202944
20181203023643.0
doi
10.1016/0022-5096(93)90007-3
0022-5096
ARTICLE
THE TOUGH TO BRITTLE TRANSITION IN BRITTLE MATRIX COMPOSITES
1993
1993
Journal Articles
A THEoRY is presented to predict the ultimate tensile strength of brittle matrix composites as a function of underlying material parameters, and specifically to investigate the origin of the tough to brittle transition often observed in these materials as the fiber-matrix interfacial sliding resistance tau is increased. The theory relaxes the usual assumption of global load sharing of the load transfer from broken to unbroken fibers in the composite [CURTIN, W. A., J. Am. Ceram. Soc. 74, 2837 (1991)] by taking the load to be equally distributed among only N(f) fibers around a broken fiber (local load sharing). The composite is then modeled as a collection of independent fiber bundles with Nf fibers per bundle, and composite failure occurs when the weakest bundle fails. Composite strength is thus controlled by the strength distribution of size-N(f) bundles, which is calculated here by analytical and simulation techniques. As N(f) --textgreater infinity the global load sharing results for composite strengths are regained, but significant composite strength degradation is predicted for bundle sizes N(f) less-than-or-equal-to 100. An ansatz relating N(f) to material parameters is then proposed and calculations of the strengths of C-Nicalon composites agree well with experiment. Model calculations on a Nicalon-LAS glass composite show that local load sharing effects lead to a tough to brittle transition between 100 and 200 MPa, much lower than predicted by the global load sharing theory although still larger than found experimentally.
ceramics
crack
fiber
fracture
interface
mechanical-properties
strength
246474
Curtin, W. A.
211624
41
217-245
Journal Of The Mechanics And Physics Of Solids
252513
LAMMM
U12614
oai:infoscience.tind.io:202944
STI
article
EPFL-ARTICLE-202944
curtin_tough_1993/LAMMM
OTHER
REVIEWED
PUBLISHED
ARTICLE