Structural Optimization Design Of Basalt Fiber Front Crash Beam

Recently,with the fast development of material science,more and more high-performance materials（such as aluminum alloy,carbon fiber,glass fiber,basalt fiber,etc.）have been gradually widely used in industrial structural design.For that matter,they can not only improve structural performance,but also have significant lightweight effect.This paper takes a Bshaped basalt fiber composite front crash beam on the car as the design object.After acquiring the material physical parameter through mechanic tests,the accuracy of constructed composite finite element model,which adopted the measured material parameters is further verified by the drop weight impact test.Then,the synchronous optimization scheme of ply thickness and ply sequence is proposed and realized,and the optimized front crash beam has both excellent crash performance and lightweight effect.The theoretical basis of composite laminates and multi-objective optimization theory to provide reference for simulation and multi-objective optimization design are described.With the aim of obtaining basic mechanical performance parameters of basalt fiber required for simulation,test samples were made according to relevant national standards,and the elastic modulus,strength,Poisson’s ratio and other parameters were measured.High-speed tensile test of the material was carried out to determine the relationship between the strain and stress of the material under different strain rates when considering the effect of strain rate efficiency in the simulation.After that,a simulation analysis model of original steel crash beam was established,and the low-speed collision simulation was carried out,from which the evaluation index value were extracted.According to the principle of equal stiffness replacement,the initial thickness of the basalt fiber crash beam was acquired.The local coordinate system of different parts of the front crash beam was established,the normal direction of the element was adjusted,and the orientation of the fiber layer was defined,thus the modeling process of the basalt fiber composite beam is completed.A low-speed crash simulation was performed and the crash index values were extracted.In order to verify the accuracy of the finite element model,a comparison between the drop impact test and the finite element simulation was carried out.The errors met the accuracy requirements,it meant that the finite element model could be used for further optimization of the ply design.The coupling problem between ply thickness and ply sequence was explained,and a fixedlength variable which was used for multi-thickness scheme using automatic code identification was proposed.This scheme introduced the concept of effective ply and ply determination,which ensured the simultaneous optimization of ply thickness and sequence.By analyzing the index values of low-speed collision,the range of ply thickness was initially determined.Using Gaussian process regression to establish surrogate models of different thicknesses,combined with the third-generation non-inferior genetic algorithm to perform a multi-objective optimization which is pursuing for smaller collision force and intrusion and constrained by collision energy absorption and number of consecutive ply,and a final ply scheme was determined.Comparing the simulation and optimization results,the error is small and the optimization results are reliable.Eventually,the optimized basalt fiber composite material front crash beam,combined with the original traditional steel crash beam and carbon fiber composite material front crash beam,was comprehensively analyzed in terms of performance,quality,cost and price.