#LAST HORIZON CRACK CRACK#
Thus, we can model the temperature-dependent crack propagation. A coupled thermo-mechanical peridynamics approach is adopted to simulate ice crack propagation, and a key component of this approach is adopted the temperature-dependent critical stretch. To develop an inhomogeneous ice model, we treat the critical stretch of inhomogeneous ice material as a random variable that obeys the Weibull distribution. In this work, we adopt a peridynamics approach to develop an inhomogeneous sea ice model and applied it to simulate crack propagation in a thermo-mechanical field of ice sheet. It is challenging to build a physically accurate sea ice model, which is highly sensitive to temperature and many uncertain factors, such as its nonuniform and inhomogeneous microstructure. The predictions capture the number of cycles to failure as well as the crack propagation paths. Its validity for predicting crack growth is established by simulating compact tension experiments under cyclic loading.
#LAST HORIZON CRACK VERIFICATION#
The verification of the coupled PD-FE approach is demonstrated by comparison against the FE prediction of displacement fields in a plate with and without a hole under tension. The coupling between the MATRIX27 elements and traditional finite elements are achieved through the coupled degrees of freedom (DOF) command available in the ANSYS framework.
The PD interactions are considered in the region of potential failure sites otherwise, traditional finite elements are employed in the discretization of the domain. The PD governing equations are constructed by using MATRIX27 element in the ANSYS framework and solved by employing an implicit method. The PD representation of the equilibrium equations and the stress–strain relations are derived based on the PD least square minimization (PD LSM) method. It specifically leads to the prediction of number of load cycles to crack initiation and its propagation path. This study presents a coupled peridynamics (PD) and finite element (FE) approach to simulate the process of failure due to cyclic loading based on the kinetic theory of fracture (KTF). The numerical, analytical and experimental results have collectively verified the proposed PD method. The critical failure surfaces of slopes are obtained by PD and compared with the results obtained by (i) the finite element method (FEM), (ii) the simplified Bishop method, and (iii) the centrifuge tests. Two numerical simulations including a classical slope model and centrifuge tests of sand slopes are performed by the proposed PD method. For PD strength reduction method, three evaluation criteria are introduced to estimate the critical damage state of slopes. The strength reduction method is adopted to estimate the critical failure surface and factor of safety. A non-physical (or negative) incremental plastic energy can be avoided under extreme non-uniform deformation in this model. In this paper, two-dimensional ordinary state-based peridynamic (OSB-PD) plastic model is coupled mechanically with the Drucker-Prager (D-P) criterion, aiming at numerically reproducing localized deformation and locating the critical failure surface of slopes. The ultimate failure modes of sandstone in the simulation are in good agreement with the experimental results, indicating the reliability of the proposed model. In addition, a fully coupled thermal–mechanical-damage constitutive model is established to predict the failure process of rocks. The uniaxial compression test of sandstone after thermal treatment is a two-stage damage process, and this process is completely simulated in COMSOL.
Subsequently, a Knuth–Durstenfeld shuffle algorithm is introduced to characterize the heterogeneity of rocks considering mineral composition, and this algorithm is verified to better reveal the thermal damage of rocks. As the temperature increases, the failure behavior of sandstone transforms from brittle to ductile. Poisson's ratio has a sudden change between 400 and 600 ☌, and this change can be attributed to the phase transition of quartz at 573 ☌. The experimental results indicate that 400 ☌ is a threshold, and the temperatures of less than 400 ☌ have little effect on the physical and mechanical properties of sandstone.
In this article, the physical and mechanical properties of sandstone after thermal treatment from 25 to 800 ☌ are investigated by laboratory tests. During oil and gas exploitation in tight sandstone reservoirs, the influence of temperature on the physical and mechanical properties of sandstone cannot be ignored, which is of great significance to the formulation of oil and gas exploitation techniques and the accurate evaluation of recovery.