stresses on bolts

[dramarc]

IN a thick walled cylindical reactor subjec to an internal pressure, a flat lid will be attached with 8 bolts.

I would like to calculate the stresses/Strains in the shell, especially radially outside the bolts in the shell in order to understand where to place the bolts and how much shell wall is necessary outside the bolts.

Since it´s cymetrical I´ve created a part of the cylindrical shell consisting of half a hole for the bolt and some shell around it.

What boundary conditions would you use? especially around the hole for the bolt?

In the 3d model, the holes is just a hole without any threads.

 

[kmount]

Apply BCs to the shell geometry to take advantage of the radial symmetry and use a tie connection between the shaft of the bolt and its associated "tapped" hole to simulate the threaded connection.

 

[dramarc]

i´m quite new to this and I´m using femlab.
What do you mean by tie connection?

 

[kmount]

Ahhh, good ol' femlab. Hmm, its been years since I've used that code and I'm not up-to-date with its capabilities. In ABAQUS you can specify that two surfaces be tied together without having to match the location of nodes on each part. Are you inputting nodal coordinates by hand? Perhaps someone with more experience with the femlab program could chime in.

 

[dramarc]

hi!

I can apply constraints and loads as BC.
FOr the "walls of the bolt" I´ve constrained them in the normal direction since it won´t be able to deform in this direction (at least I think so).

FOr the internal shell wall I´ve set the load in the normal direction the the reactor pressure. Since my 3d object only consist one hole and a segment of the shellwall around the hole, Ive constrained the "cuts" in the shell wall.

I don´t know how to apply the facts of the bolt, for eample that it is pre stressed ...