Lightweight Research On CFRP Wrapped Multi Angle Thin Wall Beam Bumper Based On Crashworthiness

Due to the impact of air quality problems and oil energy crisis,the development of new energy vehicles is getting more and more attention.In light of the key problem of saving electric energy of electric vehicles,the requirement of light weight for electric vehicles is extremely urgent.Light weight can be achieved not only by improving the structure,but also by replacing the traditional material with light material.CFRP material,that is,carbon fiber reinforced composites,has excellent specific energy absorption value(SEA)in addition to high specific stiffness and specific strength.Therefore,the crashworthiness of the CFRP structure has become an important research topic.The paper uses twelve rectangular thin-walled beam structure and uses CFRP material to replace the original material.Lightweight design of bumper assembly structure for a passenger car is carried out.First,a group of experiments on the anisotropy of composite materials are designed,and the mechanical properties of CFRP are measured and the CFRP material cards are established.The dynamic impact test of the circular tube of the CFRP material is carried out,and the acceleration time curve is extracted.A circular tube impact simulation model was established based on the material cards obtained by the material static experiment.Finally,the experimental comparative analysis was completed,and the accuracy of the CFRP material modeling method was verified.Taking the light weight of the bumper assembly as the target,the structure of the car body of the base model is analyzed,and the light weight design condition is obtained.According to the situation of vehicle deformation under two working conditions and the situation of the force deformation and energy absorption of the bumper,the energy target of the bumper design is obtained,and the energy target is transformed into the design target of the energy absorbing box.Based on the collapse theory and the equivalent design theory of thin-walled beam wrapped by composite materials,the energy absorbing box and beam material were selected according to the targets already proposed,and the energy absorbing box and crossbeam were theoretically designed respectively,and the theoretical design value of material thickness was obtained.Finally,the rationality of the theoretical scheme is verified.According to the theoretical calculation,a series of verification schemes are set up.In the vehicle model,verify the proposed in Chapter third of the energy target;then 50km/h positive full collision simulation experiments verify whether can trigger the occupant restraint system between 15ms-20ms;the last reference to bumper low-speed Collision Regulations,collision simulation experiment,namely vertical collision simulation and vehicle collision angle simulation test.Finally,the optimal scheme is selected to achieve a weight reduction of 41.5%.