Abstract: With the aim of improving the reliability of magnetic memory testing and by fully considering the characteristics of magnetic memory allcomponent signals, a novel magnetic memory testing method which combines the normal and tangential signals is proposed. First, we acquire magnetic memory signals of aeronautical ferromagnetic tensile 18CrNi4A specimens under different tensile loadings in both the normal and tangential directions. Then the signals are filtered using wavelet package method, and Lessajou figure is obtained. The location of the close area in the figure indicates the place of the stress concentration, and the size of the close area is used to judge the extent of the stress concentration. With this method, research is conducted concerning the relation of magnetic memory signals between the normal direction and tangential direction under stress concentration. It is proved that the wavelet package denoising is feasible. The signals in the stress concentration part present a close area in the Lessajou figure, and the size of the close area increases with the increasing extent of stress concentration. When the obvious submit of the material exists, the size of the close area increases more rapidly. The method is of practical value in engineering application.

Key words: nondestructive testing, magnetic memory testing, wavelet package, Lessajou figure, stress concentration