Characterization of self -healing composite materials

Abstract

Characterization of Self-Healing Composite Materials Kevin John FordDamage occurs in almost every composite material in the form of microcracks that develop in the epoxy matrix that binds the fibers together. Researchers at the University of Illinois Urbana Champaign have recently developed a method to reverse the effects of, or heal, damage in the epoxy matrix. Their in-situ self-healing system uses embedded microcapsules and a catalyst that trigger a romp reaction in an effort to rebond the microcracks. Several models have been developed in an effort to predict how a composite laminate damages. One model in particular, the Continuous Damage Mechanics model, CDM that has been developed at West Virginia University uses material properties that are easily obtained from standard ASTM and ISO testing methods. The CDM model has been extended at West Virginia University to incorporate the effects of a self-healing system to develop a Continuous Damage and Healing Mechanics model, CDHM. In this work, a testing procedure to characterize the autonomic healing of polymer matrix composites is outlined, as well as the regenerative effects of the self-healing system. The capability of the CDHM model to predict the material properties of the self-healing system is also addressed. The CDHM model is validated with experimental results for various laminates fabricated out of E-glass/epoxy. iii DEDICATION This disertation is dedicated to my family. Your support and encouragement have meant a lot to me over the years and I am forever grateful. Thank you!iv ACKNOWLEDGEMENTS I would like to thank my committee members Dr.

A two-dimensional micromechanical damage–healing model on microcrack-induced damage for microcapsule-enabled self-healing cementitious composites under compressive loading

“…According to previous literature (Ford, 2006), the size distribution of microcapsules follows the normal distribution X $ NðK, DÞ, where K and D are the mean value and variance of radii. Based on probability theory, 5 2a h 4 can be calculated…”

“…The kinked microcracks and nucleated microcracks must be considered in compressive tests of concretes. Based on previous experiments (Ford, 2006), the radius of microcapsules follows approximately a normal distribution, which should be considered in the micromechanical model. The negative influence of microcapusles on the concrete before healing should also be predicted.…”