Date Approved

8-22-2016

Embargo Period

8-24-2016

Document Type

Thesis

Degree Name

M.S. Mechanical Engineering

Department

Mechanical Engineering

College

Henry M. Rowan College of Engineering

Advisor

Riddell, William

Committee Member 1

Constans, Eric

Committee Member 2

Ranganathan, Shivakumar

Keywords

beta, Fiber, Lag, out, pull, Shear

Subject(s)

Strength of materials; Fibrous composites; Finite element method

Disciplines

Mechanical Engineering

Abstract

The strength of fiber-reinforced composites is dependent on the strength of the fiber-matrix interface bond. Thermal, chemical, and other means have been used to modify the surface of fibers, resulting in increased fiber-matrix interface bond strength. However, researchers are still dependent on empirical methods to relate surface modifications to composite performance. Additional efforts are required to develop physics-based models for micro-mechanical effects on interfacial bond strength that will be needed for the improved design and processing of fiber reinforced composites. It is anticipated that experimental, numerical, and analytical efforts will be needed to contribute toward this endeavor.

A numerical approach is presented in this thesis that allows the shear lag parameter, β, to be extracted from finite element results. Extracting the shear lag parameter from numerical data allows numerical and analytical approaches to be compared. Axisymmetric finite element analyses of fiber pull out, axisymmetric macrobond, and fully embedded fiber fracture tests are discussed in light of this approach. Material and geometric properties used in numerical models are then varied to study their effects on the fitted value of β. It is anticipated that this approach will enable and enhance future research efforts to simulate the effect of fiber surface texture on pull out strength.

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