The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Haofei Liu - One of the best experts on this subject based on the ideXlab platform.
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a novel approach for simulation of soil tool interaction based on an arbitrary lagrangian Eulerian Description
Soil & Tillage Research, 2018Co-Authors: L.b. Zhang, Z.x. Cai, Haofei LiuAbstract:Abstract Simulation of soil-tool interaction is a challenging task due to the large deformation of soil around the tool, the unconstrained deformation of the free soil surface and the dynamic soil-tool interaction behavior at the interface. In this paper, a novel approach based on an arbitrary Lagrangian-Eulerian finite element (ALE-FE) formulation is used for simulating the soil-blade interaction. Problems associated with severe mesh distortions in a Lagrangian Description and those associated with deformable material boundaries in an Eulerian Description can be solved by this formulation. By introducing the Eulerian boundaries, the cutting action is simulated as the flow of soil against a stationary blade. No element deletion is needed in ALE-FE method and thus the complete contact surface of soil is retained. The extended Drucker-Prager constitutive law is used to simulate the mechanical behavior of soil. Results indicate that the ALE-FE approach is a useful tool in investigating soil-tool interaction and it is especially suitable for cases where large plastic deformation of soil occurs. Simulations under different cutting conditions demonstrate the robustness and effectiveness of the proposed ALE-FE method. The influences of cutting angle and depth on cutting are also investigated. The failure angle, soil deformation and draft force predicted by ALE-FE model are in good agreement with the published experimental data.
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A novel approach for simulation of soil-tool interaction based on an arbitrary Lagrangian–Eulerian Description
Soil and Tillage Research, 2018Co-Authors: L.b. Zhang, Z.x. Cai, Haofei LiuAbstract:Abstract Simulation of soil-tool interaction is a challenging task due to the large deformation of soil around the tool, the unconstrained deformation of the free soil surface and the dynamic soil-tool interaction behavior at the interface. In this paper, a novel approach based on an arbitrary Lagrangian-Eulerian finite element (ALE-FE) formulation is used for simulating the soil-blade interaction. Problems associated with severe mesh distortions in a Lagrangian Description and those associated with deformable material boundaries in an Eulerian Description can be solved by this formulation. By introducing the Eulerian boundaries, the cutting action is simulated as the flow of soil against a stationary blade. No element deletion is needed in ALE-FE method and thus the complete contact surface of soil is retained. The extended Drucker-Prager constitutive law is used to simulate the mechanical behavior of soil. Results indicate that the ALE-FE approach is a useful tool in investigating soil-tool interaction and it is especially suitable for cases where large plastic deformation of soil occurs. Simulations under different cutting conditions demonstrate the robustness and effectiveness of the proposed ALE-FE method. The influences of cutting angle and depth on cutting are also investigated. The failure angle, soil deformation and draft force predicted by ALE-FE model are in good agreement with the published experimental data.
L.b. Zhang - One of the best experts on this subject based on the ideXlab platform.
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a novel approach for simulation of soil tool interaction based on an arbitrary lagrangian Eulerian Description
Soil & Tillage Research, 2018Co-Authors: L.b. Zhang, Z.x. Cai, Haofei LiuAbstract:Abstract Simulation of soil-tool interaction is a challenging task due to the large deformation of soil around the tool, the unconstrained deformation of the free soil surface and the dynamic soil-tool interaction behavior at the interface. In this paper, a novel approach based on an arbitrary Lagrangian-Eulerian finite element (ALE-FE) formulation is used for simulating the soil-blade interaction. Problems associated with severe mesh distortions in a Lagrangian Description and those associated with deformable material boundaries in an Eulerian Description can be solved by this formulation. By introducing the Eulerian boundaries, the cutting action is simulated as the flow of soil against a stationary blade. No element deletion is needed in ALE-FE method and thus the complete contact surface of soil is retained. The extended Drucker-Prager constitutive law is used to simulate the mechanical behavior of soil. Results indicate that the ALE-FE approach is a useful tool in investigating soil-tool interaction and it is especially suitable for cases where large plastic deformation of soil occurs. Simulations under different cutting conditions demonstrate the robustness and effectiveness of the proposed ALE-FE method. The influences of cutting angle and depth on cutting are also investigated. The failure angle, soil deformation and draft force predicted by ALE-FE model are in good agreement with the published experimental data.
