Traction Modeling of Military Lubricants.
Abstract
Traction behavior of military lubricants is investigated by examining both classical Newtonian and more recently postulated visco-elastic effects in the experimental traction data. An estimate of the relevant rheological parameters is derived by curve fitting the experimental traction data to predictions of the analytical models. The development process consists of several steps: (1) a regression analysis of experimental viscosity data obtained by a high-pressure viscometer is first carried out to formulate a viscosity-pressure-temperature relation, (2) analytical models for prediction of lubricant film thickness and traction are then developed and implemented in the form of a computer code, (3) the traction behavior of selected lubricants is measured experimentally over a range of operating conditions, (4) analysis of the traction data is then undertaken to derive the relevant rheological parameters for best fit of the data to the analytical models, (5) finally, the traction models are incorporated in a bearing dynamics computer code, and the bearing performance is simulated as a function of the rheological parameters. It is shown that the traction data fits fairly well to visco-elastic models based on lubricant shear modulus and a critical shear stress. While the modulus defines the traction slope at low slip rates, the critical shear stress determines the limiting traction coefficient at high slip rates. Performance simulations of turbine engine ball bearing with a combined thrust and radial load show that ball slip and cage interactions increase while bearing heat generation decreases with decreasing traction slope with the reducing shear modulus. (sdw)
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 24, 1989
- Accession Number
- ADA213866
Entities
People
- Pradeep K. Gupta