| Summary: | 碩士 === 國立成功大學 === 資源工程學系碩博士班 === 96 === This study proposes double torsion(DT) test and double cantilever beam(DCB) test to determine the fracture toughness of granite plates. In DT test, the effects of specimen geometry, loading rate, and initial crack length are investigated. In DCB test, the effects of specimen geometry, initial crack length, and specimen with or without groove are investigated. A finite element software, ABAQUS, is carried out to obtain the numerical solution of fracture toughness of DCB specimen by wedge loading. The numerical results are compared with the analytical solution of ungroove specimen. Additionally, a KYOWA crack measurement system is modified to measure the crack growth velocity in DT test and DCB test.
The major findings are as following: (1) The fracture toughness of DT test varies with initial crack length in specimen geometry. (2) The fracture toughness of the bigger DCB specimen are greater than the one from small DCB specimen. (3) In DCB test, the discrepancy between the numerical solution and analytic solution is -0.16% ~ 1.9%. (4) The difference of crack growth velocity in big size DT specimen between experimental results and analytic solution is large. Besides, the crack growth velocity measured from DT test is 1.83 times the one from DCB test.
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