Article
Engineering, Multidisciplinary
Daobing Wang, Fang Shi, Hao Qin, Dongliang Sun, Bo Yu
Summary: In this study, the mechanics of hydraulic fractures related to naturally cemented fractures were investigated using XFEM with junction enrichment functions. The study revealed that the failure mode may change after crossing an NF and switch back when kinking towards the matrix. The analysis discussed failure patterns and key factors in detail.
CMES-COMPUTER MODELING IN ENGINEERING & SCIENCES
(2021)
Article
Engineering, Mechanical
Vinh T. Le, Ha H. Bui, Giang D. Nguyen, Jayantha Kodikara, Didier Bodin, James Grenfell
Summary: This paper presents a constitutive model that considers the strain discontinuity across fracture planes and describes the fatigue behavior in cemented materials. The model effectively captures the significant influence of stress amplitudes on the fatigue lives of materials, making it an essential tool for predicting and mitigating fatigue-induced damage.
INTERNATIONAL JOURNAL OF FATIGUE
(2023)
Article
Engineering, Geological
Michal Wrobel, Panos Papanastasiou, Daniel Peck
Summary: In this paper, an efficient algorithm for the numerical simulation of hydraulic fractures in the plain strain model is proposed. The algorithm uses a finite element method subroutine to compute the deformation of the fractured material and models the flow of a generalized Newtonian fluid in the fracture using lubrication theory. The computational scheme has a relatively simple architecture, allowing for the analysis of complex cases of fractured material properties and configurations as well as various rheological models of fluid.
INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS
(2022)
Article
Energy & Fuels
Tianwei Sun, Qingdong Zeng, Huilin Xing
Summary: A quantitative model is proposed to predict hydraulic fracture propagating across cemented natural fracture, with influencing factors identified and a regression equation accuracy above 99%. Logistic regression method is employed to establish the quantitative relationship between crossing result and factors, with potential applications in fracture network propagation modeling and injection rate optimization in the real field.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2022)
Article
Computer Science, Interdisciplinary Applications
A. R. Khoei, S. M. S. Mortazavi, L. Simoni, B. A. Schrefler
Summary: There is evidence that fracture advancement in porous media can be smooth or stepwise, with pressure oscillations in saturated porous materials. The behavior is influenced by problem specifications and material properties, and not all numerical models can capture stepwise behavior. Cohesive models can model this behavior by satisfying a consistency condition for the numerical solution. Inhomogeneous media can exhibit irregular results in hydraulic fracturing, but the study shows that homogeneous media can also show such behavior. The extent of irregularity depends on the dynamic effects in the problem, and fracture forerunning contributes to stepwise fracture growth.
COMPUTERS AND GEOTECHNICS
(2023)
Article
Computer Science, Interdisciplinary Applications
Mohammad Ali Iranmanesh, Ali Pak
Summary: In this paper, a fully coupled 3D numerical simulation of hydraulic fracture propagation in saturated deformable porous media is developed using the extrinsically enriched element free Galerkin (EFG) method. Weak and strong discontinuities are simulated using the Ridge and Heaviside enrichment functions, respectively. The cohesive crack model is used to describe the nonlinear fracture processes and the fluid flow within the fracture is modeled using Darcy's law. The developed numerical framework is verified through analytical solutions and parametric studies, showing its successful simulation of various aspects of hydraulic fracturing treatment.
COMPUTATIONAL GEOSCIENCES
(2023)
Article
Physics, Multidisciplinary
Xiaotian Song, Hongyan Liu, Xiuhua Zheng
Summary: Natural fractures in reservoirs have a significant impact on hydraulic fracturing propagation. This study establishes a fractured reservoir model using ABAQUS to consider the effect of crack deformation parameters on hydraulic fracturing. The results show that hydraulic fracture initiation pressure is influenced by horizontal stress difference, crack bonding strength, injection rate, and fracturing-fluid viscosity.
FRONTIERS IN PHYSICS
(2023)
Article
Engineering, Geological
Xun Xi, Zoe K. Shipton, Jackie E. Kendrick, Andrew Fraser-Harris, Julien Mouli-Castillo, Katriona Edlmann, Christopher McDermott, Shangtong Yang
Summary: The interaction between hydraulic fractures (HF) and natural fractures (NF) during hydraulic fracturing process has a significant impact on fluid flow, proppant transport, and well productivity. This paper presents a new fracture model to investigate the near-wellbore interaction and validates the model through numerical simulations. The results show that high injection pressure tends to drive HF to cross NF located close to the wellbore, while low injection flow rate can help activate natural fractures near the wellbore.
