Consulting Mechanical Engineers

Bearing and FEA Specialists

Developers of COBRA® Bearing Analysis Software

Our Services Our Software Our Team Expert Witness

Our Services

Rolling Element Bearings

Specializes in Design, Analysis, Selection and Failure Analysis as related to Rolling Element Bearings.

Diverse Applications

Areas of involvement range from small bearings for high speed spindles to large bearings in excess of 20 feet in diameter.

Analysis of Equipment

We are also skilled in finite element stress, thermal and dynamic analysis of equipment.

Expert Witnesses

We have served as Technical Experts regarding Bearings and Stress Analysis as support to attorneys in arbitration and litigation on related issues.

Consulting Support

We are available to assist you and your staff in defining and solving any reoccurring bearing problems your company may be experiencing, or in conducting design audits on proposed bearing systems.


Given at our office in Bethlehem, PA or at client sites.

Our Software

COBRA (Computer Optimized Ball and Roller bearing Analysis) software family


ElastoHydrodynamic Lubrication

This entry-level software package is designed for the mechanical designer/engineer. COBRA-EHL analyzes the interaction of up to 6 bearing rows on a rigid shaft under combined Radial, Thrust, and Moment Loading in 3 degrees of freedom. The program has a visual front end that allows the user to interactively change input data and preview results without having to exit the program. Lubricant Film Thickness and associated Life Adjustment Factors are internally computed. COBRA-EHL can analyze both solid and spring preloaded bearings. Misalignment, axial float and hybrid bearings are included. The program includes Radial and Angular Contact ball bearings plus Cylindrical, Tapered and Spherical roller bearings. Bearing and System Classical L10 Fatigue Life is calculated using the ANSI/ISO Standard Rating Method. Timken BRR and Life are computed for Tapered Roller bearings. COBRA-EHL also contains internal geometry estimation based on envelope size of the bearing. This version includes full element results output and analysis of crowned rollers using the laminated roller model.

Limitation: shaft speeds under 1 million DN (DN=Bearing bore in mm x shaft rpm).

Click here to view/download specifications

Available now. Contact us for more information.


Analyzes up to 6 bearing rows of various types mounted on a rigid shaft under 5 degree of freedom loading. This software was deeded to JVPA upon the passing of John Rumbarger, the program’s originator. This Low to Moderate speed analysis is used in many industries where high speed effects on bearing performance are not required. Bearing types include cylindrical roller, angular contact ball, thrust ball, spherical roller, tapered roller bearing types. GENROL is also used in the large slewing bearing industries to quantify performance of three row roller, four point contact ball and crossed roller type bearings using an “approximate modeling” method. The program includes the ability to model structural deformation effects by imposing Out-of-Round, Out-of-Flat and Angular Tilt at each rolling element. These structural effects cam be determined by Finite Element analysis of the structures the bearing is mounted in. JVPA has the capability to conduct such analysis using the ANSYS FEA Software. Program results include L10 Life, Rolling Element Load Distributions, Hertz contact stress, Hertz ellipse size, crowned roller axial stress profile using the laminated roller model introduced by A.B. Jones and bearing non-linear stiffnesses in 5 DOF. The user can also generate the sub-surface stress vs depth distribution beneath the highest loaded ball or roller in the bearing. These stresses include the Principle, Maximum Shear, Octahedral Shear and Von Mises stresses. This feature is important when setting case depths for large diameter induction hardened slewing bearing races.


Analyzes a 4 Point Contact Ball Bearing under loading in 5 DOF. The theoretical basis in 4 Ball is an extension of the A.B. Jones mathematics for 2 point or Angular Contact bearings. An iterative method is employed that determines that each individual ball must satisfy the ball load deflection equations for ALL contacts. This is a more rigorous and exact method than that of approximations when using GENROL to analyze a 4 Point ball bearing. This method can determine if a ball is in simultaneous contact with all 4 contact points in the bearing. This type of contact will influence the load distributions, stresses, life and torque for such bearings. Raceway distortion input and modeling the bearing with a “reduced” ball count is included in the software. Also, Oscillating Life is calculated.


Application of two 4 Point Ball bearings stacked next to each other to represent the performance of 8 Point Ball Bearings becoming popular in slewing bearing applications. The bearing set can be loaded in 5 DOF and can include raceway distortion input as present in GENROL and 4 BALL. Comprable output results are available as from GENROL and 4 BALL.


