Research On Forward Conceptual Design Method Of Vehicle Body Containing Collision Safety

With the gradual increase of car ownership,traffic accidents occur frequently,and people pay more and more attention to the passive safety of cars.At present,the car is developing in the direction of short forward suspension,and the collision safety regulations are becoming more and more stringent.These factors increase the difficulty in developing the safety of frontal collision safety of automobiles.In order to respond quickly to market demands,the automotive development cycle has also been shortened.Collision safety that was previously considered in the detailed design phase has to be advanced to the conceptual design phase.However,the lack of detailed models in the conceptual design stage,how to consider the safety of the frontal collision of the car,while taking into account other performances,and getting the best body structure design is still a problem that needs to be discussed in depth.In this paper,with the goal of lightweighting,while considering the static bending,torsional stiffness and modal characteristics of the vehicle body,the design method of the frontal collision safety of the body during the conceptual design phase is studied.The main contents of the thesis are as follows:(1)Considering the safety of the concept design stage,the forward body design process is proposed.According to the principle of structural mechanics,the mathematical optimization model of the body stiffness chain is established,which simplifies the body into a space frame structure connected by the beam unit through the nodes.Through the simulation analysis of the benchmark car,the understanding of the collision process is deepened.(2)From the perspective of occupant protection,the vehicle body speed curve is derived to guide the structural design of the front cabin.The front longitudinal beam with the highest suction energy is divided into the crushing section and the bending section,and the design of the axial bending of the longitudinal beam is studied.(3)Exploring the application of aluminum alloy materials in automobile lightweighting,and completing the topology optimization and size optimization design of anti-collision beam and energy absorbing box.The overall simulation model of the front cabin is established,and the cross-section forces transmitted to the vehicle body by the front longitudinal beam and the upper side beam are obtained.(4)The equivalent static load method is used to simplify the dynamic large deformation condition of the frontal body collision into static linear working conditions.Combined with static bending,torsional working conditions and first-order modal frequency constraints,the genetic algorithm is used to solve the mathematical model of the rigid chain body and optimize the rectangular section parameters of the main beam element.The feasibility of the design method was verified by comparison with the benchmark car.The research in this paper incorporates the frontal collision safety of the vehicle body into the design scope,which makes the main section optimization result closer to the actual situation,and has certain reference significance for the body development in the conceptual design stage.