脉冲涡流TR探头解析模型的快速求解方法

Research on lift-off measurement method based on pulsed eddy current transmit-receive probe

摘要:

作为分析脉冲涡流响应的常用工具，解析模型因具有物理意义明确、精度高、计算速度快等优点而得到了广泛关注。近年来，随着脉冲涡流阵列探头的应用，对其阵列单元——即激励和接收线圈非同轴的Transmitter-Receiver阵列单元（以下简称TR探头）的解析分析需求迫切。而当前关于TR探头的解析模型大多数将试件缺陷等效为大面积壁厚减薄缺陷，模型精度较低。为提高TR传感器解析模型的求解精度，将构件缺陷等效为平底盲孔缺陷，建立了含平底盲孔构件脉冲涡流TR探头的解析模型，且提出了一种快速求解该模型解析解的方法：首先，通过分析典型模型解析解的形式，发现其由广义反射系数、线圈系数等乘积组成，且广义反射系数仅与构件结构有关，线圈系数仅与探头有关；然后，参考已有的含平底盲孔构件同轴式探头检测模型和均匀壁厚减薄缺陷的TR探头模型，分别获取广义反射系数和线圈系数解析表达式；最后，将其组合得到含平底盲孔构件脉冲涡流TR探头的解析解。通过和实验数据做比较验证了上述解析解的正确性。所提出的方法可应用到其他脉冲涡流解析模型的快速求解中，降低解析模型的求解难度。

Abstract:

As a common tool for analyzing the response of pulsed eddy current, an analytical model has been widely paid attention because of its advantages, such as clear physical meaning, high accuracy, fast calculation speed, etc. In recent years, with the application of pulsed eddy current array probe, an analysis of the transmitter and receiver array unit (hereinafter referred to as TR probe), whose coils are not coaxial, is in urgent need. However, the component defect is always equivalent to a large area wall thinning defect in most of the analytical models of TR probe, which causes a low calculation accuracy. In order to improve the solution accuracy of the analytical model of the TR sensor, the component defect is equivalent to a flat-bottomed blind hole defect, an analytical model of the pulse eddy current TR probe for a component with a flat-bottomed blind hole is established, and a fast method to solve the analytical model is proposed: Firstly, by analyzing the typical model, it is found that the form of its analytical solution is composed of the product of generalized reflection coefficient, coil coefficient, etc. The generalized reflection coefficient is only related to the structure of the component, and the coil coefficient is only related to the probe. Then, by referring to the coaxial probe detection model with flat-bottomed blind hole component and the TR probe model with uniform wall thickness thinning defect, the analytical expressions of generalized reflection coefficient and coil coefficient are obtained, respectively. Finally, the analytical solutions of pulsed eddy current TR probe with flat-bottomed blind hole component can be calculated by combining these two coefficients. The correctness of the above analytical solution is verified by comparison with experimental data. The proposed method can be applied to the rapid solution of other pulsed eddy current analytical models, reducing the difficulty of solving analytical models.