Influence Of Active Seatbelt On Occupants Under Emergency Braking Conditions

Emergency braking is the most effective way to avoid collisions when facing critical situation under current technical conditions.But when emergency braking cannot avoid the collisions,braking acceleration will change sitting posture of occupant and this may affect the efficiency of the restraint system,and increase occupant's injury risk.For better managing occupant's sitting posture,the idea of active seatbelt was proposed.Under this background,this paper established the traditional constraint system model and the constraint system model equipped with active seatbelt,and simulated the dynamic response of the occupant in the whole process of braking and collision phase to study the influence of active seatbelt on occupant's posture before collision and the injury risk during collision under emergency braking conditions,and made a multi-objective optimization for restraint system.The results have important reference value for the development of active seatbelt and the design of reversible restraint system.The research contents of this paper are summarized as follows:Firstly,based on Total Human Model for Safety?THUMS?,Active Human Model?AHM?and Hybrid III dummy model to establish a driver-side restraint system model,and use the data in collision test to verify the simulation accuracy of this restraint system model.Secondly,using data of real vehicle emergency brake test as boundary condition,introduced the active seatbelt to establish an integrated restraint system.Analyzed the dynamic response of three occupant models during the braking phase and the effect of active seatbelt on the occupant's out-of-position.Then,built the integrated simulation model of pre-braking and collision process,and analyzed the key parameters of the active seatbelt by single factor to study the influence on occupant's injury.And established 12 simulation conditions to analyze the pre-collision influence of emergency braking and active seatbelt on occupant's sitting posture under low-speed,medium-speed and high-speed frontal collision conditions.Finally,established a coupling optimization platform based on the multi-objective optimization software modeFRONTIER and the multi-body dynamics software MADYMO to optimize parameters of the integrated restraint system.Results show that the motion response of the active human model during braking is consistent with the response of volunteer in the emergency braking test.Although the emergency braking caused the occupant's head to lean forward under the same initial speed,the injury of each part of the occupant decreased due to the reduced speed at the time of the collision.At the same collision speed,emergency braking before the collision increased the occupant's chest acceleration and N_ij.Under emergency braking condition,the use of active seatbelt can effectively reduce the forward displacement of occupants,thereby reducing the damage of occupant during collision.The WIC value is reduced by 14.6%through multi-objective optimization of the integrated restraint system.