Stress analysis explanation

[Yashasvi23481]

Hi All,

      I have conducted stress analysis on 2 assembly. one is 0.75 of the other assembly or 3/4th scale. However, in the result, the outcome is way too far apart.  Same force is applied and all components are 3/4 from original. I cant upload the report as whole but I have gathered screenshot of them and compiled. Please see and tell how they are so different ?

What does Von Misses stress imply ? I was thinking with weight being nearly half, stress it takes should be more than full scale. As stress is Force per unit Area. Full scale has max stress as 93 whereas 0.75 has only 3MPa. Cant figure out whats causing it ? Weight is nearly slightly more than half. Loads and base points are same. I may be asked so I want to understand what this means and why so much variation. 

Thanks in advance. 

Regards,

Yash

[johnsonshiue]

Hi! Please attach the assembly here. Reading the reports does not help understand the issue better. You mentioned that the difference between the two assemblies is in size (25% difference). But, could you explain why the mass values differ almost 50%?

Many thanks!

[Yashasvi23481]

Hi Johnson,

    Difference between weight is because only height and depth has been 3/4th thickness of plate still 8mm same as full scale. also, the leg flange is same as full scale. So the stand is 3/4th only in terms of height. it has only 3 files. ignore the fasteners. please find attached full scale drawings. 

[Yashasvi23481]

Here is 3/4th scale parts....part numbers and other info has been changed to keep IP.

[JDMather · Accepted solution]

The fasteners should not have been included in the simulation.

The simulation should be Thin Feature rather than mesh.

If you fix these two issues, then I can take a second look at the problem.

Also, you should install the Updates for 2018.

[JDMather]

What is the purpose of this Hole feature?

I suspect that what you really want is a Split feature rather than a Hole feature.

[Yashasvi23481]

Hi JD,

     The hole is analyse effect on 1 single point rather than whole face. If you observe, its not see through hole just half way. I wanted to see the effect of the heavy force on extreme point. its created to analyse on 1 particular point. 

Regards,

yash

[Yashasvi23481]

Hi JD,

    How to do thin feature and where to find it in simulation environment ? I do get errors that they are being treated as solids. Please let me know. Never did thin feature before. Also, what is the difference in the result thin vs mesh ?

Regards,

Yash

[JDMather]

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@Yashasvi23481 wrote:

     The hole is analyse effect on 1 single point rather than whole face.

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This is typically done with a Split Face.

You have altered the geometry adding a Hole feature.

You should almost never include fasteners in an analysis - if there is a problem with your fasteners - you can analyze them individually.  You can use Connections to take the place of fastener geometry.

Once you have corrected these two issues and re-attached your two assemblies I can show how to do Thin-Feature analysis.

[Yashasvi23481]

Hi JD,

     After I Do split face and change to thin feature, the split face doesn't come up to apply load on. its whole face selected. 

Regards,

Yash

[JDMather]

Someone marked this thread as Solved.

Did you resolve the issues?

[Yashasvi23481]

Hi JD,

    I marked it as solved as I worked out how to split faces and do the thin feature. Turns out that we don't need to pin point  on 1 spot but apply the load across whole face. Its just to be used as an example so my issue is resolved as far as work is concerned but I do want to know how does split face and thin feature together work ? The exercise was only to show indicative effect as in reality, it will penetrate the plate with that force, which I think Inventor cant demonstrate  at the moment. 

    Is there any sort of analysis within Inventor to do impact force rather than continuous or effect of penetration ? 

Thank you very much for prompt response. Very helpful. Thin feature actually helped. 

Regards,

Yash