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A novel approach for simulation of soil-tool interaction based on an arbitrary Lagrangian–Eulerian Description
Soil and Tillage Research, 2018Co-Authors: L.b. Zhang, Z.x. Cai, Haofei LiuAbstract:Abstract Simulation of soil-tool interaction is a challenging task due to the large deformation of soil around the tool, the unconstrained deformation of the free soil surface and the dynamic soil-tool interaction behavior at the interface. In this paper, a novel approach based on an arbitrary Lagrangian-Eulerian finite element (ALE-FE) formulation is used for simulating the soil-blade interaction. Problems associated with severe mesh distortions in a Lagrangian Description and those associated with deformable material boundaries in an Eulerian Description can be solved by this formulation. By introducing the Eulerian boundaries, the cutting action is simulated as the flow of soil against a stationary blade. No element deletion is needed in ALE-FE method and thus the complete contact surface of soil is retained. The extended Drucker-Prager constitutive law is used to simulate the mechanical behavior of soil. Results indicate that the ALE-FE approach is a useful tool in investigating soil-tool interaction and it is especially suitable for cases where large plastic deformation of soil occurs. Simulations under different cutting conditions demonstrate the robustness and effectiveness of the proposed ALE-FE method. The influences of cutting angle and depth on cutting are also investigated. The failure angle, soil deformation and draft force predicted by ALE-FE model are in good agreement with the published experimental data.
Anders Ekberg - One of the best experts on this subject based on the ideXlab platform.
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Finite element analysis of transient thermomechanical rolling contact using an efficient arbitrary Lagrangian–Eulerian Description
Computational Mechanics, 2014Co-Authors: Andreas Draganis, Fredrik Larsson, Anders EkbergAbstract:A theoretical and computational framework for the analysis of thermomechanically coupled transient rolling contact, based on an arbitrary Lagrangian–Eulerian (ALE) kinematical Description, is developed. A finite element formulation featuring 2D cylinder–plate rolling contact is implemented. The implementation features penalty-type contact formulations for mechanical and thermal contact. It is noted that the ALE formulation allows for a simplified time Description, a compact computational domain and localized mesh refinement. Numerical simulations considering stationary and transient rolling conditions are presented. Highlighted aspects include the influence of variations in thermal contact conductivity, rolling speed and external mechanical load on the contact interface heat flow. The model is shown to give predictions in qualitative agreement with results in the literature. For the velocity range studied, numerical issues such as spurious numerical dissipation/oscillations in the temperature field are noted to have a prominent influence. These phenomena are addressed using a Streamline-Upwind Petrov–Galerkin stabilization scheme together with a bubble function approach.
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finite element analysis of transient thermomechanical rolling contact using an efficient arbitrary lagrangian Eulerian Description
Computational Mechanics, 2014Co-Authors: Andreas Draganis, Fredrik Larsson, Anders EkbergAbstract:A theoretical and computational framework for the analysis of thermomechanically coupled transient rolling contact, based on an arbitrary Lagrangian---Eulerian (ALE) kinematical Description, is developed. A finite element formulation featuring 2D cylinder---plate rolling contact is implemented. The implementation features penalty-type contact formulations for mechanical and thermal contact. It is noted that the ALE formulation allows for a simplified time Description, a compact computational domain and localized mesh refinement. Numerical simulations considering stationary and transient rolling conditions are presented. Highlighted aspects include the influence of variations in thermal contact conductivity, rolling speed and external mechanical load on the contact interface heat flow. The model is shown to give predictions in qualitative agreement with results in the literature. For the velocity range studied, numerical issues such as spurious numerical dissipation/oscillations in the temperature field are noted to have a prominent influence. These phenomena are addressed using a Streamline-Upwind Petrov---Galerkin stabilization scheme together with a bubble function approach.
Z.x. Cai - One of the best experts on this subject based on the ideXlab platform.
