Frontal Crash Safety Analysis And Evaluation For Front Structure Of Body-in-white

Automotive safety is an eternal theme and has attracted much attention since it wasinvented. Nowadays, as the rapidly development of China’s automobile industry, by the endof2014national civil automotive ownership has reached154million including83.07millionsaloon car, which bring more security concerns. In recent five years, the number of peopledied in traffic accidents every year is about60,000in China. Foreign made a statistic aboutaccident types that lead to serious injury and death, and found that frontal impact accidentproportion account for fifty percent above. Thus, improving frontal impact safety of salooncar has very important practical significance.BIW as one of the important parts of the car, not only to meet the demand of visualaesthetics, should also meet the requirements of aerodynamics, man-machine interaction,and NVH performance. What’s more, it should mainly played an important role in withstandcollusion and protect motorists. BIW has long been a focus and hotspot in research of theautomotive passive safety.In this paper, BIW is the mainly study object. The6061aluminum alloy material isapplied to front bumper anti-collision beam and crash box. Through topology optimization,size optimization and multi-objective optimization of front bumper anti-collision beam,crash box, forepart of front longitudinal beam, to improve the security of body white body.Analyzing and evaluating the security of BIW to verify the rationality of optimization. Theresearch idea of this paper is as following.Firstly, install the BIW on tackle and then establish frontal impact finite element model.Use the BIW frontal impact finite element model simulate and analysis full frontal impact atspeed of50km/h regulated by GB11551-2003passenger vehicle frontal impact occupantprotection. Design and implement the same BIW experiment to verify the precision of BIW frontal impact finite element model.Secondly, apply topology optimization and size optimization technology to BIWfront-end structure including front bumper anti-collision beam, crash box, and forepart offront longitudinal beam. According to the result of optimization, design a new front-endstructure, and constructs a simplified front-end structure frontal impact model. This papertaking the section shape, size, thickness of front-end structure as optimized parameters; andtaking the increment of total energy and the change in length of front-end structure asconstraints; and taking energy absorption ratio, acceleration peak, variance of rigid wallreactive force as optimization target to perform NSGA-II multi-objective optimization andget a solution set of Pareto. And select a solution from Pareto that satisfy the requirement ofminimum mass.Thirdly, replace the original front-end structural with the new one in the BIW finiteelement model. Comparing deformation modes, energy absorption ratio, B pillar accelerationpeak of joint of B pillar and threshold beam, intrusion of measuring points of firewall,variance of rigid wall reactive force between the original BIW frontal impact simulation andthe new one. Through the above compares, evaluate the security of BIW and verify thevalidity of front-end structure optimization. The result show that the energy absorption ratioincreased by1.55%, the acceleration peak of joint of B pillar and threshold beam reduced by19.77%, the maximum intrusion of measuring points of firewall reduced by32.84%, thevariance of rigid wall reactive force reduced by32.29%without increase of mass. Thus thefrontal impact safety of BIW gets an improvement.