Thermomechanical and isothermal fatigue behavior of a (90)[sub 8] titanium matrix composite

Conference · Fri Oct 01 04:00:00 EDT 1993

OSTI ID:5303783

Castelli, M G

An experimental investigation was conducted to analyze the fatigue damage mechanisms operative in a 35 fiber volume percent (90 deg) titanium matrix composite (TMC) under 427 C isothermal and thermomechanical loading conditions. The thermomechanical fatigue (TMF) tests were performed with a temperature cycle from 200 to 427 C under closely controlled conditions to define both the deformation and fatigue life behavior. Degradation of the TMC's isothermal elastic moduli and coefficient of thermal expansion were monitored throughout the TMF tests. The results indicated TMF life trends which contrasted those established in a comparable (0 deg) system, as TMF loading of the (90 deg) TMC was not found to be 'life-limiting' in comparison to maximum temperature isothermal conditions. In-phase lives were very similar to those established under 427 C isothermal conditions. High stress isothermal fatigue at 427 C produced increased strain ratchetting and stiffness degradation relative to TMF conditions. Out-of-phase loadings produced TMF lives approximately an order of magnitude greater than the lives determined under isothermal and in-phase conditions. Extensive fractography and metallography were also performed. Two key issues were identified and appeared to dominate the fatigue damage and life of the (90 deg) TMC, namely, the weak fiber/matrix interface and environmental attack of the fiber/matrix interface via the exposed (90 deg) fiber ends.

• Research Organization: Sverdrup Technology, Inc., Brook Park, OH (United States)
• OSTI ID: 5303783
• Report Number(s): N-94-14822; NASA-CR--191196; E--8156; NAS--1.26:191196; CONF-9310291--; CNN: NAS3-25266; RTOP 510-01-50
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603* -- Materials-- Properties
ELEMENTS
FATIGUE
LIFETIME
MATERIALS
MATRIX MATERIALS
MECHANICAL PROPERTIES
METALS
SERVICE LIFE
TEMPERATURE DEPENDENCE
TITANIUM
TRANSITION ELEMENTS