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Sliding boundary conditions in Solid Mechanics
Posted Mar 21, 2013, 5:50 a.m. EDT Structural Mechanics 5 Replies
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I am trying to model a sliding boundary condition between to elastic bodies.
By sliding condition here I mean, that the DIFFERENCE between the displacement fileds should always be zero in the normal direction between two bodies i sliding contact.
I understand that I need to buid an assemby and create a contact pair between two bodies. And then apply a contact condition. But there is no such contact condition, so far I know. Is there a way to create your own condition or modify the existing one?
Another easier way is to prescribe the displacement on the boundary as:
u_source * nX = u_destination * nX
v_souce * nY = v_destination * nY
But I cannot find the variables for diplacement on source boundary and destination boundary.
I appreciate any help I could get.
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you could try to use a pair elastic contact with anisotropic spring constants defined w.r.t. the surface normal (no friction this way, but that can also be fiddled ;)
You need "assembly mode" to allow to duplicate the common boundary to allow the sliding
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Good luck
Ivar
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Thanks for the quick answer!
Do you mean a "thin elastic layer"?
I used assembly mode in order to ger the source and destination boundries. This because I want to control the behavior of the boundary.
I want to set the diplacement i normal direction equal to each other in source and destination boundary.
So far I discovered that the "periodic condition" does indeed support some control, e.g
you can set u_scr = u_dst, and v_src=v_dst
I want to change that to:
u_dst*nX = u_scr*nX
Can this be done in "prescribed displacement" pairs? What is the variable name for u_src for example?
Thanks!
Alex
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I'm not by my WS so cannot check, but if I rememeber right you have "thin elastic layer" in standard BC for "union" mode AND in Pairs - thin elastic layer, use the latter one with assembly mode and pairs
test ut carefully your formulas, (I cannot check like that would have to dig into the doc again) And take a look at the "roller" boundary condition of the internal "equations"
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Good luck
Ivar
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It works great, I used thin elastic layer as you suggested and increased the stiffness in radial direction.
Is there any difference between the UNION thin elastic layer and ASSEMBLY?
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There is no big difference. It is just a matter of how you want to model the discontinuity.
If you use an assembly, then it is possible to have non-matching mesh on the two sides. In that case you should be aware of that you should select the 'destination' side of the pair to be the one having the finer mesh to obtain the best accuracy.
Regards,
Henrik