ladder frame torsion FEA
ladder frame torsion FEA
(OP)
Using generative structural analysis I'm trying to set up a pure torsion case for a ladder frame as shown in the attached image.
I think I need to restrain the part somehow, but everything I try fails.
I think I need to restrain the part somehow, but everything I try fails.





RE: ladder frame torsion FEA
You should be able to use the 'clamp' function on the two round faces at the bottom end of your ladder. This will provided a restrained condition.
If you need more restrained surface area than that, (such as if your ladder is part of an extension ladder, or restrained by a grip area) what you can do is to explode the solid, split the side legs at a particular length, and then join the whole thing back together. Now, the area that you split will appear as a separate face on the solid, and you can clamp just that area. (this method also works when appying different pressures across a surface)
-----------------------------------------------------------
Catia Design|Catia Design News|Catia V5 blog
RE: ladder frame torsion FEA
I have run 2 cases. The first was clamping the end faces on one end and the other where I clamped diagonally opposite faces. Neither quite give me what I want as the clamped ends show zero deflection.
In the pure torsion case I am trying to achieve I would like to see the zero deflection point at the c of g of the frame with all 4 corners showing deflections created by the 2 couples applied to the frame.
As the c of g is in space I'm thinking I need to create a restraint at this point, but how? A virtual restraint?
Or am I barking up the wrong tree.
As a matter of interest the frame is a simplification of a ladder frame chassis.
I have a FEA v5 tutorial book from SDC publications, but it doesn't specifically cover this point.
Is there any other literature available that may help me?
RE: ladder frame torsion FEA
Can you create a solid sphere around the CoG, and use it to apply your clamp? (It's possible to do this and use it as a restraint, but I don't know what the actual result will be)
-----------------------------------------------------------
Catia Design|Catia Design News|Catia V5 blog
RE: ladder frame torsion FEA
the following image shows that my analysis indicates zero deflection of the frame along the longitudinal and transverse axes through the c of g.
I'm assuming these pads being very small relative to the overall structure will have an insignificant affect on the analysis.
I couldn't get the cut faces or seperate sphere to work.
J