ROCK MECHANICS AND ROCK ENGINEERING
(2022)
Article
Engineering, Geological
Xun Xi, Shangtong Yang, Christopher I. McDermott, Zoe K. Shipton, Andrew Fraser-Harris, Katriona Edlmann
Summary: Soft cyclic hydraulic fracturing is an effective technology for subsurface energy extraction, inducing rock fatigue to reduce breakdown pressure and seismic risk. A numerical method is developed to model rock fracture induced by hydraulic pulses with consideration of rock fatigue. Experimental results validate the developed numerical model, showing that hydraulic pulses can reduce rock breakdown pressure by 10-18% upon 10-4000 cycles.
ROCK MECHANICS AND ROCK ENGINEERING
(2021)
Article
Engineering, Multidisciplinary
Toshio Nagashima, Chenyu Wang
Summary: In this study, a two-dimensional four-node quadrilateral element enriched with the Heaviside step function is proposed for crack analyses within the extended finite element method framework. The crack geometry is implicitly expressed using two types of signed distance functions, and finite elements interacting with the crack are appropriately partitioned based on level set values. The stiffness matrix and internal force vectors are derived through numerical integration. The proposed method is validated by evaluating stress intensity factors, analyzing crack propagation, and comparing results with reference solutions.
INTERNATIONAL JOURNAL OF COMPUTATIONAL METHODS
(2022)
Article
Energy & Fuels
Xiao Guo, Zihao Yu
Summary: In this article, the expansion law of hydraulic fractures in coal seams was studied through hydraulic fracturing experiments and numerical simulations. The results indicate that (1) high minimum horizontal stress difference in coal seams with undeveloped laminae confined the fractures within the coal reservoir, affecting multilayer fracturing. The high elastic modulus of the spacer facilitated vertical fracture expansion. Critical displacement played a vital role in vertical fracture breakthrough. Fracturing fluid concentration correlated with fracture height and inversely proportional to fracture length. (2) During the development of natural laminae in coal, fracture pressure decreased significantly. Fractures preferred to expand along the direction of laminae with a smaller angle to the maximum horizontal principal stress. When the adhesive strength of the interface was high, fractures passed directly through the interface to form vertical fractures. When interfacial cementation strength was low, cracks extended along the interface, turned to produce new vertical cracks, and eventually formed Z cracks.
PETROLEUM SCIENCE AND TECHNOLOGY
(2023)
Article
Mechanics
Long-Fei Wang, Xiao-Ping Zhou
Summary: The FE-FEM method simulates stress intensity factors (SIFs) and crack propagation paths in FGMs by using a fracture criterion and enriched field variables on nodes, avoiding the need for remeshing, level set function, and enrichment function. The method provides a simple and effective way to calibrate SIFs and simulate crack propagation in FGMs.
ENGINEERING FRACTURE MECHANICS
(2021)
Article
Mechanics
Zhi-Ming Jia, Xiao-Ping Zhou
Summary: A field-enriched finite element method is proposed to simulate the cracking behaviors of brittle solids containing cracks of complex geometries. Three different coalescence types are considered, and a predictor-and-corrector algorithm is developed to solve the problem of competing crack growth. The proposed method is validated and successfully used to simulate the evolution of complex cracks.
ENGINEERING FRACTURE MECHANICS
(2022)
Article
Engineering, Geological
Alireza Mokhtari Varnosfaderani, Ehsan Motevali Haghighi, Behrouz Gatmiri, SeonHong Na
Summary: This study presents a novel approach using the time sub-stepping method to simulate hydraulic fracture propagation in variably saturated porous media. The proposed model, based on mixture theory and two independent variables, successfully describes the behavior of intact porous media. The model is validated and shown to be robust through solving three examples.
Article
Energy & Fuels
Zhifeng Luo, Long Cheng, Liqiang Zhao, Yaozeng Xie
Summary: This study investigates the impact of thermo-poroelastic deformation on the activation of natural cracks during hydraulic fracturing. A thermo-hydro-mechanical coupled model is developed and validated against analytical models. Numerical results show that geomechanical parameters are the key factors affecting the interaction pattern between hydraulic fracture and natural cracks.
