Help with understanding structural Buckling for a leaf spring.

[Anonymous]

So I'm new to Fusion 360 and something that seemed so simple to model has become a challenge already! Grr.

I've designed a leaf spring, though instead of having it horizontal with the load applied at in the middle of "L" (arc of a circle), I'm positioning the leaf spring vertical with a load applied at the end of the arc.

I've Fixed one end and have been applying a load at the other end and am trying to understand how much the arc will compress at any given force. IE As the force is applied, I expected to see the segment length decrease and the distance between the centre to the middle of L to increase. However, the simulation isn't behaving as I expect, IE "USER ERROR on my part".

I have done a practical experiment with PLA, so I know that an arc of 45deg,  W - 13mm D - 0.6mm H - 50mm (Segment) and L - 55mm, will compress 1mm when 0.83N is applied. Why can't I get the sim to replicate this as the load looks to be rocking which I'm not expecting or wanting.

[TheCADWhisperer]

Can you File>Export and then Attach your *.f3d file here?

[Anonymous]

File attached. Thank you for looking.

[bmfrank]

This is a function of how you have constrained the model.  The behavior you are asking for is similar to taking one end of the model and gluing it to a table, then hanging a weight from it.  You would observe similar behavior. To mimic what I think you are looking for you need to constrain one edge on the bottom fully, and the edge at the top so it doesn't "twist" but is allowed to move in the "Z" direction.  If you do that you can achieve results that are more in line with your physical observations like this:

[Anonymous]

Cheer

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@bmfrank wrote:

This is a function of how you have constrained the model.  The behavior you are asking for is similar to taking one end of the model and gluing it to a table, then hanging a weight from it.  You would observe similar behavior. To mimic what I think you are looking for you need to constrain one edge on the bottom fully, and the edge at the top so it doesn't "twist" but is allowed to move in the "Z" direction.  If you do that you can achieve results that are more in line with your physical observations like this:

Cheers, this looks to be exactly what I'm trying to do. If I run into trouble with setting this up, would you mind walking me though as so far, the constraits have been my stubbling block?

Oh, and not to push the boat, I will try first before I press for an answer, but is it possible to measure the increase in the bulge as the force is applied?

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[Anonymous]

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Cheers for that @bmfrank.

Continuing with my last post, I'm still struggling to work out if I can add another displacement point on the sim. IE, as the left compresses, what is the increase at the bulge? Pic attached.

Once again, many thanks for your previous input.

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[bmfrank]

You can add a point to measure values, using the "Inspect" Commands from the tool bars.