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advice for simulation set up or suitable tutorial (3D stress distribution with multiple materials in contact)
Posted Apr 10, 2013, 2:04 a.m. EDT Structural Mechanics Version 4.3 3 Replies
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I am trying to help my fellow Orthodontics to showcase COMSOL's ability to simulate one of his problem. But I am struck and getting inconsistent results. The simulation is very basic and therefore experts here are requested to advice or direct a suitable tutorial for us.
The problem is teeth embedded in bone. when bone is subjected to a force, we want to see the stress distribution that is all. My problem is inexperience in 3D and structural modelling handing multi materials in contact. The 2D cross sectional picture is attached. Some may kindly enlighten us to proceed further?
Thanks in advance
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the easisest is to make for structural "solid" three domains in COMSOL (start in 2D, then once it runs reasonably go for full 3D): one for the dentine/enamel, one for you bone and one for your intermediate layer, wather that is.
Once the three geometry ojects are drawn, ensure that they have clean overlapping boundaries end finish in "Union mode"
Define your material properties for the 3 domains
Define a fixed boundary, (some of the external boundaries of the "bone" structure opposite to the tooth, then set a body load on part of the tooth boundary, set up a stationary solver study and go (meshing will be done automaticlly)
This should normally be enough to get first results, you might need to increase the boundary load (pressure or total force) until you see some reasonable results.
In anycase do not overdo your first geoemtry, keep it simple until you mater COMSOL, then only complexify, you will quickly be there with nice rainbow results, ut pls do not forget to check (=validate and verify) your results agains some hand calculations, it's very easy to miss a dimension a BC or something. Normally all FEM models are validated by experimentations
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Good luck
Ivar
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I am starting with your advice. Actually I misunderstood 'roller on a plane' tutorial and tried to create pairs between different domains. But now I understand it is not required. I am doing with overlapping boundary. Could you please enlighten me, in the region of overlapping, both the material property should be given by duplicating geometry?
Thanks again.
Siva
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use pairs only when you have specific physics between the two "adjacent domain" or want to have very differnt meshe densitites. Else use union mode and the default continuity.
But be aware in union mode no two domain may overlap (bewcause that would make 3 distinct domains, usefull in some cases) So one one material per domain (you might need to apply the material a SECOND time to BOUNDARIES if this is required (specific boundary physics). OK then if you have two boundaries of distinct materials, you have an issue => assembly ?I(I would to have to check and try it out fston a simple model)
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Good luck
Ivar