Connection Analysis

[ecope]

Hello, What is the best way to set up a joint anaylsis in Algor? For example, lets take a frame (3D model) that in the first example the tubing (round or sq.) is butted up against another piece of tubing (like a bicycle frame). Where the two pieces of tubing is connect by welding all around, how would you do the anaylsis on the joint? Would you use the weld command to specify the joint? Also what if the smaller tube goes inside the larger tube and is just welded on the outside, how would you set this up? Is it best to use wireframe for this, if using a 3D model what meshing should I use?

Thanks for all help!

 

[GBor]

There are a variety of ways to model something like this, but it depends on what you are really trying to look at. If you are actually interested in the stress in the weld tow, I have been known to model the beams out of plate and use bricks for the weld bead. You have to make certain that the plates and bricks overlap (so that you have a series of plates under the brick elements) to address DOF issues between plates and bricks and you also need a small gap between the plates that make up the two tubing pieces.

This basic concept works for both of the scenarios that you mentioned, but the one that has a smaller tube inside a larger tube may also have to have contact if your deflection is significant enough. If the deflection of the smaller tube would actually cause it to impact the inner wall of the larger tube, you may want to add gap elements (if your analysis is linear).

If you are not interested in the weld stress, then just use beam elements...it will run much faster and give you bending and tensile stress in the members. Set-up is easy using the library even if your section is user defined as "pipe" with an inner and outer radius.