Crack coalescence in brittle material under cyclic loading

T. Y. Ko, H. H. Einstein, J. Kemeny

Research output: Contribution to conferencePaper

15 Scopus citations

Abstract

A total of 170 tests (68 tests for monotonic loading, 102 tests for cyclic loading) have been performed to investigate crack initiation, propagation and coalescence. The specimens have two pre-existing flaws which are arranged at different distances and angles. Wing cracks and secondary cracks are observed in both monotonic and cyclic tests. Wing cracks, which are tension cracks, initiate at (or near) the tips of the flaws and propagate parallel to the compressive loading axis. Secondary cracks always appear after wing crack initiation and lead to final failure. Secondary cracks initiate at the tips of the flaws and propagate in the coplanar direction of the flaw or in a horizontal (quasi-coplanar) direction. Six types of coalescence are observed. For coplanar geometry specimens, coalescence occurs due to the internal shear cracks. For non-coplanar geometry specimens, coalescence occurs through combinations of internal shear cracks, internal wing cracks and tension cracks. Contrary to monotonic tests, cyclic tests produce fatigue cracks. Fatigue cracks usually occur when 1) after coalescence, the specimens behave as if they had only one larger crack 2) specimens have been subjected to a particular number of cycles. In these experiments, two different fatigue crack initiation directions are observed: horizontal and coplanar to the flaw.

Original languageEnglish (US)
StatePublished - Dec 1 2006
Event41st U.S. Rock Mechanics Symposium - ARMA's Golden Rocks 2006 - 50 Years of Rock Mechanics - Golden, CO, United States
Duration: Jun 17 2006Jun 21 2006

Other

Other41st U.S. Rock Mechanics Symposium - ARMA's Golden Rocks 2006 - 50 Years of Rock Mechanics
CountryUnited States
CityGolden, CO
Period6/17/066/21/06

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics

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    Ko, T. Y., Einstein, H. H., & Kemeny, J. (2006). Crack coalescence in brittle material under cyclic loading. Paper presented at 41st U.S. Rock Mechanics Symposium - ARMA's Golden Rocks 2006 - 50 Years of Rock Mechanics, Golden, CO, United States.