A micromechanics-based damage model for non-woven fiber networks

Non-woven materials are fiber networks consolidated by different bonding techniques. It has been found that interfiber bond fracture is a major damage mechanism in non-wovens and strongly affects mechanical strength and toughness. In this article, we present a micromechanically based damage model for non-wovens. The model is built upon modeling single bond breaking processes and linking local damage events to macroscopic behaviors. In this model, a nonlinear term is introduced to describe non-affine deformation of fibers at a bond. The traction load on a bonded interface is determined by considering local force balance and network constraints. A bond breaks when its traction load exceeds a critical value, and this local information is used to update the global damage state through a classical continuum damage mechanics framework. Spatial correlation of damage in the network is modeled using a non-local averaging scheme. The proposed model is applied to a commercial non-woven series. The model is able to reproduce experimentally observed behaviors including elasticity, non-linear hardening, peak load and damage localization under uniaxial tensile loading as a function of network density. Damage states predicted by the numerical simulations match well with in-situ imaging results demonstrating the predictive capability of the model. The proposed model bridges non-woven microstructure and macroscopic behaviors and thus can serve as an effective tool for future studies of the mechanics of fiber networks.