Avraham Harnoy

Contact Info

Email: avraham.harnoy@njit.edu
Office: 319 Mech
Phone: 973-596-3350
Dept: Mechanical Engineering

About Me


Dr. Harnoy is a professor in the Department of Mechanical and Industrial Engineering at New Jersey Institute of Technology where he has taught since 1986.  He has been engaged in teaching, and research in tribology, artificial joint implants, bearing design and lubrication, fluid mechanics and rheology of viscoelastic fluid.


Dr. Harnoy has many years of diversified industrial and academic experience in several countries, has spent eight years of his career in industrial research and development positions in industry.  The remainder of his career has been in academic positions, combining teaching and research. 


The first significant scientific contribution of Dr. Harnoy is in flow of viscoelastic fluids. This work includes a basic contribution to continuum mechanics in the form of a new definition of time derivative for stress and strain-rate tensors for viscoelastic fluids.  He applied this new definition to formulate new constitute models of viscoelastic fluids (J. Fluid Mechanics, 1976, vol. 76. p. 501).  The new models agreed, for the first time, with experiments at high shear rate flow of viscoelastic fluids, such as in bearings and gears lubrication. Later, he applied this theory to analyze the performance of hydrodynamic lubrication with viscoelastic lubricants under steady and dynamic loads, and boundary layer flow.  This work explained the improvement in the hydrodynamic lubrication performance of multigrade oils. He also applied this theory for analyzing viscoelastic boundary layers. This viscoelastic fluid equation became the basis of many published research work by other scientists around the world.


The second significant contribution has been the developing a dynamic friction model (Wear, J. of science and Technology, Oxford, Vol. 12, 1994).  This model has been used later in a project, "Modeling and compensation of Friction in Control", in cooperation with Dr. Friedland. This project has been supported by a grant from the National Science Foundation. Dr. Harnoy is currently continues this research by applying this model to artificial joints, which operate under dynamic loads.


On the experimental side, Dr. Harnoy has extensive experimental experience. He developed laboratories, and designed a variety of testing rigs.  He has published his theoretical and experimental research.


Dr. Harnoy served as a consultant to several companies including consulting to NASA Ames on the gyroscope bearings in the space station, as well as consultancy to Foster Wheeler Energy Corporation in bearing design of large bearings for coal pulverization in power stations.


Dr. Harnoy published a textbook “Bearing design in Machinery, Engineering Tribology and Lubrication” Published by Marcel Dekker Inc. 2003, and later took over by the publisher Taylor & Francis NRC.


Dr. Harnoy holds a B.S. (1961), M.S. (1967) in Mechanical Engineering and Doctor of Science (1972) in Mechanics, all from the Technion-Israel Institute of Technology.  His doctoral advisor was the late Professor Marcus Reiner, who is the well-known founder of the discipline of rheology.





  • Technion, Israel Institute of Technology, DSc 1972

  • Technion, Israel Institute of Technology, MS 1977

  • Technion, Israel Institute of Technology, BS.1961


Research Interests

Dr. Harnoy is investigating all aspects of bearings and bearing lubrication in machinery. In particular, design, heat transfer, material selection, testing and analysis of hydrodynamic, hydrostatic and rolling-element bearings as well as unique designs such as hybrid bearings.   Design and development testing machines for dynamic friction, tribology of bearing materials and lubricants. He is conducting research in modeling and measurement of dynamic friction in bearings. Dynamic friction models are used for friction compensation for enhancing the precision of motion in control systems. This work includes simulation and measurements of dynamic friction effects such as stick-slip friction and friction induced vibrations. In addition, research is conducted in flow behavior of viscoelastic fluids such as multigrade oils, as well as synthetic lubricants.  

Current Research

Recent activity is the investigation of the performance, design and material properties of orthopedic joint implants.



  • Avraham Harnoy, Bearing Design in Machinery, Engineering Tribology and Lubrication, Marcel Dekker Inc., ISBN: 0-8247-0703-6, 628 pgs., 2003.

