A journal bearing operating close to its design condition is

A journal bearing operating close to its design condition, is now required to operate under significantly higher radial load P. What are the concerns if the load keeps increasing? Since the design is already implemented, what can you do to allow the journal bearing to still operate at its design condition while supporting the increased radial load? (List all possible approaches you can take other than changing the geometry, and briefly justify your approaches)

Solution

In a journal bearing, coefficient of friction plays important role. For a particular value of friction the product of its pressure and velocity accounts for the temperature rise. This product also gives information about the wear rate. So, if the bearing is operating above the normal temperature and wear conditions, it can be found out that it is working above the design load.

The yield pressure of softer metal governs the contact area. The pressure P, in product PV, is defined as force divided by the Bearing contact area. Thus the product PV controls the wear rate and thus thermal stresses induced in the bearing.

Therefore, if the radial load gets increasing, there are chances for more wear and tear, induced thermal stresses which affects the area of softer material, thus changing the contact area of bearing, Clearance is lost, chances of misalignment increases. It can also cause the increase in vibration.

Journal bearing to still operate at its design condition, following parameters can be controlled

velocity: velocity of bearing can be controlled to prevent overheating and wearing.

temperature: lubricant materials which can act as temperature controlling agents such as polymers or thermosetting plastics.

Ensuring that oil or lubricant supply is continuous.