Investigation of damage mechanisms in a cross-ply metal-matrix composite under thermomechanical loading. Master's thesis

Technical Report · Sat Dec 01 04:00:00 EST 1990

OSTI ID:5590254

Schubbe, J J

Metal matrix composites (MMCs) are rapidly becoming strong candidates for high temperature and high stiffness structural applications such as the Advanced Tactical Fighter (ATF). This study systematically investigated the failure modes and associated damage in a cross-ply, (0/90)2s SCS6/Ti-15-3 metal matrix composite under in-phase and out-of-phase thermomechanic fatigue. Initiation and progression of fatigue damage were recorded and correlated to changes in Young's Modulus of the composite material. Experimental results show an internal stabilization of reaction zone size but degradation and separation from constituent materials under extended cyclic thermal loading. Critical to damage were transverse cracks initiating in the 90 degrees plies, growing and coalescing from fiber/matrix interfaces internal to the specimen, progressing outward through the 0 degree plies before failure. Maximum mechanical strain at failure was determined to be approximately 0.0075 mm/mm. A correlation was made relating maximum matrix stress to failure life, resulting in a fatigue threshold limit of 280 MPa. An attempt was made to correlate the degradation in Young's Modulus (Damage=1-E/Eo) with the applied life cycles from different TMF tests.

• Research Organization: Air Force Inst. of Tech., Wright-Patterson AFB, OH (USA)
• OSTI ID: 5590254
• Report Number(s): AD-A-230544/9/XAB; AFIT/GAE/ENY--90D-26
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603* -- Materials-- Properties
AIRCRAFT
COMPOSITE MATERIALS
CORRELATIONS
CRACKS
DAMAGE
ELEMENTS
FABRICATION
FAILURES
FATIGUE
HEAT RESISTANT MATERIALS
HEAT TREATMENTS
HIGH TEMPERATURE
MATERIALS
MATERIALS WORKING
MATRIX MATERIALS
MECHANICAL PROPERTIES
METALS
STABILIZATION
THERMAL CYCLING
THERMOMECHANICAL TREATMENTS
TITANIUM
TRANSITION ELEMENTS
WEAPONS
YOUNG MODULUS