Modeling for the lubricants industry

Rachel Fowler, Managing Editor | TLT Modeling Techniques February 2017

Longtime STLE-member Valéry Dunaevsky discusses types, applications and how this technique can be improved. 

LAST MONTH TLT ASKED ITS READERS to provide their perspectives on modeling techniques for our regular Sounding Board feature. One of our readers and a long-time STLE member, Dr. Valéry Dunaevsky, president of VVD Engineering in Monroeville, Pa., submitted an answer that was loaded with good ideas but a tad too lengthy for Sounding Board.

However, TLT still wanted to share this information with our readers. So we asked Val if he would consider summarizing his thoughts in a series of bulleted points, and he graciously agreed.

Before we get into information, here is a little background on our contributor. 

Dr. Valéry (Val) Dunaevsky received his major education in the field of mechanical engineering from the Polytechnic Institute in Riga, Latvia. His dissertation focused on problems relating to surface metrology and contact mechanics. The outcome of his research was applied to reducing wear in diesel engine components.

Dunaevsky obtained his impressive professional record while working in the positions of lead and principle engineer for several industries in his home country and the U.S., where he emigrated in 1979 with his family from Latvia. His employment includes stints with Westinghouse Air Brakes, Emerson Electric, AlliedSignal and Ingersoll Rand. His engineering input on air and refrigeration compressors, IC Engines and railroad and automotive brakes has been utilized internationally. 

Dunaevsky is included in the Marquis’ Who’s Who in Science and Engineering, 1998/1999. He also is a member of several engineering societies including SAE, ASME (and particularly of its B46 committee on standardization of the surface texture) and STLE where he was elevated to the level of Fellow. He authored and co-authored more than 30 published technical papers, has been an editor of several technical books published by ASME Press and is a leading contributor to the Tribology Data Handbook published by CRC Press. 

In addition, he has served as a reviewer for the Journal of Tribology (ASME), Tribology Transactions (STLE) and Wear (Elsevier) and is a former TLT technical editor. Dunaevsky also is the author of a series of patents in the field of compressors and engines, one of which demonstrates an ingenious and counterintuitive approach to combating wear. 

He was a force behind implementation of a computer modeling of the relevant tribological processes and phenomena at several major U.S. manufacturers. He is a leading author of several precision computerized models in the field of friction thermo-generation and heat transfer, dynamic sealing and wear prediction.

Following are his thoughts on modeling techniques as they relate to the lubricants industry.



What does tribology modeling imply? What are typical examples and uses?
• Assessment of the tribological categories of friction, wear and lubrication: (a.) from the first principles, (b.) from engineering parameters and (c.) from a systems approach.
• Assessment of the various phenomena and failure modes and mechanisms influenced by the tribological categories (e.g., friction thermodynamics, friction instabilities and cracks, auto-correlation of the tribology categories, vibration and sound and interaction of the lubricants with the process fluids).
• Contact mechanics models (probabilistic and deterministic) and design of the machine members associated with tribological categories; dimensional analysis.
• Tribochemical modeling.
• Surface effects and nanotribology.
• Tribology of data-storage systems.
• Limitations of the tribology models and misuse of a tribology concept.

What types of tribological and lubrication models are used in the industry? What are they based on?
• Design of brakes: empirical friction and wear equations, analytical/numerical friction heat generation and transfer based on empirical coefficients of friction and heat dissipation obtained via a dynamometer and full scale testing.
• Properties of lubricants.
• Empirical oil film thickness and oil leakage dependencies on operating parameters of the mechanism, fish-bone diagram of the oil loss mechanics and failure mode and effects analysis (FMEA).
• Design of sliding and rolling bearings and toothed gearing: analytical/numerical models of hydrodynamic, hydrostatic and elastohydrodynamic lubrication. 
• Static sealing, dynamic sealing (including piston rings).
• CFD modeling of the various lubricating mechanisms.

What significance has surface texture in a tribology modeling?
• Engineering and tribological effects of surface texture.
• Inefficient use of surface texture parameters in contemporary tribology models.
• The knowledge of the surface texture standards and surface metrology is a must in a successful development and application of many tribological models.

What improvement do you think is needed in the field of tribology models and software?
• Develop tribological models with a consideration of a fluid flow, dynamic coefficients of friction, variable heat transfer and a proper account of surface texture; make them user friendly.
• Initiate development of the special tribology models as a function of the operation of a whole relevant unit/mechanism/machine.
• Wider use methods of the electrical analogy in connection with friction heat dissipation modeling.
• Disseminate knowledge of the dynamometers’ design, operation of the data acquisition techniques as sources for advanced modeling.
• Initiate verification/upgrading of a Dunaevsky-Kudish friction heat transfer model. 
• Expand utilization of a cellular-automata (Dunaevsky-Vick) model of a moving heat source.
• Find practical application of the fractal methodologies.
• Develop a composite surface model for general surfaces and verify the existing composite surface model for Gaussian surfaces.

You can reach Valéry Dunaevsky at valdunay@aol.com.