“…At an axial load of 25%P max , as shown in Figure 4, a slight strain concentration becomes noticeable around the initial crack tip, with the maximum strain values between 2.0-4.0 Â 10 À4 . Based on a tensile strength of 5.39 MPa and an elastic modulus of 18.14 GPa reported for specimens at 400 C, 45 the critical strain value for tensile failure is calculated to be 3.07 Â 10 À4 . This indicates that at 25%P max axial load, the specimen is at the critical point of crack initiation.…”
Section: Load-cmod Curves and Crack Propagation Processmentioning
confidence: 99%
“…59 Nevertheless, the impact of boundary effect is believed to decrease with increasing specimen size, and for large-scale specimens, a constant crack resistance will be achieved after the full development of the FPZ. 45,49…”
Section: Crack Resistance Curvementioning
confidence: 99%
“…To date, the modified LEFM models, such as the two-parameter model, 38 effective fracture model, 39 and double-K fracture model, 40 have been applied to analyze the fracture behavior of rock after high temperature, [41][42][43][44][45] but these studies mainly concentrate on the pure mode I loading. Cracks are randomly distributed in the rock matrix, and therefore, most cracks in rock structures are under mixed mode loading instead of pure mode I loading.…”
To investigate the effects of thermal treatment and loading conditions on the crack initiation and propagation characteristics of quartz‐diorite, mixed mode I + II fracture tests were conducted by using three‐point bending (TPB) specimens. The numerical model, established on ABAQUS, couples the initial fracture toughness criterion and cohesive zone model to predict the crack initiation and propagation. The effects of thermal treatment and loading conditions on the crack propagation process, crack resistance curve, fracture path, and some fracture parameters at peak load have been analyzed and discussed. The results demonstrate that the thermal treatment has an obvious influence on the crack resistance curve of the specimen. The crack of the specimen will be dominated by the mode I fracture component with crack extension. The numerical results also show that the temperature and loading condition affect the crack length and fracture toughness at peak load.
“…At an axial load of 25%P max , as shown in Figure 4, a slight strain concentration becomes noticeable around the initial crack tip, with the maximum strain values between 2.0-4.0 Â 10 À4 . Based on a tensile strength of 5.39 MPa and an elastic modulus of 18.14 GPa reported for specimens at 400 C, 45 the critical strain value for tensile failure is calculated to be 3.07 Â 10 À4 . This indicates that at 25%P max axial load, the specimen is at the critical point of crack initiation.…”
Section: Load-cmod Curves and Crack Propagation Processmentioning
confidence: 99%
“…59 Nevertheless, the impact of boundary effect is believed to decrease with increasing specimen size, and for large-scale specimens, a constant crack resistance will be achieved after the full development of the FPZ. 45,49…”
Section: Crack Resistance Curvementioning
confidence: 99%
“…To date, the modified LEFM models, such as the two-parameter model, 38 effective fracture model, 39 and double-K fracture model, 40 have been applied to analyze the fracture behavior of rock after high temperature, [41][42][43][44][45] but these studies mainly concentrate on the pure mode I loading. Cracks are randomly distributed in the rock matrix, and therefore, most cracks in rock structures are under mixed mode loading instead of pure mode I loading.…”
To investigate the effects of thermal treatment and loading conditions on the crack initiation and propagation characteristics of quartz‐diorite, mixed mode I + II fracture tests were conducted by using three‐point bending (TPB) specimens. The numerical model, established on ABAQUS, couples the initial fracture toughness criterion and cohesive zone model to predict the crack initiation and propagation. The effects of thermal treatment and loading conditions on the crack propagation process, crack resistance curve, fracture path, and some fracture parameters at peak load have been analyzed and discussed. The results demonstrate that the thermal treatment has an obvious influence on the crack resistance curve of the specimen. The crack of the specimen will be dominated by the mode I fracture component with crack extension. The numerical results also show that the temperature and loading condition affect the crack length and fracture toughness at peak load.
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