Contact Stresses in Cantilevered Journal Bearing

In summary, the conversation discusses the analysis of static stresses on a bronze bushing in a journal bearing when used as a support for a cantilevered shaft. Equations for contact stresses on the bushing suggest a uniformly distributed load, but the manufacturer states that the bushing can only withstand a static load of 8000 psi. The conversation also mentions the option of using the compressive yield strength of the bushing material to analyze static failure. It is mentioned that the primary problem will likely be the effect of the cantilevered shaft on the bearing, with potential issues such as quick wearing or galling at the edge of each end of the bearing.
  • #1
jsed
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I am trying to analyze the static stresses on a bronze bushing in a journal bearing if I was to use that journal bearing as a support for a cantilevered shaft. All the equations I have for contact stresses on the bushing suggest a uniformly distributed load across the entire bushing, which would be applicable if the shaft were supported by two bearings, but I am interested in what happens when the shaft is only supported on one end by one bearing.

Also, the manufacturer of the bushing states that the bushing can withstand 8000 psi of static load, which represents the load on the projected bearing area (ID x Length). Based on this criteria, I am not sure if contact stresses are what I need to be looking at. I also know the compressive yield strength of the bushing material, so I could just use that to analyze the static failure of the material.

Thank you for your input.
 
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  • #2
For any reasonable responses you should give a diagram of what you are describing.

Speaking in general terms, static loading failure is not going to be your primary problem. The effect of the cantilevered shaft is going to depend upon the amount of lateral load or weight on the extended shaft. Using a single bearing with a cantilevered shaft is going to result in small contact areas at the edge of each end of the bearing, one at the top on the end opposite the cantilevered load and one at the bottom on the cantilevered end. The result,depending upon the bearing material (polymer vs metal), the amount of load and the rpm of the shaft, is most likely to be either very quick wearing or galling of the bearing at those two points.
 

1. What is a cantilevered journal bearing?

A cantilevered journal bearing is a type of bearing that supports a rotating shaft at only one end, allowing it to rotate freely. It is commonly used in machinery and equipment to reduce friction and support heavy loads.

2. How are contact stresses in cantilevered journal bearings calculated?

Contact stresses in cantilevered journal bearings are typically calculated using the Hertzian contact stress equation, which takes into account the material properties and geometry of the bearing and the applied load. Other factors, such as lubrication and surface roughness, may also affect the contact stresses.

3. What factors can affect the contact stresses in cantilevered journal bearings?

Some factors that can affect the contact stresses in cantilevered journal bearings include the material properties of the bearing and shaft, the geometry and surface roughness of the bearing and shaft, the applied load, and the lubrication used.

4. How can high contact stresses in cantilevered journal bearings be prevented?

To prevent high contact stresses in cantilevered journal bearings, it is important to select materials with appropriate properties, maintain proper lubrication, and ensure that the bearing and shaft are properly aligned. Regular maintenance and monitoring of the bearing can also help prevent high contact stresses.

5. What are the implications of high contact stresses in cantilevered journal bearings?

High contact stresses in cantilevered journal bearings can lead to increased wear and damage to the bearing and shaft, which can result in decreased performance and potentially costly repairs. In extreme cases, it can also cause bearing failure, leading to downtime and potential safety hazards.

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