Investigation of Fatigue Behavior In Notched Cross-Ply Titanium Metal Matrix Composite at Elevated Temperature

The objective of this research was to investigate the initiation and progression of damage which develops in notched (0/90) sub 2S SCS-6/Ti-15-3 at elevated temperature. Testing consisted of a monotonic tensile test at 427 deg C followed by fatigue testing performed under load control with a stress...

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Bibliographic Details
Main Author: Baker, Robert P
Format: Report
Language:English
Subjects:
CARBIDES
CRACKS
CYCLES
DAMAGE
EDGES
FAILURE
FATIGUE LIFE
FATIGUE TESTING
FATIGUE(MECHANICS)
FIBERS
Laminates and Composite Materials
METAL MATRIX COMPOSITES
METALS
OBSERVATION
Properties of Metals and Alloys
RATIOS
SILICON CARBIDES
STRESS TESTING
TEST AND EVALUATION
Test Facilities, Equipment and Methods
Thermodynamics
THESES
TITANIUM
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Summary:The objective of this research was to investigate the initiation and progression of damage which develops in notched (0/90) sub 2S SCS-6/Ti-15-3 at elevated temperature. Testing consisted of a monotonic tensile test at 427 deg C followed by fatigue testing performed under load control with a stress ratio of 0.1 at a frequency of 10 Hz. A crack was defined to have initiated when it had attained a length greater than or equal to 0.124 mm. Crack initiation and progression was monitored by strain and modulus observations and visual inspection via telemicroscope. The cracks were recorded with edge and face replicas. Metallographic and fractographic analysis was performed after specimen failure. Fatigue cracks initiated in the matrix at four locations on the front and back faces of each specimen. Two of these cracks became through-cracks and eventually developed into major cracks which caused the fracture. The applied stress (S) and fatigue lives (N) curves for both initiation and fatigue life were established. Also, crack growth curves as the function of fatigue cycles were established. A detailed metallographic analysis was performed to understand the damage mechanisms and its implication on the observed notched fatigue behavior.