Bionic Study And Design Of Vehicle Bumper Based On The Requirement Of Lightweight And Crashworthiness

Automobile crashworthiness is an important direction of automobile safety research,which is of great significance to guarantee the safety of drivers.Therefore,the design of thin wall structure with good energy absorption and bearing performance is important to improve the crashworthiness of the car and the structure strength,also is the key and difficult point for domestic and foreign scholars study.The bumper system is the main energy absorption component of vehicle.It is very important to design an optimal bumper system with best energy absorption characteristic under the premise of lightweight.In order to improve the automobile impact safety performance,this paper mainly focuses on the bumper system structure optimization,through the principle of the bionic structure design to design the bionic bumper system,providing the automotive passive safety research for new train of thought and theory basis.Through the statistical analysis of bamboo stem size parameters,on the macro level,bamboo section diameter,wall thickness and inter nodal distance show the gradient and the regularity.A bionic crush box,a variety of bionic beams and bionic cross section bumper beam were designed.The results of axial impact simulation show that the performance of bionic crush box has the best performance when the wall thickness ratio is 3/2.47/1.78 mm and the length ratio is 1/2/1.The SEA of bionic crush box increased by 6.2% than that of ordinary crush box,peak load decreased by 28.23% and crushing force efficiency increased by 7.48%.At the same time,the mass is decreased by 19.3%,which is a lightweight design.And the deformation of bionic crush box is more stable than that of the normal crush box.When the collision angle is 10°,the SEA bionic crush box increased by 39.2%than normal crush box,while the peak load was reduced by 32.7%.The structure has the advantages of strong absorption capacity,light weight,little peak load and stable deformation.At the same time,the simulation results show the consistency with experiment.Bamboo nodal samples and internode samples were tested by the quasi-static three-point bending,and the result shows that the bending strength and energy absorption of nodal samples were higher than that of internode samples.The energy absorption increased by 56.7%,the specific energy absorption and the bending strength increased by 78.8%,31.4%.Moreover,the bending strength increases with the increase of the number of nodes but the specific energy absorption decreases with the increase of the number of nodes.Based on the bending test of bamboos,6 kinds of bionic bumper beams were designed.The simulation results show that the crashworthiness performance of bionic 1 and 2 were better than that of the original bumper beam.Also,a comprehensive evaluation index S was introduced to evaluate the bumper,which covers two kinds of evaluation index under three collisions condition.After calculation,the comprehensive performance of BBS2 was the best.Its comprehensive performance value S increased by 60% than that of OBS,and its quality is lighter than OBS by 32.4%.In order to find an optimal bumper system,the response surface optimization method is adopted to optimize the bionic bumper system.After optimization,BBS2 was significantly improved compared with the original structure,as the case of 100% impact: the SEA of BBS2 was 4.5% higher than that before optimization,and the peak load was 4.2% lower than before optimization.As the case of40% bias impact: the SEA of BBS2 was 7.5% higher than that before optimization,and the peak load was 12.79% lower than before optimization.As the case of column impact: the SEA of BBS2 increased by 2.4% compared with pre-optimization,and the peak load was 34.37% lower than before optimization,while BBS2 was 76% lighter than before optimization.