The Experts below are selected from a list of 28071 Experts worldwide ranked by ideXlab platform
Grzegorz Łukaszewicz - One of the best experts on this subject based on the ideXlab platform.
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On the existence of an exponential attractor for a planar shear flow with the Tresca Friction Condition
Nonlinear Analysis: Real World Applications, 2013Co-Authors: Grzegorz ŁukaszewiczAbstract:Abstract We consider a two-dimensional nonstationary Navier–Stokes shear flow with a subdifferential boundary Condition on a part of the boundary of the flow domain, namely, with a boundary driving subject to the Tresca law. There exists a unique global in time solution of the considered problem which is governed by a variational inequality. Our aim is to prove the existence of a global attractor of a finite fractional dimension and of an exponential attractor for the associated semigroup. We use the method of l -trajectories. This research is motivated by a problem from lubrication theory.
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On the existence of an exponential attractor for a planar shear flow with Tresca's Friction Condition
arXiv: Mathematical Physics, 2012Co-Authors: Grzegorz ŁukaszewiczAbstract:We consider a two-dimensional nonstationary Navier-Stokes shear flow with a subdifferential boundary Condition on a part of the boundary of the flow domain, namely, with a boundary driving subject to the Tresca law. There exists a unique global in time solution of the considered problem which is governed by a variational inequality. Our aim is to prove the existence of a global attractor of a finite fractional dimension and of an exponential attractor for the associated semigroup. We use the method of $l$-trajectories. This research is motivated by a problem from lubrication theory.
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On a lubrication problem with fourier and tresca boundary Conditions
Mathematical Models and Methods in Applied Sciences, 2004Co-Authors: Boukrouche, Grzegorz ŁukaszewiczAbstract:The asymptotic behavior of a Stokes flow with Fourier boundary Condition on one part on the boundary and Tresca free boundary Friction Condition on the other, when one dimension of the fluid domain tends to zero is studied. The strong convergence of the velocity is proved, a specific Reynolds equation is obtained, and the uniqueness of the limit velocity and pressure distributions is established.
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Asymptotic analysis of solutions of a thin film lubrication problem with Coulomb fluid–solid interface law
International Journal of Engineering Science, 2003Co-Authors: Boukrouche, Grzegorz ŁukaszewiczAbstract:The asymptotic behavior of a Stokes flow with Coulomb free boundary Friction Condition when one dimension of the fluid domain tends to zero is studied. The strong convergence of the velocity is proved, a specific Reynolds equation is obtained, and the uniqueness of the limit velocity and pressure distributions is established.
Stefania Bruschi - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of Friction Condition in cold forging by using T-shape compression test
Journal of Materials Processing Technology, 2009Co-Authors: Qi Zhang, Eric Felder, Stefania BruschiAbstract:Friction plays an important role in metal forming, and numerical simulation of forging processes requires precise informations about the material properties and the value of the Friction factor m or coefficient μ. This paper describes the T-shape compression, a new Friction testing method by combined compression and extrusion of a cylinder between a flat punch and a V-grooved die. It can realize actual cold forging Condition and allows measuring the Friction on the cylindrical surface of the billet during forging process. The results of experiments and simulations show that the stroke-load curve and the height of the extruded part are both sensitive to Friction. In order to obtain the highest sensitivity to Friction, a FE parametric study of this test has been performed: it indicates that small corner radius and V-groove angle in the die should be chosen. Two commercial FE codes, FORGE 3D and ABAQUS, were used and provided very similar results for a given Friction Condition. Low carbon steel drawn bar with phosphate and soap coating was chosen as specimens. Friction tests with three different lubrication Conditions (solid coating, oil and oil + solid coating) were carried out, and then Friction factor m and Friction coefficient μ were determined by using experimental results and the calibration by numerical simulation of T-shape compression test.
