Learning Forum

[Mansoureh]

Hello dear all,

I need some help to find how can I mesh this structure to have an accurate result?

I want to apply a compression test of -0.196 mm in 10 seconds and with using Bilinear Isotropic Hardening and two solid plate on top and bottom.

How can I perform mesh refinement for this structure? I mean

In a paper that I extract this model they just said they did mesh refinement using mesh sensitivity and final element size is 0.002 and 0.0015 in max and min value. How can I get to this result?

Anybody can help or give me any recommendations?

[phoenix098]

You can do mesh refinement based on some convergence criteria. For example, if you have a total deformation for a base mesh and run mesh sensitivity so that the deformation change is less than 5% from last mesh refinement, the analysis stops there.
The criteria can be any of the the results objects: Deformation, stress, strain etc...(Not available for Probe results)
To set mesh sensitivity study:
Right click any result and click Insert>Convergence
Set it to 5% or any value
Go to Solution and set max refinement loop to 2 or 3 and solve it.
Check this article:
Check thsi video from Ansys:
Let me know if that helps.

[Mansoureh]

dear @phoenix098
Right now tried this way as you said and just I am waiting for the result. May I explain to you my simulation and maybe you can help me to get the result. I need the result and have no time and really I've been confused about where are my problems.
here is my definition for my structure: I should verify my result with the paper that they wrote about the process:
The Ansys non-linear mechanics was used, 2. they have assumed two plates as rigid bodies. 3. Fixed support was placed for the bottom surface and a vertical displacement ramped at 10 substeps along the y-direction. (0.196 mm in the y-direction ). 4. with solid tetrahedral element 5. Bilinear Isotropic Strain Hardening (BISO) material model. 6. frictionless contact.
the thickness in this structure is 0.3 mm.
I tried several times with frictionless contact but all the time UNconvergency accrued. and the structure escape and disappeared so I changed the connection to frictional with 0.1 coefficients and the simulation is done very well but the result did not match with the paper as you can see below in the stress-strain curve.
for this result, I use tetrahedrons mesh with the local and global size 0.3 mm. (if I make the mesh size smaller to 0.2 or 0.25 the errors happened and UNconverged, So I assumed the mesh size 0.3)
from the result, you can see anything is not matched (E and yield stress) and there is so much deviation from the paper.
in the paper, they said that: "Mesh refinements were carried out using a mesh sensitivity analysis resulting in the number of finite element nodes and elements with a maximum and minimum element sizes of 0.002 and 0.0015 mm respectively." based on their result they have 996480 Elements and 3356756 Nodes.
So I went ahead in this way that I will explain for you below.


I continued with this mesh size, ( I know it is very coarse mesh because the thickness is 0.3 and after meshing, the structure has really coarse mesh).
If I use 0.3 for the size I have better mesh but not very good and if i used 0.25 or 0.2 I had too much mesh that they were so small and after solving I got an error of unconvergency) so I left the mesh as default and continue
I used frictional (coefficient 0.1) contact for both the top and bottom plate with the structure ( but they mentioned frictionless and I do not know how to constraint the structure from moving in frictionless contact) can you help me with this problem?
here are my connections: bor both plates and structures is the same

Analysis setting :


I put two remote points for the plates and this is their boundary conditions:
Top plate:


Bottom plate:


and i defined as you said me before


I got many errors and it has stoped

can you help me to say that am I going in the correct way? I have limit time and am faced with many problems and please correct me if i am wrong

Thank you inadvanced