时域有限差分法在超声波声场特性分析中的应用

Analysis of Ultrasonic Sound Field Characteristic with FDTD

超声波无损检测结果与超声波换能器的声场特性密切相关,运用数值方法可以有效地进行超声波声场特性分析。介绍时域有限差分法(Finite difference time domain method,FDTD),分析二维流体运动方程并建立相关有限差分模型,使时域宽带超声波信号的分析更易于实现;应用完全匹配层(Perfect matched layer,PML)方法对FDTD计算的边界进行吸收处理,取得了理想的边界吸收效果;通过数值计算和仿真,研究超声波声场传播特性及圆盘声源声场分布特性,与相关文献的对比表明该算法有效可行;对脉冲波信号激励的聚焦超声波换能器分别进行有限差分法数值仿真和实际测量试验,声束轴向切面的声场分布试验结果表明两者的分布特性有很好的一致性。研究结果为超声波声场特性分析提供一种新方法。

Ultrasonic non-destructive testing result is correlative with ultrasonic transducer sound field characteristic, and numerical method can effectively analyze ultrasonic sound field characteristics. Finite difference time-domain method（FDTD） is used to analyses 2D fluid kinetic equation, FDTD model is described. Perfect matched layer method is used to achieve boundary condition and obtain desired absorbing effect. Ultrasonic sound field propagation and disc sound source characteristic is researched through numerical calculation and simulation, effectiveness and feasibility of the algorithm is confirmed in comparison with other research results. Numerical simulation and practical measurement test is accomplished in focal ultrasonic transducer with pulse stimulated. There is good consistency existing in experiment result of sound field characteristic in axial cross section.