Laboratory for Dynamics of Machines and Structures 
A Smooth Contact-State Transition in a Dynamic Model of Rolling-Element Bearings
 M. Razpotnik, G. Čepon and M. Boltežar
Journal of Sound and Vibration, Volume 430, 15 September 2018, Pages 196–213

download pdf   doi.org/10.1016/j.jsv.2018.05.041
Abstract
We present a new formulation to calculate the response of a system containing rolling-element bearings operating under a radial clearance and a dominant radial load. The nonlinear bearing force- and stiffness-displacement characteristics in combination with the bearing clearance necessitate an advanced numerical analysis. The response of a shaft-bearing-housing assembly can be unstable in the transient regions, e.g., at the start of a system run-up or when passing the critical speed of a system. This can lead to long computational times or even to non-converged solutions. In this paper, a new analytical bearing-stiffness model is presented that is capable of overcoming these problems by smoothing the nonlinear bearing force- and stiffness-displacement characteristics in the discontinuous regions. The smoothing is implemented on the deformation scale. The proposed model is modular, allowing us to define a specific value of the smoothing to each rolling element that comes into contact. A simple case study that involves two bearings of different types (ball and cylindrical roller) is presented. They support an unbalanced rotor, subjected to a constant angular acceleration. We show that a small smoothing value can significantly enhance the numerical calculation of the chosen system in terms of speed and stability.
Authors

Researcher

Matej Razpotnik, PhD Student

  Ladisk, Faculty of Mechanical Engineering, University of Ljubljana
  matej.razpotnik@fs.uni-lj.si
  +386 1 4771 229

Assistant Professor

Gregor Čepon, PhD

  Ladisk, Faculty of Mechanical Engineering, University of Ljubljana
  gregor.cepon@fs.uni-lj.si
  +386 1 4771 229
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Professor

Miha Boltežar, PhD

  Ladisk, Faculty of Mechanical Engineering, University of Ljubljana
  miha.boltezar@fs.uni-lj.si
  +386 1 4771 608
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