兰姆波在搭接焊缝上的反射和透射

采用数值模拟方法和实验研究了兰姆波在搭接焊缝上的反射和透射。数值模拟了频率500 kHz的兰姆波S0与.A0模态,分别在2 mm厚不锈钢板上的不同宽度搭接焊缝模型上的反射和透射,并计算了相应的反射系数和透射系数。发现:当搭接焊缝宽度小于4 mm时,S0模态的反射系数和焊缝宽度具有近似的线性关系,而焊缝余高和两板之间的间隙对S0模态反射系数的影响很小。基于兰姆波S0模态反射系数与焊缝宽度的线性关系。提出了通过测量S0模态反射系数快速测量搭接焊缝宽度的方法。实验测得的2 mm厚不锈钢板上不同宽度搭接焊缝对500 kHz的入射兰姆波S0模态的反射系数,验证了上述线性关系,说明了可用兰姆波反射回波测量搭接焊缝宽度。 

The reflection and transmission of Lamb waves at overlap joints

The reflection and transmission of Lamb waves at overlap joints are researched by the numerical method and the experiments. The numerical method is used to simulate the reflection and transmission occurred when the Lamb waves SO and A0 mode (at an exciting frequency of 500 kHz) propagate through welds with different widths on a 2 mm-thick stainless steel plate. The reflection and transmission coefficients are calculated as well. When the welds widths are less than 4 mm, a quasi-linear correlation is observed between the reflection coefficient of SO mode and the weld width. In contrast to the weld width, both the gap between two plates and the reinforcement of weld do not have obvious effect on the reflection coefficient. Based on the results, we propose that the width of weld could be rapidly measured through examining the echo amplitude of SO. Experiments using welds with different widths on a 2 mm-thick stainless steel plate further confirms the quasi-linear correlation and the feasibility of our proposed method.