FEA of the relationship between MMM signal and stress in pipeline inspection

2D Finite Element Analysis (FEA) is performed in order to study the relationship between the Metal Magnetic Memory (MMM) signal and the stress, and the stress-magnetic permeability coupling model and the governing equation for pipe stress and earth magnetic field are applied. First, utilizing the stress distribution calculation function provided by ANSYS, the stress strength distribution of the pipe under 4.5 MPa is computed, then, the earth magnetic field is calculated with the stress-magnetic permeability coupling model. The results show that the stress and the magnetic permeability are related and FEA is capable for detecting the stress signal, hence recognizing the pipe defects.