Research On Crashworthiness And Reliability Optimization Design Of AL/CFRP Hybrid Material Body Energy Absorption Structure

With the increasing requirements of vehicle for crash safety,energy saving and environmental protection,the use of lighter and better safety materials has become one of the most effective ways to lighten the body.Metal/carbon fiber composite material,which combines low-density composite materials with low-cost metal materials,is expected to combine the crushing deformation of composite materials with the plastic deformation of metal,and provide cost-effective and efficient energy absorption device for car body,which has great potential.Based on the national key R & D Program(2017YFC0803904)and the National Natural Science Foundation Project(51905042),a series of composite square tubes with the same geometric dimensions,type-I(aluminum tube inside,woven carbon fiber outside)and type-II(aluminum tube outside,woven carbon fiber inside),were prepared by rolling process and blow molding process.At the same time,aluminum square tube and carbon fiber square tube with corresponding size were prepared,and the crashworthiness of metal/carbon fiber composite thin-walled square tube was studied by quasi-static crushing experiment and FE simulation.By observing and comparing the deformation mode and displacement load curve data of each sample,the crushing performance of mixed material square tube was discussed.The experimental results show that the crushing degree of the composite type-II composite material square tube is greater than that of the composite type-I composite material square tube,and its energy absorption value is greater than the sum of the energy absorption values of two single material tubes with the same structural parameters,type-II showing better crashworthiness.Based on the non-linear finite element software ABAQUS/Explicit,the numerical simulation of type-II mixed tube,aluminum square tube and carbon fiber square tube with better crashworthiness was carried out,and the results were compared with the experimental results.The simulation results show that the failure mode and load displacement curve of the hybrid square tube are consistent with the experimental results,which lays the foundation for the parameter analysis and iterative optimization that need a lot of model calculation in the future,and carries out the parameter research by using the verified finite element model.Considering that the design parameters will inevitably produce error fluctuations in the process of production and manufacturing,the performance constraint index will exceed the constraint boundary.Therefore,in order to optimize the crashworthiness performance index and reduce the probability that the performance constraint exceeds the boundary of the constraint condition,a multi-objective optimization design is carried out to meet the reliability of the crashworthiness performance index.The optimization results show that: the reliability of CFE constrained by the reliability optimization solution is 98.32%,which is 10.96% higher than that of the deterministic optimization solution of 87.36%,greatly reducing the failure probability of the design value,making the design of composite square tube with higher reliability and better practical application.