Lightweight Design Of Vehicle Front Rail Beam Based On Frontal Impact

The front-end structure is the main energy-absorbing area in vehicle frontal collision,and the thin-walled front longitudinal beam vital in the energy absorption of the front-end structure,so the lightweight design of the front longitudinal beam is of great significance.For the lightweight design of the front longitudinal beam,this paper analyzes the crashworthiness of the front longitudinal beam from the crash simulation animation,and finds that the front section of the longitudinal beam is not enough to absorb energy and the middle section is not stiff enough to twist,using structural and welding design to improve the crashworthiness of the front longitudinal beam.Firstly,the structural design of the front section of the longitudinal beam,combined with the theory of deformation mechanism of thin-walled beam,and analyzed from two aspects: its own properties and induced structure.The correlation between its own properties such as section size,length,thickness and material on the energy absorption of thin-walled beam,and the main influencing factors of section size and thickness were determined through orthogonal tests;Secondly,the influence of induced structure on the energy absorption of thin-walled beam,and induced structure was designed to guide the deformation form of thin-walled beams.In order to fully improve the utilization rate of materials,the front longitudinal beam adopts laser splicing process,and the splicing position of laser splicing is determined through the force state of the front longitudinal beam under the self-weight working condition,the front longitudinal beam is divided into three regions,then the influence of materials and thickness in different regions on its crashworthiness is studied through orthogonal tests,and it is found that the material thickness properties of the front and middle sections of the longitudinal beam structure have a large impact on the crashworthiness of the longitudinal beam.It is found that the material thickness properties of the front and middle sections of the longitudinal beam have a great influence on the crashworthiness of the longitudinal beam,while the rear section of the longitudinal beam has less influence on the crashworthiness,but has a greater influence on the mass of the longitudinal beam.Therefore,in the lightweight design,stronger materials can be used for the front and middle sections of the longitudinal beam to ensure its crashworthiness,and lighter materials can be selected for the rear section to reduce the mass of the longitudinal beam.Finally,the lightweight design of the front longitudinal beam is carried out jointly by using structural design and welding design.The design variables determined by the orthogonal test are sampled using the Latin hypercube test design method,and the sample space is updated using a second-generation genetic algorithm;then the optimization process is built using Mode FRONTIER and ANSA,and a simplified model is established in order to improve the optimization efficiency;G1 and G2 in the firewall intrusion and equivalent double trapezoidal waveform are used as the constraint targets.The front longitudinal beam is lightweighted by using mass as the target.The final design results show a weight reduction of 20.3% for the front longitudinal beam while ensuring the crashworthiness of the front longitudinal beam.