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Title: Interfacial shear behavior and its influence on fiber damage in sapphire-reinforced gamma titanium aluminide composites. Doctoral thesis

Abstract

The interfacial shear behavior and its influence on fiber damage in sapphire-reinforced TiAl composites was investigated using a combination of microscopic characterization, indentation crack growth results, fiber pushout testing, fiber displacement measurements, and computational analyses. Two interrelated phenomena were studied: (1) residual stresses and resulting damage within fibers intersecting a free surface and (2) fiber/matrix interfacial strength behavior. In the first aspect of this study, experimental observations, finite element analysis, as well as analytical computations were all used to analyze the evolution of fiber damage that was observed in fibers intersecting a free surface in sapphire-reinforced Ti-48Al-IV composites. Experimental observations indicate that, under certain conditions, surface cracks introduced during specimen preparation will propagate along the fiber axis due to thermally-induced residual stresses. Finite element computations predict that significant thermally-induced residual tensile stresses exist in sapphire fibers embedded within TiAl-based matrices when they intersect and are oriented normal to a free surface. Indentation crack growth behavior within the sapphire fibers provided experimental validation of the predicted stress state. Finally, the application of an exact elastic analysis indicates that tensile stresses also exist within fibers oriented parallel to and near a free surface.

Authors:
Publication Date:
Research Org.:
Air Force Inst. of Tech., Wright-Patterson AFB, OH (United States)
OSTI Identifier:
5873164
Report Number(s):
AD-A-267943/9/XAB; AFIT/CI/CIA-93-001D
Resource Type:
Technical Report
Resource Relation:
Other Information: Doctoral thesis
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; COMPOSITE MATERIALS; STRESS ANALYSIS; FIBERS; FRACTURE PROPERTIES; INTERFACES; SHEAR PROPERTIES; ALUMINIUM COMPOUNDS; CRACK PROPAGATION; FINITE ELEMENT METHOD; INTERMETALLIC COMPOUNDS; REINFORCED MATERIALS; RESIDUAL STRESSES; SAPPHIRE; TITANIUM COMPOUNDS; ALLOYS; CALCULATION METHODS; CORUNDUM; MATERIALS; MECHANICAL PROPERTIES; MINERALS; NUMERICAL SOLUTION; OXIDE MINERALS; STRESSES; TRANSITION ELEMENT COMPOUNDS; 360602* - Other Materials- Structure & Phase Studies

Citation Formats

Galbraith, J M. Interfacial shear behavior and its influence on fiber damage in sapphire-reinforced gamma titanium aluminide composites. Doctoral thesis. United States: N. p., 1993. Web.
Galbraith, J M. Interfacial shear behavior and its influence on fiber damage in sapphire-reinforced gamma titanium aluminide composites. Doctoral thesis. United States.
Galbraith, J M. 1993. "Interfacial shear behavior and its influence on fiber damage in sapphire-reinforced gamma titanium aluminide composites. Doctoral thesis". United States.
@article{osti_5873164,
title = {Interfacial shear behavior and its influence on fiber damage in sapphire-reinforced gamma titanium aluminide composites. Doctoral thesis},
author = {Galbraith, J M},
abstractNote = {The interfacial shear behavior and its influence on fiber damage in sapphire-reinforced TiAl composites was investigated using a combination of microscopic characterization, indentation crack growth results, fiber pushout testing, fiber displacement measurements, and computational analyses. Two interrelated phenomena were studied: (1) residual stresses and resulting damage within fibers intersecting a free surface and (2) fiber/matrix interfacial strength behavior. In the first aspect of this study, experimental observations, finite element analysis, as well as analytical computations were all used to analyze the evolution of fiber damage that was observed in fibers intersecting a free surface in sapphire-reinforced Ti-48Al-IV composites. Experimental observations indicate that, under certain conditions, surface cracks introduced during specimen preparation will propagate along the fiber axis due to thermally-induced residual stresses. Finite element computations predict that significant thermally-induced residual tensile stresses exist in sapphire fibers embedded within TiAl-based matrices when they intersect and are oriented normal to a free surface. Indentation crack growth behavior within the sapphire fibers provided experimental validation of the predicted stress state. Finally, the application of an exact elastic analysis indicates that tensile stresses also exist within fibers oriented parallel to and near a free surface.},
doi = {},
url = {https://www.osti.gov/biblio/5873164}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Sat May 01 00:00:00 EDT 1993},
month = {Sat May 01 00:00:00 EDT 1993}
}

Technical Report:
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