Design, optimise, analyse, fit, analyse - Correct?

Altair Forum User

Hello,

 

In addition to my previous post regarding saving a file, I am now having trouble saving and re-analysing a part.

 

I have optimised a design, and analysed it using the shape explorer function. The minimum factor of safety is 1.5. I have then used the 'fit' function and re-analysed using the same load cases. The minimum FoS then rises to around 7.

 

I am very confused as to why this is doing this.

 

My plan is to optimise, fit, re-analyse to check the results correspond and then run another analysis on the part to ensure that it can cope with another set of independent load cases.

 

Can anyone help with this?

 

Thank you

Altair Forum User

Hi 6nwuy,

This is an excellent question - there are many users out there, which are confused the first time.

Running an optimization means, that your result can but don't has to be the optimal solution for your design. There is a very high chance your design approach is is extremly close to your requested optimum - but especially the 'minimize mass' objective design approaches are depending a lot on the 'minimum thickness constraint'.

In your case, you just have to reduce the 'minimum tickness' inside the 'run optimization' window:

If you are targeting a goal which can't be achieved by using a minimal thickness you appled, you will get no result - or a result which is overdimensioned (higher SF).

 

As an advanced or expert user:

You should also consider a difference between the two types of 'accuracy', you can choose from in the 'run analysis' and 'run optimization' window. 

  

Due to self-stiffening effects of the FE-Mesh used in the 'Faster', but highly recommended mode, your optimization results will be a little bit stiffer than they would be in reality (up to ~5%). Instead of using the 'More accurate' mode (which would cause your PC to melt, and force you to spend like 1000% more time on the optimization), you just should tweak your goals a little bit. When you once redesigned your final approach, based on the optimization result - you go and check the performance in the 'More accurate' mode. 

 

Please, let us know if this helps!

 

Kind Regards

Felix