Multiscale Analysis for Virtual Prototyping and Performance Testing of Protective Fabrics

In this paper we describe novel computational methods being used to facilitate analysis and design of textile fabrics used in functional clothing systems to protect people from threats such as extreme temperatures, radiation, ballistics, and hazardous chemicals. A multi-scale modeling approach is taken to attack this challenging problem. Beginning at the length scale of individual fiber diameters (tens to hundreds of microns), we use unit-cell methods to model frictional stick-slip interactions under various modalities of loading which give rise and contribute to the nonlinear and dissipative characteristics of textile fabrics. After assimilating these micro-scale interactions into mesoscale material models, we again use unit-cell methods to study the mechanical interactions between yarns with diameters on the order of millimeters. In particular, the nonlinear, anisotropic, and irreversible behaviors of fabrics are explored at finite deformations under various modalities of loading with these mesoscale unit cell models. Finally, we discuss how material models that integrate all of these structure-dependent behaviors are incorporated into macroscopic clothing models which are ultimately draped onto active digital human models.