Experimental Investigations and Application of Ionic Liquids in Small Self-lubricating Porous Journal Bearings.
Degree: 2017, ETH Zürich
Small, self-lubricated porous journal bearings are widely applied in all kind of
different machinery and applications and produced in enormous quantities.
Their low cost, high resistance with respect to impacts and overload make
them a very important and successful bearing solution to support a rotating
shaft carrying a radial load.
For small journal bearings, supporting shafts with diameters in the range
of mm, as applied in small machines, standard techniques of friction analysis
cannot be used, because the boundary conditions of the specific application
cannot be represented. Due to this, different friction values result when
compared to the real application and the measurements obtained are not
This work addresses systematic investigations of small journal bearings
lubricated with Ionic Liquids, which present a novel generation of fluids
with promising properties and good lubrication performance. A setup was
designed and built so as to represent the application of such bearing systems
in a small electric motor of 20mm in diameter and imposes identical
mechanical boundary conditions as experienced in such motors. A nominal
shaft diameter of 3mm was used for the experiments. The important
parameter of the radial clearance was altered by using precise shafts of different
diameters. The radial loading on the bearings was varied in the range
from 0.2N to 10N.
A novel procedure for calibration allows to take into account deviations
from perfect symmetry, as they are encountered on every part of the mechanical
system. This new calibration allows to significantly increase measurement
precision. In the case of miniature bearings, as they are used in
this work, deviations from the ideal geometry cannot be neglected because
measurement precision would suffer dramatically. The setup developed allows for the simultaneous detection of friction and
relative displacement between shaft and bearing, a key parameter in hydrodynamic
lubrication theory. This gives additional insight into the bearing
kinematics and allows to increase the precision of friction measurements even
more, if measured values of shaft-bearing eccentricity are considered for the
calculation of the friction torque. Using the developed setup, a nominal
resolution of 50 nNm could be obtained with displacement measurements
recorded at 150 nm nominal resolution.
An analysis of the displacement signal in the frequency domain was performed
in order to give additional insight into the system dynamics and
detection of whirling phenomena, which typically come along with an increase
in friction. To avoid any misinterpretation of measured friction data,
knowledge of the whirling state is important.
Viscous heating in the lubricant film strongly effects the lubricant temperature
and therefore its viscosity and was also taken into account. Considering
effects of viscous heating is especially important at high speeds.
The setup under test allows for rotational speeds up to 25000 rpm. Using
a combined experimental,…
Advisors/Committee Members: Dual, Jürg, Wegener, Konrad, Pittini, Raniero.
Subjects/Keywords: Stribeck measurement; Journal bearing; Ionic liquids; FRICTION MEASUREMENT (MECHANICS); half-frequency whirling; Experimental investigations; thermohydrodynamic friction model; info:eu-repo/classification/ddc/620; Engineering & allied operations
to Zotero / EndNote / Reference
APA (6th Edition):
Trachsel, M. (2017). Experimental Investigations and Application of Ionic Liquids in Small Self-lubricating Porous Journal Bearings. (Doctoral Dissertation). ETH Zürich. Retrieved from http://hdl.handle.net/20.500.11850/245698
Chicago Manual of Style (16th Edition):
Trachsel, Mathis. “Experimental Investigations and Application of Ionic Liquids in Small Self-lubricating Porous Journal Bearings.” 2017. Doctoral Dissertation, ETH Zürich. Accessed October 24, 2020.
MLA Handbook (7th Edition):
Trachsel, Mathis. “Experimental Investigations and Application of Ionic Liquids in Small Self-lubricating Porous Journal Bearings.” 2017. Web. 24 Oct 2020.
Trachsel M. Experimental Investigations and Application of Ionic Liquids in Small Self-lubricating Porous Journal Bearings. [Internet] [Doctoral dissertation]. ETH Zürich; 2017. [cited 2020 Oct 24].
Available from: http://hdl.handle.net/20.500.11850/245698.
Council of Science Editors:
Trachsel M. Experimental Investigations and Application of Ionic Liquids in Small Self-lubricating Porous Journal Bearings. [Doctoral Dissertation]. ETH Zürich; 2017. Available from: http://hdl.handle.net/20.500.11850/245698