TY - BOOK

T1 - Modelscale methodology for the tribological characterization of novel highly stressed journal bearing systems

AU - Renhart, Philipp

N1 - embargoed until 06-12-2026

PY - 2021

Y1 - 2021

N2 - The development of coatings for highly loaded and security related journal bearings necessitate a focused an application-orientated test strategy. Common scenarios, like overloads or repeated starts and stops of a machine must be considered. The range of tests needs to be extended by atypical events for security related components, such as short operation at high specific bearing loads superimposed by deficient lubrication. Additionally, operation states without active oil supply at low loads must be considered as well. Within this thesis an application orientated test strategy was developed, which considers operation states under deficient lubrication. This new developed test strategy consists of four scenarios, whereby two test programmes were designed for deficient lubrication. Additionally, the existing acoustic emission data acquisition system was optimised and the evaluation methods were significantly expanded and improved. High frequency measurements were filtered by octave bands and statistical indicators, such as the kurtosis, were derived in these frequency bands and applied for tribological interpretations. A complex wear mechanism, which explains the formation of particles in soft coatings, was predicted by an analysis of acoustic emissions in time- and frequency domain. Furthermore, a measuring device was developed, which enables the measurement of relative wear of journal bearings in a mounted state with a simultaneous increase of the measuring accuracy. The developed test strategy was successfully applied to copper- and silver based journal bearing coatings, which in turn were evaluated according to their operational performance. Unalloyed silver showed an excellent behaviour in standard- and emergency running situations. By the use of standardised parameters all results of the test strategy could be summarised to a global performance ranking.

AB - The development of coatings for highly loaded and security related journal bearings necessitate a focused an application-orientated test strategy. Common scenarios, like overloads or repeated starts and stops of a machine must be considered. The range of tests needs to be extended by atypical events for security related components, such as short operation at high specific bearing loads superimposed by deficient lubrication. Additionally, operation states without active oil supply at low loads must be considered as well. Within this thesis an application orientated test strategy was developed, which considers operation states under deficient lubrication. This new developed test strategy consists of four scenarios, whereby two test programmes were designed for deficient lubrication. Additionally, the existing acoustic emission data acquisition system was optimised and the evaluation methods were significantly expanded and improved. High frequency measurements were filtered by octave bands and statistical indicators, such as the kurtosis, were derived in these frequency bands and applied for tribological interpretations. A complex wear mechanism, which explains the formation of particles in soft coatings, was predicted by an analysis of acoustic emissions in time- and frequency domain. Furthermore, a measuring device was developed, which enables the measurement of relative wear of journal bearings in a mounted state with a simultaneous increase of the measuring accuracy. The developed test strategy was successfully applied to copper- and silver based journal bearing coatings, which in turn were evaluated according to their operational performance. Unalloyed silver showed an excellent behaviour in standard- and emergency running situations. By the use of standardised parameters all results of the test strategy could be summarised to a global performance ranking.

KW - Journal Bearings

KW - Tribology

KW - Testing

KW - Acoustic Emission

KW - Gleitlager

KW - Tribologie

KW - Prüftechnik

KW - Schallemissionen

M3 - Doctoral Thesis

ER -