Is a solid cylinder considered thick or thin?

[yonese]

I have a solid cylinder of diameter 40mm and length 14mm and I have used plane stress approximations in my calculations so far. I know for to assume a thin walled cylinder/tube the wall thickness needs to be less than 1/20 of tube or cylinder diameter. However, what I have found so far is that this 1/20 method applies to hollow cylinders where the thickness can be determined by the difference in the inner and outer diameter. How will I know whether my solid cylinder can be considered thin or thick? I'm guessing the length cannot be used as the thickness. Might it be that the thickness is ...0?

If my cylinder is to be considered thick, would plane stress approximations still be appropriate?

[Moderator's note: moved from a technical forum.]

 

[pbuk]

There is no such thing as a solid cylinder, what you have is a rod.