Selected Publications  

  • Radek, N., Wrzalka, Z., Sharlapro, J., Broncek, J. and Harnoy, A., "Properties of Anti-wear Electro-Spark Coatings", Materials Conference proceeding Kielce, Poland, 29-30 September 2011
  • Amin J., Friedland B. and Harnoy A. “Implementation of a Friction Estimation and Compensation Technique” IEEE Control Systems, Vol. 17, No. 4, pp.71-76, 1997   
  • A. Harnoy, “Simulation of stick-slip in control systems,” Tribology Transactions, vol. 40, pp. 360-366, 1996.   
  • A. Harnoy and M. M. Khonsari, “Hydro-Roll: A Novel Bearing Design With Superior Thermal Characteristics,” Tribology Transactions, vol. 39, No. 2, pp. 455-461, 1996. 
  • H. Rachoor and A. Harnoy., “Modeling of Dynamic Friction in Lubricated Line Contacts for Precise Motion Control, ” Tribology Transactions, STLE, vol. 39, 2, pp. 476-482, 1996.   
  • A. Harnoy, “Model Based Investigation of Friction During the Start-up of Hydrodynamic Journal Bearings,” Transactions of the ASME, J. of Tribology, Vol. 117, pp. 667-672, Oct. 1995.  
  • A. Harnoy, B. Friedland, R. Semenock, H. Rachoor and A. Aly, “Apparatus for Empirical Determination of Dynamic Friction,” Proceedings of ACC conference, Baltimore, Maryland, June 29-July 1, vol. 1, pp. 545-550, 1994.  
  • A. Harnoy, B. Friedland and H. Rachoor, “Modeling and Simulation of Elastic and Friction Forces in Lubricated Bearings for Precise Motion Control,” Wear, J. of science and Technology, Oxford, vol. 12, p.p. 155-165, 1994. 
  • A. Harnoy and B. Friedland, “Dynamic Friction Model of Lubricated Surfaces for Precise Motion Control,” Tribology Transactions, vol. 37, no. 3, pp. 608-614, July 1994.
  • A. Harnoy, “The Relation Between CDM Instability and Deborah Number in Differential Type Rheological Equations” Rheologica Acta, Vol. 32, pp. 483-489.   
  • A. Harnoy and H. Rachoor, “Angular-Compliant Hydrodynamic Bearing Performance Under Dynamic Loads,” ASME Transaction, Journal of Tribology, Vol. 115, pp. 342-347, 1993.   
  • A. Harnoy, “Enhancing Machine Tool Performance By Non-contact Hydrostatic Bearings,” presented at 9th International CAD/CAM, Robotics and Factories of the Future conference, Newark 18-20, Proceedings, Published by Elsevier, 1993.   
  • A. Harnoy 1997 and H. Zhu, “The role of the Elasticity of the lubricant in Rotor Dynamics,” Tribology Transactions, Vol. 34, pp. 353-360, 1991.  
  • A. Harnoy, "Investigation of Instability in Rheological Equations of the Differential Type". Proceedings, Third European Rheology Conference, 1990. Published by Elsevier Applied Science. 1990, pp. 208-210.  
  • A. Harnoy and S.S. Sood, “Viscoelastic Effects in the Performance of Dynamically loaded, Short Journal Bearings,” Transactions of the ASME, Journal of Tribology, vol. 111, pp. 555-556, July 1989. 
  • A. Harnoy "Normal Stresses and Relaxation Effects in Viscoelastic Boundary Layer Flow Past Submerged Bodies." Journal of Rheology, Vol. 33, 1989, pp. 93-117
  • A. Harnoy, " Investigation of Automatic Assembly Methods" CAD/CAM, Robotics and Factories of the Future, Vol. 3. Robotics and Plant Automation. Published by Springer-Verlag, Berlin, 1988, pp. 49-53.  
  • A. Harnoy and S.S. Sood, " Optimization of Angular Position and Location Accuracy in Robots". Robotics and Factories of the Future, Published by Springer-Verlag, Berlin, 1987 pp. 338-345.  
  • Harnoy, A., "An Investigation into the flow of Elastico-Viscous Fluids Past a Circular Cylinder". Rheologica Acta , Vol. 26, 1987, pp. 493-498.  
  • Harnoy, A., "Squeeze Film Flow of Elastic Fluids at Steady Motion and Dynamic Loads", ASME Transactions, Journal of Tribology, 1987, Vol. 109, pp. 691-695.  
  • Harnoy, A. and Radajewski, W., "Optimization of Grain Drying- with Rest Periods", Journal of Agricultural Engineering Research (U.K.), Vol. 27. 1982, pp.291-307. 
  • Harnoy, A., "The role of the Fluid Relaxation Time in Laminar Elastico-Viscous Boundary Layers". Rheologica Acta, Vol. 18, 1979, pp. 220-216. 
  • Harnoy A., "An Analysis of Stress Relaxation in Elastico-Viscous Fluid Lubrication of Journal Bearings", ASME Transactions, Journal of Lubrication Technology, Vol. 100, April 1978, pp. 287-295. 
  • Harnoy, A., "Three Dimensional Analysis of the Elastico-Viscous Lubrication of Journal Bearings", Rheologica Acta, Vol. 16, pp. 51-60, 1977.  
  • Harnoy, A., "Stress Relaxation Effect in Elastico-Viscous Lubricants in Gears and Rollers", Journal of Fluid Mechanics, Cambridge U.K., Vol. 19, 1976, pp. 501-517.
  • Harnoy, A. and Phillippoff, W., "Investigation of Elastico-Viscous Lubrication of Sleeve Bearing", ASLE Transactions, Vol. 19, 1976, pp. 301-308. 
  • Harnoy, A. and Friedman, M.Y., "Decreasing Angular Position Errors in Machine Tools by Adding a Degree of Freedom", Israel Journal of Technology, Vol. 13, 1975, pp. 287-292.
  • Harnoy, A. and Hanin, M., "Second Order, Elastico-Viscous Lubricants in Dynamically Loaded Bearings", ASLE Transactions, Vol. 17, 1974, pp. 166-171.
  • Harnoy, A., "The Effects of Stress Relaxation and Cross Stresses in Lubricants with Polymer Additives", CNRS publication, No. 233, 1974, pp.37-44. 
  • Harnoy, A. and Reiner, M., "Second Order Stresses in Classical Infinitesimal Elasticity", Israel Journal of Technology, Vol. 11, 1973, pp. 325-328.   
  • Levy, K., Harnoy, A., and Bar-Nefi, S., " Composite Bearing, Rolling Element with Hydrodynamic Journal", Israel Journal of Technology, Vol. 10, 1972, pp. 271-278.
  • Friedman, M. and Harnoy, A., "Optimization of Angular Positioning Time in Numerically Controlled Machine Tools", Israel Journal of Technology, Vol.10, 243-246. 
  • Reiner, M., Hanin, M. and Harnoy, A., "An Analysis of Lubrication with Elastico-Viscous Liquid", Israel Journal of Technology, Vol. 7, 1969, pp. 273-279.