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Evaluation of Friction Condition in cold forging by using T-shape compression test
Journal of Materials Processing Technology, 2009Co-Authors: Q. Zhang, E. Felder, Stefania BruschiAbstract:International audienceFriction plays an important role in metal forming, and numerical simulation of forging processes requires precise informations about the material properties and the value of the Friction factor m or coefficient μ. This paper describes the T-shape compression, a new Friction testing method by combined compression and extrusion of a cylinder between a flat punch and a V-grooved die. It can realize actual cold forging Condition and allows measuring the Friction on the cylindrical surface of the billet during forging process. The results of experiments and simulations show that the stroke-load curve and the height of the extruded part are both sensitive to Friction. In order to obtain the highest sensitivity to Friction, a FE parametric study of this test has been performed: it indicates that small corner radius and V-groove angle in the die should be chosen. Two commercial FE codes, FORGE 3D and ABAQUS, were used and provided very similar results for a given Friction Condition. Low carbon steel drawn bar with phosphate and soap coating was chosen as specimens. Friction tests with three different lubrication Conditions (solid coating, oil and oil + solid coating) were carried out, and then Friction factor m and Friction coefficient μ were determined by using experimental results and the calibration by numerical simulation of T-shape compression test
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Measurement of Friction in a cold extrusion operation: Study by numerical simulation of four Friction tests
International Journal of Material Forming, 2008Co-Authors: Qi Zhang, Laurent Dubar, Stefania Bruschi, Mogens Arentoft, Eric FelderAbstract:The measurement of Friction in the industrial metal working operations is a complex problem because the Friction test must impose at the tool/metal interface Conditions similar to those in the industrial operations. So in the European Network VIF (Virtual Intelligent Forging), a workshop (WP3) was held to evaluate Friction Condition in cold forging by using numerical simulation and experimental methods. It was chosen an industrial cold extrusion operation, in which a low carbon steel bar, covered with phosphate layer and soap, was drawn, cropped and then formed by extrusion. In order to know the Friction Condition in this industrial extrusion operation, four kinds of Friction tests, forward extrusion, double-cup extrusion, upsetting-sliding test and T-shape compression were carried out in four labs, IPU, DIMEG, LAMIH and CEMEF, respectively. In a first preliminary step we simulate the drawing and extrusion operations in order to estimate the contact Conditions in extrusion along the container and the die surfaces. Then by numerical simulation we estimate the contact Conditions in the Friction tests and define the parameters of the tests which insure the better similarity with the industrial operation. In the next step experiments will be performed in order to compare the results of these various Friction tests.
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Measurement of Friction in a cold extrusion operation: Study by numerical simulation of four Friction tests
International Journal of Material Forming, 2008Co-Authors: Qi Zhang, Laurent Dubar, Stefania Bruschi, Mogens Arentoft, Eric FelderAbstract:International audienceThe measurement of Friction in the industrial metal working operations is a complex problem because the Friction test must impose at the tool/metal interface Conditions similar to those in the industrial operations. So in the European Network VIF (Virtual Intelligent Forging), a workshop (WP3) was held to evaluate Friction Condition in cold forging by using numerical simulation and experimental methods. It was chosen an industrial cold extrusion operation, in which a low carbon steel bar, covered with phosphate layer and soap, was drawn, cropped and then formed by extrusion. In order to know the Friction Condition in this industrial extrusion operation, four kinds of Friction tests, forward extrusion, double-cup extrusion, upsetting-sliding test and T-shape compression were carried out in four labs, IPU, DIMEG, LAMIH and CEMEF, respectively. In a first preliminary step we simulate the drawing and extrusion operations in order to estimate the contact Conditions in extrusion along the container and the die surfaces. Then by numerical simulation we estimate the contact Conditions in the Friction tests and define the parameters of the tests which insure the better similarity with the industrial operation. In the next step experiments will be performed in order to compare the results of these various Friction tests
Qunji Xue - One of the best experts on this subject based on the ideXlab platform.
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comparative study on the load carrying capacities of dlc glc and crn coatings under sliding Friction Condition in different environments
Surface & Coatings Technology, 2017Co-Authors: Xiaoyan Guan, Yongxin Wang, Xiaoying Cheng, Liping Wang, Qunji XueAbstract:Abstract DLC, GLC and CrN coatings of different thicknesses were prepared by PVD technology using their respective mature process parameters. Field emission scanning electron microscope (FESEM), laser confocal microscopy, and Raman spectrometer were used to analyze the morphologies and microstructures of the coatings. Nanoindentation measurements and scratch tests were executed to characterize mechanical properties. The load carrying capacities of these coatings in ambient air, distilled water and oil environments were investigated by a reciprocating tribometer with gradually increasing applied load. Results show that the CrN(2 h) coating has the best load carrying capacity in ambient air and base oil, the GLC coating possesses the best load carrying capacity in distilled water. The DLC coating exhibits lower Friction when it survives under low load. The different load carrying capacities of these coatings under sliding-Friction Condition are closely related to their surface roughness, coating thickness and mechanical properties.
