Problem with stress simulation

Problem with stress simulation

k133004
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Message 1 of 9

Problem with stress simulation

k133004
Participant
Participant

Dear people of the fusion360 forum,

I am making a drone frame for a school project and looked into the static stress simulation. I got most of it to work but it turns out that I get weird results. I made a symmetrical design and applied the same forces and constrains on all 4 arms. But only one of them has results that are acceptable, and the other dont have results at all.

 

I would really appreciate your help!

 

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Accepted solutions (1)
2,124 Views
8 Replies
Replies (8)
Message 2 of 9

TheCADWhisperer
Consultant
Consultant

Can you File>Export your *.f3d file to your local drive and then Attach it here to a Reply?

Message 3 of 9

k133004
Participant
Participant

I attached the file here, thanks for looking into it!

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Message 4 of 9

TheCADWhisperer
Consultant
Consultant

@k133004 wrote:

I made a symmetrical design and applied the same forces and constrains on all 4 arms.


That is not what I see in the file that you attached?

Are you attempting to follow a Tutorial?

TheCADWhisperer_0-1639159025613.png

 

Message 5 of 9

k133004
Participant
Participant

First of all thank you for your fast replies.

 

No I did not follow a tutorial. I see that only two of the 4 forces are visible for you, which is quite weird since i actually applied 4.

After your reply I setup a new simulation with the forces divided in 4 individual groups of forces (Force4 -visible under gravity- is now divided in force 1, force 2, force 3, and force 4) and it turned out that I kept the exact same results. So I suppose that cant be it..?

Knipsel.PNG

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Message 6 of 9

TheCADWhisperer
Consultant
Consultant

Can you File>Export your *.f3d file to your local drive and then Attach it here to a Reply?

Message 7 of 9

k133004
Participant
Participant

It is attached again. @TheCADWhisperer 

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Message 8 of 9

TheCADWhisperer
Consultant
Consultant

Once again - the file that you attached has the Forces applied to two of the arms, not all four???

TheCADWhisperer_0-1639230526936.png

TheCADWhisperer_0-1639230799065.png

On this arm you have two Pin constraints on one side and none on the other side (like you have for the other arms).

 

You have 4 arms.

You have 2 fastening holes per arm.

That equates to 4x2=8

 

You have 14 Pin constraints.

14/8=???  (asymmetry?)

 

Fastening Holes.png

I suspect that you actually intended 4x2x2=16 Pin constraints.

 

Message 9 of 9

k133004
Participant
Participant
Accepted solution

@TheCADWhisperer Thanks for your reply and screenshots once again.

I've fixed the issue by opening the exported file and editing the forces in the Load Case Attributes menu.

For some reason the forces were applied wrong to all arms so that Arm1 and Arm2 had all of the forces coming on them. I've checked my main file multiple times and noticed that all forces were divided equally on there, which then makes it extremely weird that the exported file has these unequally divided forces. I would therefore say that there might be a bug in the static stress simulation OR that I just messed something up in my design...

I've attached a image of what it looks like now (fixed), close the circle.

Knipsel.PNG

.

 

Anyhow, thanks for your extensive help.

Kind regards,

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