Improvement Of Vehicle Crashworthiness By Lightweight Energy Absorbing Structure

It is of great significance to improve the car crash safety performance.This is able to reduce the harmfulness of traffic accident,and to protect the lives and property of occupants.The ideal characteristics of the carin collision and energy absorption are closely related to the body structure,materials and processes.The applicationof lightweight materials and energy-absorbing structure is much accounted with the rise of new energy vehicles.Basedontheconclusionsstudiedby others,in view of the present situation of the levels of production of the composite structure of aluminum foam,this paper presents the research on the safety of automobile collision for the composite structure of aluminum foam and thin-walled aluminum tube.Combined with the development process of the product,the structure improvement scheme of the energy absorption type sill cross beam and the filled front sill was put forward,and the quantitative analysis,evaluation and experiment of the improved structure design,optimization and application efficiency were carried out.The results show that the application of foam aluminum and its composite structure is able toeffectively improve the energy absorption characteristics of vehicles and the crash safety of vehicles.The requirements for the ideal energy absorbing structure of the automobile collision safety are studied.The characteristics of the energy absorption structure and material performance requirements were quantified.The existing evaluation indexes of energy absorption properties were analyzed.The evaluation index system of the deformation,acceleration,invasion,energy absorption and so on,which are related to the safety performance of vehicle collision,is established.The mechanical behavior of the light energy absorbing material and its composite structure was studied.The constitutive mechanism of cellular porosity yield,compressive strength and energy absorption of aluminum foam was studied.The combination of the foamed aluminum composite structure is proposed.The mechanical properties of aluminum tube,steel tube,foamed aluminum core and composite structure in the foamed aluminum composite structure are studied and compared.The deformation and energy absorption of the foamed aluminum composite structure under high speed impact are expounded and analyzed.On the basis of the theoretical analysis,ten kinds of composite aluminum foams with different porosity and aluminum tubes with different thickness were selected to fabricate the composite structure.The quasi-static and impact experiments of the foamed aluminum,thin-walled tubes and their composite structures were carried out respectively.A unified modeling method for the load-displacement relationship of foamed aluminum under different porosity or different strain rates was constructed.The performance curves of arbitrary density foamed aluminum materials under the same batch and the same process conditions were generated by using the cubic NURBS surface model to deal with the test point cloud.At any rate of strain,the characteristic curves of any density aluminum foam are produced.The system operation flow is simple,the model method is advanced,and theprecision meets the engineering requirement.The microstructure method and requirements of foam aluminum and its composite structure modeling model are studied.With the help of the comparison of experimental data,the modeling work of foam aluminum and its composite structure for automobile collision simulation is completed.The simulation model of collision energy absorption of aluminum foam,thin-walled tube and composite structure is compared with the experiment.Aiming at the other manifestations of automobile collision energy absorption structure,the collision simulation research of the split type foam aluminum composite tipping tube is carried out.The deformation mode and the stability of the structure were investigated when the pressure direction was changed.The characteristics and application direction of the tumbling tube filled composite structure are expounded,and the application platform of the foamed aluminum composite structure is constructed.The effects of the parameters such as the thickness of thin-walled tube and the density of aluminum foam on the crest-peak force,individual energy absorption,total energy absorption,total mass and specific energy absorption of the structural tube are discussed.The optimal solution is given by response surface method.Combined with the company’s example of model development projects,the target vehicle was selected as the object of improving and enhancing the safety of the collision.The finite element model of the whole vehicle structure and the white body structure and the simulation model of forward and side impact are established.The bending,torsional stiffness and mode of the target vehicle are analyzed to verify the simulation model of the vehicle body structure.According to the system requirements of C-NCAP,the simulation analysis of 40% offset collision and side impact of the target vehicle is carried out.The experimental results of the simulation and the experimental results of vehicle collision are verified.On the basis of the analysis,the parameters such as the deformation of the side threshold structure and the door structure deformation,acceleration,energy absorption and so on are analyzed,and the vehicle crashworthiness is quantitatively evaluated.The deformation and energy absorption of the front side girder in the frontal collision are studied.The goal and direction of improving the structure of the target vehicle are put forward.According to the structural characteristics and weakness of the original car,the energy dissipation body is designed.The simulation analysis of the vehicle collision under multi-scheme and multi-operating conditions is carried out,and the results are studied and compared in detail.The scheme integrates various characteristics of foam aluminum and thin-walled aluminum tube composite structure,and it has the advantages of improving the rigidity,high energy absorption and light weight.Based on the vehicle collision model,the influence of the side impact simulation and the parameter influence factors of the energy absorbing body were studied.Under the different collision conditions of 20km/h,50km/h and 80km/h,the law of improving the safety of automobile with foam aluminum composite structure was studied.The effect of foam aluminum composite structure on reducing the maximum acceleration peak and reducing the amount of intrusion in the low speed,medium speed and high speed working condition is studied.This is further evidence the effect of foam aluminum composite structure on improving vehicle safety.The impact of the body of the multi-program collision simulation is analyzed The results show that the foam aluminum composite structure to improve the body stiffness,reduce the maximum acceleration of the body of the dual effect of the peak.The structure of the energy-absorbing threshold beam and the prototype of the cross-beam structure of the original car were made.The reliability of the improved energy-absorbing door sill beam,the reliability of the simulation analysis and the validity of the experimental study are further verified.The impact test of high-altitude drop hammer was carried out on the structural members of the original sill beam and the structural members of the energy-absorbing threshold beam.The differences between the modified structure and the original vehicle structure in deformation energy absorption,acceleration and peak force at 50km/h speed collision are analyzed and compared.The impact and energy absorption characteristics of the energy-absorbing cross-beam structure are verified.An improved scheme of the filled front beam is designed for the target vehicle.The relationship between the porosity of foam aluminum and the wall thickness of outer tube is studied,and the characteristics of crashworthiness and structure are analyzed.The matching parameters of the aluminum foam density and the structure of the front stringer are optimized.The simulation analysis of the filling structure of the front side frame is carried out by using the simulation model of the target vehicle model.The results show that after the optimization match,the aluminum foam can be filled into the front side frame structure to improve the positive collision characteristics of the target model.This is a lightweight application of the prospects of the program.