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Energy Changes During Crack Extension in Compression

Published online by Cambridge University Press:  25 February 2011

M. El-Rahman  and
N. G. Shrive
M. El-Rahman
Affiliation:
Graduate Student and Professor, respectively, Department of Civil Engineering, The University of Calgary, Calgary, Alberta, Canada T2N 1N4
N. G. Shrive
Affiliation:
Graduate Student and Professor, respectively, Department of Civil Engineering, The University of Calgary, Calgary, Alberta, Canada T2N 1N4
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Abstract

Much is known about the tensile fracture, both brittle and ductile: theories are well developed. There is no equivalent theory for compressive failure. A generalized theorem has been developed based on the concept of cohesive strength and the fact that tensile stresses frequently develop around the surface of voids in a material subject to compression. The theory does not produce criteria on critical flaw size. The latter should result from an energy criterion. It is shown, however, that modelling compression cracks as zero width flaws results in no energy change as the crack extends: an anomalous result compared with experimental findings. Allowing compression cracks to have finite width results in strain energy reduction as the ‘crack’ gets larger. A three-dimensional ellipsoid has been used as a model of a compression ‘crack’. Strain energy reduction in the medium, due to the presence of the void, is shown to depend on both its shape and its size. Initial estimates of a compressive G - a compressive energy release rate as the ‘crack’ extends - also suggest a dependence on both size and shape of the cavity. The results indicate further investigation is warranted.

Type
Articles
Information
MRS Online Proceedings Library (OPL) , Volume 64: Symposium S – Cement-Based Composites: Strain Rate Effects on Fracture , 1985 , 139
Copyright
Copyright © Materials Research Society 1986

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References

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