An Experimental and Numerical Study of Three-Dimensional Fatigue Damage in Carbon Fibre Reinforced Polymers

Abstract

A phenomenological experimental study was presented for understanding the effect of cyclic loading, generally experienced by typical modern aircraft structures during flight, on the propagation of micro-mesoscopic damage in carbon fibre reinforced composite laminates. Testing was carried out by employing ultra-high resolution SkyScan 1173 XRmicro computed tomography to identify and assess damage progression during fatigue testing. It provided qualitative as well as quantitative assessments of the damage in the composites which supported the analytical investigations. An in-house solution was developed for statistically analyzing the occurrence, frequency and geometry of cracks throughout the fatigue life. This methodology was used to process the data from scan for the purposes of visualizing damage initiation and propagation. I would never have been able to finish my dissertation without the blessing of God. I am grateful to the God for the good health and wellbeing. I am extremely grateful to my supervisor, Professor Jeremy Laliberté, for sharing expertise and sincere and valuable guidance. He was always available and willing to help, and had constantly led me to strive for excellence. He had seriously taken a personal interest in my success and building my confidence. I take this opportunity to express gratitude to my cosupervisor, Professor John Goldak, who gave me the opportunity to join the program. Many thanks as well to Professor Mike Munro for his help and support over years and to my dear supervisor late Professor Atef Fahim, may his soul rest in peace. Thanks to all my colleagues; Camille, Pedro, Sadeem, Taran and Alex, for their valuable help on my project. I wish to express my sincere thanks to Carleton University for the financial support, to the National Research Council in Ottawa and to the Science and Technology Centre at Carleton University for the specimens' preparations. Special thanks to the laboratory technologist, Steve Truttman, for helping with the fatigue testing. I am also indebted to my mother, Soheir. I really appreciate her consistent support and encouragement. Finally, words cannot express my gratitude, appreciation, dedication and love of my sons, Eyad and Youssef. They happily allowed me for long hours, which they deserved more, to work on my thesis. They encouraged and pushed me forward, never complained nor demanded the least of what I owe them. I admit so many debts to repay, but my sons' support goes beyond any intellectual loan. xv List of Appendices Appendix A Test Sample Specifications …………….….………....… Appendix B Material: DA 409U/G35 Unidirectional Carbon/Epoxy Prepreg …………………………………………….. Appendix C CLT calculations of Laminate Constants ………..…… Appendix D MATLAB Code for 3D Plotting of MicroCT scans …….. xvi Nomenclature List of Symbols Latin a Crack length CI Constant (normal mode) CII Constant (in-plane shear mode) CIII Constant (out-of-plane shear mode) EL Longitudinal modulus ET Transverse modulus E1, E2 Elastic Constants GLT Shear modulus Gn Fracture energy (normal mo...

Exploratory Field and Laboratory Investigation on the Use of Noncontact Digital Ski Sensor in the South Korea Expressway Network

“…Many machine industries developed novel and advanced devices that may enable better surface smoothness of asphalt pavements. Multisonic sensors provide a solid alternative as they rely on the acoustic emissions [29][30][31][32] resulting in the noncontact digital ski (NCDS) system for asphalt pavement applications [31,32]. Contrary to earlier traditional approaches, the NCDS does not call for direct physical contact between the machine and the road surface.…”

“…Contrary to earlier traditional approaches, the NCDS does not call for direct physical contact between the machine and the road surface. A noncontact distance measuring technique that uses readings from several sensors automatically determines the design thickness of the layer to be paved [4][5][6][30][31][32].…”