Research On 25% Small-Overlap Collision Optimization Of Vehicle Based On Traffic Accident

The ultimate goal of automotive safety research is to avoid or alleviate injuries to drivers,passengers and pedestrians in traffic accidents.Frontal collision is the most common accident,but China ’s regulatory crash test only includes 100% frontal collisions,and the new car evaluation procedure “C-NCAP” only increases 40%frontal collision.However,in real traffic accidents,the incidence of collision overlap rate less than 25% is high(24.4%),and will cause serious injuries.In 2016,China Insurance Automobile Safety Index "C-IASI" took 25% small-overlap collision into criterion.The results showed that only 32% of vehicles had achieved “excellent” or “good” in the past 3 years.Therefore,it’s urgent to improve vehicles which received “general” and“poor”.At present,the main solutions include material replacement,structural improvement,and restraint system optimization.However,using high strength steel materials to replace overall component will increase costs,and increasing thickness of structural parts will add weight.Hence,it is of great practical significance to explore a method that can reduce the injuries of drivers and passengers without substantially increasing costs and vehicle weight.In this paper,the laser splicing technology is used to optimize the main energy-absorbing components on both sides of the vehicle to improve the performance in small-overlap collision.Then,for the sake of reducing human’s injury in small-overlap collision,this paper analysis human injury mechanism and optimizes restraint system.This paper collected 165 cases of small-overlap accidents,of which 98 were ordinary vehicles,and the average overlap rate was about 19.3%.The accident scenario and vehicle deformation characteristics are summarized: in 100% and 40% frontal collisions,there are 2 or 1 front side members to absorb energy respectively.However,in the 25% small-overlap collision,the front side member is not in the collision area and does not bear the energy absorption effect,and the energy absorption members at both sides are not sufficiently deformed.The huge impact force transmits to A-pillar and threshold through the tire and resulting in excessive passenger cabin intrusion and living space reduced.Therefore,the study of shortgun on both sides of the vehicle can effectively reduces the amount of passenger cabin intrusion.In order to study the human injury mechanism of small-overlap collision,this paper selected a typical case and used THUMS human finite model to simulate the accident.Results showed that without seat belt restraint,the driver’s head collided with the A-pillar and the windshield after contacting the airbag,causing serious head injury;and driver’s sideslip was obvious,chest contacted airbag and interior with a high speed,causing serious chest injury.And the result was basically consistent with the driver’s head and chest injuries in the accident.For the sake of making vehicle’s force-absorbing parts fully absorb energy in a small-overlap collision,this paper proposed to use laser stitching technology to optimize shortgun,an important energy-absorbing component in small-overlap collision.After the optimization of the variable section,the energy absorption increased by 25%,and the overall vehicle mass increased by less than 0.1%,effectively reducing the intrusion at each measurement point.Finally,using higher yield strength material in areas which absorbed more energy,the vehicle score was significantly improved.To further improve vehicle occupant protection,this paper selected five parameters(seat belt warning force,seat belt warning time,steering column crushing force,airbag mass flow curve proportional coefficient,airbag ignition time)to optimize restraint system.Then,referred to US-NCAP,using optimal Latin hypercubic sampling to analyze the correlation of head,neck,chest and lower limb injury risk.Finally,establishing approximate model,and optimizing comprehensive injury risk by using genetic algorithm.The optimization effect was significant: comprehensive injury risk decreased from 35.4% to 16.6%,skull stress decreased by 23.7%,rib strain decreased by 23.1%,rib compression decreased by 10.4%.