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

Characterisation of clustered cracks using an ACFM sensor and application of an artificial neural network

“…The maximum change in B x from a scan over the whole cluster is greater than for an individual crack of the same size, as shown in the example in Figure 1. While solutions to the inverse problem for isolated cracks are well established, using analytical [23,49], numerical [24,50] or empirical [23] methods, the determination of the subsurface size of cracks appearing in clusters is not yet fully reported, and is the subject of the remainder of this paper via a combined modelling and ANN approach. It will also be shown that sizing of clustered RCF cracks based on the technique that is already established for single RCF cracks could result in a large margin of error.…”

“…Another common approach is the application of the finite element method (FEM) to solve the distribution of the magnetic field in the air above the defect and tabulation of the measured ACFM signal and respective crack size using the modelled data [32]. In this study, a uniform field COMSOL model previously developed for isolated RCF cracks [20,24,50,51] has been extended to allow a wider parametric study of clustered RCF cracks closely enough spaced that their ACFM signals overlap (see Figure 2). In the model the material properties of the air and the metal domains are: conductivity ( ) 50 and 5x10 6 S/m, respectively, and relative magnetic permeability ( ) 1 and 50, respectively.…”

“…A non-zero value of air conductivity is used to avoid singularity issues when solving the forward problem with the FEM solver. In the simulation step, the probe has been modelled using a uniform field approximation, validated in previous work [20,24,50,51] to simplify resolving the FEA model for each probe position and to speed up the computations. Therefore, in the model a uniform incident field has been applied to the conductor domain and the solution of the disturbed magnetic field intensity (i.e.…”

Prediction of RCF clustered cracks dimensions using an ACFM sensor and influence of crack length and vertical angle

“…The model geometry and the standard Cartesian coordinates are shown in Figure 3a. Full details of the model and boundary conditions can be found elsewhere [14,18,19].…”

Investigation into eddy current pulsed thermography for rolling contact fatigue detection and characterization

“…These angled cracks also propagate a few millimeters (but less than 4 mm) deep into the railhead through heavily deformed surface layers at an angle of about 10°-30° to the rail running surface. A micrograph of an RCF defect [5] propagating into the railhead at a shallow angle [6] of 28° is presented in Fig. 1(b).…”