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issues with pre-stressed and initially-deformed problems

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Hi,

I am simulating the transient deflection of a simple cantilever beam under some constant load. It works fine.
In the next attempt I want to give an initial deflection before it undergoes the same external load.
But when I assign the initial deflection that has the same order of magnitude, in the following menu, no change to the solution is observed as if no initial condition was applied.

Physics > Subdomain Setting > Init

This has been of course my 2nd unsuccessful attempt in using initial values for a transient problem. In a Fluid-Structure interaction problem, the solid geometry was pre-stressed and I entered it in the Initial Stress-Strain tab.
Again nothing happened.

Does anyone have any idea how the initial values can work?

Thanks.

2 Replies Last Post 17 juin 2010, 10:36 UTC−4
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 17 juin 2010, 01:37 UTC−4
Hi

have you checked how to restart your solver from previous run ?
I
n this way you make a first run to get the initial values, save the solution and restart from there.

By default, you restart from "initial conditions" often "zero", study the "solver manager tabs" in detail in 3.5.

In V4 you must try it out by steps to get he best out of the new way, I'm not fully operational there yet, having still some surprises, but I have tested sofar nice complex assemblies of studies, so the possibilities are going far beyond V3.5 in this new solver sequences approach

Have fun Comsoling
Ivar
Hi have you checked how to restart your solver from previous run ? I n this way you make a first run to get the initial values, save the solution and restart from there. By default, you restart from "initial conditions" often "zero", study the "solver manager tabs" in detail in 3.5. In V4 you must try it out by steps to get he best out of the new way, I'm not fully operational there yet, having still some surprises, but I have tested sofar nice complex assemblies of studies, so the possibilities are going far beyond V3.5 in this new solver sequences approach Have fun Comsoling Ivar

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Posted: 1 decade ago 17 juin 2010, 10:36 UTC−4
Thanks Ivar,

I had already seen your similar advice to someone else too and had implemented it (i.e. run as steady state
first then use the solution for transient solution) and it worked for me. But it would be intuitive more
if the initial stress-strain or initial deformation could work. So the question is that what are those INITIAL tabs for?
BTW, I am using v3.5.


Thanks again.
Thanks Ivar, I had already seen your similar advice to someone else too and had implemented it (i.e. run as steady state first then use the solution for transient solution) and it worked for me. But it would be intuitive more if the initial stress-strain or initial deformation could work. So the question is that what are those INITIAL tabs for? BTW, I am using v3.5. Thanks again.

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