The Experts below are selected from a list of 0 Experts worldwide ranked by ideXlab platform
Rolf Dollevoet - One of the best experts on this subject based on the ideXlab platform.
-
A new rolling Contact method applied to Conformal Contact and the train–turnout interaction
Wear, 2014Co-Authors: Nico Burgelman, Zili Li, Rolf DollevoetAbstract:Abstract This paper introduces a new computer program called WEAR. It contains a new and more accurate method for calculating wheel–rail Contact stresses to predict degradation due to wear, deformation and fatigue. WEAR accounts for Conformal Contact by using influence numbers that are based on quasi-quarter spaces instead of the traditional half-spaces and considers the varying geometrical spin due to the varying Contact angle through a Contact patch. This new Contact method is applied to two cases: wheel–rail Contact in a turnout and Conformal Contact in a curve with a heavily worn wheel profile. In both cases, many of the assumptions commonly made in excising solution methods for wheel–rail Contact problems, such as a small Contact patch and a constant spin creepage, may be violated. The case of Conformal Contact demonstrates the effect of the influence numbers and the varying spin creepage on the resulting stresses and creep forces and provides a comparison of this new method with the well-established Contact method Contact. For the turnout case, the first task is to obtain realistic input for all timesteps of a vehicle coasting through a turnout (i.e., diverging route) in a simulation. This step is necessary because the Contact forces, which cause wear, deformation and fatigue of the wheels and rails, and the dynamics of the vehicle-turnout interaction strongly influence each other. WEAR converged for all timesteps, including many cases with multiple-point Contacts at the switch blade and with extremely high creepages. This robustness demonstrates suitability of the new method for online Contact force evaluation in vehicle dynamics simulations.
-
A new rolling Contact method applied to Conformal Contact and the train-turnout interaction
Wear, 2014Co-Authors: Nico Burgelman, Zili Li, Rolf DollevoetAbstract:This paper introduces a new computer program called WEAR. It contains a new and more accurate method for calculating wheel-rail Contact stresses to predict degradation due to wear, deformation and fatigue. WEAR accounts for Conformal Contact by using influence numbers that are based on quasi-quarter spaces instead of the traditional half-spaces and considers the varying geometrical spin due to the varying Contact angle through a Contact patch.This new Contact method is applied to two cases: wheel-rail Contact in a turnout and Conformal Contact in a curve with a heavily worn wheel profile. In both cases, many of the assumptions commonly made in excising solution methods for wheel-rail Contact problems, such as a small Contact patch and a constant spin creepage, may be violated. The case of Conformal Contact demonstrates the effect of the influence numbers and the varying spin creepage on the resulting stresses and creep forces and provides a comparison of this new method with the well-established Contact method Contact. For the turnout case, the first task is to obtain realistic input for all timesteps of a vehicle coasting through a turnout (i.e., diverging route) in a simulation. This step is necessary because the Contact forces, which cause wear, deformation and fatigue of the wheels and rails, and the dynamics of the vehicle-turnout interaction strongly influence each other. WEAR converged for all timesteps, including many cases with multiple-point Contacts at the switch blade and with extremely high creepages. This robustness demonstrates suitability of the new method for online Contact force evaluation in vehicle dynamics simulations.
Alexander Olshevskiy - One of the best experts on this subject based on the ideXlab platform.
-
analysis of parameters of Conformal Contact for wheel center and bandage of an innovative wheel
Wear, 2008Co-Authors: Leonid Vinnik, Guenrikh Bourtchak, Alexander OlshevskiyAbstract:The results of the analysis for the innovative design of wheel-sets are presented. This type of wheel-set allows different angular velocities of the bandages with respect to the wheel centers while the gravitational and frictional torsional connection between them remains the same. The results of approximate solution of the tolling Contact problem are shown. In particular, the dependencies between the creep in internal Contact of the differential rotation wheel-set (DRWS) and driving (or braking) rotational moment during rolling. The results of Contact static investigation for differential rotation wheel (DRW) are discussed. The Contact problem is solved using finite element method both in 2D and 3D with friction. The conclusion about the appropriateness of using 2D models is drawn.
