Simulation And Optimization Of Restraint System Based On Overlap Offset Collision Of Passenger Car

With the development of national economy,the number of cars is increasing,and the frequency of traffic accidents is also increasing.According to the statistics of accident type data,frontal collision is the most common accident type,and the proportion of small overlap offset collision is about a quarter.The front of offset collision vehicle does not fully contact with obstacle avoidance,so higher requirements are put forward for the front design of vehicle.25% small overlap offset collision can well simulate the real life car collision with the opposite car,obstacle avoidance,power poles,trees.At present,the domestic regulations on small offset collision are only for small passenger cars,and the relevant regulations and standards for passenger cars have not been issued.In this paper,a bus is taken as the research object,and a small offset collision model is established with reference to the iihs25% overlap rate small offset Collision Regulations.The reliability of the collision model is verified by the changes of energy and mass during the collision process.On this basis,the small offset impact analysis including passenger restraint system is completed.The results show that:(1)the deformation of the bus body frame and cockpit is very serious after the collision;(2)the acceleration of the bus center of mass is not large,the probability of passenger injury is low,but the acceleration of the driver’s seat exceeds the limit of the regulations,so the driver will be seriously injured;(3)the invasion of the cab living space exceeds the limit of the regulations,so the driver’s living space in the collision is small,and the leg injury rate is low(4)the injury index of the driver’s head and tibia of lower leg exceeds the legal limit,and the area of the head contacting the air bag is small,so the driver’s skull and tibia are at risk of fracture.Through the analysis of the load transfer path of the body frame and the deformation of the body frame and the cockpit in the collision process,the corresponding improvement scheme is proposed from two aspects of changing the body cockpit material and adding the energy absorption device in the front of the body cockpit.The analysis results of the improvement scheme show that the acceleration at the driver’s seat is significantly lower than that before the improvement,and the living space is significantly improved However,the injury index of neck and leg exceeded the limit of the regulation.The results show that the restraint system is sensitive to the exhaust hole size,air flow rate,airbag ignition time and seat belt force limit level.Therefore,the orthogonal optimization method is used to optimize the above variables to obtain the optimal combination of relevant parameters,and then the design is improved The follow-up analysis shows that the improved indicators of occupant injury meet the requirements of the regulations,and the WIC is reduced by 77.95% and 38.92% respectively after the structural improvement,material strengthening and restraint system optimization.The method used in this paper can provide a theoretical basis for the research of bus offset impact,and also help manufacturers to improve the front structure of bus and optimize the matching of restraint system.