Jessie Mayo Jr., Ph.D. (2010) 

Dissertation Topic:  Studies on Cutting and Fracture Mechanics of High Performance Fibers

Major Professor:  Dr. Mahesh Hosur, Professor of Materials Science & Engineering

M.S.:  Mechanical Engineering, Tuskegee University

B.S.:  Mathematics,  Virginia State University

Employment:  STEM Instructor, Harford Community College, Aberdeen, MD

Dissertation Abstract:

Fabric failure falls under three distinct mechanisms (windowing, cut (shear), and tension (stretching until broken).  A plethora of information is available for several materials when the concern is tension mechanics (i.e. yield strength, ultimate strength, stress-strain curves, necking region, etc.).  However, a very limited amount of information is available when the concern is the cutting of materials or concentrated transverse loading.  A study to understand the fundamentals of fiber mechanics during cutting has been conducted.  In the current study, several fiber types are being examined during different modes of cut failure.  These materials include Kevlar 129, Dyneema, Carbon fiber, S-glass fiber, Twaron, etc.  Cut resistance of high performance fibers, single Kevlar filament fracture toughness, and the role of blade sharpness in cutting high performance fibers have been examined. Micro scale observations of the cutting phenomena of several types of fibers along with failure evolution studies are also included in this study.  These are the first steps in comprehending and modeling the aspects of fiber failure due to severance and fracture due to objects with sharp edges.  Being that this study only concerns the fibers of materials, engineering aspects such as fiber number, yarn twist, and weave patterns are subtracted to reveal the science behind the cut resistance of the fibers alone.