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a novel approach for simulation of soil tool interaction based on an arbitrary lagrangian Eulerian Description
Soil & Tillage Research, 2018Co-Authors: L.b. Zhang, Z.x. Cai, Haofei LiuAbstract:Abstract Simulation of soil-tool interaction is a challenging task due to the large deformation of soil around the tool, the unconstrained deformation of the free soil surface and the dynamic soil-tool interaction behavior at the interface. In this paper, a novel approach based on an arbitrary Lagrangian-Eulerian finite element (ALE-FE) formulation is used for simulating the soil-blade interaction. Problems associated with severe mesh distortions in a Lagrangian Description and those associated with deformable material boundaries in an Eulerian Description can be solved by this formulation. By introducing the Eulerian boundaries, the cutting action is simulated as the flow of soil against a stationary blade. No element deletion is needed in ALE-FE method and thus the complete contact surface of soil is retained. The extended Drucker-Prager constitutive law is used to simulate the mechanical behavior of soil. Results indicate that the ALE-FE approach is a useful tool in investigating soil-tool interaction and it is especially suitable for cases where large plastic deformation of soil occurs. Simulations under different cutting conditions demonstrate the robustness and effectiveness of the proposed ALE-FE method. The influences of cutting angle and depth on cutting are also investigated. The failure angle, soil deformation and draft force predicted by ALE-FE model are in good agreement with the published experimental data.
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A novel approach for simulation of soil-tool interaction based on an arbitrary Lagrangian–Eulerian Description
Soil and Tillage Research, 2018Co-Authors: L.b. Zhang, Z.x. Cai, Haofei LiuAbstract:Abstract Simulation of soil-tool interaction is a challenging task due to the large deformation of soil around the tool, the unconstrained deformation of the free soil surface and the dynamic soil-tool interaction behavior at the interface. In this paper, a novel approach based on an arbitrary Lagrangian-Eulerian finite element (ALE-FE) formulation is used for simulating the soil-blade interaction. Problems associated with severe mesh distortions in a Lagrangian Description and those associated with deformable material boundaries in an Eulerian Description can be solved by this formulation. By introducing the Eulerian boundaries, the cutting action is simulated as the flow of soil against a stationary blade. No element deletion is needed in ALE-FE method and thus the complete contact surface of soil is retained. The extended Drucker-Prager constitutive law is used to simulate the mechanical behavior of soil. Results indicate that the ALE-FE approach is a useful tool in investigating soil-tool interaction and it is especially suitable for cases where large plastic deformation of soil occurs. Simulations under different cutting conditions demonstrate the robustness and effectiveness of the proposed ALE-FE method. The influences of cutting angle and depth on cutting are also investigated. The failure angle, soil deformation and draft force predicted by ALE-FE model are in good agreement with the published experimental data.
J N Reddy - One of the best experts on this subject based on the ideXlab platform.
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Mathematical models for fluid–solid interaction and their numerical solutions
Journal of Fluids and Structures, 2014Co-Authors: Karan S. Surana, B. Blackwell, M. Powell, J N ReddyAbstract:Abstract This paper considers various approaches used currently for the fluid–solid interaction problem and associated computational methodologies. The validity of the mathematical models for fluid–solid interaction is established based on the consistency in the use of continuum mechanics principles and whether the interaction between the solid and the fluid is inherent in the mathematical model or is established external to the mathematical model through interface constraint equations. Computational methodologies are considered from the point of view of unconditional stability, accuracy, and adaptivity of the numerical schemes employed. In particular, the paper establishes that fluid–solid interaction physics must be intrinsic in the mathematical model(s), the mathematical models for fluid and solid must have the same Description, either Eulerian with transport, Lagrangian, or Eulerian without transport. Since fluids require the Eulerian Description with transport, a similar Description for solid matter (hypo-elastic solid) indeed provides a mathematical model for fluid–solid interaction in which the fluid–solid interaction is intrinsic in the mathematical model. The mathematical models for solid matter in the Lagrangian Description or in the Eulerian Description without transport and for fluids in the Eulerian Description with transport can never interact due to fundamental differences in their derivations and the basic assumptions employed. For example, the Eulerian Description with transport for fluids precludes material point displacements, which are intrinsically present in the Lagrangian Description and the Eulerian Description without transport, and they are needed for interaction of the fluid with the solid. The mathematical models for solid matter in the Lagrangian Description, the Eulerian Description without transport, and for fluids in the Eulerian Description with transport are presented to illustrate why fluid–solid interaction is not possible with these mathematical models. The ALE methodologies using the mathematical models in Lagrangian and Eulerian Descriptions have been carefully evaluated and are demonstrated to be invalid for a consistent formulation of a fluid–solid interaction problem. Some numerical studies for simple model problems are presented to demonstrate various issues discussed here. The present study establishes the possible mathematical models and their limitations within the current knowledge of continuum mechanics that provide correct model for fluid–solid interaction.
