Traian Cicone

Traian Cicone
Polytechnic University of Bucharest | UPB · Department of Machine Elements and Tribology

Professor

About

35
Publications
3,861
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447
Citations

Publications

Publications (35)
Article
Full-text available
The resistance to flow of a liquid squeezed out of a soft, porous structure subjected to compression generates a high load capacity and represents the mechanism on which the XPHD lubrication is based. The process is dependent on permeability which, in turn, depends on porosity, variable during compression. This study investigates experimentally the...
Article
Full-text available
The resistance to flow of imbibed fluids in soft porous structures subjected to compression can be a solution for impact attenuation. The mechanism, named ex-poro-hydrodynamic (XPHD) lubrication, is based on permeability variation with porosity, which, at its turn, depends on the compression degree of the porous structure. A literature survey revea...
Article
Full-text available
It is well known since the pioneering work of Dowson and Castelli that load capacity increases in compliant (elastic pad) hydrostatic bearings, compared to their rigid counterparts. In a recently published paper, a new design solution of a flexible pad hydrostatic bearing was proposed and analysed theoretically. A simplified analytical model was pr...
Article
Full-text available
The resistance to flow of a fluid squeezed out from a soft and porous structure under compression, generates high load capacity. The process is dependent on permeability, which is variable during compression of the porous layer. This mechanism (named Ex-Poro-Hydrodynamic Lubrication – XPHD) plays an important role in a wide range of tribological ap...
Article
Full-text available
A new design of an elastohydrostatic bearing with a structurally elastic pad is theoretically analyzed. A single recess circular thrust bearing has the upper pad provided with a large cavity, covered with an elastic metallic membrane. The latter deflects under the pressure distribution in the bearing, creating a radial convergent gap. A simplified...
Article
Full-text available
The paper presents experimental and theoretical results for the planar squeeze flow of a finite volume of viscoplastic material through a highly deformable porous layer. The central zone of an annular disc made of a reticulated polyurethane foam with high porosity (ε > 0.97) was fully filled with tooth paste. The porous disc placed between two flat...
Conference Paper
Full-text available
It is generally accepted that actual high performance brush seals are interference seals and therefore, tribological behavior at the bristle-to-shaft interface is a major concern. As in any other sliding contact, contact temperature is an important topic, which must be addressed. In a recent paper, Pascovici & Cicone [15] proposed a simplified elas...
Article
During last two decades it was theoretically and experimentally proved that the fluid squeeze out from a soft and porous layer under the action of an external impact load produces high lifting forces. For high porosity, the elastic forces generated by the solid phase are negligible. The mechanism, strongly dependent on permeability variation with l...
Article
Full-text available
During last decade a series of theoretical studies revealed the high pressures generated in highly porous soft materials imbibed with fluids and subjected to compression, with possible application to impact damping. The mechanism, named eXPoroHydroDynamic (XPHD) Lubrication, combines the resistance to flow inside the porous matrix with its variable...
Article
Full-text available
Theoretical and experimental evidences show that high lift forces can be generated when a porous layer imbibed with a fluid is subjected to compression by a rigid and impermeable component in normal (approaching) relative motion. If the porous layer is soft enough to neglect its solid structure reaction to compression then the pressure increase can...
Article
Full-text available
This paper presents the experimental determination of permeability for unidirectional in-plane flow through a thin layer of nonwoven porous textile subjected to various rates of compression. The experiments were made on an original device that allows the variation of porous layer compression and pressure differential. The permeability was calculate...
Article
Full-text available
The present study is dedicated to the innovative 3-bar torsion spring used as suspension solution for the first time at Lunokhod-1, the first autonomous vehicle sent for the exploration of the Moon in the early 70-ies by the former USSR. The paper describes a simple analytical model for calculation of spring static characteristics, taking into acco...
Conference Paper
Full-text available
An innovative solution for damping of residual energy after the impact of a bullet on a protective vest, based on the flow of a fluid through a porous material that is placed under the protective Kevlar layers, has been recently proposed. The fluid flow through the open pores is produced by the compression of the porous material, during impact, i.e...
Article
Full-text available
The experimental study of a highly compressible porous material, made of cellulose fibers, and imbibed with water, during stress relaxation tests on a rheometer, shows that the material relaxes when kept at constant strain as long as there are open pores. Using the relaxation curves, the behaviour under compression can be divided into two distinct...
Article
Ex-poro-hydrodynamic (XPHD) lubrication describes the lifting effect produced by the flow of fluid through an extremely compressible porous material subjected to compression. Studies published recently on the behaviour of such materials, for various configurations, reveal good potential in shock absorption. The present study addresses the case of a...
Article
Full-text available
Surface texturing has been shown to reduce friction and increase the film thickness in various tribological applications (hydrodynamic bearings, mechanical seals, and cylinder–liner contacts). However, only few studies discuss optimal texturing properties, and most of them focus on the optimal dimple shape. This article proposes an in-depth study o...
Article
Fluid flow through highly compressible porous layers (HCPL) subjected to external loads is known as ex-poro-hydrodynamic (XPHD) lubrication. Several models have been proposed for squeeze in XPHD conditions and analytical solutions were obtained based on a significant number of simplifications. Consequently, an analysis of these simplifications effe...
Article
