Development and verification of a meso-scale based dynamic material model for plain-woven single-ply ballistic fabric

A meso-scale unit-cell based continuum material constitutive model has been developed for plain-woven single-ply ballistic fabric materials. This model, due to its computational efficiency, is suitable for use in computational analyses of the ballistic-protection performance of multi-layer body-armor vests. The model utilizes the continuum-level in-plane and out-of-plane deformation-state of the material, an energy minimization procedure and a simple account of yarn slip to update the structure/architecture of the fabric unit cell. Forces and moments developed within the structural components of the unit cell are then used to compute the continuum-level stress state at the material points associated with the unit cell in question. The model is implemented in a user-material subroutine suitable for use within commercial finite-element programs. To validate the model, a series of transient non-linear dynamic analyses of the impact of a square-shaped fabric patch with a spherical projectile is carried out and the computed results compared with their counterparts obtained using a more traditional finite-element approach within which yarns and yarn weaving are modeled explicitly. The results obtained show that the material model provides a reasonably good description for the fabric deformation and fracture behavior under a variety of boundary conditions applied to fabric edges and under varying fictional conditions present at the yarn/yarn and projectile/fabric interfaces. In addition, the overall ballistic energy absorption capacity of the fabric as well as its yarn-strain energy, yarn-kinetic energy, and frictional sliding contributions are predicted with reasonable accuracy by the proposed material model for fabric.