Screw Loosen Analysis 2

[Lee.Conti]

Hi I wonder if anyone has done any analysis to check if the screw get loosen due to thermal effect?

Designer feedback the screw may get loosen due to thermal cycle... and I wonder if the screw is being screwed into the part and locked, how could it get loosen?

 

[WKTaylor]

Tm...

Based on the first and second links I'm OLD.

NOTE: can't get Your last link to work... 'illegal character' warning... I need to know how old I really am.

Do the number of typos in posts-over-time also count?

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[Tmoose]

I RE-submit that it may be possible to judge a man's age by whether he believes this is a bolt or a screw -

 

[Lee.Conti]

Hi WKTaylor,

It is a system level product and the screw is normal 3x16 type.

How do you account for the thermal cycle effect or just running the analysis at high and low temperatures?

 

[drawoh]

Tmoose,

Your photograph is of a Grade[ ]8 cap screw with Unified National threads.

--
JHG

 

[WKTaylor]

Doh, TM... I would hazard a SWAG that the cap-screw [in the posted image] has high quality coarse threads.

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[mewhg]

WKTaylor,

I would think .001-.004" clearance would be perfectly acceptable. Should the bolt to hole clearance be eliminated? A core drill being is used for match drilling after the wing assembly is fit up?

 

[WKTaylor]

M... ???? OK... I am lost in translation...

Q/I I would think .001-.004" clearance would be perfectly acceptable. … based on what reasoning??
A. What kind of joint are YOU referring to?

Q/I Should the bolt to hole clearance be eliminated? Huhhh?
A. Swaged-collar Lockbolts, Hi-Lok pins, etc... can be installed in transition fit or light interference. Conventional bolts should only be installed in clearance fit holes... or with extreme care/process controls... light interference-fit by 'freeze/shrink-fit' techniques.

Q/I A core drill being is used for match drilling after the wing assembly is fit up?… OK, OK, OK... You are not opening-up generalized issues...
I sense You may be referring BACK to my prior discussion/example [4 & 6 August postings]… IE: experience with loosening bolts/nuts discovered on my 1960's-1970s' era light attack jet during a routine condition inspection...?

Please advise if I just figured-out where You were actually 'going' with Your [3] statement-questions...

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]