Nico Burgelman - One of the best experts on this subject based on the ideXlab platform.
-
A new rolling Contact method applied to Conformal Contact and the train–turnout interaction
Wear, 2014Co-Authors: Nico Burgelman, Zili Li, Rolf DollevoetAbstract:Abstract This paper introduces a new computer program called WEAR. It contains a new and more accurate method for calculating wheel–rail Contact stresses to predict degradation due to wear, deformation and fatigue. WEAR accounts for Conformal Contact by using influence numbers that are based on quasi-quarter spaces instead of the traditional half-spaces and considers the varying geometrical spin due to the varying Contact angle through a Contact patch. This new Contact method is applied to two cases: wheel–rail Contact in a turnout and Conformal Contact in a curve with a heavily worn wheel profile. In both cases, many of the assumptions commonly made in excising solution methods for wheel–rail Contact problems, such as a small Contact patch and a constant spin creepage, may be violated. The case of Conformal Contact demonstrates the effect of the influence numbers and the varying spin creepage on the resulting stresses and creep forces and provides a comparison of this new method with the well-established Contact method Contact. For the turnout case, the first task is to obtain realistic input for all timesteps of a vehicle coasting through a turnout (i.e., diverging route) in a simulation. This step is necessary because the Contact forces, which cause wear, deformation and fatigue of the wheels and rails, and the dynamics of the vehicle-turnout interaction strongly influence each other. WEAR converged for all timesteps, including many cases with multiple-point Contacts at the switch blade and with extremely high creepages. This robustness demonstrates suitability of the new method for online Contact force evaluation in vehicle dynamics simulations.
-
A new rolling Contact method applied to Conformal Contact and the train-turnout interaction
Wear, 2014Co-Authors: Nico Burgelman, Zili Li, Rolf DollevoetAbstract:This paper introduces a new computer program called WEAR. It contains a new and more accurate method for calculating wheel-rail Contact stresses to predict degradation due to wear, deformation and fatigue. WEAR accounts for Conformal Contact by using influence numbers that are based on quasi-quarter spaces instead of the traditional half-spaces and considers the varying geometrical spin due to the varying Contact angle through a Contact patch.This new Contact method is applied to two cases: wheel-rail Contact in a turnout and Conformal Contact in a curve with a heavily worn wheel profile. In both cases, many of the assumptions commonly made in excising solution methods for wheel-rail Contact problems, such as a small Contact patch and a constant spin creepage, may be violated. The case of Conformal Contact demonstrates the effect of the influence numbers and the varying spin creepage on the resulting stresses and creep forces and provides a comparison of this new method with the well-established Contact method Contact. For the turnout case, the first task is to obtain realistic input for all timesteps of a vehicle coasting through a turnout (i.e., diverging route) in a simulation. This step is necessary because the Contact forces, which cause wear, deformation and fatigue of the wheels and rails, and the dynamics of the vehicle-turnout interaction strongly influence each other. WEAR converged for all timesteps, including many cases with multiple-point Contacts at the switch blade and with extremely high creepages. This robustness demonstrates suitability of the new method for online Contact force evaluation in vehicle dynamics simulations.
Bruno Michel - One of the best experts on this subject based on the ideXlab platform.
-
Conformal Contact and pattern stability of stamps used for soft lithography
Journal of Applied Physics, 2000Co-Authors: Alexander Bietsch, Bruno MichelAbstract:Patterning in soft lithography techniques such as microContact printing or light-coupling mask lithography is mediated by surface topographical patterns of elastomeric stamps: intimate Contact with the substrate is achieved locally at the protruding areas, whereas a gap remains between the substrate and recessed zones. This principle challenges the properties of the stamp, especially when printing high-resolution or extreme aspect-ratio patterns with high accuracy. On the one hand, the stamp must be soft enough to enable Conformal Contact with the substrate, which means that it must adapt elastically without leaving voids created by the natural roughness of the substrate. On the other hand, a precise definition of micropatterns requires a rigid material. In this article, we analyze the conditions of elasticity, roughness, and energy of adhesion to establish Conformal Contact between an elastomer and the target surface. Furthermore, we address questions of replication accuracy and evaluate local elastic deformation induced by normal forces using model calculations for simple pattern geometries. Pressure applied during Contact leads to a sagging or collapse of the unsupported areas. We discuss implications on both material and pattern design that allow spontaneous propagation of Conformal Contact while inhibiting the spreading of collapse.
