Semi-empirical method for estimating the effective leak and vent areas of an airbag

A semi-empirical method that utilizes tests from a small fabric specimen to quantify the effective leak and vent areas of an entire airbag is developed in this paper. The test setup and procedure used in the airbag material coupon tests are similar to the standard method used in determining air permeability of fabrics. A test apparatus for measuring the deflection of the fabric coupon was devised. Finite element analysis is used to compute the expanded vent and airbag surface areas of the coupon under various deformations. The leak and vent models were developed based on the results of a regression analysis. The effective vent area of a fabric coupon is a function of the ratio of the pressures across the fabric and the expanded vent area. Similarly, the effective leak area of a fabric coupon is a function of the ratio of the pressures across the fabric and the expanded surface area. The tested airbag materials were characterized with these models for use with finite element airbag models.