Numerical investigation of fibre failure mechanisms of one single Kevlar yarn under ballistic impact

Abstract

This paper presents a microscopic numerical investigation of the fibre failure mechanisms of one single crimped Kevlar® KM2 yarn subjected to ballistic impact. Generally, one yarn consists of about 400 fibres, which poses many challenges for modelling. Also, a high computation time is required due to the vast number of elements. Therefore, the concept of an equivalent fibre representing one set of fibres is introduced. Then, two sub-yarn level numerical models in which 400 fibres are represented by 42 and 98 equivalent ones are conducted. These models are evaluated by comparing with the mesoscopic model and qualitatively validated by results from the literature. Fibre failure mechanisms are analysed. The evolution of yarn energies, transverse wave propagation, and projectile velocity versus time are investigated. The tension force of each fibre is also obtained. It is highlighted that both models can predict the global behaviour of the yarn. However, fibre failure mechanism and fibre–fibre interaction are only accurately captured by the 98-fibres model. Therefore, this sub-yarn level model can be used to develop a micro-mesoscopic multi-scale model of Kevlar fabric in further works.