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Force acting on a structure

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Hello,
I'm working with the Structural Mechanics module (Solid, Stress-Strain - Static analysis) in three dimensions.

My goal is to get Youngs modulus from a complex structure.
My problem is that I cannot get the reaction force acting on several points.

I implemented this complex structure from Matlab. Next I definded the boundary conditions which are applied to the uppest and lowest points of the structure. The upper points were displaced by a relative small length and the lower points were fixed. Comsol was able to solve it.
I need to get the force acting on the upper points (which causes the displacement). Is it possible to get it and if this is the case, could you tell me how or give me a hint?

Thank you.
Best regards,
René

1 Reply Last Post Jun 16, 2010, 1:22 a.m. EDT
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago Jun 16, 2010, 1:22 a.m. EDT
Hi

first of all if you use point constraints, do not forget that these are mathematical "singularities" and your results will be extremely mesh dependent, try if possible to use small areas by cutting the violume around the points and have anough mesh elements there.

Normally, the reaction forces are calculated on boundary conditions (BC) with hard constraints as you mention, but are they orrect for single points, would need to check the doc. Another way is to turn on the weak constraints, butagain integration on a single po9nt is not very precise ;)

Good luck
Ivar
Hi first of all if you use point constraints, do not forget that these are mathematical "singularities" and your results will be extremely mesh dependent, try if possible to use small areas by cutting the violume around the points and have anough mesh elements there. Normally, the reaction forces are calculated on boundary conditions (BC) with hard constraints as you mention, but are they orrect for single points, would need to check the doc. Another way is to turn on the weak constraints, butagain integration on a single po9nt is not very precise ;) Good luck Ivar

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