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| 1 | Cracks coalescence mechanism and cracks propagation paths in rock-like specimens containing pre-existing random cracks under compression显示文摘The mechanism of cracks propagation and cracks coalescence due to compressive loading of the brittle substances containing pre-existing cracks(flaws)was modeled experimentally using specially made rock-like specimens from Portland Pozzolana Cement(PPC).The breakage process of the specimens was studied by inserting single and double flaws with different inclination angles at the center and applying uniaxial compressive stress at both ends of the specimen.The first crack was oriented at 50° from the horizontal direction and kept constant throughout the analysis while the orientation of the second crack was changed.It is experimentally observed that the wing cracks are produced at the first stage of loading and start their propagation toward the direction of uniaxial compressive loading.The secondary cracks may also be produced in form of quasi-coplanar and/or oblique cracks in a stable manner.The secondary cracks may eventually continue their propagation in the direction of maximum principle stress.These experimental works were also simulated numerically by a modified higher order displacement discontinuity method and the cracks propagation and cracks coalescence were studied based on Mode I and Mode II stress intensity factors(SIFs).It is concluded that the wing cracks initiation stresses for the specimens change from 11.3 to 14.1 MPa in the case of numerical simulations and from 7.3 to 13.8 MPa in the case of experimental works.It is observed that cracks coalescence stresses change from 21.8 to 25.3 MPa and from 19.5 to 21.8 MPa in the numerical and experimental analyses,respectively.Comparing some of the numerical and experimental results with those recently cited in the literature validates the results obtained by the proposed study.Finally,a numerical simulation was accomplished to study the effect of confining pressure on the crack propagation process,showing that the SIFs increase and the crack initiation angles change in this case. | Hadi Haeri Kourosh Shahriar Mohammad Fatehi Marji Parviz Moarefvand | 2014 | Journal of Central South University2014，21，6： | 16 |
| 2 | Numerical analysis of confinement effect on crack propagation mechanism from a flaw in a pre-cracked rock under compression显示文摘In many situations rocks are subjected to biaxial loading and the failure process is controlled by the lateral confinement stresses. The importance of confinement stresses has been recognized in the literature by many researchers, in particular, its influence on strength and on the angle of fracture, but still there is not a clear description for the influence of confining stress on the crack propagation mechanism of rocks. This paper presents a numerical procedure for the analysis of crack propagation in rock-like materials under compressive biaxial loads. Several numerical simulations of biaxial tests on the rock specimen have been carried out by a bonded particle model (BPM) and the influence of confinement on the mechanism of crack propagation from a single flaw in rock specimens is studied. For this purpose, several biaxial compressive tests on rectangular specimens under different confinement stresses were modeled in (2 dimensional particle flow code) PFC 2D . The results show that wing cracks initiate perpendicular to the flaw and trend toward the direction of major stress, however, when the lateral stresses increase, this initiation angle gets wider. Also it is concluded that in addition to the material type, the initiation direction of the secondary cracks depends on confinement stresses, too. Besides, it is understood that secondary cracks may be produced from both tensile and shear mechanisms. | Amin Manouchehrian Mohammad Fatehi Marji | 2012 | Acta Mechanica Sinica2012，28，5： | 9 |
| 3 | Numerical modelling of stress analysis around rectangular tunnels with large discontinuities(fault) by a hybridized indirect BEM显示文摘Tunnels are one of the major transportation routes to pass mountains and difficult geological conditions. The behavior of these structures is significantly influenced by rock mass and discontinuities. Orientation of discontinuities is one of the most important geometrical parameters affecting discontinuities behavior. The effect of large discontinuities(faults) behavior on a jointed medium around rectangular tunnels is studied. A hybridized indirect boundary element code named TFSDDM(fictitious stress displacement discontinuity method) is used to study the stress distribution around the tunnels excavated in jointed rock masses. The code uses advantages of both fictitious stress and displacement discontinuity methods to analyze discontinuity effects more accurately. Results show that the dip angle of discontinuities has significant effect on stress distribution around the tunnel. It is also shown that increase in the discontinuities dip angle located in the roof will result in decrease in tensile stress of the roof. Stresses reaches to 8 MPa in the roof while due to dilation effect they reach up to 13 MPa. | Nooraddin Nikadat Mohammad Fatehi Abolfazl Abdollahipour | 2015 | Journal of Central South University2015，22，11： | 7 |
