Design of Machinery Term Pa

The purpose of this report was to optimize a sufficient load capacity and power loss of a journal bearing and determine the life expectancy of a ball bearing. This was to be done with only a given set of parameters and set of variables were to be chosen. The parameters of a given shaft with flywheel were shaft details: diameter = 90mm, total weight of shaft and flywheel = 25kN, RPM = 1500 and power of 3.5MW. Design Variables | Design Parameters | State Variables | Diameter | Shaft Diameter | Bearing Diameter | Length | RPM | Bearing Length | Clearances | Load | Diametric Clearance | Lubrication | | Ocvirk Number | | | Absolute Viscosity |

Journal Bearing

Ball Bearing Diameter | 0.36 meter | Length | 0.1 meter | Diametric Clearance | 1.0E-08 meter | Ocvirk Number | 30 | Lubricating Fluid | ISO VG 680 oil @ 220°F | Absolute Viscosity | 31cP | Bearing Number | 6318 | Dynamic Load Rating | 23,200 lb. |

Results: Load Capacity “ P “ | 30.1 kN | Power Loss | 1.96 Watts | Life | 6251.5 Hours |

Appendix:
Diametric Clearance; Cd
Bearing Diameter: d
Clearance Ratio: Cd/d
Ocvirk Number: ON
Angular velocity: n’= 1500rpm/60sec
New Clearance Ratio: Cd= ON*(Cd/d)
Fluid Viscosity: ƞ = 30cP = 30x10-9MPa-s
Eccentricity: e=Cr=Cd/2
Dimensionless Parameter: Kε= On/4π
Empirical Eccentricity Ratio: εx=0.21394+0.38517 ON -0.0008(ON – 60)
Force Par: P= Kε*(4π ƞdn’l3)/ Cd2
Torques:
To=ƞπ2d3n’l/ Cd Ts=To/(1- εx2)1/2 Tr=Ts + Pesinφ
Angle to Result force: φ = arctan(π(1- εx2)/4εx)
Power Loss: Φ= 2πn’Tr
RPM=1500
Load per bearing: P2=Total Load/ 2
Dynamic Load Rating: C= 23200
Bearing Bore: 90mm
Design Life: L10= (C/P2)3
Life: