A Research On The Performance Of Airbag With Double Chamber In Vehicle Front Impact

The rapid development of the economy has brought a lot of convenience to people.There is more and more disposable income in each family.Every family has almost one car.In the front impact,the occupant restraint system is the most important passive safety protection system,and the front airbag of the car is one of the most critical components in the occupant restraint system.As a kind of auxiliary safety tool,the front airbag of the car mainly provides passive restraint protection for the occupants on the head,neck and chest.However,for some large-sized occupants,the large inertia caused by the collision of the car easily causes the occupant's head to break through the airbag and strikes the steering wheel or other car interiors,causing more serious damage.Most of the existing studies have studied the Hybrid III 50^th male dummy?ordinary body type?which specified in the regulations,and there are few studies on the Hybrid III 95^th male dummy.Therefore,in order to improve the protection of the front airbag on the large occupants in the front impact,this paper designs a new type of airbag structure,namely the front and rear airbag with double chamber.The specific research contents are as follows:Through reviewing many literatures,we have studied the research status of passive safety of automobiles,including research techniques for front impact of vehicles,safety research of different body dummy and research status of automotive airbags.At the same time,the occupant damage evaluation index and the front impact regulations at home and abroad are understood.Then the injury limits of the Hybrid III 95^th male dummy are calculated according to the Hybrid III 50^th male dummy using dummy scaling theory and then the formulas of the weighted injury criterion for Hybrid III 95^th male dummy are defined,and the weighted injury criterion is used as the basis for evaluating the safety of the occupants.Finally summarize the research ideas and determine the research content of this paper.With the support of fund project,a joint research and development of a 100%full-width impact test with a state enterprise is carried out.In the MADYMO,a collision simulation model of the front 100%full-width impact of the original model is established.The model includes basic body structure,seats,airbags,seat belts and dummy.The data collected from the actual vehicle test and the simulation results are verified to prove the validity of the model.The model of the front and rear airbag with double chamber is established in HYPERMESH.The airbag geometry design is based on the size of the airbag in the actual vehicle test.And than fold the airbag in PRIMER.Finally,introduced the model into the MADYMO and defined them.The parameters mainly include:airbag simulation time integral step size,airbag vent hole size,airbag burst time,gas generator parameters,etc.The established front and rear airbag with double chamber were introduced into a collision model carrying Hybrid III 95^th male dummy for simulation.For airbags,there are many parameters that can affect their performance,such as airbag ignition time,vent hole size,airbag draw tape length,airbag fabric material,air chamber mass flow rate,etc.According to the related literatures,several parameters that have a greater influence on the airbag are selected:two chamber's vent size,ignition time,two chamber's mass flow rate,and two chamber's length of the belt for screening.Through the sensitivity analysis method,the ignition time,two chamber mass flow rate and two chamber vent diameters are greatly affected the protection of the airbag.The other parameters have little effect on the airbag protection effect.Five parameters were optimized by orthogonal experiment,and it is found that the optimized double-chamber airbag has improved protection effect on the large-sized occupant under the condition that the protection effect of Hybrid III 50th dummy?normal body type?is basically unchanged and the comprehensive injury assessment is improved.The results show that after optimization,the weighted injury criterion decreased by 10.2%compared with the before,the value of weighted injury criterion is reduced by 30.6%compared with the traditional single airbag.The overall protection performance of the restraint system for the large occupants has also been greatly improved,and the optimization of the front and rear airbag with double chamber has achieved results.