ACTIVITIES

The Tribology Laboratory was setup at the University of Suceava in 1978.  The first research activities carried out involved elastohydrodynamic traction as phenomenon and application in traction drives and rolling contact fatigue. Many original test rigs were conceived and build to assess the effect of various factors upon EHD traction and the effect of traction upon contact fatigue. 

These results led to more than 10 design versions of EHD traction drives, four of which were applied in Romanian industry.  After 1985, realizing that considering the EHD contact as a black box cannot lead to progress, the research effort was slowly shifted towards the understanding of physical phenomena which govern the shear behavior of EHD oil films.

Starting from quantum mechanics and involving thermodynamics, statistical physics and physical chemistry, a new scientific domain was established, called Physics of lubrication. 

The research group advanced theoretical explanations for shear behavior of EHD oil films, which are validated by extensive experimental work.  Naturally, due to the availability of personal computers, Contact Mechanics became a new field of interest both as theory and experiment.

MAIN RESEARCH EQUIPMENT

Laboratory space: more than 120 square meters in a newly refurbished building. Main apparatus: 2 AFMs (atomic force microscopes), 2 laser profilometers with spare laser heads, 1 spectrometer, 1 photo-stress analyzer, strain gauge measurement instruments, digital oscilloscopes, signal generators, high speed video-camera, video-cameras, digital photo-cameras.   Test rigs: 15.   Computers: 20.

3d plot of reflectivity of the gel solidified in a finite length line contact, Eccentrically loaded

MAIN RESEARCH THEMES

The Tribology laboratory produced many scientific tribological research novelties in the following fields:

A. CONTACT MECHANICS

Behavior and optimization of conformal contacts for uniform contact pressure;

Evaluation of the effect of inner circular concavities in plane contacts;

Proposal of a new, more correct, optimization criterion for conformal contacts; 

A new experimental method to measure accurately contact area by laser profilometry in a contact model made of a metal punch pressed against a sapphire window;

 A new experimental method to assess contact pressure between real surfaces by measuring the reflectivity of a gel layer solidified in the contact; 

Establishing a direct correlation between second order polynomial surfaces and resulting contact pressure; 

Theoretical design of circular and elliptical contacts between bodies bounded by high order polynomial surfaces to get a centrally flat pressure surrounded by a zone of decreasing pressure;

Investigation of rough contacts in the elastic-plastic domain;

Effective plastic strain in elastic-plastic spherical contact

 Investigation of dynamic viscoelastic contacts;  Optimization of micro-contacts seeking both the load capacity and electrical resistance;

A combined analytical-numerical approach to the elastic contact between bodies bounded by symmetrical, high order surfaces;

 Pressure distribution in fourth order polynomial surface contacts

Development of modern numerical methods (GC+DCFFT) for solving elastic and elastic-plastic contact problems;

The effect of dents and furrows upon contact pressure, contact stress state and rolling contact fatigue in lubricated contacts;

Pressure distribution in elastic-plastic spherical contact

The elastic contact between low thickness bodies; 

The nonlinear elastic contact between incompressible bodies;

End effect attenuation in finite length line contacts applied to cylindrical and tapered roller bearings.

Improved pressure distribution in tapered roller contact

B. TRIBOLOGY AND NANOTRIBOLOGY

A new physical model for the shear viscosity of molecular liquids subjected to EHD conditions, including the piezo-viscous coefficient; 

A new theoretical model for solid-like properties of molecular liquids in EHD conditions (shear modulus and limiting shear stress); 

Experimental study of high pressure oil compressibility;  Experimental study of traction properties of Romanian lubricating oils; 

Theoretical and experimental assessment of the effect of oil plastic shear upon HD and EHD lubrication;  Theoretical and experimental investigations in nano-elastohydrodynamic  lubrication; 

Experimental investigation of oil film thickness in impact tests;

Theoretical explanation of rolling friction coefficient by the energy losses and experimental validation of this proposal;

Experimental assessment of the degree of metal fatigue by hysteretic measurements;

Controlled slipping clutches with visco-magnetic liquids;

Finite dimensions combined journal bearings; The hysterezis of biological solids; Behavior of bioarticular contacts.

3d plot of reflectivity in a circular contact

SCIENTIFIC PRODUCTION AND PUBLICATIONS OF THE LABORATORY

During the last five years the members of the laboratory published:

- ISI indexed papers: 5;  COMPENDEX indexed papers: 33;  CNCSIS indexed papers: 137;  National conferences works: 97;  Books: 7.

- The laboratory organizes (since 1980) the International Conference VAREHD (15 editions);

- The laboratory edits the journal ACTA TRIBOLOGICA;  16 PhD degrees awarded in Tribology in the laboratory;  13 national grants;  4 international grants.

MAIN COLLABORATIONS

International collaboration with: Imperial College London, INSA of Lyon, University of Poitiers, Queen Mary and Westfields College London, Trinity College Dublin, Cranfield University.

TEAM

Head of research team:

Professor Emanuel DIACONESCU, PhD, Eng., Corresponding member of the Romanian Academy;