## Abstract

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.

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 contribution | Nauwkeuriger alfawaarden gebruikmakend van een indirecte methode: Door een nauwkeuriger formule voor de centrale filmdikte |
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Original language | English |

Title of host publication | 14. Arnold Tross Kolloquium, May 25th, 2018 |

Editors | Erik Kuhn |

Place of Publication | Aachen |

Publisher | Shaker-Verlag |

Pages | 105-137 |

Number of pages | 33 |

ISBN (Electronic) | 978-3-8440-6409-4 |

Publication status | Published - 28 Feb 2019 |

Event | 14th Arnold Tross Kolloquium - Aachen, Germany Duration: 25 May 2018 → 25 May 2018 |

### Publication series

Name | Reihe Maschinenbau |
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ISSN (Print) | 0945-0874 |

### Conference

Conference | 14th Arnold Tross Kolloquium |
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Country | Germany |

City | Aachen |

Period | 25/05/18 → 25/05/18 |

## Keywords

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