Application of force

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Sebastian
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Application of force

Beitrag von Sebastian »

Hello,

I would like to apply a uni-directional force to a round bar at an oblique angle. See attached image. The bar is fixed at one end. The other end is angled at thirty degrees, yet I want the force to be applied in the direction of the arrow. Unless I am mistaken Z88 only applies forces perpendicular to the surface. Can this be done?
application of force.png
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Thanks in advance.
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MNeidnicht
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Re: Application of force

Beitrag von MNeidnicht »

Hi Sebastian,

there is a way to apply forces that may have an any desired direction. You just have to compose it by single forces in x- / y- and z- direction.
force_decomposition.JPG
force_decomposition.JPG (15.57 KiB) 3282 mal betrachtet
So it works faster if you mark the corresponding nodes one time. Only the values ​​for individual forces have to be changed and applied.
force_direction.png
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With best regards
Martin Neidnicht
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Sebastian
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Re: Application of force

Beitrag von Sebastian »

Thanks Martin,

A follow up question: After selecting the nodes where the force is to be applied do I use the total force as the load or do I use the force per node. If the latter, how do determine the number of nodes selected?
ccad
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Re: Application of force

Beitrag von ccad »

Hello Sebastian,

the answer of Martin is (of course) correct but your problem can be solved much easier: Z88 accepts forces in X, Y or Z direction, either. The forces need not be perpendicular to the surface - this is only true for surface and pressure loads but not for single forces.
Thus, concerning your sketch with the beam, if your coordinate system is defined like - let's assume - this way:
X points from left to right
Y points from bottom to top
Now apply your force simply in Y direction - with a negative value because Y points from bottom to top. That's it.

Prof. Rieg
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Sebastian
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Re: Application of force

Beitrag von Sebastian »

Super!! Thanks so much! :D
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Sebastian
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Re: Application of force

Beitrag von Sebastian »

ccad hat geschrieben:Hello Sebastian,

the answer of Martin is (of course) correct but your problem can be solved much easier: Z88 accepts forces in X, Y or Z direction, either. The forces need not be perpendicular to the surface - this is only true for surface and pressure loads but not for single forces.
Thus, concerning your sketch with the beam, if your coordinate system is defined like - let's assume - this way:
X points from left to right
Y points from bottom to top
Now apply your force simply in Y direction - with a negative value because Y points from bottom to top. That's it.

Prof. Rieg
I am having trouble replicating this. If I choose several nodes and apply a force it appears as if that force is applied to each node. Obviously this gives me results which are not true. Rather I would like to have that force spread out many nodes. :?
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MNeidnicht
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Re: Application of force

Beitrag von MNeidnicht »

Hello Sebastian,

you're totally right.
There are always two questions: What direction and what value has a force? And: On which nodes it should be distributed according to which rule?

The force you choosed is applied to every node, wich is selected. The option "FE-rules" helps you dividing the total force into as many parts, as nodes are selected.
apply_forces.png
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Greetings
Martin
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