Tensile fatigue damage and degradation of random short-fiber SMC composite
Fatigue damage and degradation in a random short-fiber SMC-R50 composite were investigated experimentally and theoretically. In the study of homogeneous damage, experiments were conducted to examined fundamental mechanisms and characteristics of fatigue damage and its evolution. The statistical nature of microcracks was evaluated by the introduction of damage distribution functions. Results showed that the cumulative distribution and density of microcrack length followed the form of a three-parameter Weibull function, whereas those of orientation followed a power form of the cos(theta) function. Constitutive equations for the damaged composite are derived based on the self-consistent mechanics scheme in conjunction with a three-dimensional elastic crack theory and probabilistic functions. Agreement between theoretical predictions and experimental data is excellent. The theory and analysis are able to evaluate the tensorial nature of fatigue damage and degradation of all material elastic constants. A damage tensor is introduced to describe quantitatively the degree of homogeneous fatigue damage. Stiffness degradation is related to the rate of change of microcrack evolution and accumulation, and a power-law relationship is found between the rate of damage development and fatigue loading cycles.
- Research Organization:
- Illinois Univ., Urbana (USA)
- OSTI ID:
- 6266249
- Country of Publication:
- United States
- Language:
- English
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