Multiscale and Multifield Multiphysics of High Current Pulse Static Contact With Rough Surfaces

2013 ◽  
Author(s):  
John G. Michopoulos ◽  
Marcus Young ◽  
Athanasios Iliopoulos
Keyword(s):  
Electric Current ◽  
Current Pulse ◽  
Mechanical Load ◽  
Bulk Material ◽  
Rough Surfaces ◽  
High Current ◽  
Mechanical Pressure ◽  
Static Contact ◽  
Macro Scale ◽  
Scale Properties

We are presenting a multi-field and multiscale theory leading to derivations of physical properties from surface topography and bulk material properties for the interface between two rough surfaces in contact activated by mechanical load and high current pulses. At the macro-scale our proposed model involves multi-field coupling of conduction and induction currents with heat conduction induced by Joule heating. The structural mechanics of the conducting materials are also considered. At the meso-scale and micro-scale the associated model contains an asperity based comprehensive model that leads to homogenized macro scale properties for the interface boundary. The mechanical pressure and the repulsion effect from electric current through the micro-contacts are accounted for as well. Numerical analysis results illustrate the dependence of the derived properties on the surface characteristics, external load and the electric current. Finally, the entire framework is applied to an actual conductor configuration of hollow cylinders under compression and a high current pulse to demonstrate the feasibility of the entire approach.

Towards Static Contact Multiphysics of Rough Surfaces

2012 ◽  
Author(s):  
John G. Michopoulos ◽  
Athanasios Iliopoulos ◽  
Marcus Young
Keyword(s):  
Electric Current ◽  
Mechanical Load ◽  
Bulk Material ◽  
Rough Surfaces ◽  
Thermal Response ◽  
Surface Characteristics ◽  
Current Status ◽  
Plastic Behavior ◽  
Mechanical Pressure ◽  
Static Contact

This paper is describing the current status of ongoing work on developing a comprehensive modeling and simulation infrastructure capable of addressing the multiphysics behavior aspects of rough surfaces in contact. The electrical and thermal response of bodies in contact under the influence of mechanical load electric currents and thermal fluxes, is a topic of interest for many application areas. We are presenting a multiscale theory leading to derivations of expressions of electric and thermal conductivities for the case of static contact. The associated model contains both an asperity based comprehensive model as well as its continuum level coupling. The mechanical pressure and the repulsion effect from electric current through the micro-contacts as well as temperature and strain rate dependence of the plastic behavior of the asperity are accounted for as well. This formalism enables the derivation of physical properties from surface topography and bulk material properties for the interface between two rough surfaces in contact. Numerical analysis results present the dependence of the derived properties from the surface characteristics applied external load and the electric current.

On the Validation of a Multiphysics Theory for a Static Contact With Rough Surfaces

2014 ◽  
Author(s):  
John G. Michopoulos ◽  
Marcus Young ◽  
Athanasios Iliopoulos ◽  
Harry N. Jones
Keyword(s):  
Contact Resistance ◽  
Contact Surface ◽  
Mechanical Load ◽  
Acquired Resistance ◽  
Contact Theory ◽  
Electric Current Pulse ◽  
Mechanical Pressure ◽  
Annular Disk ◽  
Static Contact ◽  
Hollow Cylinders

In an effort to address the validation of a recently developed multifield and multiscale rough contact theory we are applying it for a particular experiment. The experiment involves the contact between two hollow cylinders with an annular disk in between them. The contact surface is rough and the entire stack is exposed to compressive mechanical load and a high electric current pulse. Solving the necessary multi-physics partial differential equations leads to establishing the spatiotemporal distribution of relevant fields and the identification of the contact resistance as a function of mechanical pressure and current. In addition to providing typical results for all selected fields present during the experiment and the simulation, we also provide a comparison between the experimentally acquired resistance histories with the numerically derived ones to address validation aspects of the general multiphysics contact theory.

The Future of Plasma-Based Surface Engineering Techniques in Tribology (Keynote)

2005 ◽  
Author(s):  
Allan Matthews ◽  
Adrian Leyland
Keyword(s):  
Surface Engineering ◽  
Performance Enhancement ◽  
Bulk Material ◽  
Cost Savings ◽  
Cost Effective ◽  
Ceramic Coatings ◽  
Performance Improvements ◽  
Treatment Techniques ◽  
Wide Range ◽  
Macro Scale

