Impact Force when Fabric Inflates at High Speed

Abstract

Occupant protection systems for automobiles are currently highly publicized. An airbag inflating at high speed impacts an occupant with great force. Airbag safety relies on its construction with primarily woven fabrics. We have referred to a typical pressure-time history of an airbag and developed a device to measure impact load when the fabric airbag inflates at high speed. When interior pressure in the airbag increased, impact load increased. Also, the impact load on a body increased as the distance between the body and airbag decreased. The impact force of an airbag inflating at high speed was simulated by a non-linear finite element method (FEM) combined with an incremental method, where the sample was modeled by a thin elastic shell. An experiment was conducted to verify the theory and this calculation method. Good agreement was obtained between the theoretical and experimental values for two types of fabric sample. This demonstrated that the mathematical technique developed here can satisfactorily predict the impact force when an airbag inflates at high speed and that the impact force depends appreciably on the mechanical properties of fabrics.