corus ,
this is with reference to another thread that I had started. (
In simulating a uniform radially outward heat flow through concentric tubes (snug fit ) , I find that the values HFL1 and HFL2 vary which cause small oscillations in the HFL magnitude as well. I haven’t performed the stress analysis after transferring these values as I know the varying directional heat fluxes will cause the directional stresses and contact pressures to vary as well .
Could this be due to the elements being used ? I tried various element combinations
- hex mesh , quad elements for heat transfer
- hex mesh , linear elements for heat transfer
- tet mesh , quad elements for heat transfer
- tet mesh , linear elements for heat transfer
- inner tube – tet mesh quad heat transfer elements
- outer tube- hex mesh quad heat transfer elements
But none of these seem to iron out the directional HFL ‘noise’ on the surfaces. I’ve run extremely huge meshes as well , but it doesn’t seem to make any difference .
I learnt that quad elements model curved surfaces accurately , but at times give problems in transmitting loads due to a force acting in the opposite direction ( to the applied load ) in the corner nodes. However , when I just take a single tube , use quad elements , the results are perfect with uniform values .
This also makes me think that the contact might be causing issues. If you could look at my contact definitions in the cae file I have posted on the other thread it would help me iron out possible problems.
Here is an attached pic of the HFL1 contours of the assembly which I’m pretty sure is wrong . Also , if you notice in Figure 1 and Figure 2 that there isn’t much of a difference after the coordinate transformation. I don’t know if the transformation is being done as it should considering my temperature values are constant throughout and hence the heat flux values should be constant as well . Figure. 5 shows a similar trend as Figure 2. However the plot becomes better with the transformation . Again , is Abaqus unable to transform surfaces that are in contact or is there a special way to do this. I guess I’m looking at this issue from all angles .