Simulation of the Propagation Behavior of Short Cracks in Q235 Steel Based on Stress-Magnetic Coupling

A stress-magnetic coupling model was established from the perspective of energy conservation to study the variation rule of the magnetic signals in the process of short crack propagation in Q235 steel. The stress distribution and magnetic induction intensity caused by the propagation of surface short cracks in different directions can be solved using the finite element method. The effect of early short crack propagation under the tensile load on the magnetic signals of the surface space was analyzed. Results showed that magnetic induction intensity linearly increased with the increase in tensile stress. The propagation of short cracks in all directions would affect the surface magnetic induction intensity, wherein the magnetic signal was most sensitive to depth change and least sensitive to length change. The peak value of magnetic anomaly first increased and then decreased with the increase in the length and depth of short cracks and gradually increased with depth. Early damage in Q235 steel can be determined by measuring the magnetic induction intensity of the surface. This approach provided a new idea for the application of the magnetic detection method in the quantitative problem of short cracks.