Design And Research Of Automobile Energy Absorption Box With CFRP/AL Hybrid Structure Filled With Aluminum Foa

Carbon Fiber Reinforced Plastic（CFRP）is widely used in energy-absorbing structures due to its excellent mechanical properties.However,the single CFRP thin-walled structure has the disadvantages of brittle fracture,unstable failure mode and high cost in the energy-absorbing process.The CFRP/AL hybrid structure can combine the low density of the composite with the high ductility of the aluminum alloy.In the energy absorption process,the energy absorption stability of the structure can be improved by relying on the relationship between the components.In this paper,the crashworthiness of CFRP/AL hybrid structure was studied by means of experiment,theoretical analysis and simulation.The application of aluminum foam filled hybrid structure in automobile energy absorbing box was discussed,which provides reference for the structural design and optimization of CFRP/Metal hybrid structure automobile parts.The research contents are as follows:Firstly,in order to study the crashworthiness of various types of thin-walled structures,four kinds of thin-walled structures,hollow aluminum alloy tube,hollow CFRP tube,CFRP/AL-2 mixed tube and CFRP/AL-4 mixed tube,were prepared in turn.The crushing response of each sample was obtained by axial crushing test,and its deformation mode and crashworthiness were analyzed to select thin-walled structures with better crashworthiness.Secondly,the energy absorption mechanism of CFRP/AL-4 hybrid tube was studied.The damage failure mode was divided into axial splitting and crack propagation at the four corners of CFRP tube,transverse shear,delamination between each component,dynamic friction between CFRP and upper pressure plate and plastic deformation of aluminum alloy tube.The theoretical calculation formula of the average load of CFRP/AL-4 hybrid structure under axial crushing was derived.The accuracy of the theoretical calculation formula was verified by the experimental results,and the energy absorption mechanism of CFRP/AL-4 hybrid structure was quantitatively characterized.Then,the finite element model of axial crushing of each thin-walled structure was established.The accuracy of the finite element model was verified by comparing the deformation mode and force displacement curve of the test and simulation.On this basis,the effects of the thickness of aluminum alloy tube,the cross-sectional size of aluminum alloy tube and the number of CFRP layers on the crashworthiness of CFRP/AL-4 hybrid structure were studied.Finally,in order to improve the crashworthiness of CFRP/AL-4 hybrid structure,aluminum foam was filled into the CFRP/AL-4 hybrid tube in different ways to form two filling structures:C_L8/AF1 and C_L8/AF2.By comparing the crashworthiness of the two structures,the C_L8/AF2 structure with better crashworthiness was selected and applied to the front bumper system of the vehicle for low-speed collision simulation.The crashworthiness of the C_L8/AF2 crash box and the traditional aluminum alloy crash box was compared and analyzed.In order to further explore the energy absorption potential of the C_L8/AF2 energy absorbing box structure,the multi-objective optimization of the parameters affecting the crashworthiness of the C_L8/AF2 structure was carried out.The results showed that compared with the traditional aluminum alloy energy absorbing box,the mass of the optimized C_L8/AF2 energy absorbing box was reduced and the crashworthiness was significantly improved.