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interlayer design for the graphite like carbon film with high load bearing capacity under sliding Friction Condition in water
Applied Surface Science, 2014Co-Authors: Yongxin Wang, Jiafan Wang, Jianmin Chen, Qunji XueAbstract:GLC films with single Ti interlayer, single Cr interlayer, thickness gradient Cr/C interlayer and composition gradient Cr/C interlayer were fabricated by magnetron sputtering technique. The microstructures, mechanical properties and tribological performance under sliding Friction in distilled water and sea-water of the as-deposited GLC films were investigated. Results showed that the adhesion strength and the load-bearing capacity under sliding-Friction Condition in water of GLC film could be improved effectively by interlayer design. GLC film with composition gradient Cr/C interlayer exhibited highest adhesion strength and load-bearing capacity under sliding-Friction Conditions in water, which was closely related to nano-interlocked microstructure and hard carbide phase formations inside the interlayer. The adhesion strength in scratch test and the critical bearing load under sliding-Friction in water of the GLC film with composition gradient Cr/C interlayer exceeded 50 N and 2.73 GPa, respectively. (C) 2014 Elsevier B.V. All rights reserved.
Qi Zhang - One of the best experts on this subject based on the ideXlab platform.
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Analysis of Stretching Load in Tension Stretching Process of Aluminum Alloy Thick-Plate by Using Finite Element Method
Advanced Materials Research, 2014Co-Authors: Da Wei Zhang, Qi Zhang, Shengdun Zhao, Fei Jing, Shu Qin FanAbstract:Tension stretching process is an important link in production of aluminum alloy thick-plate. Exploring the change of load in tension stretching process is important for the structure designing and key component checking of large-scale tension stretcher. In this paper, the changing law of stretching force in the tension stretching process of aluminum alloy 6063 thick-plate has been investigated by numerical simulation method, and the influence of initial thickness of plate and Friction Condition in clamping area was analyzed. The results indicated that the initial thickness has a notable influence but Friction Condition has a little influence on stretching load; and the stretching force increases at first and then decreases slightly, and then it is tending toward stability; and the larger the values of thickness and Friction, the more stable the stretching force in the process.
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Improve the Friction Condition to Realize Less-loading Forming
Journal of Mechanical Engineering, 2013Co-Authors: Qi ZhangAbstract:The Friction is a key factor in metal forming,it comes into being with the existence of the contact surface between metal and die which have relative motion.The severe Friction Conditions will inhibit the flow of metal,increase the forming load significantly and increase the forming energy consumption.Therefore,it has an obvious practical application value of finding a suitable Friction Conditions in metal forming to reduce the forming load,promoting the metal flow,increasing the forming precision and quality of the workpiece,and improving the die life.Currently,the finite element numerical simulation technology has been used as an important method to analyze the metal flow,the forming load and the die force.The Friction criterion and its parameters,as one of the important boundary Condition,have got extensive attention and been deeply investigated.The Friction factor and coefficient increase with the increasing of new surface generation rate and contact pressure,on the basis of studying the different Friction experiment methods.The approaches to realize less-loading is briefly introduced including metal surface treatment for improving Friction Conditions,sheath extrusion,vibration auxiliary forming.
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Evaluation of Friction Condition in cold forging by using T-shape compression test
Journal of Materials Processing Technology, 2009Co-Authors: Qi Zhang, Eric Felder, Stefania BruschiAbstract:Friction plays an important role in metal forming, and numerical simulation of forging processes requires precise informations about the material properties and the value of the Friction factor m or coefficient μ. This paper describes the T-shape compression, a new Friction testing method by combined compression and extrusion of a cylinder between a flat punch and a V-grooved die. It can realize actual cold forging Condition and allows measuring the Friction on the cylindrical surface of the billet during forging process. The results of experiments and simulations show that the stroke-load curve and the height of the extruded part are both sensitive to Friction. In order to obtain the highest sensitivity to Friction, a FE parametric study of this test has been performed: it indicates that small corner radius and V-groove angle in the die should be chosen. Two commercial FE codes, FORGE 3D and ABAQUS, were used and provided very similar results for a given Friction Condition. Low carbon steel drawn bar with phosphate and soap coating was chosen as specimens. Friction tests with three different lubrication Conditions (solid coating, oil and oil + solid coating) were carried out, and then Friction factor m and Friction coefficient μ were determined by using experimental results and the calibration by numerical simulation of T-shape compression test.
