The Experts below are selected from a list of 126231 Experts worldwide ranked by ideXlab platform
Roman Y Makhnenko - One of the best experts on this subject based on the ideXlab platform.
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brittle Failure of rock a review and general linear criterion
Journal of Structural Geology, 2018Co-Authors: Joseph F Labuz, Feitao Zeng, Roman Y Makhnenko, Yuan LiAbstract:Abstract A Failure criterion typically is phenomenological since few models exist to theoretically derive the mathematical function. Indeed, a successful Failure criterion is a generalization of experimental data obtained from strength tests on specimens subjected to known stress states. For isotropic rock that exhibits a pressure dependence on strength, a popular Failure criterion is a linear equation in major and minor principal stresses, independent of the intermediate principal stress. A general linear Failure criterion called Paul-Mohr-Coulomb (PMC) contains all three principal stresses with three material constants: friction angles for axisymmetric compression ϕ c and extension ϕ e and isotropic tensile strength V 0 . PMC provides a framework to describe a nonlinear Failure Surface by a set of planes “hugging” the curved Surface. Brittle Failure of rock is reviewed and multiaxial test methods are summarized. Equations are presented to implement PMC for fitting strength data and determining the three material parameters. A piecewise linear approximation to a nonlinear Failure Surface is illustrated by fitting two planes with six material parameters to form either a 6- to 12-sided pyramid or a 6- to 12- to 6-sided pyramid. The particular nature of the Failure Surface is dictated by the experimental data.
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paul mohr coulomb Failure Surface of rock in the brittle regime
Geophysical Research Letters, 2015Co-Authors: Justice Harvieux, Roman Y Makhnenko, Joseph F LabuzAbstract:The Paul-Mohr-Coulomb Failure criterion includes the intermediate principal stress sigma(II) and friction angles at the limiting stress states of sigma(II)= sigma(III) and sigma(II) = sigma(I), where sigma(I) and sigma(III) are major and minor principal stresses. Conventional triaxial compression (sigma(II) = sigma(III)), extension (sigma(II) = sigma(I)), and plane strain (sigma(I) not equal sigma(II) not equal sigma(III)) experiments were performed on dry rock. The Failure data were plotted in principal stress space, and material parameters were determined in the context of two internal friction angles and the theoretical uniform triaxial (all-around equal) tensile strength. Assuming isotropy, the triaxial compression and extension results were used to construct a six-sided pyramidal Failure Surface, and the extension friction angle was larger than the compression friction angle, a sufficient but not necessary condition of the intermediate stress effect. To capture the behavior of the rock in multiaxial loading, the Paul-Mohr-Coulomb criterion was extended to form a 12-sided pyramid with best fit planes.
Erxiang Song - One of the best experts on this subject based on the ideXlab platform.
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active earth pressure analysis based on normal stress distribution function along Failure Surface in soil obeying nonlinear Failure criterion
Acta Geotechnica, 2016Co-Authors: Yujin Sun, Erxiang SongAbstract:In this paper, the normal stress distribution function along the Failure Surface in soil obeying general nonlinear Failure criterion is first derived, and then a method for calculating the static and seismic active earth pressure for soils obeying nonlinear Failure criteria is proposed. The method proposed yields not only the active earth pressure and its action point, but also the Failure Surface and the stress distribution along it. Results of the calculated examples by the proposed method are more reasonable than those reported in the literature. The influence of the parameters of the nonlinear Failure criterion on the active earth pressures is also investigated.
Joseph F Labuz - One of the best experts on this subject based on the ideXlab platform.
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brittle Failure of rock a review and general linear criterion
Journal of Structural Geology, 2018Co-Authors: Joseph F Labuz, Feitao Zeng, Roman Y Makhnenko, Yuan LiAbstract:Abstract A Failure criterion typically is phenomenological since few models exist to theoretically derive the mathematical function. Indeed, a successful Failure criterion is a generalization of experimental data obtained from strength tests on specimens subjected to known stress states. For isotropic rock that exhibits a pressure dependence on strength, a popular Failure criterion is a linear equation in major and minor principal stresses, independent of the intermediate principal stress. A general linear Failure criterion called Paul-Mohr-Coulomb (PMC) contains all three principal stresses with three material constants: friction angles for axisymmetric compression ϕ c and extension ϕ e and isotropic tensile strength V 0 . PMC provides a framework to describe a nonlinear Failure Surface by a set of planes “hugging” the curved Surface. Brittle Failure of rock is reviewed and multiaxial test methods are summarized. Equations are presented to implement PMC for fitting strength data and determining the three material parameters. A piecewise linear approximation to a nonlinear Failure Surface is illustrated by fitting two planes with six material parameters to form either a 6- to 12-sided pyramid or a 6- to 12- to 6-sided pyramid. The particular nature of the Failure Surface is dictated by the experimental data.
