Research On Vehicle Structure Optimization And Occupant Constraint System Matching Under Frontal 25% Collision Condition

Vehicle frontal 25%(overlap rate)collision accidents account for about a quarter of the total frontal collision accidents.Compared with the frontal 100 % and 50 % collision conditions,the front cabin structure of the vehicle in this condition has less buffering effect,more serious deformation of the passenger compartment and greater acceleration of the vehicle,resulting in reduced passenger compartment space and more serious occupant injury.Therefore,based on the frontal 25 % collision condition,it is of great practical significance to carry out the research on vehicle crashworthiness and occupant restraint system matching to improve the occupant safety in the vehicle.The main research contents are as follows :(1)Frontal 25% overlap collision safety analysis.In this paper,a SUV is taken as the research object.According to the requirements of C-IASI regulations,the finite element model and working condition setting of the vehicle are established,and the collision simulation calculation is carried out by LS＿Dyna.By evaluating the energy change and mass increase of the simulation results,the effectiveness of the model is ensured.The vehicle collision deformation and motion state,acceleration and velocity curve,deformation of key components and cross-section force are analyzed in detail,and the reasons for poor collision force transmission path and vehicle crashworthiness rating are summarized.(2)Vehicle crashworthiness structure optimization based on force path.Aiming at the problems of insufficient energy absorption in the front cabin of the vehicle and poor crashworthiness rating in the frontal 25% overlap collision condition,this paper proposes to optimize the front cabin structure and the passenger cabin structure from the force transmission path of the collision condition.Orthogonal test design and range analysis were used to match the thickness of the main collision structural parts to determine the optimal combination.(3)Occupant restraint system matching based on orthogonal design.ANSA and Primer are used to complete the construction of the occupant restraint system model on the driving side,including extracting the body,adjusting the dummy sitting position and seat,constructing the seat belt system and airbag,and boundary conditions and loading.The evaluation indexes and standards of dummy injury are introduced,and the causes of dummy injury are analyzed.Based on orthogonal test and range analysis,the DAB ignition time,DAB deflation time,DAB mass flow and seat belt limit force were matched and optimized to reduce the dummy head injury HIC15,neck injury Nij and chest compression deformation D.The optimization results show that the energy absorption of the optimized key structure anti-collision beam energy absorption box increases by 101.9%,the energy absorption of the front longitudinal beam and the upper finger beam increases by 33.3%and 69.9% respectively,the energy absorption of the A-pillar increases by 3.6%,and the energy absorption of the upper side beam and the threshold of the A-pillar decreases by46.6% and 51.2% respectively.The crushing deformation of the A-pillar and the threshold is small,and the bending angle of the upper side beam of the A-pillar is reduced,which better ensures the living space of the occupants,and the vehicle crashworthiness rating is improved from the poor level to the general level.The dummy head HIC15 was 621.6 and evaluated as good.The dummy neck index Nijwas 0.58,evaluated as excellent;the peak value of dummy chest compression deformation D is 57.1 mm,which is evaluated as excellent.