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Bend specimens: Numerical support in software ANSYS
Viszlay, Viliam ; Šimonová, Hana (referee) ; Seitl, Stanislav (advisor)
The aim of the thesis is the investigation of fracture-mechanics parameters on specimens made of quasi-brittle materials. The principles of two-parameter fracture mechanics are used. Couple of numerical simulations were done and their outputs are used for two main analysed specimen geometries. For simulations the finite element method software ANSYS is used. In the first part, the thesis focuses on bended specimens. The influence of different geometric parameters on fracture mechanics behaviour of cracked specimen is investigated. For model calibration the outputs of other authors are used. In the second part the specimens for modified compact-tension test (CT test) are analysed. Similar to the first part, the influence of geometric parameters of the specimen (in this case, the specimen size) on fracture mechanics parameters were investigated. The modified CT test was derived from CT test which is commonly used for metal materials testing as the suitable geometry for cement-based composite materials testing. The outputs of both parts are calibration polynomials, which are expressions obtained for different specimen geometries, giving the value of fracture mechanics parameter as the function of specimen geometry. As the example, calibration curves are used to obtain fracture toughness of tested material using the outputs from recent experiment.
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Numerical support for analysis of the fatigue behavior of cement based composites
Viszlay, Viliam ; Keršner, Zbyněk (referee) ; Seitl, Stanislav (advisor)
This thesis is focused on numerical analysis of fracture mechanics parameters in modified compact tension (CT) test. This CT test appears to be a suitable alternative to classic compact tension test for using for testing of quasi-brittle materials. The classic compact tension test is commonly used for fatigue testing of metallic materials and the geometry of used specimens does not allow using this test for quasi-brittle materials like cement based composites. The modified version of this test with cylindrical shape of the specimen allows us to test fatigue behaviour of quasi-brittle materials. In this thesis the influence of the modification of classic CT test on fracture mechanic parameters are determinated. In the next step, the influence of the position of steel bars (the position of loading force) on fracture mechanic parameters are evaluated. Obtained values are presented in graphs and calibration polynomials for each geometry are proposed.
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Bend specimens: Numerical support in software ANSYS
Viszlay, Viliam ; Šimonová, Hana (referee) ; Seitl, Stanislav (advisor)
The aim of the thesis is the investigation of fracture-mechanics parameters on specimens made of quasi-brittle materials. The principles of two-parameter fracture mechanics are used. Couple of numerical simulations were done and their outputs are used for two main analysed specimen geometries. For simulations the finite element method software ANSYS is used. In the first part, the thesis focuses on bended specimens. The influence of different geometric parameters on fracture mechanics behaviour of cracked specimen is investigated. For model calibration the outputs of other authors are used. In the second part the specimens for modified compact-tension test (CT test) are analysed. Similar to the first part, the influence of geometric parameters of the specimen (in this case, the specimen size) on fracture mechanics parameters were investigated. The modified CT test was derived from CT test which is commonly used for metal materials testing as the suitable geometry for cement-based composite materials testing. The outputs of both parts are calibration polynomials, which are expressions obtained for different specimen geometries, giving the value of fracture mechanics parameter as the function of specimen geometry. As the example, calibration curves are used to obtain fracture toughness of tested material using the outputs from recent experiment.
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Numerical support for analysis of the fatigue behavior of cement based composites
Viszlay, Viliam ; Keršner, Zbyněk (referee) ; Seitl, Stanislav (advisor)
This thesis is focused on numerical analysis of fracture mechanics parameters in modified compact tension (CT) test. This CT test appears to be a suitable alternative to classic compact tension test for using for testing of quasi-brittle materials. The classic compact tension test is commonly used for fatigue testing of metallic materials and the geometry of used specimens does not allow using this test for quasi-brittle materials like cement based composites. The modified version of this test with cylindrical shape of the specimen allows us to test fatigue behaviour of quasi-brittle materials. In this thesis the influence of the modification of classic CT test on fracture mechanic parameters are determinated. In the next step, the influence of the position of steel bars (the position of loading force) on fracture mechanic parameters are evaluated. Obtained values are presented in graphs and calibration polynomials for each geometry are proposed.
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Stress analysis of modified compact tension specimens: K-calibration curves
Seitl, Stanislav ; Viszlay, V.
Compact tension (CT) test is in engineering frequently used test for metallic materials to determiner fracture parameters/properties, e.g. fracture energy, fracture toughness, crack propagation rate, J-R curves etc. [20]. The modified compact tension (MCT) specimen for cement based composites has to be prepared due to negligible concentration around the holes for tenons. An accurate determination of fracture parameters requires the use of a valid calibration curves, there for in this contribution the stress analysis near the crack tip and calibration curve for modified compact tension test are introduced. The calibration curve is introduced for diameter 150 mm (the specimen could be easy made from the specimen for compression test) and includes all theoretical imperfections that results from preparation of the MCT specimens.
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