| 4 | Synthetic and lignin-based surfactants:Challenges and opportunities显示文摘Surface active agents(surfactants)are chemicals that can accumulate at the surface of a liquid,or interface between two phases with the role of changing the surface tension of the interface.Depending on their structures,they have many applications in industries,such as the petroleum,mining,pulping and textiles,wherein they are utilized as detergents,wetting agents,emulsifiers,foaming agents and dispersants.Most of commonly used surfactants are oil-based chemicals.However,using environmentally friendly feedstocks to produce surfactant is desirable to lessen the environmental impact of surfactant production and use in industry.Lignin is an attractive candidate for this purpose as it is inexpensive and readily available.Lignin and lignin derivatives,such as lignosulfonates,can be chemically modified to produce surfactants with different chemical and physical properties,which makes them suitable for a wide variety of applications.The lignin types and the processes performed for lignin production affect the properties of generated lignin significantly,which in turn influence the reactivity and the efficiency of the reaction for surfactant generation.In this review,the characteristics and applications of oil-based surfactants,and the efforts to produce lignin-based surfactants are reviewed.As oil-based surfactants with altered properties are available in the market,several different pathways can be followed for producing lignin-based surfactants.The advantages and disadvantages of using lignin-based surfactants are also discussed. | Norah Alwadani Pedram Fatehi | 2018 | Carbon Resources Conversion2018，1，2： | 6 |
| 5 | CC chemokines CCL2, CCL3, CCL4 and CCL5 are elevated in osteoporosis patients显示文摘Osteoporosis is defined as a disorder associated withlow bone mineral density (BMD). Evidence indicatesthat the immune system is strongly related to bonemetabolism in terms of osteoimmunology, noticeably,interplay between the skeletal and immune system likecellular and non-cellular components, including innateand adaptive immune responses and cytokines andchemokines. Very few studies are available thatinvestigated the role of chemokines in osteoporosis. | Fatehi Farangis Mollahosseini Majid Hassanshahi Gholamhossein Falahati-pour Soudeh Khanamani Khorramdelazad Hossein Ahmadi Zahra Noroozi Karimabad Mojgan Farahmand Habib | 2017 | The Journal of Biomedical Research2017，31，5： | 5 |
| 6 | Simulation of crack coalescence mechanism underneath single and double disc cutters by higher order displacement discontinuity method显示文摘The present research is focused on the numerical crack coalescence analysis of the micro-cracks and cracks produced during the cutting action of TBM disc cutters. The linear elastic fracture mechanics(LEFM) concepts and the maximum tangential stress criterion are used to investigate the micro crack propagation and its direction underneath the excavating discs. A higher order displacement discontinuity method with quadratic displacement discontinuity elements is used to estimate the stress intensity factors near the crack tips. Rock cutting mechanisms under single and double type discs are simulated by the proposed numerical method.The main purposes of the present modeling are to simulate the chip formation process of indented rocks by single and double discs.The effects of specific disc parameters(except speed) on the thrust force Ft, the rolling force Fr, and the specific energy ES are investigated. It has been shown that the specific energy(energy required to cut through a unit volume of rock) of the double disc is less than that of the single disc. Crack propagation in rocks under disc cutters is numerically modeled and the optimum ratio of disc spacing S to penetration depth Pd(i.e. S/Pd ratio) of about 10 is obtained, which is in good agreement with the theoretical and experimental results cited in the literature. | Mohammad Fatehi Marji | 2015 | Journal of Central South University2015，22，3： | 4 |
| 7 | Experimental and numerical study of crack propagation and coalescence in pre-cracked rock-like disks显示文摘 | Hadi Haeri Kourosh Shahriar Mohammad Fatehi Marji Parviz Moarefvand | 2014 | International Journal of Rock Mechanics and Mining Sciences2014，，： | 2 |
