Tapped holes and fatigue
Tapped holes and fatigue
(OP)
I am currently designing a system that requires an actuator to be fastened to a horizontal baseplate via a clevis plate. During operation, the actuator will transmit cyclic loading to the baseplate (normal to baseplate) with a high force. After a significant number of cycles, the actuator and clevis plate will be replaced but the intention is to keep using the baseplate.
My question is: can I use tapped holes in the baseplate, i.e. can tapped holes be re-used for an application where fatigue failure is a risk? (the baseplate itself is designed such that it is below the endurance limit). Because of space issues I can't get a nut on the underside of the baseplate.
Thanks in advance, KDB
My question is: can I use tapped holes in the baseplate, i.e. can tapped holes be re-used for an application where fatigue failure is a risk? (the baseplate itself is designed such that it is below the endurance limit). Because of space issues I can't get a nut on the underside of the baseplate.
Thanks in advance, KDB
RE: Tapped holes and fatigue
RE: Tapped holes and fatigue
Also, I don't know what the cumulative effects on the thread are when re-using the hole for this kind of application
RE: Tapped holes and fatigue
(**) http://www.newtonsapple.org.uk/wp-content/uploads/...
RE: Tapped holes and fatigue
No reason why you can't use tapped holes rather then nuts, however depending on the material the tapped holes are in you would need to check the shear stress for that material and compare it with that of the nut mterial.
I the preload is high enough on the bolt then the cyclic stress in the fixings should be quite small, it is interesting to note that when you tighten on a female thread whether it's a nut or tapped hole the stress is actually compressive unlike the bolt which is in tension.
“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein
RE: Tapped holes and fatigue
RE: Tapped holes and fatigue
RE: Tapped holes and fatigue
Two bolts per cap proved sufficient for a bunch of years.
http://blog.ecklerscorvette.com/wp-content/uploads...
The cap sits snugly in a shallow register in the engine block, but that is to maintain accuracy of the machined hole ( 0.0005" or less ) thruout repeated disassemblies, not to resist the considerable forces in operation.
Bolt clamping forces, for decades controlled by installation tOrQuE, applied to decently machined faying surfaces created friction and was dead reliable.
RE: Tapped holes and fatigue