JOURNAL OF NATURAL GAS SCIENCE AND ENGINEERING
(2022)
Article
Engineering, Chemical
A. R. Khoei, A. Rezaei Sameti, H. Mofatteh
Article
Engineering, Multidisciplinary
A. R. Khoei, S. Saeedmonir
Summary: This paper develops a computational modeling tool for fully coupled multiphase flow in deformable heterogeneous porous medium using the computational homogenization approach. It employs first-order homogenization technique to perform multi-scale analysis and defines proper energy types to link micro- and macro-scales. The finite element squared strategy is utilized to resolve the two scales simultaneously, and the effects of various parameters on the model are investigated through numerical examples.
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
(2021)
Article
Engineering, Multidisciplinary
Amir R. Khoei, Danial Amini, S. Mohammad S. Mortazavi
Summary: In this article, a computational model is introduced for analyzing coupled thermo-hydro-mechanical processes with phase change in fractured porous media. The model uses the extended finite element method to simulate multiphase fluid flows, heat transfer, and discontinuous deformation. By solving numerical examples, the study demonstrates the robustness of the proposed computational model and investigates the impact of crack orientation, intrinsic permeability, and elastic modulus on fluid flow patterns, relative humidity, and temperature distribution. Additionally, edge-crack propagation under mode I fracture due to drying conditions is also examined.
INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING
(2021)
Article
Engineering, Chemical
N. Hosseini, A. R. Khoei
Summary: The cubic law is commonly used to predict fluid velocity within fractures, but for fractured porous media, the velocity profile inside the fracture can be affected by interface conditions between the fracture and porous matrix. This paper introduces a correction factor to the flow equation along the fracture and considers various non-dimensional numbers to determine the mean velocity inside the fracture.
TRANSPORT IN POROUS MEDIA
(2021)
Article
Mathematics, Applied
R. Yasbolaghi, A. R. Khoei
Summary: A novel coupling technique is developed for continuum-atomistic multi-scale analysis of temperature field problems, introducing a new thermostat based on the single-atom sub-system. The capability of controlling temperature and producing the canonical ensemble is investigated, and the performance of the proposed thermostat is verified by comparing velocity distributions. The coupling continuum-atomistic model is demonstrated through numerical examples and applied in lattice heat conduction simulations in two-dimensional phononic nano-structures.
FINITE ELEMENTS IN ANALYSIS AND DESIGN
(2022)
Article
Engineering, Geological
S. Mohammad S. Mortazavi, Pouriya Pirmoradi, Amir R. Khoei
Summary: This paper presents a computational technique for isothermal and non-isothermal water injection into naturally fractured oil reservoirs. The study quantifies the effectiveness of hot water injection over cold water injection in oil production, and discusses the impact of long and short fractures on oil recovery. The proposed computational model shows promise for use in cold or hot water injection and in economic feasibility studies of recovery methods.
INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS
(2022)
Article
Engineering, Multidisciplinary
Saeed Saeedmonir, Amir R. Khoei
Summary: This paper presents a numerical multiscale formulation for analyzing transient heat and fluid flow in deformable heterogeneous porous media. The proposed method uses first-order computational homogenization to simulate THM problems at two scales, providing an efficient computational procedure. Proper virtual power relations bridge the scales, and microscopic boundary conditions are enhanced to consider transient effects. Macroscopic properties are determined from the microscopic solution using appropriate mathematical procedures. An upwind finite element squared method is employed for accurate spatial results in highly advective heat transfer.
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
(2022)
Article
Materials Science, Multidisciplinary
Amir R. Khoei, Mehrdad Youzi, G. Tolooei Eshlaghi
Summary: The aim of this study was to investigate the role of temperature, stress, and rhenium (Re) on the gamma/gamma' interfacial misfit dislocation network and mechanical response of Ni-based single crystal superalloys. The results showed that increasing temperature dispersed the atomic potential energy at the interface, diminishing the strength and stability of the networks. Loading resulted in dislocation propagation as the dominant deformation mechanism. Additionally, the study evaluated the effect of Re atoms, finding that they hindered dislocations in the gamma phase. The investigation also revealed that increased temperature led to escalated damage to the interfacial network and the domination of softening mechanisms on deformation.
MECHANICS OF MATERIALS
(2022)
Article
Engineering, Multidisciplinary
A. Rezaei Sameti, A. R. Khoei
Summary: This paper presents the development of an atomistic-continuum homogenization multiscale method to study the nonlinear behavior of heterogeneous nanomaterials. The method combines atomistic and coarse-scale modeling to analyze the impact of nanoscale material defects on the macroscopic behavior. Statistical procedures are applied to investigate the influence of influential parameters.
