Energetic and Statistical Size Effects in Fiber Composites and Sandwich Structures: A Precis of Progress
Abstract: The conference lecture gives an overview of the problems of scaling and size effect in solid me-chanics, which have not come to the forefront of attention until late in the last century. The classical view that any observed sIZe effect was statistical was reversed during the 1 980s. As is...
| Main Authors: | , , |
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| Format: | Text |
| Language: | English |
| Published: |
2003
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| Subjects: | |
| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.694.5283 http://www.civil.northwestern.edu/people/bazant/PDFs/Papers/P183.pdf |
| Summary: | Abstract: The conference lecture gives an overview of the problems of scaling and size effect in solid me-chanics, which have not come to the forefront of attention until late in the last century. The classical view that any observed sIZe effect was statistical was reversed during the 1 980s. As is now widely accepted, quasib-rittle materials including concrete, rock, tough ceramics, sea ice, snow slabs and composites exhibit major size effects on the mean structural strength that are determimstic in nature, being caused by stress redistribution and energy release assocIated WIth stable propagatIon of large fractures or with formation of large zones of distributed cracking. The lecture beginS by reviewing the general asymptotic properties of size effect implied by the cohesive crack model or crack band model, and highlights the use of asymptotic matching techniques as a means of obtaining scale-bndgmg size effect laws representing a smooth transitIon between two power laws. AttentIon ·tS focused on SIze effects observed in fiber-polymer composites falling eIther by tensile fracture or by propagatIOn of compreSSIOn kink bands with fiber mIcrobucklmg. The size effects in polymeric foams and sandWIch str"1J.ctures are also dIscussed. A nonlocal model for mcorporating the We!bull-type statistical sIze effect due to local strength randomness into the energetic size effect theory is outlined next, and the predic-tIons of the combmed nonlocal energetic statistical theory are compared to experimental evidence. Finally, a new probabILIstIc analysis of the size effect on the statts tical distributIOn of nommal strength of structures is |
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