Research On The Occupant Impact Injury And Optimization Design Of Restraint System For Vehicle Integrated Active And Passive Safety

Integrated active and passive safety technology has become an inevitable tendency of the automobile safety technology.Compared with traditional passive safety experiments and simulations,the effects of active safety devices and passive occupant restraint systems need to be taken integrated into account in integrated active and passive conditions.During the collisions for integrated active and passive safety,active safety devices involvement may have an effect on pre-crash conditions,such as vehicle kinematics and occupant pre-crash posture,both of which will affect occupant injury risks during frontal crashes.Therefore,the potential advantage of an integrated active and passive safety system is not likely to be the sum of these two single systems.This paper presents a methodology to analyze the occupant impact injury risk through analyzing the coupling factors of active and passive safety and conducting frontal impact simulations using MADYMO.The optimization design of occupant restraint system is conducted based on the occupant injury results.First of all,coupling factors of active and passive safety which affect the impact injury risk are analyzed,including delta-V,occupant postures and active human muscles.The frontal impact simulation model is set up in MADYMO,and this model is validated based on the data from volunteer real vehicle tests and C-NCAP crash test.Occupant sitting postures are divided into five sets,and using non-AEB involvement condition represents normal condition,only AEB involvement condition represents active device interaction condition,both AEB and active pretension seat belt involvement represents integrated active and passive condition,then impact injury risks in every sitting posture under each condition are analyzed.At last,for rightwards sitting posture,six occupant restraint system parameters are defined as the optimization design variables,and head,neck,chest and femur injury value are defined as the optimization objectives.Optimization design of the active pretension restraint system is conducted based on Latin Hypercube DOE,approximation model response surface,NSGA-II optimization algorithm and WIC injury weighting criterion.The impact injury analyses show that,the joint impact injury risk is minimum in SP01 normal sitting posture,and maximum in SP05 rightwards sitting posture,only AEB involvement condition increase the joint impact injury risks;In SP01-SP04 sitting postures,both AEB and active pretension seat belt involvement significantly reduce the joint impact injury risks,and the condition when both AEB and active pretension seat belt interact in SP05 sitting posture still has an significantly high injury risk of 25.9%.The optimization results of the restraint system parameters for SP05 sitting posture show that,occupant head,neck and femur injury value are distinctly reduced compared with those before optimization,the WIC injury value decreases by 11.29%;Occupant in SP05 sitting posture has the largest decreasing amplitude of joint impact jury risk,and the joint impact jury risks in other four sitting postures go down compared with the condition before optimization.