Numerical Simulation Of Airbag Dynamic Mechanical Performance Based On Fluid-Structure Interaction Approach

At the moment of uncoated airbag deployment, the two properties that contribute to the energy absorbing capabilities of the fabric are its permeability and biaxial stress-strain characteristics. And the two factors are interactional. So the deformation is the principal factor influencing the performance and safety of the airbag.Firstly, this paper gives the inflation height and shape of airbag fabric at different time using the airbag dynamic deformation tester, which is designed by the team. The results showed that the central region of deformation curve remains flat at the beginning of the inflation, then gradually disappears, and finally becomes arc as the pressure increases.Secondly, this paper simulates the airbag fabric inflation process without considering the case of interaction using finite element method. The inflation height and deformation result from the simulation agree with the experiment under certain accuracy. But the numerical simulation of airbag fabric inflation process don't well reflects the phenomenon that the central region of deformation curve remains flat at the beginning. So in the framework of simulation system the fluid-structure interaction between the inflation gas and the airbag fabric should be taken into account.Thirdly, this paper explores simulation techniques for airbag inflation problems using a coupled fluid structure approach, and a multi material arbitrary Lagrange Euler technique in the explicit finite element code is used. The simulation results show that the centra! region of deformation curve remains flat at the beginning of the inflation, then gradually disappears, and finally becomes arc as the pressure increases. The final inflation height of airbag fabric has been measured by the photographs. The inflation height error is less than 3%, so the simulation results agreed well with the experiment data.Fourthly, this paper gives the stress and strain distribution in the airbag fabric dynamic inflation process. The results show that the stress of airbag, as well as the strain, nearly presents an annular distribution. Moreover, the strain at the fabric center is the maximum and becomes the minimum on the edge. The strain in the X direction is approximately equal to that in the Y direction, and both of them are the biggest at the fabric center. However, the strain in the Z direction has the opposite characters, which is the maximum on the edge.Finally, the model constructed in this paper is used to forecast the airbag fabric inflation height, the factors such as thickness, bulk density, Poisson's ratio and the modulus of elasticity are discussed. Moreover, the effect of airbag fabric structure on the dynamic performance of airbag fabric is discussed using experimental method.