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non 0 initial velocity in solid mechanics takes no effect in stationary analysis?

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In stationary analysis, if one sets a non 0 initial velocity in solid mechanics, is that simply ignored? That is, stationary analysis doesn't at all allow straight line uniform motion with no acceleration? Or stationary analysis doesn't allow any steady motion at all?


4 Replies Last Post 2024年3月31日 GMT-4 01:25
Henrik Sönnerlind COMSOL Employee

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Posted: 8 months ago 2024年3月27日 GMT-4 06:33

Yes, initial velocities do not affect stationary results.

In a stationary analysis, it is necessary that there are enough constraints to suppress any rigid body motions.

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Henrik Sönnerlind
COMSOL
Yes, initial velocities do not affect stationary results. In a stationary analysis, it is necessary that there are enough constraints to suppress any rigid body motions.

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Posted: 8 months ago 2024年3月27日 GMT-4 07:12

Thank you. Why do we sometimes see that the solution is still obtained even when there's not enough boundary conditions to suppress rigid body motions?

Thank you. Why do we sometimes see that the solution is still obtained even when there's not enough boundary conditions to suppress rigid body motions?

Henrik Sönnerlind COMSOL Employee

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Posted: 8 months ago 2024年3月27日 GMT-4 08:39

That can sometimes happen if there are 'enough' numerical inaccuracies so that the stiffness matrix is not identified as singular. Also, sometimes an iterative equation solver can happen to find a solution.

When it happens, there is typically an arbitrary rigid body superimposed over the deformations.

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Henrik Sönnerlind
COMSOL
That can sometimes happen if there are 'enough' numerical inaccuracies so that the stiffness matrix is not identified as singular. Also, sometimes an iterative equation solver can happen to find a solution. When it happens, there is typically an arbitrary rigid body superimposed over the deformations.

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Posted: 8 months ago 2024年3月31日 GMT-4 01:25

Thank you

Thank you

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