英语翻译

英语翻译
2.2.AE source during gear meshing
Understanding the source of AE activity at the gear mesh is a fundamental pre-requisite if this technique is
to be successfully employed for gear diagnostics and prognostics.Toutountzakis [11] highlighted limitations in
the current understanding of the source mechanism of AE during gear meshing.Tan et al.[17] ascertained the
AE source mechanism through a series of experimental programmes.These experimental programmes
consisted of isothermal tests on undamaged gears to explore the effects of rotational speed and applied torque
on AE levels.From the isothermal test results,it was observed that variation of the applied torque had a
negligible effect on the AE root mean square (rms) levels,similar to the negligible effect of load on film
thickness under elastohydrodynamic lubrication (EHL) of non-conforming mating surfaces.It also noted that
the variation in rotation speed had a more pronounced effect on AE rms levels relative to the load.Tan et al.
[17,29] concluded that the source of AE during gear mesh was asperity contact under rolling and sliding of the
meshing gear teeth surfaces.These observations detailed by Tan et al.[17,29] were under isothermal
conditions.In conditions other than isothermal,an increase in speed and load will result in increased AE
levels [26].
ARTICLE IN PRESS
C.K.Tan et al./ Mechanical Systems and Signal Processing 21 (2007) 208–233 209
2.3.Vibration characteristics and gear damage
Yesilyurt et al.[18] utilised the vibration analysis technique for damage detection and assessment,and stated
that gear tooth damage would cause a reduction in tooth stiffness and the extent of this damage could be
monitored.Yesilyurt concluded that for distributed damage condition the reduction of tooth stiffness and loss
of gear tooth involute profile contribute to the increase in vibration.However,in the case of localised defect,
tooth stiffness reduction was the sole contributor to the increase in vibration levels.Choy et al.[19] came to a
similar conclusion.Drosjack et al.[20] presented an experimental and theoretical study on the effect of
simulated pits located on the pitch-line using vibration technique.Drosjack concluded that pitting on gear
teeth surfaces altered the vibration characteristics via the change in stiffness of the gear teeth.
In summary,the presence of damage such as pitting,either localised or distributed,will alter the stiffness of
the gear due to modification of the Hertzian contact zone.In addition,an impulsive reaction between gears
that have lost the original involute profile will change the vibration levels from the gears.