Carbon Fiber Reinforced Composite Car Bumper Lightweight Design

Automobile passive safety has always been a hot issue in domestic and foreign research,and its performance is affected by the crashworthiness of automobile bumper.With the advantages of light weight and high strength,carbon fiber reinforced plastic(CFRP)has gradually expanded its application range in the field of automobile,and has begun to replace metal thin-walled structures for automobile energy absorption components.However,the failure mode of carbon fiber reinforced plastic is complex and the bearing capacity is unstable.The hybrid thin-walled structure with metal and composite can guide and control the progressive failure of composite materials through metal stable plastic deformation,and improve the stability of the failure process.Therefore,in order to improve the crashworthiness and lightweight level of automobile bumper,this paper designs an automobile bumper containing a carbon fiber reinforced plastic/aluminum alloy(CFRP/Al)hybrid thin-walled tube crash box and a CFRP bumper beam,and studies the lightweight design method of automobile bumpers,which has important engineering application value and has certain reference significance for the design and development of lightweight and high strength automobile energy absorption components.Firstly,the basic mechanical theory of carbon fiber reinforced plastic was briefly introduced.On this basis,the test samples of carbon fiber reinforced plastic laminates were made according to the test standards,and the mechanical properties were tested.The test data were collated and calculated,and the mechanical properties parameters of carbon fiber reinforced plastic were obtained.Secondly,quasi-static axial compression tests of aluminum alloy tube,CFRP tube and CFRP/Al hybrid thin-walled tube were carried out,and their failure modes and energy absorption characteristics were compared and analyzed.Three finite element models of quasi-static axial compression of circular tubes were established.By comparing the simulation and experimental results,the model parameters were corrected,and the finite element model with high accuracy was obtained.Then,orthogonal experimental design and entropy-based TOPSIS approach are used to study the influence of structural size parameters and material layer parameters on the energy absorption characteristics of CFRP/Al hybrid thin-walled tube under axial compression.The CFRP/Al hybrid thin-walled tube is applied to the crash box of automobile front bumper.Taking the original aluminum alloy crash box as a reference,the energy absorption characteristics of CFRP/Al hybrid thin-walled tube crash box under axial compression are optimized by multi-objective optimization,and the Pareto optimal solution set is obtained.The optimal design parameters of the energy absorption box are determined.Finally,the optimized CFRP/Al hybrid tube crash box is applied to the front bumper of automobile,and the material of steel bumper beam is replaced by carbon fiber reinforced plastic.Referring to the relevant regulations of automobile impact,the finite element models of low speed impact and high speed impact of automobile bumper are established.The crashworthiness and lightweight effect of aluminum alloy crash box-steel bumper beam,aluminum alloy crash box-CFRP bumper beam and CFRP/Al hybrid tube crash boxCFRP bumper beam are compared and analyzed.Then the multi-level optimization method including free size optimization,size optimization and layer sequence optimization is used to optimize the CFRP bumper beam to realize the lightweight design of automobile bumper.