Characterization of mechanical damage mechanisms in ceramic composite materials. Technical report, 23 May 1987-24 May 1988
High-strain-rate compressive failure mechanisms in fiber-reinforced ceramic-matrix composite materials were characterized. These are contrasted with composite damage development at low-strain rates, and with the dynamic failure of monolithic ceramics. It is shown that it is possible to derive major strain-rate strengthening benefits if a major fraction of the fiber reinforcement is aligned with the load axis. This effect considerably exceeds the inertial microfracture strengthening observed in monolithic ceramics, and non-aligned composites. Its basis is shown to be the trans-specimen propagation time period for heterogeneously-nucleated, high-strain kink bands. A brief study on zirconia focused on the remarkable inverse strength-strain rate result previously observed for both fully and partially-stabilized zirconia single crystals, whereby the strength decreased with increasing strain rate. Based on the hypothesis that the suppression of microplastic flow, hence, local stress relaxation, might be responsible for this behavior, fully stabilized (i.e., non-transformable) specimens were strain-gaged and subjected to compressive microstrain. The rather stunning observation was that the crystals are highly microplastic, exhibiting plastic yield on loading and anelasticity and reverse plasticity upon unloading. These results clearly support the hypothesis that with increasing strain rate, microcracking is favored at the expense of microplasticity.
- Research Organization:
- Southwest Research Inst., San Antonio, TX (USA)
- OSTI ID:
- 6257604
- Report Number(s):
- AD-A-204233/1/XAB; SWRI-8124
- Country of Publication:
- United States
- Language:
- English
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Characterization of mechanical-damage mechanisms in ceramic composite materials. Technical report, 24 May 1985-23 May 1986
Characterization of mechanical-damage mechanisms in ceramic-composite materials. Technical report, 24 May 1986-23 May 1987
Related Subjects
CERAMICS
MATRIX MATERIALS
COMPOSITE MATERIALS
MECHANICAL PROPERTIES
CAVITATION
COMPRESSION STRENGTH
CRYSTALS
DAMAGE
DYNAMICS
FAILURES
GLASS
PLASTICITY
PLASTICS
PROGRESS REPORT
STABILIZATION
STRAIN RATE
STRESS RELAXATION
ZIRCONIUM OXIDES
CHALCOGENIDES
DOCUMENT TYPES
MATERIALS
MECHANICS
OXIDES
OXYGEN COMPOUNDS
PETROCHEMICALS
PETROLEUM PRODUCTS
RELAXATION
SYNTHETIC MATERIALS
TRANSITION ELEMENT COMPOUNDS
ZIRCONIUM COMPOUNDS
360603* - Materials- Properties
360203 - Ceramics
Cermets
& Refractories- Mechanical Properties