Experimental Study Of Spontaneous Magnetic Flux Leakage Signals Of Type LZ50Axle Steel

Because of the properties of high intensity and good plasticity, L250axle steel is widely used in passenger and freight trains of railway transports system. In recent years, railway system has been rapidly developed, tending to be more and more high-speed and high-load. Then, in order to ensure its security, it is particularly important to diagnose the early damage.The method of metal magnetic memory (MMM) is a new non-destructive testing technology, which was first presented by the scientist of Russian, Dc Doubov. Compared with the traditional electromagnetic non-destructive testing methods, MMM is quicker in detection speed, more economic for which can be used without external excitation source, smaller and easier to carry, and especially, it tends to be more sensitive when detecting the stress concentration fields. However, so far, the method can only be used in qualitative analysis. For well application in quantitative analysis, there is still a lot of research to do. The texts try to carry out the shape and the size of the deficiency for inversion experimentally and numerically. The main contents and conclusions include:Experimentally, do the plane and the curved indentation experiments and practice magnetic flux leakage detection with L250axle steel. Obtain the shape of the stress concentration fields according to the3D magnetic flux leakage signal which measures from the experiments and compare it to the actual pressure zones. The results show that it is feasible and high-precision to achieve the shape of the damage zone through the inversion of3D magnetic flux leakage signal.Numerically, FEM is used for3D numerical simulation of the above indentation experiments to get the stress distributions of the corresponding stress concentration fields. They are agree well with each other when comparing the three dimensional stress distribution picture calculated from numerical investigation with the3D magnetic flux leakage signal chart detected from experiments, which demonstrates once again the MMM is more accurate and precise for the stress concentration fields.