Is an interference fit considered a pre-load?

[kkomschl]

Hello,

I was wondering if the hoop stress from a bushing interference fit inside of a bore can be considered a preload.

From my understanding, if a bushing is installed in a bore with an interference fit, the interference fit creates a hoop stress around the entire diameter of the bore. If a shaft is installed in a bore (slip fit) and then loaded in one direction, it creates a hoop stress at a single point in the bore. If a bushing is installed in a bore with an interference fit, and then a shaft is installed (slip fit) in the bushing and loaded, the locations of the hoop stresses coincide. (See the attached .pdf)

Can the hoop stress from the interference fit be considered a preload, similar to a preloaded stud? Where any similar external stresses up to the preload can be considered negligible. Or, do both of the hoop stresses need to be added together?

I have searched online and in my personal book collection and nothing I have found seems to address this topic.

Thank you,
Kyley

 

[desertfox]

Hi kkomschi

This might help:-

http://www.roymech.co.uk/Useful_Tables/Mechanics/Cylinders.html

desertfox

 

[rb1957]

interference fit and preload are two completely different topics.

if the interference is not mechanical created (as in a freeze fit, where the bush is shrunk by freezing it and it expands in situ creating the interference) then there is clearly no preload created.

if the interference is machanically created (as in a swaging a hole with a tapered fastener) then you would induce preload into the fastener by installing it. but they (interference and preload) are still two different things.

 

[chicopee]

As stated above, two separate subjects for two different applications.