I have different models of the same geometry yet only an interior object has a different rotation. (see attached please). For the importance of mesh consistency among different models, I am looking for a way to design similar mesh for the different cases (orientation degrees for the interior slit).
My understanding is to keep the whole model partition the same. by isolating the interior zone where the only difference. Then do partition for the interior zone in a similar way. However, I got some irregular zones where it kind of hard to mesh uniformly (with element shape does not distort due to sharp edges)
I am going to simulate 3D models. The partition is so challenging here. simply the error of the loop is not closed to extrude which revealed that the curves are not connected fully for two reasons. the first is there is a hole. second even I draw and trim curve in NX, I found NX itself leave a gap between curves.so they are not connected.
The following are some inquiries around this problem
1- Is the suggested way practical/acceptable or even is necessary for your opinion for consistency (I mean in the results for all model) ..do you recommend it or it has its issue that needs to avoid.
2-Do you have any suggestions in this regards (meshing such models) please or could you refer to similar examples to study them and follow their concepts.
3-For such a model, using dependent mesh (for mesh around the hole sides (hatched in brown color) as it could be regarded as a type of symmetric (I mean both should have the same displacement and deformation in my case).
4- do you recommend using a discontinuous mesh that will be glued by edges-to-edge in 2D, or surface to surface in 3D.
Your comments are so much appreciated
Solved! Go to Solution.
I got this partitioned now, but the first mesh fails at the slot. I keep trying to modifying it.
I planned to use the surface contact for later so the mesh was not always continuous. However, I could not have that many coarse elements far from the area of interest as the smallest element size though thickness (it is size related to the size of the smallest element at the slot based on the aspect ratio criteria) in some way limit the maximum element size in the model.
I have found that quite often if you split the faces/bodies like you did i.e. overthinking then you are not helping NX mesher - sometime less is more! I think in your case you have created to many split. With fewer splits the starting pont is not too bad. Transition zone will be the "problem" orange blue meshes on the attached pdf
If you are planning to use the contact-glue option them one might be able to create a circular "split" and then manualy rotate the mesh to create the different slots position -it means that you contact gluedges are now on that circluar cut. mind you this could work even with coincident meshes
Still do not kwno whay 1/4 model would not work
Here you are some ideas for meshing the part with 3-D solid CHEXA 8-nodes elements, I run FEMAP but you can do the same using NX AdvSim. The key is to define a PAD around the slot. Also, do not split bodies, simply divide surfaces in the idealization environment, later when 2-D QUAD4 mesh available simply extrude to create 3-D solid HEX mesh.
The key is to split top surfaces like the following picture:
And mesh using CQUAD4 elements: the mesh quality is perfect, it pass all the minimum NX NASTRAN control quality checks:
Check Element Quality 745 Element(s) Selected... No Elements Outside of Maximum NX NASTRAN Allowable Value. Quality Check Number Failed Worst Value Quad Skew 0 44.97235 Quad Taper 0 0.256011 Quad Warp 0 0. Quad IAMin 0 43.83203 Quad IAMax 0 135.0003 Quad AR 0 2.650163 0 Elements Failed out of 745 Checked.
You can perform a mesh transition, but do not use a ratio bigger than 2.0 because remember you have to extrude the 2-D QUAD mesh to generate the 3-D solid CHEXA elements.
This is the full 2-D mesh (all are QUADs, not any triangle exist):
And finally extrude the 2-D mesh to generate the 3-D solid CHEXA elements: I have used and element size = 0.2, resulting in 25 divisions in the direction of extrusion, and here you are the resulting element quality checks, the maximum aspect ratio is 5.1. If you want to reduce it, simply use 30 elements in the extrusion direction:
Check Element Quality 267775 Element(s) Selected... No Elements Outside of Maximum NX NASTRAN Allowable Value. Quality Check Number Failed Worst Value Hex AR 0 5.107534 Hex DetJ 0 0.0000548154 Hex Warp 0 1. 0 Elements Failed out of 267775 Checked.
32 GB RAM is not too bad, but you can cut the model size more if instead to performing a mesh transition from local to global you use GLUE SURFACE-TO-SURFACE condition, this is a valid feature, I use it a lot as well. You can split the body and perform local mesh with best quality, and then gradually use GLUE in different stages, I suggest to keep the ratio 2:1 for every mesh transition, this way the quality & accuracy of both mesh & results won't be at risk.