目前电磁超声在测厚、无损检测等领域得到了广泛的研究，但在螺栓轴向应力测量方面的研究较少，为了促进电磁超声在螺栓轴向应力测量中的应用，通过建立多物理场有限元仿真模拟了电磁超声的激发、传播过程。建立螺栓二维模型，利用电磁超声激发超声波得到了纵波在螺栓内部传播的信号；通过有限元模拟，得到了螺栓在轴向载荷作用下内部的应力分布。有限元计算表明轴向载荷和声时差存在一定的线性关系，该线性关系受到轴向载荷的影响；不同的夹紧长度会影响材料的应力系数，而夹紧长度和应力系数的乘积为定值。试验结果表明，有限元模拟结果与真实试验情况均表现为在轴向应力作用下，超声波传播时间增大，并和轴向应力呈良好的线性关系。

At present, electromagnetic ultrasound has been widely studied in the fields of thickness measurement and nondestructive testing, but there is little research on bolt axial force measurement. In order to promote the application of electromagnetic ultrasound in bolt axial force measurement, in this paper, the process of electromagnetic ultrasonic excitation and propagation is simulated by establishing multi-physical field finite element method. Create a two dimensional bolt model, the signal of longitudinal wave propagation inside the bolt is obtained by electromagnetic ultrasound, and the stress distribution inside the bolt under axial load is obtained by finite element simulation. The finite element calculation shows that there is a certain linear relationship between axial load and acoustic time difference, and the linear relationship is affected by axial load. Different clamping length will affect the stress coefficient of the material, and the product of the tightening length and the stress coefficient is a fixed value.The test results show that both the finite element simulation results and the real test conditions show that under the action of axial stress, the ultrasonic propagation time increases, and a good linear relationship is presented with the axial stress.