Due to the non-uniformity of microstructure and complex mechanical properties of composite materials, the difficulty of component design is greatly increased.Adopt the method of multi-scale analysis, according to the T300 / Epoxy twill woven composites mesoscopic geometrical parameters, the unit cell geometry model, the introduction of periodic boundary conditions on the unit cell structure finite element analysis, then composite laminated plates is 3 d elastic performance parameters, and through mechanical test prove that the test results and the predicted results are close to;MAT_54 in LS-DYNA was used to establish the progressive failure model of composite materials, and the model parameters were adjusted through the results of three-point bending test. Finally, the simulation results of the progressive failure model of composite materials were consistent with the experimental results.The modified progressive failure model is applied to the lightweight design of electric vehicle composite body frame, and the top pressure simulation and column collision simulation of composite body frame are carried out.The analysis results show that the composite body frame design meets the requirements of laws and regulations. Compared with the aluminum alloy frame, the composite body frame has a better impact resistance performance with a weight reduction of 59%.

With the increasing impact of energy problems on people, the development of electric vehicles has attracted more and more attention.But their heavy batteries make the payloads too low and the range too small.In order to solve this problem, the lightweight technology, including the application of new materials and structural optimization, can be used to reduce the weight of electric vehicles, so as to reduce energy consumption and improve the mileage.Thus it can be seen that lightweight technology is of great significance to the development of electric vehicles.Fiber reinforced composites are popular in electric vehicle lightweight because of their high specific strength and specific stiffness.Therefore, the design and manufacturing methods of composite automotive parts and assemblies have become the focus of research.Scholars at home and abroad have systematically studied the mechanical properties of composites by means of theory, experiment and numerical simulation.MAMALIS et al. conducted systematic experimental studies on the crashworthiness of composite thin-walled tubes.The test results show that the strain rate, fiber lay-up sequence, fiber volume fraction and tube wall thickness play a decisive role in the impact resistance of the structure.YANG et al. conducted in-depth research on the energy absorption characteristics of 3D braided composite square pipes.NG et al. obtained the two-dimensional constitutive model of woven composites by using finite element method, and verified the correctness of the model by comparing with experiments.A Representative elemental Volume (RVE) finite element model was established for the meso structure of the tabby fabric laminar plate to predict the modulus of the composite material, and the strength of the RVE was predicted according to the failure criterion.The results show that the modulus predicted by finite element method is consistent with the actual value and the strength of single cell is consistent with the actual strength.DENG et al. used the method of finite element numerical simulation to analyze the elastic properties of plain glass fiber composite, and the predicted results were consistent with the experimental results.OBRADOVIC et al. used commercial finite element software LS-DYNA to model the woven carbon fiber reinforced composite and applied it to the design of the front-end components of high-speed racing cars.FEREBOLI et al. used MAT54 in LS-DYNA to introduce the finite element model of corrugated composite plate in detail, and carried out numerical simulation of its axial crushing, and then compared it with the test.MAMALIS et al. established a progressive failure finite element model for square pipes of woven composite materials and carried out axial static and dynamic analysis on them.