Failure Mode and Engineering of 3D Networked Fabrics against Ballistic Impact

Abstract

Conventional ballistic textiles, such as plain-woven fabrics and unidirectional laminates, are two-dimensional (2D). Each ply of them dissipates impact energy in the plane of the fabric. The networked fabrics (NFs) are three-dimensional (3D) textile with interconnections between adjacent sublayers by combining yarns from two adjacent sublayers into one then separating them alternatively in the warp or weft direction. The interconnections extend impact energy dissipating in through-the-thickness direction. This thesis focuses on the failure mode and engineering of NFs for ballistic application utilising experimental and finite-element (FE) methods. Two-sublayer NF has been produced using aramid yarns and subjected to shooting tests, setting a baseline for further numerical analysis. Geometric and FE modelling of NFs adopting plain weave as basic weave style has been established and validated based on experimental observation and empirical knowledge. Semi-automation of model setup is achieved using Python scripts to work with TexGen® and Abaqus®. Different cross-section shapes and material properties can be applied to the yarn segments in the separate and combined sections so that the geometric model could be more realistic. Such method can be referred to for modelling other textile structures that have non-uniform local fabric densities. A profound knowledge has been developed on NFs subjected to ballistic impact. By comparing to the layup of plain-woven fabrics, the failure mode and mechanisms of NFs resisting ballistic impact were identified with the effects of the combining yarns and the combined sections elaborated. The combined section has higher yarn gripping ability than the separate section does. They work as a transition between impact zone and the hard fixture at edges, enhancing the energy transfer between the combining warp yarns and the secondary yarns. The study was numerically extended to cover the effects of in-ply and inter-ply parameters. Fabric density and width of sections were found to have significant influence on the energy absorption capacity of NFs. For 2-sublayer NFs, the highest energy absorptions of dense and loose NFs are around 13.3% and 17.1% higher than those of their counterpart layups of plain-woven fabrics, respectively. Energy absorption of dense NFs is less sensitive to change of section width than that of loose NFs. With number of sublayers increased to four, the increase of specific energy absorption drops to 10% for dense NF. Layup of NFs outperforms layup of plain-woven fabric with nearly the same areal density. In summary, this thesis introduced a semi-automatic approach to generate and setup FE model for NFs, developed an extensive understanding of the response of NFs against ballistic impact based on experimental and FE analyses, and found the influences of structural parameters on the performance of NFs for engineering NFs to achieve improved energy absorption capacity against ballistic impact.

Date of Award	31 Dec 2019
Original language	English
Awarding Institution	The University of Manchester
Supervisor	William Kennon (Supervisor) & Xiaogang Chen (Supervisor)