Simulation Analysis Of Out-of-position Occupant Protection In Side Impact With Automatic Emergency Braking Introduction

With the improvement of passive safety and the rapid development of active safety,the technology convergence of the two fields has become an inevitable trend.The active safety system represented by the Automatic Emergency Braking(AEB)technology have a great impact on passenger’s posture in the pre-collision stage.The traditional restraint system developed for the collision stage cannot play the original occupant protection efficiency.Therefore,the technology development in the field of integrated safety has become a research hotspot in automobile safety.Most of the related researches at home and abroad focus on the analysis and improvement of occupant injury in frontal impact after AEB introduction,but little attention is paid to side impact.Therefore,based on the scene that the struck car is impacted by the striking car after collision avoidance of the former’s AEB,combined with the active and passive safety simulation technology,this paper studies the influence of the braking deceleration of AEB and the key parameters of the active seatbelt on dummy’s kinematics in the pre-collision stage and injury risk in the side collision stage,and optimizes the key parameters finally.The main research works are as follows: firstly,based on the dangerous driving scenario of side impact counted by NHTSA,the scenario of side impact of the struck vehicle after AEB working was established,from which the braking deceleration in the pre-collision stage was obtained.Secondly,according to the US-NCAP,the finite element model of side impact was built and verified.Based on the movement of vehicle sub-structure,the dummy injury benchmarking of PSM model was completed in MADYMO software,and the integrated safety model of side impact was built.Then the active seatbelt was introduced to the model,the effects of different braking deceleration,different pretension force and pretension time on the posture of ES-2re dummy during braking and injury during side impact were analyzed.At the same time,the protection effects of two pretension methods,retractor pretension and buckle pretension,on the dummy were compared,and the Spearman correlation coefficients between input and output variables were studied.Finally,based on the integrated model with braking deceleration of 1g,the injury index value of WIC was taken as the optimization objective,retractor pretension force,retractor pretension time,buckle pretension force and buckle pretension time as design variables,orthogonal test design method was used to sample,and the sensitivity of variables was sorted by range analysis,and the optimal parameter solution was obtained finally.The simulation results show that AEB has a great impact on the maximum rib deflection and VC of the dummy,the former is 60.94% higher than the deflection at in-position,and the AIS3+ risk of chest injury is increased by 4.3 times.The active seatbelt can reduce occupant’s out-of-position and injury well.When preloaded with 250 N at 0ms by seatbelt,the displacements of head and T1 are reduced by 107 mm and 75 mm with the retractor,92 mm and 66 mm with the buckle,respectively.The two pretension methods can reduce chest rib deflection by 15.6mm and 13.9mm respectively.Furthermore,the retractor model has a better effect on the dummy’s out-of-position and injury risk.It is found that the head,T1 displacement and rib deflection are highly correlated with the pretension force and the pretension time with Spearman rank correlation analysis.Finally,experimental design and range analysis are used to optimize the pretension force and pretension time,and the rib deflection is reduced by 19.2 mm,and the WIC value is reduced by 25.55%,which plays the expected protective effect.