| The 2018 edition of China's new vehicle evaluation regulation was finally promulgated in April 2017,as most people expected,the new edition has made great adjustments from the grading system and the star classification system,the areas involved extend from single passive security to pedestrian protection and active safety,and the evaluation rules become more rigorous and perfect.This marks a new step in the overall manufacturing level of the automobile industry in China,but it also means that the automobile industry will face a higher technical threshold and higher requirements for the safety of the car.On the other hand,with the rapid development of national infrastructure construction,the highway has reached more than 130 thousand kilometers,which brings convenience to people,while the number of accidents on the highway accounts for a rapid rise in the proportion of the total number of accidents,Traffic accidents in China appear to be "high-speed",which often brings more serious consequences.Based on the above background,in order to improve the safety performance of the vehicle frontal crash,this paper studies the stiffness matching between the main energy absorption structures in the front of the body which is current mainstream compact SUV models on the market,the author puts forward an optimization design method for stiffness matching of tailor welded blanks and constructed a set of stiffness matching design and optimization system based on the energy absorption target,and verified the effect of the design results to the crash performance improvement with the help of simulation and test.The work and achievements obtained in this paper are as follows:(1)Build a simulation model and the thin-walled straight beam is used instead of the longitudinal beam to remove the shape surface.Through the orthogonal experiment design,all kinds of material and thickness of the welded blanks are arranged in a uniform and comprehensive combination.The combination of energy absorption and peak force is combined with different weights,and the evaluation model is added to evaluate the optimal stiffness combination.The simulation results show that the key indexes such asdeformation mode,energy absorption and peak force of thin-walled beams are in good agreement with the score of the evaluation model,and the feasibility of the design method is verified.(2)Taking the 100% overlapping rigid wall collision in the C-NCAP as the design condition,according to the actual demand and the energy absorption capacity,the energy absorption target values of the front end structures are set up reasonably.On this basis,the preliminary conceptual data of each structure are obtained by theoretical calculation,and the shortcomings of the indexes are found according to the simulation results.Considering the interrelation between the three types of deformation mode,energy absorption and peak force,and weighing the proportion of the three in various possible situations,a complete set of optimization process is built,and the corresponding method can be selected to optimize the interstructural stiffness gradient according to the shortcomings.Finally,the effectiveness of the system is verified by the combination of simulation and test.(3)Considering that the simplified model structure is simple and the force is simple,it can not simulate the complex stress situation of the front end structure in the formal collision.Finally,the complete vehicle finite element model is used to carry out the vehicle collision simulation with the above research results.The results show that the front structure still has better stiffness matching,its deformation mode and energy absorption characteristics meet the expected requirements and the vehicle crash resistance.,the performance is more excellent. |
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