Capabilities and limitations of pure-shear based macroscopic forming simulations for 0{\textdegree}/90{\textdegree} biaxial non-crimp fabrics

TL;DR

This paper evaluates the effectiveness of pure-shear based macroscopic simulations for 0/90 biaxial non-crimp fabrics, highlighting their strengths in predicting fiber orientation but noting limitations in peak shear angle accuracy due to neglected slippage.

Contribution

It adapts a hyperelastic pure-shear model for biaxial NCFs and assesses its accuracy in forming simulations, considering stitching and slippage effects.

Findings

Model predicts fiber orientation well.

Peak shear angles are overestimated.

Pure-shear assumption is valid at moderate shear angles.

Abstract

Macroscopic modeling of a non-crimp fabric's (NCF's) forming behavior is challenging as it strongly depends on the textile architecture, fiber type, and stitching type. While shear is the main deformation mode of woven fabrics, membrane modeling approaches for NCFs should also consider stitching deformation and roving slippage. However, for 0{\textdegree}/90{\textdegree} biaxial NCFs (Biax-NCF) with a symmetrical stitching pattern and high stitch pretension, deviations from a pure-shear assumption in coupon tests are only observed at higher shear angles due to limited roving slippage. In this work, a hyperelastic approach initially proposed for unidirectional NCFs is adopted for a tricot stitched 0{\textdegree}/90{\textdegree} Biax-NCF based on a pure-shear assumption. The shear behavior is experimentally characterized through 45{\textdegree} off-axis-tension tests, and the parameterization is derived from energetic approaches originally developed for woven fabrics. This approach efficiently and adequately describes the general behavior in forming simulations of different geometries. Fiber orientation and location of areas with high shear angles are predicted well, but the peak shear angles are overestimated due to the neglected roving slippage.