-
Conformal Contact and pattern stability of stamps used for soft lithography
Journal of Applied Physics, 2000Co-Authors: Alexander Bietsch, Bruno MichelAbstract:Patterning in soft lithography techniques such as microContact printing or light-coupling mask lithography is mediated by surface topographical patterns of elastomeric stamps: intimate Contact with the substrate is achieved locally at the protruding areas, whereas a gap remains between the substrate and recessed zones. This principle challenges the properties of the stamp, especially when printing high-resolution or extreme aspect-ratio patterns with high accuracy. On the one hand, the stamp must be soft enough to enable Conformal Contact with the substrate, which means that it must adapt elastically without leaving voids created by the natural roughness of the substrate. On the other hand, a precise definition of micropatterns requires a rigid material. In this article, we analyze the conditions of elasticity, roughness, and energy of adhesion to establish Conformal Contact between an elastomer and the target surface. Furthermore, we address questions of replication accuracy and evaluate local elastic de...
Thami Zeghloul - One of the best experts on this subject based on the ideXlab platform.
-
experimental bench for studying the relation between the dynamic characteristics of the frictional motion and the electric potential at the surface of polymer slabs in sliding Conformal Contact
Tribology International, 2017Co-Authors: Bogdan Neagoe, Horianicolai Teodorescu, Yopa Prawatya, Lucian Dascalescu, Thami ZeghloulAbstract:Abstract Quantifying the triboelectric charging that occurs at polymer-on-polymer Contact is crucial in the appropriate design of sliding or rolling components of various mechanisms. The paper describes the key devices and instrumentation of a laboratory bench developed for the accurate study of the tribocharging characteristics of polymer slabs in frictional sliding Conformal Contact. The bench enables the adjustment of several factors that affect the electrostatic charge generation (relative sliding speed, normal Contact force, and number of back-and-forth cycles), and is equipped with sensors for the continuous monitoring of sample displacement, as well as of both normal and tangential forces. The triboelectric charge is evaluated by non-Contact 2-D mapping of the electric potential at the surface of the samples at the end of the frictional process. The experimental methodology includes appropriate filtering of the signals provided by the sensors, before being recorded and interpreted. The cartography of the surface potential is put in relation with the dynamic characteristics of the frictional motion. The effectiveness of the laboratory bench is illustrated by the study of the electric potential generated by frictional sliding Conformal Contact between rectangular slabs of Polyvinyl Chloride (PVC) and Acrylonitrile Butadiene Styrene (ABS).
-
Sliding Conformal Contact Tribocharging of Polystyrene and Polyvinyl Chloride
IEEE Transactions on Industry Applications, 2016Co-Authors: Thami Zeghloul, Lucian Dascalescu, Karim Rouagdia, Ali Fatihou, Pascal Renoux, Dominique SouchetAbstract:The electric double layer is known to affect thin-film lubrication. Other researchers have shown that tribocharging affects the breaking torque in a metal shaft-oil-lip seal system and that an external electric field may be employed to control this phenomenon. One main issue in all these studies is the characterization of the charging state of the bodies in Contact. This is quite a difficult challenge when the Contact occurs between two insulating materials. The ultimate aim of this paper is to validate an experimental procedure appropriate for ensuring the reproducibility of the tribocharging conditions in sliding Contacts between polymeric materials. The experiments were performed with samples of polystyrene and polyvinyl chloride. Surface potential measurements were done to evaluate the tribocharging effects. The experiments pointed out that the amount of charge accumulated on the sliding bodies depends on the external force applied to the Contact and the number of tribocharging cycles (i.e., back-and-forth relative motions). However, this charge is nonuniformly distributed on the surface of the samples. This means that it will be difficult to use the tribocharging effect for controlling the charging state and, hence, the lubrication of the Contact between two insulating bodies.