Draudvilienė Lina, Tumšys Olgirdas, Raišutis Renaldas
Ultrasound Research Institute, Kaunas University of Technology, K. Baršauskas St. 59, LT-51423 Kaunas, Lithuania.
Department of Electrical Power Systems, Faculty of Electrical and Electronics Engineering, Kaunas University of Technology, Studentu St. 48, LT-51367 Kaunas, Lithuania.
Materials (Basel). 2021 Nov 18;14(22):6990. doi: 10.3390/ma14226990.
The possibilities of an effective method of two adjacent signals are investigated for the evaluation of Lamb waves phase velocity dispersion in objects of different types, namely polyvinyl chloride (PVC) film and wind turbine blade (WTB). A new algorithm based on peaks of spectrum magnitude is presented and used for the comparison of the results. To use the presented method, the wavelength-dependent parameter is proposed to determine the optimal distance range, which is necessary in selecting two signals for analysis. It is determined that, in the range of 0.17-0.5 wavelength where δcph is not higher than 5%, it is appropriate to use in the case of an A mode in PVC film sample. The smallest error of 1.2%, in the distance greater than 1.5 wavelengths, is obtained in the case of the S mode. Using the method of two signals analysis for PVC sample, the phase velocity dispersion curve of the A mode is reconstructed using selected distances = 70 mm and = 70.5 mm between two spatial positions of a receiving transducer with a mean relative error δcph=2.8%, and for S mode, = 61 mm and = 79.7 mm with δcph=0.99%. In the case of the WTB sample, the range of 0.1-0.39 wavelength, where δcph is not higher than 3%, is determined as the optimal distance range between two adjacent signals. The phase velocity dispersion curve of the A mode is reconstructed in two frequency ranges: first, using selected distances = 225 mm and = 231 mm with mean relative error δcph=0.3%; and second, = 225 mm and = 237 mm with δcph=1.3%.
研究了一种用于评估不同类型物体（即聚氯乙烯（PVC）薄膜和风力涡轮机叶片（WTB））中兰姆波相速度色散的有效方法，该方法基于两个相邻信号。提出了一种基于频谱幅度峰值的新算法，并用于结果比较。为了使用所提出的方法，提出了与波长相关的参数来确定最佳距离范围，这对于选择两个信号进行分析是必要的。确定在0.17 - 0.5波长范围内，当δcph不高于5%时，适用于PVC薄膜样品的A模式情况。在距离大于1.5波长的情况下，S模式获得了最小误差1.2%。对于PVC样品，使用两个信号分析方法，通过选择接收换能器两个空间位置之间的距离 = 70 mm和 = 70.5 mm，重建了A模式的相速度色散曲线，平均相对误差δcph = 2.8%；对于S模式，选择 = 61 mm和 = 79.7 mm，δcph = 0.99%。对于WTB样品，确定0.1 - 0.39波长范围为两个相邻信号之间的最佳距离范围，其中δcph不高于3%。在两个频率范围内重建了A模式的相速度色散曲线：首先，使用选择的距离 = 225 mm和 = 231 mm，平均相对误差δcph = 0.3%；其次， = 225 mm和 = 237 mm，δcph = 1.3%。
