Date of Award

5-2015

Document Type

Thesis

Degree Name

Master of Science in Materials Science and Engineering (MSMSE)

Department

Mechanical Engineering

First Advisor

Abdel-Hamid Ismail Mourad

Second Advisor

Samir Imam

Third Advisor

Jeff Wood

Abstract

Composite materials have applications in a wide range of aspects of research in many advanced technologies and industrial engineering fields (e.g. aerospace, civil, military and marine). They are usually subjected to a wide range of loading during in-service use. These materials have superior properties such as light weight, high strength-to-weight ratio, high stiffness and low density. Therefore, they are designed to achieve unique thermo-mechanical properties and outstanding performance characteristics that aren’t possible with traditional materials.

Fabrics, made from high-modulus and high strength fibers, possess the merits of low weight, high specific strength and high flexibility. They offer superior impact-resistance-to-weight properties. Kevlar fibers are among the best impact resistant fibers, which have been widely used as impact-resistant reinforcement in composite materials. Moreover, the addition of low concentrations of nano-particles into composites improves their mechanical performances without compromising the density, toughness or manufacturing process.

The main objective of this research is to experimentally investigate the low velocity impact response of nano-reinforced laminated composite Kevlar KM2Plus using drop-weight technique. The tests were carried out on laminated structures based on Kevlar/epoxy resin with different nano-fillers weight percentages. These include silicon carbide (SiC), aluminum oxide (Al2O3) and multi-wall carbon nano-tubes (MWCNT). A non-destructive test, using X-ray, was performed to examine the possibility of delamination formation around the impact tested area. The mechanical properties of the composite samples were measured, using three-point bending test, nano-identification test and hardness test. Furthermore, the thermal properties of the laminated Kevlar samples were investigated using Thermal Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). The laminated Kevlar enhanced with 0.5% MWCNT exhibited the optimum results in terms of the impact test, where no delamination was observed around the impacted area; while delamination was observed in other samples. The addition of nano-fillers had significantly enhanced the mechanical properties of the composite samples, including the flexural strength and hardness. It is evident that as content of the nano-filler increases, these mechanical properties increase too. Also, the Kevlar composite enhanced with 0.5% MWCNT showed the maximum flexural strength among all the Kevlar samples. This might be the reason behind the Kevlar composite enhanced with 0.5% MWCNT had the least delamination percent among all the samples. The thermal stability of all composites depends on the thermal stability of the resin. The addition of the nano-fillers had no effect on the thermal properties of the composite samples. Therefore, laminated Kevlar KM2Plus enhanced with 0.5% MWCNT could be used to enhance several composites, used in our daily life such as helmets, goggles, and heavy –duty gloves.

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