Wear studies using acoustic emission techniques

Correlation Between Acoustic Emission Activity and Asperity Contact During Meshing of Spur Gears Under Partial Elastohydrodynamic Lubrication

“…As has already been discussed both load and speed influence the AE levels during sliding [3,4]. An increase in rotational speed, and hence sliding speed of the meshing gears, will result in an increase in AE levels on the basis that asperity contact exists during the sliding portion of the mesh cycle.…”

“…Boness et al [3] stated that the sliding of mating surfaces was a continuous process and as such the AE signature from such a process would be predominantly continuous with superimposed burst emissions due to rapid high-amplitude events, for instance, a single asperity fracture. The investigation reported by Boness at al [3] involved the measurement of AE for dry and lubricated contacts under pure sliding conditions.…”

“…The investigation reported by Boness at al [3] involved the measurement of AE for dry and lubricated contacts under pure sliding conditions. It was reported that with a full elastohydrodynamic film between highly polished surfaces no AE r.m.s activity above the electronic noise of the acquisition system, inferring that asperity contact was the prime source for the generation of AE activity.…”

Detection of shaft-seal rubbing in large-scale power generation turbines with acoustic emissions. Case study

“…The generation of AE during the sliding motion of two mating surfaces is attributed to adhesion, contact and deformation of asperities and the ploughing action of wear particles [18]. It has been shown [18,19,20,21,22] that the strength and rate of AE activity is dependent on sliding velocity, friction coefficient of mating surfaces, contact pressure and the height of surface roughness. In addition, these studies have been undertaken with and without lubrication.…”

“…As the low pressure cylinders were of identical size, and on the assumption that the transmission path to the receiving sensors are identical, it was observed that the strongest AE source was from 'LP2 Rear', and as such, it is highly probable that rubbing of mating surfaces at this position was at a particular stage of wear that resulted in higher AE activity than at 'LP1 Rear'. The relationship between AE levels and wear has been investigated for sliding of lubricated and dry mating surfaces [18,19,20,21,22,27]. Acoustic Emission activity was shown to be dependent on the asperity contact, surface roughness and third body interactions.…”