考虑电磁机械耦合效应的电磁超声数值模拟方法

Numerical Simulation of Electromagnetic Acoustic Testing Signals with Consideration of Electromagneto-Mechanical Coupling Effect

提出了考虑速度效应电磁机械耦合的电磁超声数值模拟方法,并开发了相应的程序。该方法在控制方程中导入了速度诱发电场项,并采用退化向量位法(Ar)进行涡流场数值模拟和采用有限元及逐步积分方法进行超声波计算。数值模拟所得EMAT信号和超声波传播过程均证实了本方法和程序的有效性。为了确定耦合效应的影响,对考虑耦合和忽略耦合两种情况分别在不同条件下进行了数值模拟。通过比较振动幅值和洛伦兹力的模拟结果,证实耦合效应对EMAT数值模拟结果影响并不显著。

To clarify the influence of the electromagneto-mechanical coupling effect due to the additional electric field induced by the velocity effect on the simulated EMAT signals, a numerical code with consideration of the coupling effect was developed. Through introducing the v X B term to the governing equation of eddy current problem, the reduced vector potential（Ar} method and a step by step time integration algorithm were adopted with the finite element method for the simulation. The feature of the simulated EMAT signals and the propagation pattern of the simulated ultrasonic wave demonstrated that the algorithm and the corresponding numerical code were efficient. To investigate the influence of the coupling effect, EMAT signals of different conditions were simulated by using both the codes with and without the coupling effect considered. By comparing the numerical results of amplitude and Lorentz force, it demonstrated that the coupling effect did not give significant influence on the EMAT signals, which could be ignored in practice.