Numerical Simulation Of Array Probe Signal In Eddy Current Testing

Eddy current test technique is irreplaceable for testing the stream generator tubes of nuclear power plant. With the advantages of high testing speed, strong flaw features identifying ability, array probe is a very ideal choice. Numerical simulation is an important method to study the eddy current test technique. But since the structure of array probes is very complex, the computation model of array probe using finite element method and boundary element method can be very slow and requires large amount of RAM. Sometimes it can be very difficult to realize. This paper researches on the modeling method and compute method for eddy current array probe.The model of tube test array probe is in 3D. However, when the tube is much bigger than the probe coil, to one probe coil the tube is very similar to a plate which can be compute by a 2D axial symmetry model. Based on this point, the paper has deeply studies the Equivalence of tube model and plate model and found a way to transform the tube model into plate model which can reduce the compute difficulty.The eddy current test model can be divided into an incident field and a disturbed field. The incident field of an infinite plate model can be solved by analytic method, and the disturbed field can be solved by finite element method or volume integration method. The integration kernel of volume integration method is determined by the unflawed conductor boundary condition which is very easy to get in a plate model. So analytic method and volume integration method are chosen as the main tools to solve the eddy current test problem. Base on the methods mentioned above, a program is written to compute the tube test array probe model by a plate model. The program's compute results achieve the expectations. The researches in this paper can provide strong foundations to understand the theory of array probe eddy current test and an easy way to optimize the array probe.