Limits...
Studies on tribology.

Hori Y, Kato K - Proc. Jpn. Acad., Ser. B, Phys. Biol. Sci. (2008)

Bottom Line: Oil whip is one of such vibrations due to oil film action of journal bearing.Some mechanisms of wear are introduced for better understanding of tribo-layer.In the last part of this paper, the mechanisms of generating static friction are shown for the cases of plastic contact and elastic contact, which is the base for understanding the mechanism of initiation of macroscopic sliding.

View Article: PubMed Central - PubMed

Affiliation: Kanazawa Institute of Technology, Tokyo, Japan.

ABSTRACT
In high speed rotating machines such as turbines and generators, vibrations of a rotating shaft often hinder the smooth operation of the machine or even cause failure. Oil whip is one of such vibrations due to oil film action of journal bearing. Its mechanism and preventive method is explained and proposed in this paper. Further theoretical and experimental analyses are made for considering heat generation and temperature rise in hydrodynamic lubrication. The usefulness of the lubrication theory based on the k-epsilon model is also shown for bearings with high eccentricity ratios. In the latter half of this paper, water lubrication, nitrogen gas lubrication and tribo-coated indium lubrication are shown as new promising methods, and their mechanisms are discussed and the importance of tribo-layer is explained. Some mechanisms of wear are introduced for better understanding of tribo-layer. In the last part of this paper, the mechanisms of generating static friction are shown for the cases of plastic contact and elastic contact, which is the base for understanding the mechanism of initiation of macroscopic sliding.

Show MeSH

Related in: MedlinePlus

The relationship between the average amplitude of plastic strain Δεp in the contact region of CNx coating sliding against a diamond pin and the critical number of friction cycles Nc for delamination of coating surface.58),80)
© Copyright Policy - open-access
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3722018&req=5

f49-287: The relationship between the average amplitude of plastic strain Δεp in the contact region of CNx coating sliding against a diamond pin and the critical number of friction cycles Nc for delamination of coating surface.58),80)

Mentions: Figure 49 shows the relationship between the average amplitude of plastic strain Δεp in the contact region of CNx coating and the number of friction cycles Nc for delamination of coating surface observed in the load range of nN∼mN. The observed linear relationship on log-log scale described by[4.6]Δεp=C/Ncβ(β;C:constants)confirms the wear mechanism as low cycle fatigue.80),81) It is obvious that flow wear observed in Figs. 43∼45 and low cycle fatigue wear in Fig. 49 are wear of tribo-layers. The mild wear in Fig. 47 is also generated by forming tribo-layers on wear surfaces.


Studies on tribology.

Hori Y, Kato K - Proc. Jpn. Acad., Ser. B, Phys. Biol. Sci. (2008)

The relationship between the average amplitude of plastic strain Δεp in the contact region of CNx coating sliding against a diamond pin and the critical number of friction cycles Nc for delamination of coating surface.58),80)
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3722018&req=5

f49-287: The relationship between the average amplitude of plastic strain Δεp in the contact region of CNx coating sliding against a diamond pin and the critical number of friction cycles Nc for delamination of coating surface.58),80)
Mentions: Figure 49 shows the relationship between the average amplitude of plastic strain Δεp in the contact region of CNx coating and the number of friction cycles Nc for delamination of coating surface observed in the load range of nN∼mN. The observed linear relationship on log-log scale described by[4.6]Δεp=C/Ncβ(β;C:constants)confirms the wear mechanism as low cycle fatigue.80),81) It is obvious that flow wear observed in Figs. 43∼45 and low cycle fatigue wear in Fig. 49 are wear of tribo-layers. The mild wear in Fig. 47 is also generated by forming tribo-layers on wear surfaces.

Bottom Line: Oil whip is one of such vibrations due to oil film action of journal bearing.Some mechanisms of wear are introduced for better understanding of tribo-layer.In the last part of this paper, the mechanisms of generating static friction are shown for the cases of plastic contact and elastic contact, which is the base for understanding the mechanism of initiation of macroscopic sliding.

View Article: PubMed Central - PubMed

Affiliation: Kanazawa Institute of Technology, Tokyo, Japan.

ABSTRACT
In high speed rotating machines such as turbines and generators, vibrations of a rotating shaft often hinder the smooth operation of the machine or even cause failure. Oil whip is one of such vibrations due to oil film action of journal bearing. Its mechanism and preventive method is explained and proposed in this paper. Further theoretical and experimental analyses are made for considering heat generation and temperature rise in hydrodynamic lubrication. The usefulness of the lubrication theory based on the k-epsilon model is also shown for bearings with high eccentricity ratios. In the latter half of this paper, water lubrication, nitrogen gas lubrication and tribo-coated indium lubrication are shown as new promising methods, and their mechanisms are discussed and the importance of tribo-layer is explained. Some mechanisms of wear are introduced for better understanding of tribo-layer. In the last part of this paper, the mechanisms of generating static friction are shown for the cases of plastic contact and elastic contact, which is the base for understanding the mechanism of initiation of macroscopic sliding.

Show MeSH
Related in: MedlinePlus