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Rate constitutive theories for ordered thermoviscoelastic fluids: polymers
Continuum Mechanics and Thermodynamics, 2014Co-Authors: K. S. Surana, J N Reddy, Daniel Núñez, A. RomkesAbstract:This paper presents development of rate constitutive theories for compressible as well as in incompressible ordered thermoviscoelastic fluids, i.e., polymeric fluids in Eulerian Description. The polymeric fluids in this paper are considered as ordered thermoviscoelastic fluids in which the stress rate of a desired order, i.e., the convected time derivative of a desired order ‘ m ’ of the chosen deviatoric Cauchy stress tensor, and the heat vector are functions of density, temperature, temperature gradient, convected time derivatives of the chosen strain tensor up to any desired order ‘ n ’ and the convected time derivative of up to orders ‘ m −1’ of the chosen deviatoric Cauchy stress tensor. The development of the constitutive theories is presented in contravariant and covariant bases, as well as using Jaumann rates. The polymeric fluids described by these constitutive theories will be referred to as ordered thermoviscoelastic fluids due to the fact that the constitutive theories are dependent on the orders ‘ m ’ and ‘ n ’ of the convected time derivatives of the deviatoric Cauchy stress and conjugate strain tensors. The highest orders of the convected time derivative of the deviatoric Cauchy stress and strain tensors define the orders of the polymeric fluid. The admissibility requirement necessitates that the constitutive theories for the stress tensor and heat vector satisfy conservation laws, hence, in addition to conservation of mass, balance of momenta, and conservation of energy, the second law of thermodynamics, i.e., Clausius–Duhem inequality must also be satisfied by the constitutive theories or be used in their derivations. If we decompose the total Cauchy stress tensor into equilibrium and deviatoric components, then Clausius–Duhem inequality and Helmholtz free-energy density can be used to determine the equilibrium stress in terms of thermodynamic pressure for compressible fluids and in terms of mechanical pressure for incompressible fluids, but the second law of thermodynamics provides no mechanism for deriving the constitutive theories for the deviatoric Cauchy stress tensor. In the development of the constitutive theories in Eulerian Description, the covariant and contravariant convected coordinate systems and Jaumann measures are natural choices. Furthermore, the mathematical models for fluids require Eulerian Description in which material point displacements are not measurable. This precludes the use of displacement gradients, i.e., strain measures, in the development of the constitutive theories. It is shown that compatible conjugate pairs of convected time derivatives of the deviatoric Cauchy stress and strain measures in co-, contravariant and Jaumann bases in conjunction with the theory of generators and invariants provide a general mathematical framework for the development of constitutive theories for ordered thermofluids in Eulerian Description. This framework has a foundation based on the basic principles and axioms of continuum mechanics, but the resulting constitutive theories for the deviatoric Cauchy stress tensor must satisfy the condition of positive work expanded, a requirement resulting from the entropy inequality. The paper presents a general theory of constitutive equations for ordered thermoviscoelastic fluids which is then specialized to obtain commonly used constitutive equations for Maxwell, Giesekus and Oldroyd-B constitutive models in contra- and covariant bases and using Jaumann rates.
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Rate constitutive theories for ordered thermofluids
Continuum Mechanics and Thermodynamics, 2013Co-Authors: K. S. Surana, J N Reddy, Daniel Núñez, A. RomkesAbstract:The paper considers developments of constitutive theories in Eulerian Description for compressible as well as incompressible ordered homogeneous and isotropic thermofluids in which the deviatoric Cauchy stress tensor and the heat vector are functions of density, temperature, temperature gradient, and the convected time derivatives of the strain tensors of up to a desired order. The fluids described by these constitutive theories are called ordered thermofluids due to the fact that the constitutive theories for the deviatoric Cauchy stress tensor and heat vector are dependent on the convected time derivatives of the strain tensor up to a desired order, the highest order of the convected time derivative of the strain tensor in the argument tensors defines the ‘order of the fluid’. The admissibility requirement necessitates that the constitutive theories for the stress tensor and heat vector satisfy conservation laws, hence, in addition to conservation of mass, balance of momenta, and conservation of energy, the second law of thermodynamics, that is, Clausius–Duhem inequality must also be satisfied by the constitutive theories or be used in their derivations. If we decompose the total Cauchy stress tensor into equilibrium and deviatoric components, then Clausius–Duhem inequality and Helmholtz free energy density can be used to determine the equilibrium stress in terms of thermodynamic pressure for compressible fluids and in terms of mechanical pressure for incompressible fluids, but the second law of thermodynamics provides no mechanism for deriving the constitutive theories for the deviatoric Cauchy stress tensor. In the