More accurate alpha values using an indirect approach: Through a more accurate central film thickness formula

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Previous publications have shown that numerical calculations on the central film thickness in EHL lubricated circular contacts approach the measured values very closely. With an approximation formula for the numerical results, the pressure viscosity coefficient of the viscosity of liquids (alpha) can be determined. It is customary to write such an approximation formula as a product of powers of nondimensional exponents. By now changing the value of alpha in this formula, to its best value, the best possible approach to the experiments is created.
The issue then is whether it is possible to find a better approximation formula for the central film thickness than the best that presently exists.

The publication shows the requirements which the exponents in the approximation formula must meet. Then a considerable number of propositions fall short. A new approach is needed.
A better approach formula appears feasible, and the result is about 25% less inaccurate than the best formula so far, for three series of measurements.
Translated title of the contributionNauwkeuriger alfawaarden gebruikmakend van een indirecte methode: Door een nauwkeuriger formule voor de centrale filmdikte
Original languageEnglish
Title of host publication14. Arnold Tross Kolloquium, May 25th, 2018
EditorsErik Kuhn
Place of PublicationAachen
Number of pages33
ISBN (Electronic)978-3-8440-6409-4
Publication statusPublished - 28 Feb 2019
Event14th Arnold Tross Kolloquium - Aachen, Germany
Duration: 25 May 201825 May 2018

Publication series

NameReihe Maschinenbau
ISSN (Print)0945-0874


Conference14th Arnold Tross Kolloquium


  • pressure viscosity coefficient
  • EHL circular contact
  • accurate film thickness measurement
  • accurate curve fit


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