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Measurement of Friction in a cold extrusion operation: Study by numerical simulation of four Friction tests
International Journal of Material Forming, 2008Co-Authors: Qi Zhang, Laurent Dubar, Stefania Bruschi, Mogens Arentoft, Eric FelderAbstract:The measurement of Friction in the industrial metal working operations is a complex problem because the Friction test must impose at the tool/metal interface Conditions similar to those in the industrial operations. So in the European Network VIF (Virtual Intelligent Forging), a workshop (WP3) was held to evaluate Friction Condition in cold forging by using numerical simulation and experimental methods. It was chosen an industrial cold extrusion operation, in which a low carbon steel bar, covered with phosphate layer and soap, was drawn, cropped and then formed by extrusion. In order to know the Friction Condition in this industrial extrusion operation, four kinds of Friction tests, forward extrusion, double-cup extrusion, upsetting-sliding test and T-shape compression were carried out in four labs, IPU, DIMEG, LAMIH and CEMEF, respectively. In a first preliminary step we simulate the drawing and extrusion operations in order to estimate the contact Conditions in extrusion along the container and the die surfaces. Then by numerical simulation we estimate the contact Conditions in the Friction tests and define the parameters of the tests which insure the better similarity with the industrial operation. In the next step experiments will be performed in order to compare the results of these various Friction tests.
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Measurement of Friction in a cold extrusion operation: Study by numerical simulation of four Friction tests
International Journal of Material Forming, 2008Co-Authors: Qi Zhang, Laurent Dubar, Stefania Bruschi, Mogens Arentoft, Eric FelderAbstract:International audienceThe measurement of Friction in the industrial metal working operations is a complex problem because the Friction test must impose at the tool/metal interface Conditions similar to those in the industrial operations. So in the European Network VIF (Virtual Intelligent Forging), a workshop (WP3) was held to evaluate Friction Condition in cold forging by using numerical simulation and experimental methods. It was chosen an industrial cold extrusion operation, in which a low carbon steel bar, covered with phosphate layer and soap, was drawn, cropped and then formed by extrusion. In order to know the Friction Condition in this industrial extrusion operation, four kinds of Friction tests, forward extrusion, double-cup extrusion, upsetting-sliding test and T-shape compression were carried out in four labs, IPU, DIMEG, LAMIH and CEMEF, respectively. In a first preliminary step we simulate the drawing and extrusion operations in order to estimate the contact Conditions in extrusion along the container and the die surfaces. Then by numerical simulation we estimate the contact Conditions in the Friction tests and define the parameters of the tests which insure the better similarity with the industrial operation. In the next step experiments will be performed in order to compare the results of these various Friction tests
Boukrouche - One of the best experts on this subject based on the ideXlab platform.
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On a lubrication problem with fourier and tresca boundary Conditions
Mathematical Models and Methods in Applied Sciences, 2004Co-Authors: Boukrouche, Grzegorz ŁukaszewiczAbstract:The asymptotic behavior of a Stokes flow with Fourier boundary Condition on one part on the boundary and Tresca free boundary Friction Condition on the other, when one dimension of the fluid domain tends to zero is studied. The strong convergence of the velocity is proved, a specific Reynolds equation is obtained, and the uniqueness of the limit velocity and pressure distributions is established.
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Asymptotic analysis of solutions of a thin film lubrication problem with Coulomb fluid–solid interface law
International Journal of Engineering Science, 2003Co-Authors: Boukrouche, Grzegorz ŁukaszewiczAbstract:The asymptotic behavior of a Stokes flow with Coulomb free boundary Friction Condition when one dimension of the fluid domain tends to zero is studied. The strong convergence of the velocity is proved, a specific Reynolds equation is obtained, and the uniqueness of the limit velocity and pressure distributions is established.
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COULOMB FLUID-SOLID INTERFACE LAW IN LUBRICATION
Solid Mechanics and Its Applications, 2002Co-Authors: Guy Bayada, BoukroucheAbstract:The asymptotic behaviour of a Stokes flow with Coulomb free boundary Friction Condition when one dimension of the fluid domain tends to zero is studied. The specific Reynolds equation associated with variational inequalities is obtained and uniqueness is proved.
