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Problems solving the resulting force at given displacement

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Hello,

I have got a problem to solve the resulting force of a model with a given displacement.

My intention is to measure the resulting force at the top of the model, with a given displacement of 0.2mm at the bottom of the model.

I attached the model, could someone help me?


Thanks


1 Reply Last Post 29 oct. 2010, 03:09 UTC−4
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 29 oct. 2010, 03:09 UTC−4
Hi

a few comments first:

1) in your case you could create your full section (all with the same width) in the first workplane, then to add the "wings" only in the second workplane, and keep the extra domains (a few interiour boundaries are not important for the calculations. This would allow you to use a sweep mesh in the constant crosssection part, hence easier to make a denser meshing in the blade thickness, and mesh the "wings" therafter

2) applying edge loads/fixing is always delicate in 3D as this mostly put singularities in your model and you allow for rotations that might not be fully "real" or as expected. I always try to use boundaries (surfaces) for loads and fixing in 3D (respectively edges in 2D)

To get the forces use the "reaction forces" and "reaction moments", these exist on faces that are constrained or fixed (you can check that the integrated (use Integration Settings SUMMATION to get right units) reaction forces on your edge are opposed but equal to the one of the constrained surface. These can be made available in a table by using the "Results-Derived Values - Surface/Line Integration" then hit CNTRL Space in the Expression window and select SolidMechanics - Reaction Forces/Moments sub item. Then add them into the same table it's easier to compare
--
Good luck
Ivar
Hi a few comments first: 1) in your case you could create your full section (all with the same width) in the first workplane, then to add the "wings" only in the second workplane, and keep the extra domains (a few interiour boundaries are not important for the calculations. This would allow you to use a sweep mesh in the constant crosssection part, hence easier to make a denser meshing in the blade thickness, and mesh the "wings" therafter 2) applying edge loads/fixing is always delicate in 3D as this mostly put singularities in your model and you allow for rotations that might not be fully "real" or as expected. I always try to use boundaries (surfaces) for loads and fixing in 3D (respectively edges in 2D) To get the forces use the "reaction forces" and "reaction moments", these exist on faces that are constrained or fixed (you can check that the integrated (use Integration Settings SUMMATION to get right units) reaction forces on your edge are opposed but equal to the one of the constrained surface. These can be made available in a table by using the "Results-Derived Values - Surface/Line Integration" then hit CNTRL Space in the Expression window and select SolidMechanics - Reaction Forces/Moments sub item. Then add them into the same table it's easier to compare -- Good luck Ivar

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