First, I am trying to find a sim setup that can be a validation of the theoretical final size that the plastic coin will get pressed into (simply to the diameter that my CAD program says is the final diameter of a cylinder of equal volume as the un-pressed coin but with a thickness of the final distance between the dies two contact surfaces after the full ram movement at iteration time 1.0s).
To achieve #1 in the sim setup, I decided to initially try to apply Ram Movement to the actual face that makes physical contact with the plastic coin, my brain said that this would likely be the best way to ensure that there would be no compression (or uneven compression) of the upper die to take into account. In a similar thought process I decided to support this whole press setup on the physical contact face of the lower die.
My run 3, simply changed the Ram movement face and the lower die support face to the upper face of the ram die and lower face of the lower die. (which would seem to add some die compression possibilities and make it harder to use as a validation setup)
The problem is that at the very first solution step, contacts are not activated and then the body is not constrained, this is why we use the elastic constraint. It is numerical stuff and pointless to get into that details now.
Also wanted to point out, what are your plans for the material model? I saw you have a bi-linear plastic, but I think a hyperelastic model should be better suited.
Edit. Don’t worry about core hours, failed simulations do not count.
I will try that but I am just assuming that long thin triangular faces would not be such a problem with FEA, is this face that tapers to the cyclic rotation center line the badly shaped element you see :
So if 1 degree slice gives 50/1, and with this center slice in our ‘area of interest’, where we want 5/1, wouldn’t I try ~10 degree slices
Ah, I am beginning to ‘see’ all this in my brain, watch out for fallout
So, perhaps I would have seen this earlier had I simply placed the 3 solids 1 mm apart from each other in the CAD file…
In all cases, ‘Physical contacts’ do not engage until some movement of objects has occurred or pressure applied, even if the part faces are coincidental to begin with …
Before that contact happens (that is infinitesimally small movement with respect to coincidental faces to begin with), all parts must be fully constrained except in the direction we want them to move …
So, the simulation starts to move the ram (or apply pressure), at some point contact is made with the coin, then those 2 parts move together until the coin hits the lower die where ‘contact’ is made and the coin should start expanding until the limit of ram movement.
Does my brain now ‘see’ this correctly
If so I think my next attempt may work better
Footnote: Is this elastic spring rate for an ideal spring of infinite length and the geometry parts are assumed to have no mass
Do the elastic springs ever impart loads to the face they are attached to that would affect say, how big a diameter the coin gets pressed to
P.S. Stll unanswered:
The Ram movement is dx =0 dy = 0 and dz is a t dependent formula…
So, I gave up with the cyclic symmetry. I think I know what is going on and maybe @rszoeke can correct me if I am wrong. As far as I can tell the Cyclic Symmetry boundary condition does not stop the model from rotating about the axis. Normally what I would do is create a local (r, theta, z) coordinate system at the center of rotation and then constrain the side faces to theta=0. Another option to constrain the model would be to apply a boundary condition to a node or point but in WB 2.0 we don’t have this option anymore.
I went back to a quarter model and aligned the side to the global coordinate system and I came up wit the following results.