Simulation And Optimization Of Automotive Side Airbag Deployment

During a collision, sensors detect the resulting impact, and seat belts, airbags and other safety devices all go into action to reduce passenger injuries. These systems and devices are referred to as passive safety systems. In China, the current urban traffic situations leads to high probability of side impact at intersections. Thus, it is necessary to pay more attention to occupant protection in side impact. Vehicle body side with weak structural strength and small space,makes the occupant during a side impact vulnerable to serious injury, while the seat belt cannot provided protection in side impact, so side airbag is particularly vital. With the improvement of China’s automotive research and development ability of technology as well as Emphasis on self-knowledge, developing new models is increasingly adopting positive development methods. Positive development of airbag involves many critical factors: body strength, occupant space and restraint systems components, in addition, the influence of different factors on the airbag protection is not the same, Therefore, studying the characteristics of airbag helps to improve the working efficiency of restraint system and reduce the occupant injury in side impact.Based on the nonlinear analysis software LS-DYNA, this paper discusses the airbag modeling and simulation methods, corrects numerical model with dynamic impact test results and improves the accuracy of numerical simulation, meanwhile, considers the occupant injury evaluation criteria, making the simulation results of airbag more realistic. On the basis of analysis the current main airbag numerical model, this paper studies in details on Hybrid model which belongs to control volume methods. Analyzes the influence of mesh quality on the model with different modeling methods, searches the setting methods of the parameters in the model, with variety pre-post-processing software and analyzes the resulting data. Then, this paper builds the numerical model,which simulates the tests in side airbag development, optimizes the model through comparison between the test results and simulated results, achieves the numerical model correlating with the tests characteristic.In these studies, the test includes tank test, static test and the dynamic impact test, which are crucial process to determine the key parameters in numerical model during the airbag development. The inflator parameters obtained through the tank test determine the amount of gas generated with time. Static test using a high speed camera to record the airbag fully inflated time analyzes the influence of airbag folding. Dynamic impact test using a hammer with certain speed to impact airbags simulates the effect of the actual side impact collision process between human and airbags, thus, obtaining the deflation characteristics by this test method.Based on the above studies, further studies is about the function of side airbags in the ccupant restraint system help to more realistically evaluate the safety performance of the constraint system, with setting methods of damage mechanism and occupant injury criteria by trauma biomechanics, in which NCAP(New Car Assessment Program) regulations are the most widely used injury criterion. These studies show that within a certain range the larger the vent hole diameter value of the side airbag, the smaller the amount of occupant rib displacement, however, if the diameter exceeds the certain value, it could easily cause airbag excessive deflation, and the phenomenon that the relative velocity still exists between the occupant and the door. Body side strength directly affects the body`s intrusion, side airbags react as an intermediary body between car body and the occupant, through cross-comparison test, this paper indicates that rational choice of the side airbags models helps to reduce the occupant injury.