目的 针对Q235钢材的表面裂纹，在电位法检测原理的基础上，进行有限元仿真模拟。方法 首先，设计不同宽度、不同深度及不同的裂纹与激励夹角等多组方案仿真计算。其次，基于直流电位法原理的解析解与有限元模拟对比验证，证明其有限元模拟的准确性。结果 不同宽度的表面裂纹，两侧的电位值不同，有明显的极值拐点，且随着裂纹宽度的增加，两侧的电压降趋势逐渐平缓。不同深度的表面裂纹，两侧的电位幅值随着裂纹深度增加而增大，最小可检测0.02 mm的裂纹深度。不同方向的裂纹，其周围的电场线疏密程度及走向趋势不一样，当夹角30o≤α≤90o时，直流电位法可以较好地检测表面裂纹。通过解析解验证有限元仿真结果，在裂纹处的电位信号趋势一致，幅值略有不同，表明结果可靠。结论 直流电位法对Q235钢材表面不同宽度、不同深度及不同夹角的裂纹检测分辨率较好。该研究为电位法检测Q235钢材表面裂纹提供了一定的可行性依据，证明此检测方法具有重要的工程实用价值。

The work aims to apply finite element simulation to surface cracks of Q235 steel based on principle of potentiometric detection. Firstly, several schemes consisting of different width, different depth and different angle between crack and excitation were designed firstly for simulation calculation. Secondly, analytical solution based on the principle of DC-bit method and finite element simulation were compared and validated to verify accuracy of the finite element simulation. For surface cracks of different width, potential values on both sides were different, there was obvious extremum inflection point, and voltage drop on both sides became gentle as the crack width increased. Potential amplitude on both sides increased with the increase of crack depth, and minimum detectable crack depth was 0.02 mm. Density and trend of electric field lines were different around the cracks in different directions. When 30o≤α≤90o, the surface crack could be detected in the DC potential method smoothly. The finite element simulation results were verified based upon analytical solution, trend of potential signal at the cracks was consistent, the amplitude was slightly different, hence the results were reliable. The DC potential method has higher resolution in detecting different width, different depth and different angle of the surface cracks of Q235 steel, which provides a certain feasibility basis for detecting surface cracks of Q235 steel in potential method, and is of significant engineering practical value.