Accession Number : ADA258922


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


Descriptive Note : Master's thesis


Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING


Personal Author(s) : Baker, Robert P


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a258922.pdf


Report Date : Dec 1992


Pagination or Media Count : 170


Abstract : 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.


Descriptors :   *FATIGUE LIFE , *CRACKS , *FATIGUE(MECHANICS) , *SILICON CARBIDES , *METAL MATRIX COMPOSITES , TEST AND EVALUATION , METALS , RATIOS , FAILURE , TITANIUM , CYCLES , CARBIDES , THESES , OBSERVATION , EDGES , FIBERS , DAMAGE


Subject Categories : Laminates and Composite Materials
      Properties of Metals and Alloys
      Test Facilities, Equipment and Methods
      Thermodynamics


Distribution Statement : APPROVED FOR PUBLIC RELEASE