Advanced High Speed

COBRA-AHS analyzes up to 5 bearing rows on a flexible or rigid shaft loaded in 5 degrees of freedom. Bearing models include high-speed ball, cylindrical roller and tapered roller bearings. Housing and shaft distortion effects due to out-of-round, out-of-flat and local slope at each rolling element are included. Bearing heat generation and cage forces are calculated. Roller edge stress concentration is calculated due to local roller misalignment for crowned rollers and displayed as a 3D color contour plot. Bearing fit-up analysis is performed using classical thick ring press fit theory as well as a seamless interface to ANSYS FEA models of the bearing row that are automatically constructed and analyzed with results returned to COBRA. Shaft and housing sleeves are also included if present. Data I/O is easy via a visual front end and numerous pre-defined results plots. Skid load estimates and duty cycle analysis are included. Individual bearing temperature models are included for estimating inner and outer race operating temperatures using the pre described ANSYS models. An iterative thermal/dimensional interaction analysis option is also available. COBRA-AHS is available in 3 versions- Baseline, Intermediate and Full. Please view the related .pdf file for details.

Click here to view/download specifications

Available now. Contact us for more information.


COBRA-2G, the 2nd Generation of COBRA-AHS, is a High Speed bearing analysis program that analyzes the behavior of up to 5 bearing rows on a flexible or rigid shaft loaded in 5 DOF. COBRA-2G retains all of the original features of COBRA-AHS with the addition of a Split Inner Race (3 Point) bearing model with or without Under Race Lubrication/Cooling and is integrated with ANSYS to perform fit-up and temperature-distribution analyses, including iterative thermal/dimensional interaction and sub-surface stress distribution. Additional features include 6 DOF Ball Kinematics for prediction of Sliding and Skidding as well as the legacy Jones Race Control model. A physics based Non Linear Thermal Viscoelastic (NLTV) mixed film traction model incorporating a Maxwell Viscoelastic Fluid and Johnson-Trevaawerk Traction formulation is integrated into the contact analysis for improved estimates of heat generation and contact flash temperature. Stress models include Heat Treat Residual Stress and Hoop Stress from fits and operation speed. COBRA-2G automatically prepares files for input into the Wedeven Associates Single Contact Model (SCM) for rigorous analysis of Mixed Elastohydrodynamic Lubrication (EHL) loaded contacts with actual surface topography. COBRA-2G has been benchmarked against high speed/high thrust measured bearing Heat Generation and Race Temperature data. COBRA-2G is scheduled for release during the 1st Quarter of 2022.

Click here to view/download specifications

Our Seminars

Topics available:

  • Types and Applications
  • Standards and Clearances
  • Failure Modes, Life and Reliability
  • Materials and Processes
  • CAD and Optimized Applications
  • Kinematics and Special Topics

Past seminars:

  • Introductory Rolling Element Bearing Design
  • Advanced Rolling Element Bearing Design

