Modelling and experimental measurements of idealised and light-moderate RCF cracks in rails using an ACFM sensor

Alternating current field measurement (ACFM) sensors can be used to detect surface breaking defects in metal components. In rails rolling contact fatigue (RCF) cracks form due to the wheel-rail contact stresses. These cracks are surface breaking and can have complex shapes. A COMSOL model has been developed for a commercial ACFM system and RCF cracks in rails. In this paper model results are compared to experimental measurements using an ACFM pencil probe for calibration defects machined into a rail and real RCF defects (light and moderate categories;