APPLIED MATHEMATICAL MODELLING
(2022)
Article
Engineering, Chemical
A. R. Khoei, R. Ehsani, N. Hosseini
Summary: This paper develops a numerical model for assessing carbon dioxide transport through naturally fractured cap-rocks during CO2 sequestration. The model considers micro-cracks and macro-cracks, and incorporates their effects using implicit and explicit methods. The flow of water and CO2 within the fractured porous medium is governed by Darcy law and Poiseuille flow, and mass conservation law is fulfilled through integral formulation. The X-FEM technique is applied to model the explicit representation of macro-cracks. The effects of cracks' aperture, orientation, temperature, and injection depth are investigated through numerical examples.
TRANSPORT IN POROUS MEDIA
(2022)
Article
Chemistry, Multidisciplinary
G. Tolooei Eshlaghi, Amir R. R. Khoei
Summary: This research uses molecular dynamics simulations to study the atomistic phenomena causing anisotropy and orientation dependence of mechanical characteristics and creep deformation in Ni(gamma)/Ni3Al(gamma') superalloys. The findings show that dislocations and elevated-temperature diffusional processes play important roles in creep at tiny scales. Various deformation processes are observed in each orientation model, such as dislocation accumulation, shearing of gamma' precipitates, micro-twinning, and dislocation climbing through diffusion.
JOURNAL OF NANOPARTICLE RESEARCH
(2023)
Article
Water Resources
A. R. Khoei, S. M. Mousavi, N. Hosseini
Summary: This paper presents a numerical model for simulating density-driven flow in heterogeneous porous media with micro- and macro-fractures. The model takes into account the influence of both micro- and macro-fractures on solute spread. It is found that micro-fracture aperture has a significant and predictable effect on solute spread in the absence of macro-fractures. However, the presence of macro-fractures creates a vacuum-like region that diminishes the influence of nearby micro-fractures.
ADVANCES IN WATER RESOURCES
(2023)
Article
Multidisciplinary Sciences
A. R. Khoei, S. Saeedmonir, N. Hosseini, S. M. Mousavi
Summary: This paper presents a computational model for solute transport in fractured porous media using the extended finite element method. The model takes into account the presence of fractures and accurately predicts the transport behavior. Numerical simulations of traditional problems and fractured problems demonstrate the accuracy and versatility of the proposed computational model.
Article
Mechanics
Amir R. Khoei, Tahmaz Ahmadpour, Yousef Navidtehrani
Summary: In this paper, an enriched-FEM method based on X-FEM technique is proposed to investigate the effect of FRP strengthening on concrete arch using a damage-plasticity model. The accuracy of the proposed plastic-damage model and cohesive fracture model is validated under different loading conditions and compared with experimental data. A parametric study is also conducted to evaluate the effects of high to span ratio, longitudinal reinforcement ratio, and strengthening method on the behavior of reinforced concrete arches.
EUROPEAN JOURNAL OF COMPUTATIONAL MECHANICS
(2021)
Article
Materials Science, Multidisciplinary
H. Ahmadi, M. Jahanshahi, A. R. Khoei, S. Bordas
Summary: This paper presents a multi-scale technique to study the mechanical behavior of nano-composites by linking atomistic information from lower scale to continuum model in upper scale. Molecular dynamics simulations are used to compute material properties, while hyperelastic strain energy functions are utilized on the continuum level to calculate material parameters and stress and elasticity tensors. The proposed technique is shown to efficiently solve large problems within acceptable computational time, demonstrating its superiority over conventional molecular dynamics approaches.
Article
Mechanics
Xiaolong Liu, Kelian Luo, Pengcheng Gao, Tao Cong, Xi Wang, Wenjing Wang
Summary: This paper investigates the formation mechanisms of the zig-zag crack region on the shattered rim of railway wheels. The zig-zag crack region, identified as a typical region for crack propagation in rolling contact fatigue behavior, was observed using scanning electron microscopy and transmission electron microscopy. The formation of the zig-zag morphology is attributed to the periodic deflection of the propagation path relative to the initial propagation plane, caused by the limited plastic deformation zone at the crack tip. Grain refinement and secondary cracks in the zig-zag crack region are a result of the large compressive and shear stresses induced by rolling contact loading.