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paul mohr coulomb Failure Surface of rock in the brittle regime
Geophysical Research Letters, 2015Co-Authors: Justice Harvieux, Roman Y Makhnenko, Joseph F LabuzAbstract:The Paul-Mohr-Coulomb Failure criterion includes the intermediate principal stress sigma(II) and friction angles at the limiting stress states of sigma(II)= sigma(III) and sigma(II) = sigma(I), where sigma(I) and sigma(III) are major and minor principal stresses. Conventional triaxial compression (sigma(II) = sigma(III)), extension (sigma(II) = sigma(I)), and plane strain (sigma(I) not equal sigma(II) not equal sigma(III)) experiments were performed on dry rock. The Failure data were plotted in principal stress space, and material parameters were determined in the context of two internal friction angles and the theoretical uniform triaxial (all-around equal) tensile strength. Assuming isotropy, the triaxial compression and extension results were used to construct a six-sided pyramidal Failure Surface, and the extension friction angle was larger than the compression friction angle, a sufficient but not necessary condition of the intermediate stress effect. To capture the behavior of the rock in multiaxial loading, the Paul-Mohr-Coulomb criterion was extended to form a 12-sided pyramid with best fit planes.
Laura M. Caldeira - One of the best experts on this subject based on the ideXlab platform.
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Limit Equilibrium Analyses for Internal Design of Geosynthetic Reinforced Slopes: Influence of Potential Failure Surface and Strength Distribution
Geotechnical and Geological Engineering, 2013Co-Authors: Castorina Silva Vieira, Maria De Lurdes Lopes, Laura M. CaldeiraAbstract:The paper presents results from a computer code, based on limit equilibrium analyses, able to quantify earth pressure coefficients for the internal design of geosynthetic reinforced soil structures and identify the potential Failure Surfaces. Failure mechanisms assuming bilinear or logarithmic spiral Failure Surfaces are considered. The influence of the potential Failure Surface and geosynthetic strength distribution on the earth pressure coefficient is analysed. Required reinforcement tensile strengths calculated by the developed program are compared with values published in the literature. To further evaluate the capabilities of limit equilibrium analyses, the numerical modelling of a geosynthetic reinforced steep slope, designed at ultimate limit state conditions (FS = 1), is also presented. Good agreement was achieved between the potential Failure Surfaces predicted by limit equilibrium analyses and those obtained with numerical modelling.
A R Azami - One of the best experts on this subject based on the ideXlab platform.
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Reproducing Kernel Particle Method in Plasticity of Pressure-Sensitive Material with Reference to Powder Forming Process
Computational Mechanics, 2007Co-Authors: Amir R. Khoei, Mansooreh Samimi, A R AzamiAbstract:In this paper, an application of the reproducing kernel particle method (RKPM) is presented in plasticity behavior of pressure-sensitive material. The RKPM technique is implemented in large deformation analysis of powder compaction process. The RKPM shape function and its derivatives are constructed by imposing the consistency conditions. The essential boundary conditions are enforced by the use of the penalty approach. The support of the RKPM shape function covers the same set of particles during powder compaction, hence no instability is encountered in the large deformation computation. A double-Surface plasticity model is developed in numerical simulation of pressure-sensitive material. The plasticity model includes a Failure Surface and an elliptical cap, which closes the open space between the Failure Surface and hydrostatic axis. The moving cap expands in the stress space according to a specified hardening rule. The cap model is presented within the framework of large deformation RKPM analysis in order to predict the non-uniform relative density distribution during powder die pressing. Numerical computations are performed to demonstrate the applicability of the algorithm in modeling of powder forming processes and the results are compared to those obtained from finite element simulation to demonstrate the accuracy of the proposed model.
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extended finite element method in plasticity forming of powder compaction with contact friction
International Journal of Solids and Structures, 2006Co-Authors: Amir R. Khoei, Amir Shamloo, A R AzamiAbstract:In this paper, a new computational technique is presented based on the eXtended Finite Element Method (X-FEM) in pressure-sensitive plasticity of powder compaction considering frictional contact. In X-FEM, the need for mesh adaption to discontinuity interface is neglected and the process is accomplished by partitioning the domain with some triangular sub-elements whose Gauss points are used for integration of the domain of the elements. The technique is applied by employing additional functions, which are added to approximate the displacement field of the elements located on the interface. The double-Surface cap plasticity model is employed within the X-FEM framework in numerical simulation of powder material. The plasticity model includes a Failure Surface and an elliptical cap, which closes the open space between the Failure Surface and hydrostatic axis. The moving cap expands in the stress space according to a specified hardening rule. The frictional behavior of contact between two bodies is modeled by using the X-FEM technique and applying the Heaviside enrichment function. The application of X-FEM technique in simulation of pressure-sensitive material is presented in an incremental manner and the role of sub-elements in simulation of contact treatment is demonstrated. Finally, several numerical examples are analyzed with special reference to plasticity forming of powder compaction.
