Investigation On Magnetic For Fibre Reinforced Composite Material

The composite materials are made up of two or more kinds of materials. There are some physical property of the raw material itself, like its Low intensity and low Fatigue resistance. And it is anisotropic in the course of material forming. Fiber-reinforced composites are used in the complicated parts as new materials. Its internal quality is difficult to foresee and it is easily to be structural abnormalities just like delaminating and porosities. The kind of structural abnormalities is not always appeared externally, but fractured inside. This greatly reduces its mechanical performance and the carrying capacity. The fatigue damage of materials gradually exposed. It raises new requirements to the non-destructive testing.There are dead zone when we used ultrasonic testing on the fiber-reinforced composite materials.The operation mode is complex and the detecting image cannot be saved in the thermal imaging detection method. Therefore, the project proposed a magnetic detection technology. The relative permeability of the fiber-reinforced composite material is greater than that of the air, by means of its magnetic analysis. It shows that this material is paramagnetic material and the magnetic detection technology can be used on it. We used the high-precision magnetic detection on the preset artificial defects and the natural defects to get magnetic signature. We assessed the defects according to the difference between the signals of the magnetic induction. According to the results of the experiment, if the peak of the magnetic signature is greater than the area of30nT, we can judge it as aberrant area. We used differential processing on the original data. If the differential signals suddenly go beyond the red threshold line or greater than lOnT, we can judge it as the central area of the defect to locate it. We did some correlation processing on the original data. If the correlation coefficient is greater than0.15, we can judge it as the boundary of the defect to determine the equivalent value of it. We used the automatic magnetic detection system after proving the feasibility of the magnetic detection on the fiber-reinforced composite material. According to the data that the multi-channel sensors got, we did a2D imaging processing to the fiber-reinforced composite material to make a location, quantification and qualitative determination on the defect. We did all above to proving the feasibility of the magnetic detection on the fiber-reinforced composite material.