Our Team

Joseph V. Poplawski

Mechanical Engineer

Steven M. Peters

Mechanical Engineer

Hermes Galatis

Structural/Mechanical Engineer

Robert Flower

Chief Software Engineer

Our Partners

Our Clients

Click to show client list 62
  • Acutus Gladwin - Continuous Caster Segment Roll Bearing Failures
  • Advanced Energy Supply Co. - Drilling Rig Bearings & Seals
  • Allied Signal Aerospace - APU Bearing Failures
  • ARCO Alaska - RB211 Gas Turbine Mainshaft Bearing Life Review
  • Arthur D. Little, Inc. - Contact Stress Analysis
  • Barbour Stockwell Turbine Co. - 40,000rpm brgs.
  • Beloit Corporation - Paper Slurry Pump Brgs. & Seals
  • Bethlehem Steel Corp. - Cold Rolling Model Additions, Vertical Edger Roll Brgs., Science of Flat Rolling Seminar, CTM WR Brg./Chock FEA Analysis, HSM WR Brg./Chock FEA Studies, HSM/WR Bending/Crown Studies, 5 Stand CTM Set-Up Model Dev., Coil Winding Model, Caster Segment Rolls
  • BTU, Inc. - Motor Bearing/Grease Problems
  • Caterpillar Paving Prod. - Eccentric Pod Bearings
  • Cessna - High Speed ACU Bearing Failures
  • Cleveland Utilities - Centrifuge Bearing Failures
  • Combustion Engineering - Coal Pulverizer Brg. Failures, Pulvirizer Brg. Redesign - all Units, Boiler Stoker Brg. Failures, Boiler Feedwater Pump Brg. Failures
  • D.G. Peterson Assoc. - Ski lift chair support bearing failures
  • E & M Power - Motor Bearing Failures
  • Energy Technology, Inc. - Drilling Rig Brgs.
  • FEC/UNITED - Mill Drive Static Stress Rating
  • Franklin Institute Research Labs - 100,000 rpm Brgs.
  • Fuller Company - Brgs. on Crushers, Separators, Clinker Compaction Model, Roll Sleeve Slip, Crushing Roll Spalling Failure, FEA Stress Analysis on Various Components, Stacker/Reclaimer Slew Bearing
  • Gardener Denver, Inc. - Screw Compressor Bearing Failures
  • GE CONMEC, Inc. - High Speed Impeller Test Spindle
  • General Dynamics - FEA Stress MSW Pump Casings, Bearing Excitation Model, Motor Bearing Design (Seawolf) Quiet Bearing Development, Catcher Bearings for Magnetic Bearing Supported Rotor, Hybrid Bearings
  • General Electric Company - 6 Hi Model with Roll Shift
  • Glowe-Duffy Inc. - WR Bending Brg/Chock FEA Analysis
  • Grundler Crusher Co. - Drive & Hammer Mill Brgs.
  • Harley Davidson - seminar
  • Harris Corp. - Printing Press Bearers, Bearings & Seals
  • Hughes Helicopter, Inc. - APACHE AH64 Main Rotor Brg. Failures
  • HYTORC - FEA Stress of Threads in Clampnut & Hydraulic Torquing Wrench
  • Ingersoll Rand Energy Systems (formerly - High Speed Design for Microturbines
  • Ingersoll-Rand Company - Compressor Brgs.
  • Inland Steel - Bar Mill Torque Amplification Study
  • ITB Inc. - Bearing Raceway FEA Stress Analysis
  • Jerome Medical Group - Cervical Spine/Collar FEA Model, Carbon Composite Halo Design
  • Keystone Rod & Wire - Reliance Motor Bearing Failures
  • LAFARGE Cement - Clinker Crusher Bearing Issues, Crushing Roll Journal Failures, Gearbox Bearing Failures
  • Lakeside Equipment Company - 6’ Support Roll Distress
  • Leybold Vacuum Products - Vacuum Pump and Motor Bearing Failures
  • Lukens Steel Co. - Combustion Air Fan Bearing Failures
  • McDonnell Douglas Helicopter Co. - APACHE Crash/ Tail Rotor Swashplate Bearing Problems
  • Motorola - Iridium System Earth Tracking Terminal Bearing Problems
  • NASA - Space Shuttle LOX Turbopump Brg. FEA Contact Stress Analysis
  • NASA LeRc - New Bearing Life Theories
  • National Cement Co. - Cement Crusher Brg. Preload
  • NTN Bearing Co. - FEA Stress Analysis of Bearing Systems for large Truck Wheels
  • Olsen Technologies, Inc. - 96” Gate Valve Failure (FEA)
  • Pennsylvania Crusher Corp. - Bearing Design and Failure Analysis on various mining equipment
  • Polysius Corporation (Germany) - Clinker Crushing Model
  • PRETECH Inc. - Howden Wind Turbine GB Bearing Failures
  • Raritan River Steel Co. - Morgan Gearbox Gears/Bearing Failures
  • Rexroth Corporation (USA & Germany) - CAD System Review, 12”, 4000 psi Valve Failures (FEA)
  • SI Handling - Hurth Transmission Bearing & Seal Failures
  • Southwestern Portland Cement Co. - Motor Shaft Stress , 600 mm Bearing Failures
  • Sterling Drug Co. - HVAC Fan Bearing & Seal Failures
  • STI Optronics - Vertical Shaft Centrifuge Bearings
  • Structural Dynamics Research Corp. - ID Fan Brgs., Caster Turret Brg. @ Great Lakes, Starker/Reclaimer Slewing Brg.
  • Thermoguard Company - Hammermill Brg. Overtemperature
  • TLT Babcock - 1.3 Million SCFM Mine Shaft Fan Bearing Failures
  • Torrington Company - CTM BUR Brgs. Brg. Preload Practice & Spacer Grind
  • VALCO Industrial Corp. - Brgs. & Seals for Gun Drills
  • Voest - Alpine AG, Linz, Austria - Caster Turret Brg. Design Review
  • Wetherill Associates - Technical Support on Various Bearing Application Issues

