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#1
12-07-2005, 04:17 AM
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Re: CHallenger disaster
[ QUOTE ]
I was wondering specifically what effect the pin retainer band had on joint bending. aka whether to include it in an FEM [/ QUOTE ] I'm an EE, not an ME, but I think the retainer band is structurally insignificant-- it is just there to keep the pins from falling out. Feynman gives more interesting insights in some of his autobiographical books, especially What Do You Care What Other People Think. The steel cases are ~3x thicker at the joint than in the middle so when the cases are pressurized, the joint tends to open-- they call this "rotation." You shouldn't have any trouble seeing this effect in your model. Good luck. 
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#2
12-07-2005, 11:35 PM
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Re: CHallenger disaster
[ QUOTE ]
[ QUOTE ] I was wondering specifically what effect the pin retainer band had on joint bending. aka whether to include it in an FEM [/ QUOTE ] I'm an EE, not an ME, but I think the retainer band is structurally insignificant-- it is just there to keep the pins from falling out. Feynman gives more interesting insights in some of his autobiographical books, especially What Do You Care What Other People Think. The steel cases are ~3x thicker at the joint than in the middle so when the cases are pressurized, the joint tends to open-- they call this "rotation." You shouldn't have any trouble seeing this effect in your model. Good luck. [/ QUOTE ] i am having a lot of trouble seeing it in my model. any idea as to how to model the pin effect in axisymetric elements?
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#3
12-08-2005, 03:17 AM
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Re: CHallenger disaster
[ QUOTE ]
i am having a lot of trouble seeing it in my model. [/ QUOTE ] Sorry if this is obvious, but are the results otherwise reasonable? Check your dimensions and material properties. Do you have the operating pressure right (~500 psi, IIRC)? Make sure you're using consistent units. Also keep in mind that rotation is significant to the extent that it changes the o-ring "squeeze," which is only ~0.05" on an o-ring with a nominal cross-sectional diameter of 1/4". (See The Parker O-ring Handbook, http://www.parker.com/o-ring/Literature/04-5700.pdf) That's a small change when the case diameter is 12 feet. Conceptually it's easy to see that this effect will happen, but it may not be so easy to see in a model-- sorry about that. I can't promise much, but if you want me to take a closer look, PM me more details.
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Hybrid Mode
