Calculate compression strain on thick walled Polycarbonate Pipe

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Rayal Participant Join Date: May 2008 Posts: 2	Calculate compression strain on thick walled Polycarbonate Pipe 05/28/2008 7:52 PM
	I am trying to establish the amount of deflection caused by hydrostatic pressure of up to 50 000 psi on a 2" diameter solid rod of Polycarbonate that has been board out to have a 0.75" hole through 75% of the 3" in length. Right now I have the Modulus of elasticity and I am simply tempted to use the outside area of the rod wall in order to find the strain. After some internet research it is pretty obvious that the wall thickness should also be considered. I need the strain calculation to be accurate to ensure a proper pressure seal with the rest of the device. If anyone has a good reference for where I could get some well derived equations or just want to let me know about how to do the calculations it would be greatly appreciated. In addition if anyone has suggestions for an alternative types of plastics that are machinable and have a high impact strength let me know
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nick name Guru Join Date: Mar 2007 Location: City of Light Posts: 3943 Good Answers: 183	#1 Re: Calculate compression strain on thick walled Polycarbonate Pipe 05/29/2008 4:35 AM
	Use the Lammé equations which you can find either on the net or in Roark. They are for thick wall tubes.
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Codemaster Guru Join Date: Jul 2005 Location: Stoke-on-Trent, UK Posts: 4496 Good Answers: 137	#2 Re: Calculate compression strain on thick walled Polycarbonate Pipe 05/30/2008 9:59 AM
	Rayal I found formulas below in Roark, Table XIII, Case 28. It's an old issue but I don't know which one as I only have a photocopy. p = pressure, 50000psi. a = inside radius, 3/8 inch. b = outside radius, 1 inch. Don't know Modulus of elasticity so taken as ~ 0.1 x steel, = 3.10⁶. Don't know Poisson's ratio ν so taken as 0.26, same as steel. Maximum stress s₂, compressive of course, circumferential at inside surface This seems a very high stress. I know polycarbonate is wonderful stuff but I don't it's as strong as that, even in compression. Change in a, Δa Change in b, Δb The figure you're looking for but you need to put the right modulus etc in. Cheers.......Codey __________________ Give masochists a fair crack of the whip
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Rayal Participant Join Date: May 2008 Posts: 2	#3 Re: Calculate compression strain on thick walled Polycarbonate Pipe 05/30/2008 2:36 PM
	Thanks for the help, That was exactly what I needed Rayal
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Codemaster (1); nick name (1); Rayal (1)

You might be interested in: Strain Gauges, Strain Reliefs, Polymers and Plastic Materials

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