Due to commercial television almost everyone is familiar ‘automotive inflatable restraint system,’ commonly referred to as airbag. Traditionally these bags were made of polyamide fabrics coated with polychloroprene, which made them essentially impermeable. Even though this restraint technology has been in use for more than fifteen years, there remain some features that still need to be improved; i.e., the high cost, the high package volume, the weight and the need for replacement of coated fabrics. In this paper special attention is given to uncoated fabrics.
A novel blister-inflation technique was utilized to evaluate the permeability of test fabrics under biaxial stretching conditions. Further, the effect of inflation temperature and internal pressure drop across the fabric on the permeability of the fabrics can be evaluated by this technique.
The performances of two different fabrics were evaluated; namely the traditional polyamide offered in the construction of airbags, nylon 66, and a high strength poly(ethylene terephthalate). This paper looks beyond the phenomenological linear response of the fabrics' air permeability versus δp. The changes in the permeability of the fabric were explored for both increased pressure drops across the fabric and increased temperature. Temperature is especially significant around and above the glass-transition temperature of these polymers. The authors believe that this unique technique can be a useful tool for simulating the pressure-temperature-time history of the airbag during deployment.