Rotating Electromagnetic Field for Crack Detection in Railway Tracks

The main problem about a railway analysis is detection of cracks in the structure. If these deficiencies are not controlled at early stages they might cause huge economical problems affecting the rail network (unexpected requisition of spare parts, handling of incident and/or accidents). Within this framework, the early and continuous use of Non Destructive Tests can be useful. In this context, Eddy Current Testing is increasing in importance and popularity. Particularly, in this paper we exploit the measure of normal component, with respect to the scanned surface, of magnetic field. Whilst the scientific literature proposes a lot of solutions for detecting sub-superficial defects, an open problem is related to the geometrical complexity of the structure and the relevant difficulty of crack detection. In this paper, we propose a Finite Element Method based approach for modelling a fast and accurate evaluation of the defect in railways tracks. The modelled system is strongly versatile and the choice of electrical parameters affect the design of new probes for this kind of inspection. In particular, we propose a solution exploiting a rotating electromagnetic field with very encouraging results: The proposed model is able to recognize deep and surface cracks even if their orientations is vertical to the longitudinal direction of the sensor.