| In this paper, the study of the processing technique, reinforcing mechanism and mechanical property of hat stiffener wall structure reinforced by Z-pin was carried out in order to generalize the application of Z-pin 3D reinforced in the field of certain new type advanced training aircraft's hat stiffener structure. The processing technique of hat stiffener wall structure reinforced by Z-pin was proposed, the hat stiffener wall structure samples reinforced by Z-pin were prepared successfully and tested under tensile loading, bending loading and impact loading, reinforcing mechanism with Z-pin and influence law with different parameters of the joint performance on interface between the skin and the stiffener of polymer composite' hat stiffener wall structure were researched, which would ensure the practical application of Z-pin technology in stiffener wall structure of the aerospace field.The processing technique of the hat stiffener wall structure reinforced by Z-pin with metal-rubber soft mold was adopted, the expansion model of silicone rubber was establishe d, the optimum technological gap of 0.4mm was obtained, and the corresponding metal cavity model and rubber mandrel were designed; The strength of interface between Z-pin and composite matrix and the shear performance of Z-pin were tested, by bridge tow of single pin pull-off test and convex shear test; Meanwhile a technological method of Z-pin inserting through the improvement of Z-pin inserting technology was proposed, which could control the angle and depth of Z-pin inserting accurately; The curing process of thermal expansion mixed with hot-press which is suitable for hat stiffener wall structure reinforced by Z-pin was explored, and samples with high quality were prepared successfully.The study of the tensile property of composite' hat stiffener wall structure reinforced by Z-pin was carried out. It turned out that: comparing with the samples without Z-pin, the pull-off strength of hat joints reinforced by Z-pin was greatly improved, and increased with the Z-pin volume fraction on the first state and deceased with the Z-pin volume fraction after, Z-pin reinforcing hat joint increased the peak value up to 31.15% than samples without Z-pin; The effect of the diameter of Z-pin on the pull-off strength of hat joint was not obvious; With the increasing of the load span, the pull-off strength of hat joints reinforced with Z-pin decreased with the principal failure model transforming from pull-off-dominating to shear-dominating; In addition to the defect locates inside the R part, the pull-off strength of samples reinforced by Z-pin with prefabricated defect was higher than samples without Z-pin.The study of the bending property of composite' hat stiffener wall structure reinforced by Z-pin was carried out. It turned out that: the bending property of hat stiffener wall structures reinforced by Z-pin improved with the increase of Z-pin volume fraction, when the volume fraction of Z-pin is 2.6%, the bending property was best through theoretical analysis; The effect of the diameter of Z-pin on the bending load of stiffener wall structures was not obvious; When the distribution length of Z-pin is 48% of the total length, the bending peak load of hat stiffener wall structure reinforced by Z-pin equals the bending peak load of samples with the 100% Z-pin inserting length.The study of impacting property of hat stiffener samples reinforced by Z-pin was carried out, the reinforcing mechanism with Z-pin of impacting property of hat stiffener wall structure was studied combining the ultrasonic C scan and tensile test after impact. It turned out that: the impacting property and pull-off strength after impact of hat stiffener were improved by Z-pin; With the increase of Z-pin volume, the defect area decreased, pull-off strength after impact increased, and when the volume of Z-pin is 1.0%, the effect of 10 J impacting energy on the pull-off strength was not obvious; With the increase of Z-pin diameter, the defect area increased, pull-off strength after impact decreased; Increasing the impacting energy, the defect area increased, pull-off strength after impact decreased; When the impacting energy is 18 J, the defect area was 82.0% of the total area of the interface between the skin and the stiffener, while the pull-off strength of decreased to 25.1% of intact samples' pull-off strength; When the impacting location was the center site of hat stiffener, the effect of 10 J impacting energy on the pull-off property of samples was not obvious. |
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