bolted flange

[amith014]

hi all,

I am doing fe analysis of bolted flange analysis. I have modeled this with solid elements only one segment.

I want to know the how to give the boundary conditions for this assembly.
Please help.

amit

 

[rb1957]

are your three components really one piece, or are they bolted together ? if they're bolted together, modelling them as one integral piece is unconservative. cut the model into the different pieces if that's the way it is.

i'd start modelling the fasteners by connecting the two sides with an x-, y-, z- constraint. you can contraint the two nodes together, or insert (zero length) springs between them. fancier would be to include the contact area around the bolts (where the faces are clamped together.

 

[GBor]

What software are you using? And what stresses are you looking for? Some softwares have built-in bolts that use specialized beam elements to form the appropriate attachment, but this doesn't tell you much about the stress in your actual bolt. If you are looking for stress in the bolt, seems like a hand calc would be easier. Otherwise, go with rb's suggestions.

 

[FILGUEIRAS]

Once I modeled a blind flange as shown in the picture, substituting bolts and gasket by axial displacement restrictions. I was interested in the nozzle, so I've skipped the bolt holes. This model is, as rb1957 said, unconservative towards the flange itself.
I think that your model shoul include the whole bolt ( that is, a slice that double yours , model the bolt hole and, unless you're interested in the bolt, model it as rigid, or as a bar w/ suitable properties.
As boundary conditios, I'd use peripheral continuity in the faces of the slice, and fix the end of the pipe - provided it's far enough.

http://files.engineering.com/getfil...c-9262-4585-8684-340ca8ded534&file=FLANGE.pdf