Study On The Injury Mechanism Of Out-of-position Children Next To The Driver

Automotive safety system restraint products are composited of steering wheel,seatbelt,airbag,steering column,and etc.Most of them can protect passengers form crashing the passenger compartment during the traffic accident.However,many safety products are designed for the adult and they can't protect the children very well.Sometimes they will also cause some damage to children.For example,the passenger airbag can prevent the 50 percentile adult male from damage,but it will be harmful to children who sit next to the driver.This thesis is based on the fact that children suffer damage from passenger airbag deployment in most situations,the federal vehicle safety regulations FMVSS208 are researched,the injury standard of children in out-of-position and airbag low risk deployment test are learned,the injury theory of child accident and the head,chest and neck damage mechanism during the traffic accident are studied too.In this thesis,the main research method is simulation.Firstly,the model of airbag is built in MADYMO software and the airbag algorithm selection and fold is finished.Then,the airbag static deployment test and linear impact test are conducted to verify the airbag model.The seat and dummy are added and.then the simulation model with child in out-of-position in co-driver position is built too.After that the child in out-of-position test is also conducted.To reduce the maximum strain of door hinge of airbag cover,the stress and strain distribution on cover are analyzed and the relevant structure optimization parameters and the optimization levels are determined,orthogonal optimization is conducted to reduce the strain.SPSS software is used to analyze the optimization results.The conclusion is that the thickness of the door hinge makes main contribution to the strain change of cover.After the optimization,the door hinge doesn't break anymore.The airbag parameters such as vent diameter,fabric permeability,child position,airbag deployment angle are chosen to research the influence caused by them on the out-of-position child damage.The results can be listed as follows: within limit,the larger the diameter,the slighter the injury;the larger the fabric permeability,the slighter the injury.When the deployment angle increases,the neck may suffers more damage and the deployment angle decreases,the head may suffer more damage.Extending ignition interval of two inflators can protect the child better.When child in position which far away from the airbag module,the damage will be reduced too.The correlation between gas physical quantity and child injury is studied in SPSS software.The results show that gas pressure contributes mainly to the child injury.At the same time,all model calculation data regression analysis is conducted.The results show that: during the integration interval of HIC15,the head centroid resultant acceleration is linearly related to gas pressure.The continuous 3ms chest acceleration is linearly related to gas pressure.The maximum neck axial tension force is linearly related to maximum head-to-chest relative displacement in Z axial direction.