Question on Equations for Calculating Forming Strains 1

[Transient1]

In the 2007 edition of the code, the first equation which pertains to one piece double curved circumferential products, has three variables Db, Do, and t. Db is the diameter of the blank or the diameter of the intermediate product. Do is the original outside diameter and t is the thickness.

(1) It would be great to find the reference these formulas came from. Any one have any info on that?

(2) The language confuses me a little. For a single forming step, I do not have an original diameter since I only have the blank. So what is the original diameter?

(3) If that piece is a more complicated shape, like a dish with a hemispherical nipple in the center, then what do those values mean?

I'm looking into getting some texts on the mechanics of sheet metal forming as well. Any suggestions?

Have a good weekend and thanks for the help.

 

[TGS4]

First question - which Code?

Second question - which article/paragraph are you referring to?

 

[Transient1]

ASME Boiler and Pressure Vessel Code Section VIII, Division 2, Part 6, Table 6.1

 

[jamesl]

That equation was from a paper "Heat Treatment in Pressure Vessel Technology" by C. Bouhelier of France. It is also in EN 13445-4.

 

[Transient1]

Thank for for the reference jamesl. However, that paper is very difficult to find. Any suggestions on its location? The equation is perplexing to me since it the original diameter term is divided by the final diameter term. In the text mechanics of sheet metal forming, the strain is the natural logarithm of the final diameter divided by the original diameter. It also, does not include a thickness term.

 

[jamesl]

The paper did not explain how they came up with the equations. It just showed that the strains calculated from these equations matched better with the experiments. The equations in the paper did not have a thickness term if thickness is no more than 10mm.

Derivation of UCS-79 formula was in WRC-158.