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

Technical Report · Sat May 01 00:00:00 EDT 1993

OSTI ID:5873164

Galbraith, J M

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.

• Research Organization: Air Force Inst. of Tech., Wright-Patterson AFB, OH (United States)
• OSTI ID: 5873164
• Report Number(s): AD-A-267943/9/XAB; AFIT/CI/CIA-93-001D
• Resource Relation: Other Information: Doctoral thesis
• Country of Publication: United States
• Language: English

Related Subjects

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