I hope I'm not getting annoying saying this so many times, but have you done a mesh convergence study? Missing that is by far and away the most common cause of wrong FEA results I see. Run the same models with 3 or 4 mesh densities (can be both coarser and finer than what you have) and make sure...
I see. That large region on the left does look suspicious. I agree that away from trouble areas, the stresses should agree.
Have you checked with mesh refinement? That's quite important since you can't make much of a claim about accuracy without it. It will at least tell you which high stresses...
They both seem to have the same maximum (227). Which feature concerns you?
The two peak stresses on the left of the plate mesh look like a point connection to me. Are you sure the different plates are properly connected all the way along their edges? Check the deformed view to see if any gaps...
It looks like a qualitatively correct graph for an object bouncing off a surface with some loss of energy and then flying away. Maybe the soil is mostly deforming elastically? Maybe you don't have enough friction? No gravity? The long linear region suggests that the pile is weightless since it's...
Some ideas:
The picture shows the surface shear stress which is supposed to be zero, isn't it? What about inside?
Are you sure it's wrong? The picture is consistent with what you predict "should be 0 at the extremes of the flanges and increase linearly until the center of the flange" because...
Sorry, I misunderstood the problem so please ignore my previous reply. Now plates 1 and 2 look like they should behave the same to me.
Have you already found that it works correctly for more intuitive cases like released Y-rotation on nodes B and E? If so, then perhaps the bug is that you've...
Which direction is X?
If X is parallel to AB in the diagram, then, no, the two problems aren't the same. The one without the X-rotation connected allows the two plates to shear differently at that node. If you put a moment load about X on node F, then you should see the 2nd element having shear...
I don't have any idea about an analytical solution. It sounds next to impossible for a plastic dynamic model. But here are some suggestions for comparing the FEA solutions:
Just because each program has the same mesh doesn't mean they'll have similar results. You still have to check for mesh...
8-node hex elements often have all sorts of different formulations because the basic textbook one is quite terrible. Several programs seem to use identical formulations for 10-node tets though. 20-node hex is also more likely to be the same.
Other things to check:
Make sure you have the same...
Why do you only have one Cauchy stress tensor for the whole element? I would expect to do it at each Gauss point. It will be different across the element, so you'd lose information by summarizing it with a single tensor.
In case you do need a single tensor for the whole element. Then perhaps...
I can't quite tell the problem - maybe post pictures of the other case with the different stress? However, it sounds like the two gears are interfering, so that when you have contact on both sides, it prevents the interference by causing a very high pressure to push the gears apart.
Mecway developer here. That's correct what jhardy1 said. Mecway is now more advanced, not just allowing an order of magnitude larger models but also nonlinear analysis, CalculiX interop, units, more powerful boundary conditions, and more file formats, just off the top of my head.
These and a...
Do you want the complete stiffness matrix or just a few nodes to use it as a superelement? For the complete matrix, my software Mecway (see Google) can do that using traditional 5 DOF shell elements. It can also import a mesh in .inp format. The matrix file format is a row,column,value triple on...
Yea that is suspicious. In CCX's matrix, the displacement DOFs in each row don't sum to zero which seems to indicate there's some constraint to ground when there shouldn't be. For Abaqus's matrix they do sum to zero.
There have been bugs with beams and shells in CCX related to the way it...
There's no reason to expect different programs to produce the same stiffness matrix. They might order the DOFs differently, use different element formulations or even scale some values differently. In this case, since you have 2-node beams, CCX expands them to 8 node hex elements with no...
Can you not put a path in the FILE NAME parameter of *SUBSTRUCTURE MATRIX OUTPUT?
You'll probably have more luck asking on the CalculiX forum where the programmer sometimes answers questions: https://groups.yahoo.com/neo/groups/CALCULIX/conversations/messages
Sure, but this DIANA seems to be very old and unfriendly. Maybe it requires you to choose a solution algorithm. Incrementing force is the basic way to solve non-linear problems but you're using displacement so maybe you have to tell it to use displacement control...
I'm not familiar with DIANA and this might sound facetious but have you tried doing what the error message recommends? Or are you wondering why you need to specify loads when you only want a fixed deformation? Some nonlinear solvers don't work with only constant displacements and need changing...
Look at the solution leading up to the failure. That can reveal what's happening. Something might be moving in an obviously wrong way.
I suspect buckling is happening. I've seen cases where refining the time steps caused convergence failure while coarser ones didn't. That doesn't mean the...
Stress isn't. You won't have specified the shape of any fillet/etc so it can't know the stress concentration factor. The shell elements might also assume a plane stress state which isn't valid at a corner.
