Numerical Analysis of the Magnetic Flux Leakage Field Induced by Internal Defects in Longitudinal Ferromagnetic Structures

Abstract

This paper discusses approaches to improving the magnetic non - destructive testing (NDT) method for longitudinal ferromagnetic bodies, leveraging the advanced simulation capabilities of modern Multiphysics engineering software. The subject of the research is steel wire ropes composed of individual wires of various shapes and cross - sections. Since steel wire ropes do not constitute a homogeneous, continuous body, the application of magnetic NDT methods encounters significant challenges. This is primarily manifested in the difficulty of reliably detecting the magnetic flux leakage (MFL) field generated by wire breakages, as the discrete, multi - wire structure of the rope increases background electromagnetic noise and complicates the extraction of the useful signal. Although modern flaw detectors partially address this issue, the reliable registration of internal wire breaks remains a critical challenge to this day. In this work, the numerical calculation of the MFL field intensity resulting from an internal breakage within a simplified, two - layer steel wire structure is modelled in an engineering software environment. The spatial distribution of the leakage field induced by defects of varying widths and depths is investigated both within the ferromagnetic medium itself and in the surrounding atmospheric environment. The latter is of particular importance for practical NDT applications, given that magnetic sensing devices are typically positioned outside the ferromagnetic component. Based on the obtained results, it can be concluded that the utilization of modern engineering software tools enables a detailed and highly reliable study of the detection and registration processes for internal defects in ferromagnetic wire structures. In the future, developing an accurate geometric model of real steel wire ropes and conducting simulation studies will allow for the precise numerical computation of the MFL field spatial distribution, thereby establishing a foundation for the optimization and refinement of magnetic sensor mechanisms.