ENGINEERING FRACTURE MECHANICS
(2024)
Article
Mechanics
Anastasia Iziumova, Aleksei Vshivkov, Ivan Panteleev, Virginia Mubassarova, Oleg Plekhov, Denis Davydov
Summary: The aim of this study was to investigate the correlation between structural, acoustic emission, and thermal characteristics of fatigue crack growth in titanium alloys. Cluster analysis of the acoustic emission signals revealed two different types of signals observed during the fatigue crack development. It was experimentally demonstrated that the stored energy tends to reach an asymptotic value at the final stage of fatigue crack growth and this is correlated with the twinning process intensification in titanium alloy Ti Grade 2. A correlation was assumed between the stages of change in heat flux, the cumulative energy of the first cluster of acoustic emission signals, and the crack length.
ENGINEERING FRACTURE MECHANICS
(2024)
Article
Mechanics
M. Vieira de Carvalho, I. A. Rodrigues Lopes, F. M. Andrade Pires
Summary: This study investigates the numerical challenges of fracture mechanics models within implicit quasi-static frameworks and proposes an instability criterion. The ratio of cohesive to internal power is identified as a crucial factor. Two strategies for handling fracture problems with instabilities are discussed and a comparative assessment is performed. The study also examines more complex material responses, including transformation-induced plasticity effects.
ENGINEERING FRACTURE MECHANICS
(2024)
Article
Mechanics
Thomas Duminy, Aurelien Doitrand, Sylvain Meille
Summary: This study conducted in situ wedge splitting tests on millimeter-size PMMA samples and proposed a method to determine the material tensile strength and critical energy release rate using digital image correlation and a full finite element implementation of the coupled criterion.
ENGINEERING FRACTURE MECHANICS
(2024)
Article
Mechanics
Xin Chang, Xingyi Wang, Chunhe Yang, Yintong Guo, Yanghui Wan
Summary: The influence of cyclic thermal shock and high-temperature acid etching on the Mode I fracture of shale was investigated in this study. It was found that cyclic thermal shock severely degrades the strength and fracture toughness of shale, while high-temperature acid etching treatment improves the fracture toughness. These findings are valuable for optimizing process parameters to reduce initiation pressure in deep shale formations.
ENGINEERING FRACTURE MECHANICS
(2024)
Article
Mechanics
Liaojun Yao, Mingyue Chuai, Zhangming Lyu, Xiangming Chen, Licheng Guo, R. C. Alderliesten
Summary: Methods based on fracture mechanics have been widely used in fatigue delamination growth (FDG) characterization of composite laminates. This study proposes appropriate similitude parameters to represent FDG behavior with different R-ratios.
ENGINEERING FRACTURE MECHANICS
(2024)
Article
Mechanics
Zesheng Zang, Zhonghui Li, Yue Niu, Shan Yin
Summary: This study conducted experiments and recorded signals to investigate the fracture behavior and damage evolution characteristics of coal samples. The results showed that as loading proceeds, the stress, electric potential (EP), and acoustic emission (AE) values increase, and EP and AE signals are excited when stress drops. The fracture behavior of coal samples is altered by flaw inclination, and the destruction mode becomes increasingly complicated. The damage evolution characteristics of coal samples can be evaluated and analyzed by defining the coefficient of variation (CV value) of EP and the b value of AE.
ENGINEERING FRACTURE MECHANICS
(2024)
Article
Mechanics
Clotilde Berdin, Nathalie Prud'homme
Summary: In this study, zirconia layers with different fractions of tetragonal phase and thicknesses were tested for multi-cracking behavior. Cracks perpendicular to the tensile direction were observed, showing a blunting effect into the substrate. The ratio of crack spacing at saturation to layer thickness decreased as the layer thickness increased. Unit cell modeling was used to establish a relationship between crack spacing and layer strength, which fell within the bounds of Hu and Evans model and was found to be insensitive to the tetragonal zirconia fraction.
ENGINEERING FRACTURE MECHANICS
(2024)
Article
Mechanics
Huadong Zhang, Weichen Kong, Y. H. Liu, Yuh J. Chao
Summary: Williams' series expansion crack tip solution in linear elasticity is modified to include a uniform crack face pressure. Practical methods to calculate T-stress from near crack tip stresses are outlined. The analytical results are consistent with numerical results.
ENGINEERING FRACTURE MECHANICS
(2024)
Article
Mechanics
Jiahao Kong, Haoyue Han, Tao Wang, Guangyan Huang, Zhuo Zhuang
Summary: This paper introduces a phase-field model for polymer foam materials by combining the phase-field method with the crushable foam model. The model is calibrated using experimental data and successfully simulates the fracture processes of polyurethane under different loading conditions. The study is important for the engineering applications of polymer foam materials.
ENGINEERING FRACTURE MECHANICS
(2024)
