SimScale CAE Forum

Will the program inform me of a fracture or the critical stress to which it will fail?


#1

I’m running a FEA on a plate bolted in and a distributed load applied upon it. I know that the holes will provide stress concentrations but I need to know the maximum stress that will cause the specimen to fracture.

Thank you!


#2

Hi @tsloan,

a good and easy approach for this has already been mentioned by @rszoeke in this post: Show Overload of a structure

Let me know how things go!

All the best,

Jousef


#3

Thank you. Do you know how he links the von_Mises_stress for the factory of safety calculation?


#4

Hi @tsloan,

the factor of safety equals \frac{\text{Yield stress}}{\text{v. Mises stress}} as stated in the post.

Is that what you wanted to know?

Cheers,

Jousef


#5

I understand that but if you look at the link you posted. He creates a calculation in the post processing tab and links the von Mises stress data points to create a visual showing the factors of safety throughout the object. How does he link the function for the von Mises stress?
Ex. His says something like
4e8/von_Mises_stress and that is the function in his calculator filter.

edit: Also i’m going to make my project public but i’m running a pressure test on a symmetrical rectangle plate with the holes fixed and for some reason the von mises stress field is showing a high stress concentration around one of the holes. However, theoretically wouldn’t it make sense for all of the holes to experience the same stress?


#6

Hi @tsloan,
for the facor of safety calculation you need to know he yield stress (or a similar measure that of your material tells you when your material “fails”), then you can calculate the FOS easily in the online post-processor (assuming you have only one material). Just do the following steps:

  • open your result in the post-processor
  • add a filter of type calculator
  • change result array name to “Factor Of Safety”
  • in the function insert: your_yield_stress_value/von_Mises_stress
  • click on Apply

Now you can choose a new solution field called “Factor Of Safety” and visualize it:


In the above example I used 6e5Pa as the yield stress and updated the salar range to make the low FOS zones better visible (beware that in this plot red means actually low stress and blue means high stress)

Hope this clears things up.
Best,
Richard


#7

Yes that ended up working, thank you. Is there a simple way to invert the scale just for a better visual?


#8

Add a “-” in front of your formula. All values will be negative but at least you have the scale inverted.
Best,
Richard