The objective of this article is the study of the load-carrying capacity of a Rayleigh step slider (RSS) for both direct motion (+RSS – which generates lifting effects) and reverse motion (−RSS – which generates suction or cavitational effects). Normal force was measured on a pin-on-disc test rig, with two lubricants (SAE-20 W-50 oil and glycerin)...
Article
Ex-poro-hydrodynamic (XPHD) lubrication, a mechanism that generates self-sustained films when highly compressible porous layers (HCPL) imbibed with liquids are squeezed, is strongly dependent on permeability variation of the porous structure. The present paper analyzes the variation of the permeability with layer compression. The experiments were p...
Article
Full-text available
Despite a large amount of work dedicated to the study of the effects of textured surfaces in tribological pairs, there is still a need for accurate and convincing experimental results to prove the benefic effects predicted theoretically. This paper presents an original experimental set-up with a partially textured flat pin sliding on a rotating dis...
Article
The paper proposes a model for the squeeze process under impact for highly compressible porous layers imbibed with fluids (HCPL). It is assumed that the normal forces generated by elastic compression of the fibers comprising the solid phase are negligible compared to the pressure forces generated in the imbibed fluid, within the porous layer. The p...
Article
The article presents a one-dimensional isothermal flow model with analytical solution for partially textured surfaces, nominally parallel. The model allows a simple and elegant parametric analysis of slider performance characteristics (load-carrying capacity, friction force, and friction coefficient) in terms of texture dimensions. It is shown that...
Article
The present paper presents an original, quasi-analytical, thermoelastohydrodynamic (TEHD) model for a fluid film, parallel surface, elastic slider. Temperature variation along the slider is included in a simplified manner, based on Tipei assumption (viscosity variation along the pad is proportional to film thickness variation) [Tipei N. Theory of l...
Article
L'utilisation des surfaces micro-texturées dans les paliers et butées hydrodynamiques peut avoir des effets positifs sur les performances de ces composants. Cependant, une étude analytique suffit pour montrer qu'une mauvaise distribution ou un dimensionnement inadapté des textures peuvent conduire à des pertes de performance et non à des gains. Afi...
Conference Paper
Surface texturing has been shown to have friction reducing / load capacity increasing effects in parallel sliders, as well as in cylinder-liner contacts and in hydrodynamic seals. However, if texture is to be regarded as the sole mean of hydrodynamic lift in parallel sliders, or as a way of improving hydrodynamic performance in slider, thrust and j...
Article
Full-text available
Lubricated textured surfaces reduce the friction coefficient and the surface wear rate. The present work is dedicated to the analytical and numerical study of load capacity and friction coefficient of a single, square dimple, typical for textured surfaces realized by lithography. The analytical model is based on the pressure linearization while the...
Article
Optimal operation of mechanical face seals (MFS) requires the existence of fluid film between the mating faces to avoid wear, but the gap has to be as thin as possible to keep leakage within acceptable limits. This compromise leads to a fine balance control of the forces acting on the floating ring. The amount of heat dissipated in the very thin fl...
Conference Paper
Full-text available
The squeeze film for layered, compliant and porous contacts is a challenging subject with application in Biotribology as well as for a better insight of principles of natural joints for designing of performant artificial joint replacements. The paper presents an original approach of flowing process both in the lubricant film and trough the complian...
Article
Compliant and permeable layered surfaces are used in natural synovial joints and have been proposed for the bearing surface in artificial joint replacements. The squeeze-film lubrication mechanism plays an important role in long-term performance of both natural and artificial joints. The full lubrication solution of the present problem including co...
Article
Full-text available
A simplified solution of the Reynolds equation for non-isoviscous conditions, based on a 3rd degree polynomial representation of the velocity profile is proposed. It allows uncoupling the energy and momentum equations and leads to an analytical solution, independent of the law of temperature-viscosity dependence. Using the proposed solution, correl...
Chapter
This chapter deals with explanation of friction in lubricated contacts. Friction is the resistance to motion that occurs when one body slides over another. The resistive force acting in the opposite direction of the relative motion is known as the friction force. The friction force has two forms: the force required to initiate sliding, known as the...
Book
Full-text available
This book is a collection of tests for applied mechanics. The paper is addressed to all students who study or deepen technical disciplines such as machine organs, mechanisms, general technology, technical drawing, mechanics, as well as other complementary disciplines, which contribute to the training of a specialist in the design of mechanical sys...
Article
Published experimental data and results of numerical modelling have shown that in certain cases the temperature gradient along the radius of the sealing gap of mechanical face seals (MFSs) can be significant. As a consequence, isothermal calculation of seal performance characteristics can induce some errors. In a recent paper, Pascovici and Etsion...
Article
Full-text available
The use of temperature and pressure induced deformations to generate hydrodynamic lift-off for flat and parallel surfaces is relatively new and scarcely present in literature. The present paper analyses theoretically the load carrying capacity of a typical thrust bearing with elastic pad in order to define optimal pad parameters. The study is made...

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Projects

Project (1)
Archived project
The present project has as main objective the development of an improved protection equipment for human personnel or vehicles which will contain in the backing an encapsulated highly compressible porous layer (HCPL), imbibed with a liquid, capable to absorb a large part of the energy produced by the bullet impact or the shock waves generated by an explosion.