Engineering and analysis of quasi isotropic textile composites for ballistic application

Abstract

The present research aims at engineering textile composites with improved performances for ballistic application. With the requirement of improvements on ballistic protection, the quasi-isotropic structure is developed based on the hypotheses that more materials are able to be involved in the impact event which could result in increased energy absorption correspondingly. This research focuses on the influences of quasi-isotropic structures on the ballistic performances of woven and multi-directional (MD) composites which have been widely used in the ballistic application. Twaron®/epoxy composites are chosen in this investigation in relation to the excellent mechanical properties and it’s low weight. Two complementary methods are employed named experiment and finite element (FE) simulation respectively. The ballistic performance of the orthotropic and quasi-isotropic woven and MD composites were experimentally investigated using a ballistic test apparatus with a panel clamping system to evaluate energy absorption. In order to further investigate the ballistic mechanisms, yarn-level woven and MD composite models were established using ABAQUS®. Good agreements were achieved between the simulations and experiments regarding the energy absorptions and morphological observations. Quasi-isotropic woven composites with ply numbers of 2, 3, 4 and 6 were investigated to increase energy absorption up to more than 10% than their orthotropic counterparts. This is believed to be attributed by the more evenly dissipated stress with enlarged stress dissipation areas induced by the superimposition of angled plies. Moreover, the angled plies also resulted in up to 17.1% backface deformations which helped to improve the ballistic performance. Increased yarn directions in quasi-isotropic woven composites were observed to further improve the energy absorptions. The increased ply number was found to result in a decreased sensitivity between plies which will result in degraded ballistic performance. Thus, a quasi-isotropic woven composite repeat with a large ply number is not preferred. The quasi-isotropic structure was investigated to improve the ballistic performance of MD composites as well. Up to 12.9% increased energy absorptions were produced in 6-ply, 8-ply and 12-ply quasi-isotropic MD composites than their orthotropic counterparts. With the increase of yarn directions, up to 30% increased stress dissipation areas and 12% increased back face deformation areas were observed which are believed to attribute to the improved energy absorptions. Compared with quasi-isotropic woven composites, higher energy absorbing efficiency was investigated in the quasi-isotropic MD composites. Up to 33.4%, improved energy absorptions were produced in quasi-isotropic MD composites than their woven composite counterparts with the same thickness and yarn directions.

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