Characterization of mechanical behavior of Kevlar 49 fabrics

Woven fabrics are used in many applications, including ballistic armors, propulsion engine containment systems and fabric reinforced composites. In order to facilitate the design and improvement of such applications, this paper presents the experimental programs of quasi-static uniaxial tension, biaxial tension and picture frame test to obtain the material properties of Kevlar® 49 fabric. This study discusses the stress-strain response in both the warp and the fill directions of the fabric under uniaxial tension, the effective Poisson's ratio and the in-plane shear response, and also investigates the possible effect of specimen size on the responses of the fabric. The results show that the fabric exhibits non-linear and orthogonal behavior in tension, and can deform up to 20% before the complete failure. The effective Poisson's ratio is a nonlinear function of strain. The shear response is nonlinear to the shear angle, but not dependent upon the specimen size after normalization. Images were used to demonstrate the deformation and failure behavior of the fabric. All these results are very important for the numerical modeling of the Kevlar® 49 fabric used in engine fan containment systems and other ballistic protection.