development of the constitutive theories in Eulerian Description, the covariant and contravariant convected coordinate systems, and Jaumann measures are natural choices. Furthermore, the mathematical models for fluids require Eulerian Description in which material point displacements are not measurable. This precludes the use of displacement gradients, that is, strain measures, in the development of the constitutive theories. It is shown that compatible conjugate pairs of convected time derivatives of the deviatoric Cauchy stress and strain measures in co-, contravariant, and Jaumann bases in conjunction with the theory of generators and invariants provide a general mathematical framework for the development of constitutive theories for ordered thermofluids in Eulerian Description. This framework has a foundation based on the basic principles and axioms of continuum mechanics but the resulting constitutive theories for the deviatoric Cauchy stress tensor must satisfy the condition of positive work expanded, a requirement resulting from the entropy inequality. The paper presents a general theory of constitutive equations for ordered thermofluids which is then specialized, assuming first-order thermofluids, to obtain the commonly used constitutive theories for compressible and incompressible generalized Newtonian and Newtonian fluids. It is demonstrated that the constitutive theories for ordered thermofluids of all orders are indeed rate constitutive theories. We have intentionally used the term ‘thermofluids’ as opposed to ‘thermoviscous fluids’ due to the fact that the constitutive theories presented here describe a broader group of fluids than Newtonian and generalized Newtonian fluids that are commonly referred as thermoviscous fluids.
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Rate constitutive theory for ordered thermoelastic solids
Annals of Solid and Structural Mechanics, 2012Co-Authors: K. S. Surana, J N Reddy, Daniel Núñez, A. RomkesAbstract:When the mathematical models for the deforming solids are constructed using the Eulerian Description, the material particle displacements and hence the strain measures are not known. In such cases the constitutive theory must utilize convected time derivatives of the strain measures. The entropy inequality provides a mechanism for determining constitutive equations for the equilibrium stress with the additional requirement that the work expanded due to the deviatoric part of the Cauchy stress tensor be positive, but provides no mechanism for establishing the constitutive theory for it. In the development of the constitutive theory in the Eulerian Description for thermoelastic solids, one must consider a coordinate system in the current configuration in which the deformed material lines can be identified. Thus the covariant, contravariant and Jaumann convected coordinate systems are natural choices for the development of the constitutive theory. The compatible conjugate pairs of convected time derivatives of the stress and strain measures in these bases in conjunction with the theory of generators and invariants provide a general mathematical framework for the development of the constitutive theory for thermoelastic solids. This framework has a foundation based on the basic principles and axioms of continuum mechanics but the resulting constitutive theory must satisfy the conditions resulting from the entropy inequality to ensure thermodynamic equilibrium of the deforming matter. This paper presents development of rate constitutive theories for compressible as well as incompressible, homogeneous, isotropic solids. The density, temperature, and temperature gradient in the current configuration and the convected time derivatives of the strain tensor up to any desired order in the chosen basis are considered as the argument tensors of the first convected time derivative of the deviatoric Cauchy stress tensor and heat vector. The thermoelastic solids described by these constitutive theories are termed ordered thermoelastic solids due to the fact that the constitutive theories for the deviatoric Cauchy stress tensor and heat vector are dependent on the convected time derivatives of the strain tensor up to any desired order, the highest order defining the order of the solid.
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Development of Mathematical Models and Computational Framework for Multi-physics Interaction Processes
Mechanics of Advanced Materials and Structures, 2010Co-Authors: Karan S. Surana, Albert Romkes, J N ReddyAbstract:This paper presents development of mathematical models for multi-physics interaction processes in which the physics of solids, liquids and gases are described using conservation laws, appropriate constitutive equations and equations of state in Eulerian Description. The use of conservation laws in Eulerian Description for all media of an interaction process and the choice of the same dependent variables in the resulting governing differential equations (GDEs) for solids, liquids and gases ensure that their interactions are intrinsic in the mathematic model. In the development of the constitutive equations and the equations of state, the same dependent variables are also utilized as those in the conservation laws. The dependent variables of choice due to the Eulerian Description (which is necessary for liquids and gases) are density, pressure, velocities, temperature, heat fluxes and stress deviations. For solid, liquids and gases the development of constitutive equations is based on rate constitutive equa...