Some COBRA-AHS Users

Click to show sample list of users 30
  • Bell Helicopter
  • Boeing Helicopter
  • Borg Warner Turbo Systems
  • Blue Origin
  • Clipper Windpower
  • CW Bearing
  • Dunlee-Phillips Healthcare
  • Eaton Aerospace
  • Federal Aviation Agency
  • GE Aircraft
  • GE China R&D
  • GE India Tech Center
  • Honeywell
  • Jet Propulsion Lab
  • KAWASAKI Gas Turbine Division
  • L3 Communications
  • Lockheed-Martin Space Systems
  • MOOG Aircraft Group
  • MOOG Space & Defense Systems
  • NASA Glenn Research Center
  • NASA Marshall Space Center
  • Naval Surface Warfare Center
  • Northrop Grumman
  • Pratt & Whitney
  • Rocketdyne
  • Samsung
  • Teledyne Turbine Engines
  • Trane Technology Center
  • US ARMY - Redstone

Our Publications

Click to show publications 30
  • Jones, A.B. and Poplawski, J.V., "A Computer Study of Design Parameters on Rolling Element Bearing Performance", Bearings Conference at Dartmouth University, September, 1966.
  • Poplawski, J.V., and Mauriello, J. "Skidding in Lightly Loaded High Speed Ball Thrust Bearings", ASME Joint Lubrication Conference, San Francisco, CA, June, 1969, 69 - LUBES - 20.
  • Poplawski, J.V., "Static and Dynamic Seals - ASME Literature Review for 1968", ASME Trans., Journal of Lubrication Technology, April, 1970.
  • Poplawski, J.V., "A Method to Predict Slip and Cage Forces in a High Speed Roller Bearing", Master of Science Thesis, Rensselaer Polytechnic Institute, June, 1970.
  • Poplawski, J.V., "A Method to Predict Slip and Cage Forces in a High Speed Roller Bearing", ASME Transactions. Journals of Lubrication Technology, April, 1972.
  • Panelists, "Trends in Concentrated Contacts", ASME Lubrication Symposium, Atlanta, GA, May, 1976.
  • Poplawski, J.V., Predicting Operating Temperatures in Rolling Element Bearings for Backup Rolls", presented at the 1976 AISE Annual Convention, Pittsburgh, PA and published in Iron and Steel Engineer, March 1977. Subsequently translated into French and German.
  • Poplawski, J.V., "Using a Computer Model to Determine the Effects of Chock Distortion on Backup Roll Bearing Load Distribution and Life", Oral Presentation at the 1981 AISE Annual Convention.
  • Poplawski, J.V., and Seccombe, D.A., "Mathematical Modeling of Cold Rolling in Tandem Mills", 1979 AISE Annual Convention, Cleveland, OH and publication in the Iron and Steel Engineer, December, 1980. Won AISE Kelley Award for 1980.
  • Cichelli, A.E. and Poplawski, J.V., "Tribology and Energy Considerations in the Rolling of Steel", Energy Sources and Technology Conference, New Orleans, LA, February, 1980 and ASLE Annual Meeting, Anaheim, CA, May, 1980.
  • Poplawski, J.V., "Roll and Strip Thermal Considerations", International Conference on Flat Rolling", September, 1980 and publication in the conference proceedings, Japan.
  • Poplawski, J.V., Chen, T.F. and Seccombe, D.A., Influence of Rolling and Roll Bending Forces on Strip Crown”, Presented at the 1981 AIME Mechanical Working and Steel Processing Conference; Pittsburgh, PA, Oct 1981 and published as part of the conference proceedings.
  • Poplawski, J.V. "Condensed Work Roll Temperature Model", Presented at the 1984 Mechanical Working and Steel Processing Conference, Chicago, IL, and published as part of the conference proceedings.
  • Poplawski, J.V., "Analytical Design of Backup Roll Rolling Bearings - A Step Beyond the Catalogue", 1985 ASLE Annual Meeting, Las Vegas, Nevada, May, 1965. (Oral Presentation)
  • Poplawski, J.V., "Friction in Cold Rolling", 1985 ASLE Annual Meeting, Las Vegas, Nevada, May, 1985. (Oral Presentation)
  • Poplawski, J.V., "Rolling Element Bearing Design Seminar", 1986 AISE Rolling Mill Conference Seminar on The Lubrication Engineering Program and Its Impact On Profitability and publication as a special AISE proceeding, Philadelphia, PA, April, 1986.
  • Poplawski, J.V., "Continuous Caster 'Turret Bearings - Will Yours Survive", Presented at the 1987 ASLE Annual Meeting, Houston, TX, May, 1987. (Oral Presentation)
  • Poplawski, J.V., "Analysis of Continuous Fracture Mills", 22nd International Rock Products Conference, Chicago, IL, December 1986.
  • Poplawski, J.V., "Friction Distribution in Cold Rolling Analysis", Presented at the 1989 ASME Winter-Annual Meeting, Chicago, IL, December, 1989 and published in ASME MD-Vol. 10 entitled Friction and Material Characterization.
  • Poplawski, J.V., "Modern Engineering Approach to Solving Rolling Bearing Problems", Lehigh Valley Section, ASLE, 1981. (Oral Presentation)
  • Poplawski, J.V., “Skidding in High Speed Bearings”, Lehigh University, 1980.
  • Poplawski, J.V., "Mathematical Models for Cold Flat Rolling of Steel", Presented at the Conference on Computer Assisted Analysis of Rolling Processes, Battelle Memorial Institute, Columbus, OH. (Oral Presentation)
  • Poplawski, J.V., Peters, S.P. and Rumbarger, J.H., "Economic Advantages Gained Through Computerized Analysis of Rolling Bearing Systems', oral presentation at the 1992 STLE Annual Meeting in Philadelphia, PA.
  • Rumbarger, J.H. and Poplawski, J.V., "Correlating Computerized Rolling Bearing Analysis Techniques to the ISO Standards on Load Rating and Life", 1992 STLE Annual Meeting in Philadelphia, PA, STLE Tribology Transactions, vol. 37 (1994), 4, pp 793 - 801.
  • Poplawski, J.V., "Merging Technologies Solve Rolling Mill Bearing Failures," Power Transmission Design, November, 1992.
  • Zaretsky, E.V., Poplawski, J.V., and Peters, S.M., "Comparison of Life Theories for Rolling - Element Bearings," Tribology Transactions, 39, 2, pp. 237 - 248 and 501 - 503, (1996).
  • Poplawski, J.V., Peters, S.M., and Zaretsky, E.V., "Effect of Roller Profile on Cylindrical Roller Bearing Life Prediction," Parts I and II, STLE Annual Meeting, Nashville, TN, May 7 - 11, 2000.
  • Zaretsky, E.V., Poplawski, J.V. and Miller, C.R., "Rolling Bearing Life Prediction - Past, Present, and Future," International Tribology Conference 2000, Japanese Society of Tribology, Nagasaki, Japan, October 30 to November 2, 2000.
  • Poplawski, J.V., and Wang, S., "Ceramic Bearing Development Program for Sea Water Pump Application," Industrial Tectonics Bearing Corp. Final Report, March 31, 1993, General Dynamics Electric Boat Division Contract No. SNC 140-025.
  • Poplawski, J.V., Atwell, D.A., et. al, "Predicting Steady State Temperature, Life, Skid and Film Thickness in a Grease Preloaded Hybrid Ball Bearing," ASME International Gas Turbine Conference, Houston, TX, Paper No. 95-GT-392.

