Compound Thin Cylinder/Tube Analysis

[kbujuru]

Hello All,

Sorry if this topic has been discussed elsewhere but I have been doing quite a bit of research on this topic and found minimal help. We have a compound thin tube with PTFE liner on the inside and Nylon jacket on the outside. The dimensions are below

PTFE thickness- 0.002"
Nylon thickness- 0.008"
Inner Radius of the tube-0.237"

Length of the tube- .8"

Problem statement- When the tube is subjected to radial displacement of 0.0075", determine the hoop stresses in Nylon and PTFE liner?

I have attached my calculations but I am not convinced that this is correct- as the assumption here is that neither PTFE liner nor Nylon are influencing each other in handling the stresses

Thanks in advance for your ideas

-Karthik

 

[chicopee]

I haven't study your calculations since I have no inclination in doing so, however, I may have some information that could help you out. GE NORYL has published a design guide pamphlet that you may find useful. I have attached the table of contents that goes back to the early '90's and I wouldn't be surprised if that pamphlet has been updated. Equations presented in this pamphlet may be useful and would need to be adapted to your material. Here is the address: GE, Plastics Department, NORYL Products section, NORYL Avenue, Selkirk, New York 12158.