Conceptual Design And CAE Optimization Of Driver Side Overhead Airbag

In recent years,with the gradual advancement of electricity,connectivity,intelligence,and sharing of automobiles,autonomous vehicles have become a key direction for the future development of the automobile industry.Autonomous driving technology can help to improve road traffic safety and reduce the number of road traffic accidents,but it also brings new challenges to the integrated design of active and passive safety of vehicles and the protection of occupants.At present,the new type of occupant restraint system adapted to autonomous vehicles is still in the exploratory stage.It is of great significance to develop the new type of occupant restraint system to deal with the challenges of occupant collision protection brought by autonomous vehicles.This research aims to carry out a pre-research on a new type of occupant restraint system adapted to autonomous vehicles.Based on the concept of smart cockpit,the conceptual design for a foldable steering system equipped with overhead airbag was proposed.The applicability analysis of the overhead airbag restraint system and the CAE integration optimization were carried out by means of simulation analysis.First,a frontal collision occupant restraint system MADYMO model was established based on a compact SUV from a domestic OEM,and the effectiveness of the model was validated through the frontal 100%rigid barrier collision and the frontal 40%overlapping deformable barrier collision test data.Secondly,based on the interior data of the SUV,the foldable steering system and overhead airbag model were established,then the benchmarked occupant restraint system model was updated and the overhead airbag restraint system model with Hybrid III 50^th male dummy and Hybrid III 05^th female dummy was established to carry out simulation analysis of applicability.Finally,taking into account both multiple collision conditions and different dummies,the comprehensive weighed injury criterion（WIC）was set as the optimization goal.The DACE-Kriging model was constructed and the MOGA-Ⅱgenetic algorithm was introduced for integrated optimization to improve the protective performance of the overhead airbag restraint system.The applicability simulation analysis results indicated that the overhead airbag restraint system can better adapt to the collision safety protection requirements of various collision conditions and different occupant sizes.After replacing with the overhead airbag,the relative motion state between the head and the chest of the male and female dummy under different collision conditions was all changed significantly,and the overhead airbag did not touch the occupant’s chest during the deployment process,which effectively reduced the occupant’s chest injury.The male dummy’s neck had obvious bending movement which aggravated the neck injury,and the dynamic stiffness of the overhead airbag was relatively high when the female dummy’s head came into contact with the airbag which resulted in obvious changes in head injury.The CAE integrated optimization results indicated that by increasing the diameter of the airbag vent hole,the gas mass flow rate and the seat belt pretensioner force,advancing the seat belt pretensioner time,reducing the seat belt force limit level and delaying the ignition time of the overhead airbag,etc.It was helpful to improve the protective performance of the overhead airbag restraint system on different collision conditions and different occupant sizes.The WIC_50th of male dummy was decreased by 13.72%,the WIC_05thof female dummy was increased by 1.35%,but the synthetic acceleration of the head was reduced by 9.94%under the frontal 100%rigid barrier collision.The WIC_50th of male dummy was decreased by 10.29%,the WIC_05th female dummy was decreased by8.16%under the frontal 40%overlapping deformable barrier collision.The comprehensive weighed injury criterion WIC was decreased by 9.62%.It basically satisfied the requirements of optimization design.