Our Awards

 AISE Kelley Award

Recipient of 1980 AISE Kelley Award for best work published during the year that significantly enhanced steel industry technology. Paper entitled "Mathematical Modeling of Multi-Stand Steel Strip Rolling.

Expert Witness

Click to show firms
  • Baker & Botts L.L.P., Washington, D.C. - Customs Issue - Scroll Compressor Anti-Rotation Device
  • Boardman, Suhr, Curry, & Field, Madison, WI - Motor Bearing Failure as cause for plant fire - Representing Oscar Meyer Food Corp.
  • Cozen & O'Connor, Philadelphia, PA - Sikorsky CH53 Crash - Representing Kaydon Bearing Company
  • D.G. Peterson, Boston, MA - Ski Lift Chair Support Bearing Failures
  • Kern & Wooley, Irving, TX - APACHE AH64 Crashes - Representing McDonnell Douglas Helecopter Company
  • Lague, Newman & Irish, Muskegon, MI - Sikorsky CH53E Crash - Representing Kaydon Bearing Company
  • Mayer, Brown & Platt, Chicago, IL - Great Lakes Dredge Bearing Failure - Representing General Electric
  • McGuire, Woods, Battle & Boothe, Richmond, VA - Air Handeling Fan Bearing & Seal Failures - Representing University of Virginia Medical Center
  • Weingarten, Schurgin, Gagnebin & Hayes, Boston, MA - Motor Bearings & Seals - Representing BTU, Inc.
  • Wiggens & Dana, New Haven, CT - High Speed Train Wreck - Representing New Haven Railroad
  • Zimmer & Kunz, Pittsburgh, PA - Allegheny Ludlum BOF Bearing Failure - Representing Cooper Bearing Company

Contact Us

44 East Broad Street
Suite 207
Bethlehem, PA 18018