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Block Verification
Posted Apr 24, 2012, 4:05 p.m. EDT Structural Mechanics 2 Replies
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Why must you have all 3 roller boundary conditions (RBC) to get a correct solution? If you just keep the RBC opposite the prescribed displacement boundary, and turn the others to free, you don't get a correct result (forget the boundary loads and plasticity, just a simple linear block). Doesn't make sense, with all 4 sides free the block should't rotate or asymmetrically move under a uniaxial and uniform displacement, but it does.
What am I missing?
~C
Hello Chris Layman
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In a stationary structures problem you need to have enough boundary conditions to remove all rigid body modes even if your loading does not trigger these rigid body modes. Without proper constraints the stiffness matrix is singular and there is no unique solution since you can add a rigid body displacement and stiff satisfy equilibrium. If you pose this as a transient problem you should get a unique solution.
Nagi Elabbasi
Veryst Engineering
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