Long term behavior of polymer matrix composites -- Probabilistic assessment
- NYMA, Inc., Brookpark, OH (United States)
- NASA Lewis Research Center, Cleveland, OH (United States)
Probabilistic fatigue life assessment methodology for polymer matrix laminated composites has been developed and demonstrated. Degradation of matrix due to long term environmental exposure and mechanical/thermal cyclic loads are accounted for using a unified time-temperature-stress dependent multi-factor interaction relationship. Probabilistic distribution of response is computed using the fast probability integration method. Sensitivity of fatigue life reliability to uncertainties in the primitive random variables, e.g., constituent properties, fiber volume ratio, void volume ratio, ply thickness, etc. are quantified and their significance in the reliability based design for maximum life is discussed. Effect of variation in the thermal cyclic loads on the fatigue reliability for a graphite/epoxy laminate with ply thickness 0.127 mm, with respect to impending failure modes has been studied. At low mechanical cycle loads and low thermal cycle amplitudes, fatigue life for 0.999 reliability is observed to be most sensitive to matrix compressive strength, matrix modulus, thermal expansion coefficient and ply thickness. However, at high mechanical cyclic loads and high thermal cyclic amplitudes, fatigue life at 0.999 reliability is found to be more sensitive to the shear strength of matrix, longitudinal fiber modulus, matrix modulus and ply thickness.
- OSTI ID:
- 376003
- Report Number(s):
- CONF-960154--; ISBN 0-9648731-8-4
- Country of Publication:
- United States
- Language:
- English
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