Meshing my beam 1

[OJM]

Hi all,

Currently trying to mesh my A-symmetric beam properly using C3D8R elements, I know that i'm supposed to add partitions to improve the mesh so I've partitioned the holes in the beam. Is this how it is supposed to look like? shouldn't all of the beam be either pink or green?

Thanks

 

[FEA way]

Orange means that it can’t be meshed using currently selected technique. Pink indicates free meshing (undesirable). Yellow and green symbolise swept and structured meshing respectively. These are what should be achieved. Make the squares around holes wider and divide areas near the holes into 4 parts.

And remember - usually the more partitions the better mesh.

 

[OJM]

Thanks, I've now managed to get yellow and green for my beam I deleted the partitioning around the holes and it seems to look better??

I'm still struggling to get the same for the concrete slab part of the design, as you can see the slab is awkward shape, this is because its cast against the side of the beam, i've paritioned as much of it as possible but there are still extrusions that i'm not sure how to partition?

Thanks

 

[FEA way]

You should also cut these extrusions of the base cuboid part. Think of the partitions as how to divide the model into simple shapes such as cuboids and cylinders.

 

[OJM]

Thanks I have now managed to partition the slab into green and yellow parts. However when I go to mesh it, i'm getting this error,

w

hat should I do?

 

[FEA way]

Either change meshing technique for green regions to swept (yellow) or (recommended) apply further partitions to make it all green. Start with cutting those extrusions from the base part. Use display group tools to hide outer regions and see how ot looks like inside.

 

[OJM]

I clicked the top option and managed to get a mesh that kind of worked. However when I run the model I get two errors, these are shown in the 2nd picture below. I think the first one is about the mesh (Volume of 18 elemnts is zero small or negative) Should I make sure all the partitions of each part is fully yellow or green? Or can I have a mix?

2nd error is due to the displacements that I've set but i'm not sure why. SO I'm doing a four point bending test by by specifying the deflections instead of loads. I've attached a copy of the model so you can see. I set the displacements as a boundary condition over a small area directly underneath the loads maybe this is wrong?

Thanks

 

[FEA way]

Regarding first error message - check mesh quality (Verify Mesh tool in Mesh module) and try to make the mesh finer or remesh with another technique. This error often happens when tie constraints adjust the slave nodes too much - check their tolerances to make sure that they don’t adjust the nodes that are too far.

When it comes to the second error - it means that the model is overconstrained. Basically you specified two different BCs at the same location.

Can you attach inp file ?

 

[OJM]

don't think I can attach a inp file one cae or jnl

 

[OJM]

only*

 

[FEA way]

Fine, then please attach jnl file too and try the steps I suggested in the previous post. You should be able to fox these errors.

 

[OJM]

Please find the jnl file attached

 

[OJM]

I have solved the 2nd error, now only the meshing error needs addressing, I've verified the mesh and there are only warnings but no errors. Seems strange why it won't run. I've tried to partition the concrete so that it's all green but i can't manage to, i think the shape is too complicated - I may try and simplify it.

 

[FEA way]

Did you check your tie constraint settings (tolerances) ? They may cause this error. See if the set ErrElemVolSmallNegZero contains elements in the area where tie is used.