Accession Number : ADA291479

Title :   Investigation of Tension-Compression Fatigue Behavior of a Notched Cross-Ply Metal Matrix Composite at Elevated Temperature.

Descriptive Note : Master's thesis,

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

Personal Author(s) : Yocum, Matthew W.

PDF Url : ADA291479

Report Date : DEC 1994

Pagination or Media Count : 148

Abstract : This research extends the existing knowledge of MMC fatigue damage mechanisms by studying the tension-compression fatigue behavior of a notched cross-ply laminate MMC at elevated temperature. A (0/90)25 SCS-6/Ti-15-3 laminate with a center hole was subjected to tension-compression fatigue at 427 deg C (800 deg F). Stress and strain data was taken to evaluate macro-mechanic behavior of the material. Microscopy and fractography were performed to characterize the damage on a micro-mechanical level. Crack initiation and progression was monitored using acetate face replicas. Four cracks were found to develop around the periphery of the hole, two of which became dominant and proceeded through to the end of the specimen. On a maximum applied stress basis, tension-compression notched specimens had shorter fatigue lives than tension-tension notched specimens. Also, tension-compression adds more damage due to the compressive portion of the loading, and tension-compression loading increased the time to crack initiation for a given maximum stress and increased the rate of crack propagation over tension-tension cases. (MM)

Descriptors :   *METAL MATRIX COMPOSITES, *FATIGUE(MECHANICS), STRESS STRAIN RELATIONS, FATIGUE LIFE, STRESS ANALYSIS, COMPOSITE MATERIALS, HIGH TEMPERATURE, LAMINATES, TENSILE STRESS, STIFFNESS, DAMAGE ASSESSMENT, FIBER REINFORCED COMPOSITES, THESES, LOAD DISTRIBUTION, FRACTOGRAPHY, CRACK PROPAGATION, BRITTLENESS, BUCKLING, FAILURE(MECHANICS), AEROSPACE INDUSTRY, MICROMECHANICS, COMPRESSIVE STRENGTH, CYCLIC LOADS, NOTCH TOUGHNESS.

Subject Categories : Laminates and Composite Materials

Distribution Statement : APPROVED FOR PUBLIC RELEASE