A simulation study of flaw detection for rail sections based on high frequency magnetic induction sensing using the boundary element method

摘要

Damage on rail increasingly originates from the surface of the rail as a result of for example rolling contact fatigue (RCF). This is a major concern for track operators, who operate test regimes for flaw detection and monitoring. The paper aims to assess the feasibility of applying electromagnetic (EM) simulation techniques to high frequency magnetic induction sensing of flaws in a section of rail head using the Boundary element method (BEM). When the driving frequency is significantly high (~MHz), the rail with high conductivity can be treated as perfect electric conductors (PEC) with negligible errors. In this scenario, BEM based on scalar potential and integral formulations becomes an effective way to analyze this kind of scattering problems since meshes are only required on the surface of the object. A simple high frequency magnetic induction sensing system was chosen to inspect the surface flaw of the rail. Different kinds of flaws were tested with different sensor configurations. The simulations were carried out using an algorithm the authors have developed in MATLAB. The paper provides new insights into the application of magnetic induction sensing technique using BEM in non-destructive testing. Based on the simulation and mathematical analysis, hardware system can be built to verify the proposed detection strategy.