Wrong results during simulation?

[AlexD_autodesk]

As a teacher in the UK we are having great student outcomes using Fusion 360.

However, we keep running into problems/erroneous results using the 'simulation' environment - hopefully somebody can tell us what we are doing wrong?

No matter how much we reduce the load and no matter what materials we use, there always seems to be a failure of the material that does not seem consistent.

For example, having completed the 'laptop stand' tutorial available on YouTube, we placed a load of 1N (about 0.1kg under gravity) on the face of the stand and we get significant deformations when the material is set to 4mm aluminium (see attached screenshot) - seems unrealistic!

Seems we always get the same kind of results no matter what the structure/material is - always seems to react way more severely than expected...

Any ideas?

[JDMather]

Looking at the legend on the color bar - what is the indicated deformation value?

Are the students familiar with exponential (scientific) notation?

What are the deformation units that go along with the indicated magnitude of deformation?

[TMC.Engineering]

@AlexD_autodesk

Deformation is exaggerated.  Change the load and look at the change in value.  Next time I get on my computer I will try to do a video.  

To gain personal confidence in the software you could also perform simple hand calculations for something like a simply supported beam and then duplicate in fusion.

[AlexD_autodesk]

The load is 1N or aprox. 0.1kg perpendicular and centre to the structure (it looks like Fusion spreads this load uniformally by default).

So, the units displayed when results are given should be entirely consistent with the simulation environment and it makes no difference to the deformation if you alter them post analysis.

Thanks for looking into this but this anomaly does not seem solved yet...

[TMC.Engineering]

What are you expecting to see the results look like?  I'm still am having difficulties understanding what you are after.  You attached a image that has no units.

Fusions does distribute the load over the entire surface.  and your picture looks reasonable.

Units are set in the preferences and you can do custom.

 

[James.Youmatz · Accepted solution]

Hi @AlexD_autodesk,

I think I know what is going on here. As @TMC.Engineering mentioned - small results are "exaggerated" so that you can physically see how the deformation will occur. As we can see from your image - the deformation is actually pretty small based on your units (it is 2.31x10-5). So what Fusion is doing, is scaling those results visually so that you can see the results. To change this, if you go to the Results Menu and then Deformation scale, you can change the results to display actual deformation, as opposed to scaled.

[AlexD_autodesk]

Bingo - solved!

Thank you James and apologies to Timm who tried to explain this earlier but I did not realise that Fusion 'exaggerates' deformations by default.

Scale and visualisation now make sense!

[JDMather]

I was trying to get you to look critically at the numbers rather than mere "pretty pictures".

If you looked at the numbers and examined what they mean - you would have seen that the reported actual displacement was miniscule.

It is important to pay attention to the magnitude and units of displacement (and all values).