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Mahbod, Mahshid

University of British Columbia

Fiber-reinforced polymer composites are widely being used in aerospace, automotive, and marine industries, among others, owing to their lightweight and superior mechanical properties. Among various composite materials, ultra-high molecular weight polyethylene (UHMWPE) woven fabrics have gained attention particularly in the applications requiring high ballistic and/or puncture resistance, such as armors. However, to achieve the desired performance, multiple fabric layers are often necessary, which increases the weight of the final product. One promising solution to this challenge is the incorporation of shear-thickening fluid (STF) into the fabric layers, which enhances the mechanical properties of UHMWPE fabrics, reducing the number of layers and overall weight. This study investigates the mechanical performance of a novel material system composed of UHMWPE-based composite fabric enhanced with STF and crosslinkers. The crosslinkers used are based on Bis–Diazirine polymers. Initially, fabrics impregnated with various crosslinkers were evaluated through tensile, shear, bending, yarn pull-out, friction, tear, and puncture tests. The fabrics were compared using a multi-criteria decision-making (MCDM) technique to identify the most effective crosslinker for subsequent STF impregnation. The selected crosslinked fabric was then impregnated with STF, which consists of fumed silica nanoparticles suspended in polyethylene glycol. The mechanical behavior of the resulting composite material was evaluated under tensile, shear, bending, puncture, and impact loading conditions. The combined and individual effects of the selected chemical crosslinking and STF on the base fabric’s mechanical behavior were analyzed for the first time. The impact of strain rate on tensile and shear behavior was also investigated. Pertinent to armor applications at low-to-medium velocity loading regimes, the results demonstrated a significant improvement in puncture resistance, with an increase up to 92%, when compared to the control fabric. Finally, the finite element (FE) modeling of the MCDM-selected material system was established and validated against experimental data. Statistical analysis combined with an optimization study identified key material parameters that are often difficult to characterize directly from experimental tests. These included the friction coefficient between the ply ‘in the weave form’ and the punch, and the maximum stress threshold within the material system for element deletion. Using the optimized parameters as input to the model resulted in predictions that agreed very well with the experimental data (with a minimal error of 5% in the absorbed energy during the puncture test).

Text

2025-01-16

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/90130

Mechanical Engineering

University of British Columbia

UBCO

http://creativecommons.org/licenses/by-nc-nd/4.0/