Solid vs Shell elements for plate structures ?
Solid vs Shell elements for plate structures ?
(OP)
I have been ask to evaluate an analysis done on a bifurcation. The analysis was done using solid-shell elements (SOLSH190 – Ansys – 8 node brick), with one element across the thickness. Apparently this element can handle bending quite well and give accurate answers
My FEA knowledge is about 5 years out of date. The type of solid elements I am use to give bad results for plate structures (especially using low order elements – with 1 element across the thickness). I know the solid mesh is quick to build from the CAD model. Making a shell mesh takes longer and more skill.
Despite the new solid-shell element I am uncomfortable with it, and don't know whether to trust the results.
Does anyone have advice, or maybe a link to a article where they compare the accuracy to tradition shells?
My FEA knowledge is about 5 years out of date. The type of solid elements I am use to give bad results for plate structures (especially using low order elements – with 1 element across the thickness). I know the solid mesh is quick to build from the CAD model. Making a shell mesh takes longer and more skill.
Despite the new solid-shell element I am uncomfortable with it, and don't know whether to trust the results.
Does anyone have advice, or maybe a link to a article where they compare the accuracy to tradition shells?





RE: Solid vs Shell elements for plate structures ?
Tata
RE: Solid vs Shell elements for plate structures ?
ht
RE: Solid vs Shell elements for plate structures ?
RE: Solid vs Shell elements for plate structures ?
Your best bet is to test, test and test again (as said) against simple benchmarks for your structure. If in doubt - and if practicable - go with solids for bending-dominated problems that are of questionable shell geometry. If the problem is non-linear, then consider using multiple solids through-thickness, preferably hexehedrals. Three as an absolute lower limit, and anything upwards of this if possible/practicable. Avoid single order tets like the plague for stress-related problems, and always use plenty of higher order tets where possible.
------------
See FAQ569-1083: Asking questions the smart way on Eng-Tips fora for details on how to make best use of Eng-Tips.com
RE: Solid vs Shell elements for plate structures ?
Do a test to prove that the FEM can replicate the classical solution you find from a reference.
These types of special elements can work well, but can also introduce some unknown issues if you are not familiar with them.
The basic elements should work just fine. The only exception I can think is if the b/t ratio is low then the transverse shear stiffness will have an effect. It is more significant in composites though. You would need an element capable of accounting for that, but again you would first want to check the results with known solutions.
Brian
www.espcomposites.com
RE: Solid vs Shell elements for plate structures ?
Ansys 12 allows you to layer the SOLSH190, so you can get 3 elements thick on a plate if needed and keep mesh size down (rather than using SOLID186).
How well this works I do not know, I have not gotten around to setting up some test runs.
See the benchmarks provided in the Ansys help file, they will show how the element performs compared to some hand calcs.
____________
JohnyGluebag
RE: Solid vs Shell elements for plate structures ?
here is the link to the SOLSH190 discussion
http://w
____________
JohnyGluebag
RE: Solid vs Shell elements for plate structures ?
Thanks especially JohnyGlueBug for the link to the paper. Very informative. Looks like Ansys are onto a good thing with the Solid shell element.
I did run my own model for the first round of analysis which were linear static. Here the contractor used Nastran with Shell elements which I could check easily with my program (Strand7).
It was discovered that the structure needed to be embedded (or partially embedded) in concrete to withstand the pressure. At this stage a new contractor was bought in and the analysis change from a linear static to a nonlinear contact analysis (using Ansys) which I afraid to say are basically beyond the abilities of my program.
RE: Solid vs Shell elements for plate structures ?
You can do a non-linear contact analysis in Strand7.
Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/
RE: Solid vs Shell elements for plate structures ?
Regarding the original question, I personally find the SOLSH190 element to be very useful. Only slightly more expensive than traditional shell elements for thin shells and considerably more accurate for thicker shells, and cheaper than a very fine solid mesh. Just as mentioned in the interesting presentation posted by johnyGluebag.
As mentioned in the above posts, you should make your own test though. The purpose of these tests will be to verify that you are using the element correctly and that it is suitable for your model (not that it functions properly, because this is a heavily tested element with a good formulation).
Nagi Elabbasi
Veryst Engineering