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   http://doi.org/10.1016/j.jsv.2018.05.041
Povzetek
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

R&D

Matej Razpotnik, dr.

  Yaskawa Europe Robotics
  
  

Profesor

Gregor Čepon, dr.

  Ladisk, Fakulteta za strojništvo, Univerza v Ljubljani
  gregor.cepon@fs.uni-lj.si
  +386 1 4771 229
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Profesor

Miha Boltežar, dr.

  Ladisk, Fakulteta za strojništvo, Univerza v Ljubljani
  miha.boltezar@fs.uni-lj.si
  +386 1 4771 608
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