Tek-Tips is the largest IT community on the Internet today!
Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!
-
Congratulations MintJulep on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!
Acceptable deflection of a 25mm solid steel shaft
- Thread starter Lehane
- Start date
Shaft of what?
In what context?
How long of a shaft?
What cross section?
...
In what context?
How long of a shaft?
What cross section?
...
Posting guidelines faq731-376 (probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484
What is Engineering anyway: faq1088-1484
- Thread starter
- #3
Hi Lehane
I would look at the stress in the shaft and then consider the fatigue as the shaft is loaded and unloaded.
Try to get the stres i the shaft below half its tensile strength if possible,then fatigue might not be such a problem.
desertfox
I would look at the stress in the shaft and then consider the fatigue as the shaft is loaded and unloaded.
Try to get the stres i the shaft below half its tensile strength if possible,then fatigue might not be such a problem.
desertfox
Lehane,
Why does deflection matter to you?
[ol]
[li]Your shaft ought to not break, hence desertfox's remarks, above.[/li]
[li]You have an alignment issue with your bowl of liquid. This will dictate what your acceptable deflection is. You don't need to ask us.[/li]
[li]Your liquid and container have a mass. Your bar has a spring rate. [ω]=sqrt(k/m). Your container full of liquid will bounce up and down and rotate at resonant frequency when it is bumped, or emptied and filled.[/li]
[li]???[/li]
[/ol]
Do you really need to cantilever the thing? I crudely figure that tension/compression structures are around three orders of magnitude stiffer than cantilevers.
JHG
Why does deflection matter to you?
[ol]
[li]Your shaft ought to not break, hence desertfox's remarks, above.[/li]
[li]You have an alignment issue with your bowl of liquid. This will dictate what your acceptable deflection is. You don't need to ask us.[/li]
[li]Your liquid and container have a mass. Your bar has a spring rate. [ω]=sqrt(k/m). Your container full of liquid will bounce up and down and rotate at resonant frequency when it is bumped, or emptied and filled.[/li]
[li]???[/li]
[/ol]
Do you really need to cantilever the thing? I crudely figure that tension/compression structures are around three orders of magnitude stiffer than cantilevers.
I don't know. How much deflection is acceptable in your device? Deflection only equals failure if it causes something to function improperly.
Stress, on the other hand, is how you determine whether your part will break. For parts under a static load, permanent deflection (yielding) is often the criteria for failure. For parts under a repeated load, the maximum stress is determined by the endurance limit of the material or a fatigue life analysis (cycles to failure).
Stress, on the other hand, is how you determine whether your part will break. For parts under a static load, permanent deflection (yielding) is often the criteria for failure. For parts under a repeated load, the maximum stress is determined by the endurance limit of the material or a fatigue life analysis (cycles to failure).
- Status
Similar threads
- Question
- Locked
- Question