Over the past twenty years or so, there have been major steps forward both in the understanding of tribological mechanisms and in the development of new coating and treatment techniques to better “engineer” surfaces to achieve reductions in wear and friction. Particularly in the coatings tribology field, improved techniques and theories which enable us to study and understand the mechanisms occurring at the “nano”, “micro” and “macro” scale have allowed considerable progress to be made in (for example) understanding contact mechanisms and the influence of “third bodies” [1–5]. Over the same period, we have seen the emergence of the discipline which we now call “Surface Engineering”, by which, ideally, a bulk material (the ‘substrate’) and a coating are combined in a way that provides a cost-effective performance enhancement of which neither would be capable without the presence of the other. It is probably fair to say that the emergence and recognition of Surface Engineering as a field in its own right has been driven largely by the availability of “plasma”-based coating and treatment processes, which can provide surface properties which were previously unachievable. In particular, plasma-assisted (PA) physical vapour deposition (PVD) techniques, allowing wear-resistant ceramic thin films such as titanium nitride (TiN) to be deposited on a wide range of industrial tooling, gave a step-change in industrial productivity and manufactured product quality, and caught the attention of engineers due to the remarkable cost savings and performance improvements obtained. Subsequently, so-called 2nd- and 3rd-generation ceramic coatings (with multilayered or nanocomposite structures) have recently been developed [6–9], to further extend tool performance — the objective typically being to increase coating hardness further, or extend hardness capabilities to higher temperatures.

scholarly journals Double electric layer influence on dynamic of EUV radiation from plasma of high-current pulse diode in tin vapor

2013 ◽  
Vol 377 (3-4) ◽  
pp. 307-309 ◽  
Author(s):  
I.V. Borgun ◽  
N.A. Azarenkov ◽  
A. Hassanein ◽  
A.F. Tseluyko ◽  
V.I. Maslov ◽  
...  
Keyword(s):  
Current Pulse ◽  
Double Electric Layer ◽  
High Current

Refinement of inclusions in molten steel by electric current pulse

2015 ◽  
Vol 31 (13) ◽  
pp. 1555-1559 ◽  
Author(s):  
W. B. Dai ◽  
J. K. Yu ◽  
C. M. Du ◽  
L. Zhang ◽  
X. L. Wang
Keyword(s):  
Electric Current ◽  
Current Pulse ◽  
Molten Steel ◽  
Electric Current Pulse

Electric Current Pulse Welding of Titanium with 18-10 Stainless Steel

2009 ◽  
Vol 83-86 ◽  
pp. 1251-1253 ◽  
Author(s):  
E.G. Grigoryev ◽  
V.N. Bazanov
Keyword(s):  
Stainless Steel ◽  
Electric Current ◽  
Current Pulse ◽  
Contact Zone ◽  
Welded Joints ◽  
High Speed ◽  
Welded Joint ◽  
Electric Current Pulse ◽  
Pulse Effect ◽  
Different Thickness

The purpose of the work was to determine the capabilities of the pulse effect of electric current and pressure to produce welded joints of various component parts of different thickness from 18-10 stainless steel and titanium. Application of electric current pulses on the surfaces of contacting metallic conductors leads to considerable changes in the surface structure. Depending on the initial state of the surfaces and parameters of the pulse effect this can result in melting without formation of joints, formation of a strong welded joint with characteristics no worse than those of welded metals, and in destruction of the contact zone. A combination of a short electric pulse with simultaneous application of mechanical pressure in the weld zone causes high-speed deformation of the contact zone. The process of joint formation itself does not cause any appreciable diffusion during welding. The greatest energy emission and the maximal heating occur on the contacting surfaces being welded with the passage of an electric current pulse through the welding zone. Simultaneously with intensive heating, and due to applied pressure, high-speed deformation of materials takes place and a strong welded joint is formed. Optimal parameters for the welding of titanium and 18-10 stainless steel have been determined on the basis of the tests conducted. Investigations into the welding of titanium and 18-10 stainless steel have shown that application of a short electric current pulse and pressure produces stronger welded joints composed of both similar and different metals of considerably different thickness.

Leakage Prediction in Mechanical Seals Under Hydrostatic Operating Condition

2007 ◽  
Author(s):  
S. Elhanafi ◽  
K. Farhang
Keyword(s):  
Closed Form ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Rough Surfaces ◽  
Mechanical Seals ◽  
Operating Condition ◽  
Form Equation ◽  
Macro Scale ◽  
The Mean

This paper considers leakage in mechanical seals under hydrostatic operating condition. A contact model based on the Greenwood and Williamson contact of rough surfaces is developed for treating problems involving mechanical seals in which both the micron scale roughness of the seal face and its macro scale profile are used to obtain either a closed-form equation or a nonlinear equation relating mean plane separation to the mass flow rate. The equations involve the micron scale geometry of the rough surfaces and physical parameter of the seal and carriage. Under hydrostatic condition, it is shown that there is an approximate closed-form solution in which mass flow rate in terms of the mean plane separation, or alternatively, the mean plane separation in terms of the leakage mass flow rate is found. Equations pertaining to leakage in nominally flat seal macro profile is considered and closed form equation relating to leakage flow rate to pressure difference is obtained that contain macro and micron geometries of the seal.

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