Modeling of Tensile Properties of Woven Fabrics and Auxetic Braided Structures by Multi-Scale Finite Element Method

Abstract

This study is undertaken to build an appropriate mechanical model for the analysis of mechanical properties of forming fabrics by incorporation of multi-scale modeling concept comprising micro-mechanical model, meso-mechanical model and macro-mechanical model. The fabric is analyzed at three different scales: yarn, unit cell and fabric sheet. The micro-mechanical model is to obtain the overall properties of yarn structure. The meso-mechanical model concentrates on the mechanical analysis of the unit cell of the fabric with the periodic boundary conditions by inputting yarns’ properties from the micro-mechanical model. The macro-mechanical model is to get the overall properties of desired fabric structure by extracting the results from meso-mechanical model. In the first part, six single-layer woven fabric samples, five two-layer fabric samples are analyzed. In the second part, a tubular braiding fabric structure made of helical auxetic yarns is manufactured and its properties are investigated by a similar multi-scale model. The models for both parts are validated by the comparison of simulation data and experimental data, which had good agreement. Detailed stress-strain field throughout the entire unit cell is determined, which can be further used in the analysis of fatigue and fracture properties.