电磁加载对超声传播特性的影响

近年来,非线性超声技术在检测结构微损伤方面的能力引起了国内外学者广泛的关注。如何提高闭合裂纹引起的非线性声学响应是非线性超声检测技术要解决的关键问题。本文提出利用电磁加载的方式激励闭合裂纹处于动态扩展状态,并实现对超声的调制过程,进而产生较为强烈的超声非线性效应。通过研究电磁加载过程对闭合裂纹的激励效果,分析不同电磁加载参数对超声传播过程的影响特性,给出超声回波信号与电磁加载之间的对应关系,为超声非线性检测技术的工程应用提供重要依据。

Impacts of the Electromagnetic Loading on the Propagation of the Ultrasonic Wave

In recent years,the detectability of the nonlinear ultrasonic technology on the micro-damage has caused extensive concern.The key problem of the nonlinear ultrasonic technology was how to enhance the nonlinear acoustic response.For this purpose,this paper proposed a new method.The state of the metal closed-crack was changed by the eddy current loading.The ultrasonic had been modulated in the crack area which could produce the nonlinear ultrasonic phenomenon.Through analyzing the loading effects of the eddy current coil on the closed-crack and its dynamic behaviors,the impacts of the electromagnetic (EM) loading parameters on the ultrasonic nonlinear response were discussed.The ultrasonic nonlinear phenomena with the eddy current loading was studied by the modulated ultrasonic echo,and the corresponding relationship between the echo signal and the EM loading is demonstrated.It could provide the theory basis for engineering application of the nonlinear ultrasonic testing method.