Research On The Structure And Processing Of 3D Braided Material Based On Space Group P4 Symmetry

3D braided materials have great potential applications in aerospace,sports and automotive industries,because it has a lot of advanced properties,such as its modulus and damage tolerance and fracture toughness are high.The most of novel 3D braided geometries deduced by group theory are restricted by the complicated process.Since the traditional three-dimensional braided material has low production efficiency and high cost,the material with new geometrical structures and new braiding process should be developed urgently.For the 3D braided materials based on space group P4 symmetry,the following research work is mainly made in this paper:The rationality of yarns intersection method for the 3D braided geometry based on space group P4 symmetry has been proved.Considering the integrity of the geometry and the continuity of the surface yarns,the motion law of braiding yarns in the space was analyzed,and the complete geometry of rectangular 3D braided material was obtained.The geometry of 3D braided material was analyzed by the method of representative volume unit.The mathematical model was established to calculate its structural parameters and predict the fiber volume fraction.The feasibility of its braiding process was provided by experiment.The meso-structure and unit characteristics of tubular 3D braided material based on space group P4 symmetry was analyzed.The geometric model of tubular 3D braided material was established to analyze the relationship between geometric parameters of braiding,and predict the fiber volume fraction and its variation tendency.The braiding process and yarns topological structure was analyzed,and the feasibility of tubular braiding process was provided by experiment.For the processing requirements of the rectangular 3D braided material based on the space group P4 symmetry,the movement rule of carriers in braiding process was analyzed,and its process equipment was designed tentatively.The chain transmission mechanism was used in lateral movement of carriers to realize the precise positioning and movement cycle of carriers,and the power was provided by stepper motor to realize the interval feed;The vertical movement of carries was driven by air cylinder to realize rapid location,and programmable logic controller was adopted to realize sequence control of movement in lateral and vertical.In this paper,according to the theory of 3D braided geometry satisfied the symmetry of space group P4,the braiding process of rectangular and tubular structure were analyzed,the mathematical model of 3D braided geometry was established,and the equipment for rectangular process was designed,which provide the theoretical basis for further research of new 3D braided geometry,and it is beneficial to enrich the varieties of 3D braided materials.