Analysis of Finite Element Modeling of Magnetic Flux Leakage Technique in Plates with Defect

In the area of non destructive testing ultrasonic testing using wave propagation is an emerging field. Ultrasonic testing uses transmission of high frequency sound waves into a material to object and reflections (echoes) are returned to a receiver from internal imperfections. The waves travel through a given medium at a specific speed, velocity, in a predictable direction and when they encounter a boundary with a different medium they will be reflected or transmitted. The aim of the simulation is to find out how different flaw geometries and orientations influence the measured signal. To find flaws near the surface, a magnetic flux leakage (MFL) inspection system can be applied. 3D FEM is used to analyze the MFL signals, a generalized potential formulation to the magneto static field, MFL problem is discussed.Typical 3D defects are accurately modeled and detailed comparison is done for model with defect. Finally, we want to infer the flaw geometry from the signals. In the pulse echo method, a piezoelectric transducer with its longitudinal axis located perpendicular to and mounted on or near the surface of the test material is used to transmit and receive ultrasonic energy. The characteristics of wave propagation problems are that the frequency content of the exciting force is very high.COMSOL Multiphysics was used as an analytical tool to model the wave propagation. This paper presents the three-dimensional FE modeling of leakage magnetic fields from surface and sub-surface defects of different dimensions in 12 mm thick carbon steel plate. The details of 3D model and results of FE study of the effects of depth location and depth on the detestability of sub-surface defects in the MFL technique are discussed in the paper.