Tiwari Kumar Anubhav, Raisutis Renaldas, Mazeika Liudas
Ultrasound Research Institute, Kaunas University of Technology, K. Baršausko St. 59, LT-51423 Kaunas, Lithuania.
Department of Multimedia Engineering, Kaunas University of Technology, Studentu g. 50, LT-51368 Kaunas, Lithuania.
Sensors (Basel). 2020 Apr 17;20(8):2280. doi: 10.3390/s20082280.
Analytical modelling is an efficient approach to estimate the directivity of a transducer generating guided waves in the research field of ultrasonic non-destructive testing of the large and complex structures due to its short processing time as compared to the numerical modelling and experimental techniques. The wave patterns or the amplitude variations along the region of ultrasonic transducer itself depend on its behavior, excitation frequency, and the type of propagating wave mode. Depending on the wave-pattern of a propagating wave mode, the appropriate value of the amplitude correction factor must be multiplied to the amplitudes of the excitation signal for the accurate evaluation of directivity pattern of the ultrasonic transducers generating guided waves in analytical modelling. The objective of this work is to analyse the wave patterns under the region of macro-fiber composite (MFC) transducer to improve the accuracy of a previously developed analytical model for the prediction of directivity patterns. Firstly, the amplitude correction factor based on the wave patterns under the region of P1-type MFC (MFC-2814) transducer at two different frequencies (80 kHz, 3 periods and 220 kHz, 3 period) glued on 2 mm Al alloy plate has been estimated analytically in the case of an asymmetric (A0) guided Lamb wave. The validation of analytically estimated amplitude correction factor is performed by a proposed experimental method that allows analyzing the behaviour of MFC transducer under its region by gluing MFC on bottom surface and scanning the receiver on the top surface of the sample. Later on, the estimated amplitude correction factor is included in the previously developed 2D analytical model for the improvement in the directivity patterns of the A0 mode. The modified analytical model shows a significant improvement in the directivity pattern of the A0 wave mode in comparison to the results obtained by the previous model without considering the proper wave patterns. The results reveal that errors between the directivity estimated by the present modified 2D analytical model and experimental investigation are reduced by more than 58% in comparison to the previously developed analytical model.
在大型复杂结构的超声无损检测研究领域，分析建模是一种估计产生导波的换能器方向性的有效方法，因为与数值建模和实验技术相比，其处理时间较短。沿超声换能器自身区域的波型或幅度变化取决于其特性、激励频率和传播波模式的类型。根据传播波模式的波型，在分析建模中，必须将幅度校正因子的适当值乘以激励信号的幅度，以便准确评估产生导波的超声换能器的方向性图。这项工作的目的是分析宏观纤维复合材料（MFC）换能器区域下的波型，以提高先前开发的用于预测方向性图的分析模型的准确性。首先，在粘贴于2毫米铝合金板上的P1型MFC（MFC - 2814）换能器区域下，针对非对称（A0）导波兰姆波，在两个不同频率（80千赫兹，3个周期和220千赫兹，3个周期）下，通过分析估计了幅度校正因子。通过一种提议的实验方法对分析估计的幅度校正因子进行验证，该方法通过将MFC粘贴在样品底面并在顶面扫描接收器，从而分析MFC换能器在其区域下的行为。随后，将估计的幅度校正因子纳入先前开发的二维分析模型，以改善A0模式的方向性图。与未考虑适当波型的先前模型所获得的结果相比，改进后的分析模型在A0波模式的方向性图上显示出显著改善。结果表明，与先前开发的分析模型相比，当前改进的二维分析模型估计的方向性与实验研究之间的误差减少了58%以上。
