A novel approach for evaluating the air permeability of Airbag fabrics

An approach based on the shock tube experiment is proposed to evaluate the permeability of airbag fabrics. Shock tube experiments were conducted to imitate airbag inflation by fixing an airbag fabric sample near the end of an open driven section. When a plane shock wave impinges the airbag fabric, it will be reflected. Meanwhile, an increase in pressure will form at the front face of the airbag fabric and this will lead to a flow through the fabric, due to the permeable structure of the fabrics. The air permeability of airbag fabrics can therefore be determined by measuring the velocity of the reflected shock wave. It was found that at relatively high pressure the dynamic permeability results from the shock tube experiment were lower than the static results from the conventional permeability testing method. This phenomenon appears to be related to the different influences on the airbag fabric structure of the steady pressurization that occurred in the static experiments and the instantaneous pressurization that occurred in the shock tube experiments.