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Statistical scaling relationships and size effects in the strength and creep rupture of fibrous compositesIn this presentation we discuss a new theoretical model and supporting experimental results for the strength and lifetime in creep rupture of unidirectional, carbon fiber/epoxy matrix composites at ambient conditions. First we review the 'standard' Weibull/power-law methodology that has been standard practice. Then we discuss features of a recent model which build on the statistical aspects of fiber strength, micromechanical aspects of stress transfer around fiber breaks, and time-dependent creep of the matrix. The model is applied to 'microcomposites' consisting of seven fibers in a matrix for which strength and creep-rupture data are available. The model yields Weibull distributions in an envelope format for both strength and lifetime. The respective shape, scale and power-law parameters depend on such parameters as the Weibull shape parameter for fiber strength, the exponent for matrix creep, the effective load transfer length (which grows in time due to matrix creep) and the critical cluster size for failed fibers. The experimental results are consistent with the theory, though time-dependent debonding appears to be part of the failure process.
Document ID
19940033298
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Phoenix, S. Leigh
(Cornell Univ. Ithaca, NY, United States)
Date Acquired
September 6, 2013
Publication Date
July 1, 1994
Publication Information
Publication: NASA. Langley Research Center, Workshop on Scaling Effects in Composite Materials and Structures
Subject Category
Structural Mechanics
Accession Number
94N37809
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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