, Imperial College London, Exhibition Road, South Kensington, London SW7 2AZ, UK.
Sensors (Basel). 2019 Aug 22;19(17):3659. doi: 10.3390/s19173659.
A parametric investigation of the effect of impactor stiffness as well as environmental and operational conditions on impact contact behaviour and the subsequently generated lamb waves in composite structures is presented. It is shown that differing impactor stiffness generates the most significant changes in contact area and lamb wave characteristics (waveform, frequency, and amplitude). A novel impact localisation method was developed based on the above observations that allows for variations due to differences in impactor stiffness based on modifications of the reference database method and the Akaike Information Criterion (AIC) time of arrival (ToA) picker. The proposed method was compared against a benchmark method based on artificial neural networks (ANNS) and the normalised smoothed envelope threshold (NSET) ToA extraction method. The results indicate that the proposed method had comparable accuracy to the benchmark method for hard impacts under various environmental and operational conditions when trained only using a single hard impact case. However, when tested with soft impacts, the benchmark method had very low accuracy, whilst the proposed method was able to maintain its accuracy at an acceptable level. Thus, the proposed method is capable of detecting the location of impacts of varying stiffness under various environmental and operational conditions using data from only a single impact case, which brings it closer to the application of data driven impact detection systems in real life structures.
本文对冲击器刚度以及环境和运行条件对复合结构中冲击接触行为和随后产生的兰姆波的影响进行了参数研究。结果表明，不同的冲击器刚度会在接触面积和兰姆波特性（波形、频率和幅度）上产生最显著的变化。基于上述观察结果，开发了一种新颖的冲击定位方法，该方法通过修改参考数据库方法和赤池信息准则（AIC）到达时间（ToA）选取器，考虑了由于冲击器刚度差异而产生的变化。将该方法与基于人工神经网络（ANN）的基准方法和归一化平滑包络阈值（NSET）ToA提取方法进行了比较。结果表明，当仅使用单个硬冲击案例进行训练时，在各种环境和运行条件下，对于硬冲击，所提出的方法与基准方法具有相当的精度。然而，当用软冲击进行测试时，基准方法的精度非常低，而所提出的方法能够将其精度保持在可接受的水平。因此，所提出的方法能够利用仅来自单个冲击案例的数据，在各种环境和运行条件下检测不同刚度冲击的位置，这使其更接近数据驱动的冲击检测系统在实际结构中的应用。
