Strain gradient calculation as a basis for localized roving slip prediction in macroscopic forming simulation of non-crimp fabrics

Abstract

Abstract. The utilization of the Finite Element Method (FEM) in forming simulation presents the possibility for a thorough examination of the deformation behavior exhibited by engineering textiles during the draping processes. In macroscopic forming simulations the relevant forming effects are depicted in a homogenized way. Slippage of fibers is an essential deformation mechanism of non-crimp fabrics (NCF). Experimentally, this is already observed at coupon level performing the bias-extension test (BET). Significant slippage occurs locally in the transition areas between shear zones with deviating shear angles. In existing macroscopic simulation approaches, roving slippage is only considered homogenized over the shear zones. A localized slip between individual fiber rovings cannot be modelled. Therefore, in the present work a neighboring element method for ABAQUS/EXPLICIT is introduced. This method uses multiple subroutines to transfer information between elements. The functionality of the neighboring method is confirmed by calculating a cross element gradient of the shear angle. The calculation of the shear angle gradient is shown in the simulation of the BET, giving rise to the transition zones which have been experimentally highlighted.