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Crack coalescence in rock-like material under cycling loading

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dc.contributor.advisor Herbert H. Einstein. en_US Ko, Tae Young, 1973- en_US
dc.contributor.other Massachusetts Institute of Technology. Dept. of Civil and Environmental Engineering. en_US 2006-03-24T18:29:12Z 2006-03-24T18:29:12Z 2005 en_US 2005 en_US
dc.description Thesis (Civ. E.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2005. en_US
dc.description Includes bibliographical references (p. 181-184). en_US
dc.description.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 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. en_US
dc.description.statementofresponsibility by Tae Young Ko. en_US
dc.format.extent 184 p. en_US
dc.format.extent 31606880 bytes
dc.format.extent 31630176 bytes
dc.format.mimetype application/pdf
dc.format.mimetype application/pdf
dc.language.iso eng en_US
dc.publisher Massachusetts Institute of Technology en_US
dc.rights M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. en_US
dc.subject Civil and Environmental Engineering. en_US
dc.title Crack coalescence in rock-like material under cycling loading en_US
dc.type Thesis en_US Civ.E. en_US
dc.contributor.department Massachusetts Institute of Technology. Dept. of Civil and Environmental Engineering. en_US
dc.identifier.oclc 60686969 en_US

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