Geometry-Dependent R-Curve for Quasi-Brittle Materials |
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Authors: | Chengsheng Ouyang Surendra P Shah |
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Affiliation: | NSF Center for Science and Technology of Advanced Cement-Based Materials, Northwestern University, Evanston, Illinois 60208 |
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Abstract: | Fracture of quasi-brittle materials such as ceramics and cement-based materials can be described by an R -curve, defined as fracture resistance. The R -curve can be constructed as the envelope of the strain energy release rates ( G ). In this study, R -curve is defined as an envelope of G -curves obtained by varying the dimensions of identical specimens, while keeping the geometry and the initial flaw size constant. By approximating the G -curve with a second-order function of the crack length, a simple formulation of the R -curve is derived by solving a differential equation. Three parameters are needed for the proposed R -curve. These parameters can be obtained by testing a notched-beam specimen and using linear elastic fracture mechanics. The proposed R -curve simulates well the geometry dependency as well as other characteristics of the fracture response of quasi-brittle materials. |
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Keywords: | R curve brittle materials cracks cements models |
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