Thread Load Distribution

[dlybbert]

I am designing a stub acme connection, and in this case, I will be pushing its limits more than normal. I am looking for any information about load sharing between threads for 2g or 4g threads. I have read in some more basic books to use two threads with equally distributed loads, but from my experience this assumption is quite conservative. Other books that distribute the load over the entire thread length, which is fine so long as you don't come anywhere close to failure.

Thanks in advance for your input. I think this could be a very interesting and useful topic of research!

"If it has been done... there is a better way."

 

[desertfox]

Hi

Try this:-

http://www.ewp.rpi.edu/hartford/use...n Between Threads in Threaded Connections.pdf

 

[desertfox]

http://www.bastiontechnologies.com/gfx/Bolt Thread Loading.pdf

 

[dlybbert]

desertfox,
That was a good read. I may be able to show that this data can (at least somewhat) extrapolate from square and buttress threads to ACME and stub ACME connections. I am surprised that so much load is borne through only 2-4 threads.

"If it has been done... there is a better way."

 

[dlybbert]

There is another paper (I found the paper copy around the office, but I can't find an online version) called "Loading Analysis on the Thread Teeth in Cylindrical Pipe Connection" By Shou-Jun Chen and Qi An (2010) in the Journal of Pressure Vessel Technology, that is a bit more involved, but seems more robust. It looks like it will work quite well for "n" number of threads, and so should work quite well with matrix operations. I will post my analysis in case anybody is interested.

I would still be interested if anybody else has information to throw in.

"If it has been done... there is a better way."

 

[desertfox]

Hi

Here is another paper

http://www.scribd.com/doc/217736061/Stress-Analysis-of-Screws

 

[desertfox]

hi Freddy

Yes post you're calculations it will be interesting.

 

[dlybbert]

Alright. I have a problem with equation #10 from "Loading Analysis on the Thread Teeth in Cylindrical Pipe Thread Connection" (2010 Journal of Pressure Vessel Technology).
I have attached an image of the equation, and their sample calculation.
The "In" I assume is a natural logarithm. But I cannot validate their calculation using a natural logarithm. I started to do the derivation myself (phew...it is unbearably long), and I began (although not finished) a much different looking equation (although it may be the same in solution). Do you know what this "In" function is? OR can you validate their calculation?


"If it has been done... there is a better way."

 

[rb1957]

would "Integer" make sense ?

maybe ask the authors ?

Quando Omni Flunkus Moritati

 

[dlybbert]

Excellent thought rb1957, but it doesn't work either. They all round off to "1", and give me a final answer of -14.
I have attempted to contact the authors, but they haven't got back to me.

"If it has been done... there is a better way."