Modeling a composite structure

[adai8636]

Preface: I've looked through a few other posts but I don't believe they were resolved or a there was much detailed information.

So I have a simple learning test I'm trying to do. I want to do static stress with linear material models using laminate bonded to steel. Does anyone have a tutorial? If anyone would like me to upload what I've done so far, I can provide any geometry and any FEM file. I'm just looking for help. I built a small square frame and then put faces on each side and attempted a loading configuration like it was twisting about a central axis with a 1000 lbf load on each face. I got 0 deflection and zero stress which means somewhere my setup is bad. (Let alone knowing the in's and out's of the calculations going on BEHIND the software) I used tetrahedron for the square tubes and thin composite for the faces like a single layer of carbon.   Can anyone help me?

[AstroJohnPE · Accepted solution]

Hi adai8636,

Your description sounds fine. So results of 0 imply that you did not apply the load properly, or you accidentally put constraints at the same locations as the loads. For example, tet elements do not recognize a nodal moment. (The nodes of a tet element do not calculate rotation which would be needed to transmit a moment.) Showing the loads and constraints in the Results environment may indicate which (if either) of my guesses is correct.

Otherwise, read this post to attach your model: "Create, Post, or Provide an Archive of your model"

[adai8636]

AstroJohnPE, thanks. I think what I was doing was applying the load normal to the composite surface on the thin composite mesh. I assume since it is a thin composite it can't react normal loads? I ended up applying the loads to the tetrahedron faces below the composites and then I got results. Not sure if this is the correct methodology or not. Also, I get a warning that I'm not sure how to interpret. "warning: max/min stiffness ratio = 7.1437e+13" Not sure what that means or how my simulation is affected.