多层奥氏体钢中超声相控阵辐射声场分析

Study on the acoustic fields characteristics radiated by ultrasonic phased array in multilayered anisotropic medium

针对一维线性超声相控阵透过楔块,在多层不同晶轴取向的奥氏体钢中的声场辐射问题,结合高斯声束等效点源模型以及基于时间最小原理的射线追踪法,给出了各层介质中透射声场的计算方法。将奥氏体钢近似为横向各向同性介质,计算了相控阵透过楔块,在晶轴取向为0°的奥氏体钢中的无延时纵波声场,计算结果与COMSOL仿真结果相吻合,从而验证了所用方法的正确性。通过加入不同的延迟法则,仿真计算了三层含有不同晶轴取向(0°,30°,100°)的奥氏体钢中的纵波声场,实现了相控阵声场的偏转与聚焦,分析了偏转声场与聚焦声场的传播特性。仿真结果表明,不同的晶轴取向将导致不同的声束偏转以及聚焦效果。通过延迟激励各阵元,虽然可以控制声束偏转或聚焦到预定位置,但是晶轴取向仍会对声束宽度以及幅值产生一定的影响。

Combining ray tracing technique based on minimal time principle and the Gaussian Beam Equivalent Point Source(GBEPS) model,a systematic method is given to calculate the acoustic fields from ultrasonic phased array in multilayered austenitic steel medium.In this method,the austenitic steel is assumed as a transverse isotropic medium.The acoustic fields from ultrasonic phased array mounted on a wedge,in an austenitic steel with grain orientation of0 degree are calculated,and the results are in good agreement with that obtained by COMSOL.Using different time delay laws,beam steering and focusing in three layered austenitic steels with different grain orientations(0°,30° and100°) are realized and the characteristics of fields are discussed.Simulation results show that different grain orientation generally results in different beam steering and beam focusing.Although the fields can be controlled to steer or focus at desired place through time delay laws,the width and amplitude of steered and focused fields will be still affected by the difference of grain orientation.