Material thickness before shear

Hi all,

As you guys were so helpful with solving my last problem I thought I would return with another :).

I have a pressure vessel that will hold 250 bar. At 1 end the vessel diameter will step down from 25mm to 18mm, I need to calculate the thickness the material should be before it shears off under pressure where it steps down in size.

Please see the picture attached for a better idea of what I mean.

The material is brass with the following specification from elginfastners.com:
Tensile Strength, Ultimate - 50,000 psi
Tensile Strength, Yield - 19,600 psi.

All help is greatly appreciated.

[IMG]http://www.engineersedge.com/engineering-forum/attachment.php?attachmentid=1416&stc=1[/IMG]
Many Thanks.

A generally accepted ratio of Sshear to Syield is .5 and the I.D. of the tank determines both the shearing diameter and the total pressure area for the shearing force. You should be able to take it from there.

Hi,
Sorry to bring up an old thread, I have just picked up this old project again in an attempt to tackle it. Please could you elaborate I have googled shear diameter and total pressure area however I still have no idea how to work it out.

Many Thanks.