| 8 | Fracture analyses of different pre-holed concrete specimens under compression显示文摘Crack propagation processes in specially prepared concrete discs and rectangular specimens containing a single cylindrical hole or multiple holes of varying diameters have been studied both experimentally and numerically.In this research, the cracks coalescence paths in Brazilian disc and rectangular specimens made from rock-like material containing multi-holes are investigated. These concrete specimens are specially prepared from an appropriate mixture of Portland Pozzolana Cement(PPC), fine sands, and water.The pre-holed Brazilian discs and rectangular specimens are experimentally tested under compression. The breakage load in the ring type disc specimens containing an axial hole with varying diameters is measured and the distribution of the induced lateral stress is obtained. The mechanism of cracks propagation in the wall of the ring type specimens is also studied. In the case of multi-hole Brazilian disc and rectangular specimens, the cracks propagation and cracks coalescence are also investigated. These experiments are numerically modeled by a modified higher order displacement discontinuity method. It has been shown that the corresponding experimental and numerical results are in good agreement with each other. The results presented in this research validate the accuracy and applicability of these crack analyses procedures. | Hadi Haeri Alireza Khaloo Mohammad Fatehi Marji | 2015 | Acta Mechanica Sinica2015，31，6： | 2 |
| 9 | Experimental and Numerical Study of Shear Fracture in Brittle Materials with Interference of Initial Double Cracks显示文摘A simultaneous experimental and numerical study of shear fracture of concrete-like materials is carried out using Brazilian disc specimens with initial double edge cracks and fourpoint bending beam specimens with double edge-notches.The interference effects of two cracks/notches are investigated through varied ligament angles and crack lengths.It is shown that shear fracturing paths change remarkably with the initial ligament angles and crack lengths.The cracked specimens are numerically simulated by an indirect boundary element method.A comparison between the numerical results and the experimental ones shows good agreement. | Hadi Haeri Vahab Sarfarazi Mohammad Fatehi Marji Ahmadreza Hedayat Zheming Zhu | 2016 | Acta Mechanica Solida Sinica2016，29，5： | 2 |
| 10 | DEM simulation of confining pressure effects on crack opening displacement in hydraulic fracturing显示文摘Hydraulic fracture is one of the key methods in well stimulation to increase production of oil and gas.Crack Opening Displacement(COD) is of great importance in this method since it is in direct relation with permeability and production rate.In this paper COD is measured by a distinct element model which has been validated by an exact solution.A comprehensive study has been performed on confining pressure effect on COD which is neglected in the analytical solution.Numerical results showed that confining pressure considerably affects COD.A multi-parameter regression(considering effect of confining pressure,rock mass properties and fluid pressure) was performed on numerical results which resulted in an equation.The proposed equation considers the effect of confining pressure and its results are in good agreement with numerical results. | Abdollahipour Abolfazl Fatehi Marji Mohammad Yarahmadi Bafghi Alireza Gholamnejad Javad | 2016 | International Journal of Mining Science and Technology2016，26，4： | 2 |
| 11 | Estimates of Genetic Parameters for Canadian Holstein Female Reproduction Traits显示文摘 | J. Jamrozik J. Fatehi G.J. Kistemaker L.R. Schaeffer | 2005 | Journal of Dairy Science2005，，6： | 2 |
| 12 | DNA damage in bovine sperm does not block fertilization and early embryonic development but induces apoptosis after the first cleavages显示文摘 | Fatehi A N Bevers M M Schoevers E | 2006 | J Androl2006，27，2： | 1 |
| 13 | The role of nitric oxide and protein kinase C in lipopolysaccharidemediated vascular hyporeactivity显示文摘 | Karimi G Fatehi Z Gholamnejad Z | 2006 | J Pharm Sci2006，9，1： | 1 |
| 14 | Separation of lignocellulosie ma- terials by combined processes of pre-hydrolysis and ethanol extraction 显示文摘 | Liu Z Fatehi P Jahan M S | 2011 | Bioresour Technol2011，102，2： | 1 |
| 15 | Cationic-modified PVA as a dry strength additive for rice straw fibers显示文摘 | Fatehi P Tutus A Xiao H | 2009 | Bioresource Techno ogy2009，，： | 1 |
| 16 | Adsorption characteristics of cationicmodified poly (vinyl alcohol) on cellulose fibers-A qualitative analysis 显示文摘 | Pedram Fatehi Huining Xiao | 2008 | Colloids and Surfaces A: Physicochemieal and Engineering Aspects2008，327，： | 1 |
| 17 | Temperature data analysis for 22 patients with advanced cervical carcinoma treated in Rotterdam using radiotherapy,hyperthermia and chemotherapy:a reference point is needed显示文摘 | Fatehi D Van der Zee J Van der Wal E | 2006 | Int J Hyperthermia2006，22，4： | 1 |
| 18 | Temperature data analysis for 22 patients with advanced cervical carcinoma treated in Rotterdam using radiotherapy, hyperthermia and chemotherapy: a reference point is needed显示文摘 | Fatehi D van der Zee J van der Wal E | 2006 | Int J Hyperthermia2006，22，4： | 1 |
| 19 | Separation of methane nitrogen mixtures by pressure swing adsorption using a carbon molecular sieve 显示文摘 | Fatehi A | 1995 | Gas Separation&Purification1995，31，9： | 1 |
| 20 | A rapid molecular method for differentiating two special forms ( lycopersici and radicis-lycopersici) of Fusarium oxysporum 显示文摘 | Attitalla I H Fatehi J Levenfors J | 2004 | Mycological Research2004，108，07： | 1 |
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