March 2019 Newsletter

“Published Now and Then (When We Have Something We Want To Share)”

2018 was a very big year for Xdot! The highlights included solving vibration problems for clients, researching topics in rotating machinery and providing foil bearings to customers on three continents.
Foil Bearing Innovations
  • The Xdot wing foil bearings are proving to be a game-changer. The idea of providing oil-free, affordable bearings to the world in a standardized yet flexible manner is gaining momentum. In 2018, these bearings were tested for different applications that included aerospace, industrial commercial, automotive and power generation.
  • The Xdot wing foil thrust bearing has now demonstrated 20psi load capacity at 80,000rpm. This performance milestone demonstrates the technology is capable of handling thrust conditions that are relevant to applications as demanding as UAVs. The testing was conducted using Xdot’s new high speed thrust performance rig, which is designed to operate at speeds up to 130,000rpm.

Xdot High Speed Thrust Bearing Test Rig
  • The Xdot wing foil radial bearing has now demonstrated successful performance at high temperature conditions relevant to some of the most demanding gas turbine applications. The testing was done using a new Xdot test rig which is equipped with a high temperature testing environment. The rig allows for radial bearings to be subjected to thousands of consecutive start-stop cycles at over 1000 °F. This phase of testing has resulted in identification of a new high temperature coating for foil bearings.
Xdot High Temperature Radial Bearing Test Rig (With Furnace)
  • Continued development of the QC process for foil bearing production at Xdot has led to improvements in surface coatings, wing foil design, and top foil fabrication. The QC testing rig for thrust bearings, which began operation in 2018, has been used to identify areas for cost reduction and process improvement.
  • Preliminary work has begun at Xdot to develop a foil bearing software package to model and predict performance of radial and thrust foil bearings. The goal of this project is to leverage Xdot test data, along with software development experience to create a commercially available software package that may be used to guide design and analysis of foil bearing machinery.
Research & Development News
  • As part of an externally funded R&D program, Xdot has been developing a multiphysics model of water lubricated bearings. The primary feature of this software is the ability to model the transition between the three primary operating regimes: hydrodynamic, mixed, and boundary. This code utilizes a finite element solution to the Reynolds equation, and couples this solution to the shaft motion, liner deformation, and surface contact.
  • Xdot has continued testing with a sub-scale rig for investigating water lubricated bearings. The testing performed by Xdot in 2018 has led to improved understanding of the influence of bearing wear and friction on overall performance. The data from this testing effort will be used for validation of the Xdot bearing analysis model.
  • Xdot’s Dr. Erik Swanson is a co-author of a paper that has been accepted to the 2019 ASME/IGTI Turbo Expo. This paper describes foil thrust bearing testing in a high-pressure environment.
  • Xdot’s second wing foil bearing patent was awarded in 2018. Two additional patents are expected to be issued in 2019.
  • In 2018 we upgraded our facility with the addition of a large air compressor and new equipment for bearing inspection and quality control.
Rotordynamics Consulting and Upcoming Training
  • Spring 2019 Short Course: Practical Rotordynamics For Real Machinery – This year’s Spring short course is scheduled for April 8-11 in Charlottesville Virginia. Xdot has been offering this course since 2012. For more details visit
  • In 2018 Xdot performed rotordynamics studies for a very wide range of rotating machinery. This included lateral and torsional analyses for applications from oil and gas, refrigeration, aerospace, vacuum equipment, and medical devices.
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