Learning Forum

[albin.linderstam]

Hello!

I would like to compare my Random Vibration Analysis performed in Mechanical with the results performed in Sherlock. 

In Mechanical, I select Scale Factor 1-3 Sigma (or user-defined) for e.g. the Directional Deformation. 
In Sherlock, Sigma 1 is scaled using Random Vibration Scale Factor, which is set to 1.95 by default according to Sherlock User's Guide, see below. 

Is Scale Factor in Mechanical equal to Random Vibration Scale Factor in Sherlock? 
So if my colleague has performed a Random Vibration Analysis in Sherlock using this default value, is that equal to Scale Factor 1.95 (user-defined) in Mechanical? 
I'm just concerned so I actually compare apples to apples and not two different Sigma values. 

Best regards,
Albin

[Tom David]

Hello Albin,

The two scale factor both using 1.95 should be the same. this wasn`t the case with earlier versions, so make sure you are using an updated version 
The FEA results you get in both cases should be the same, but, in order to compare apples to apples, follow the exact way Sherlock uses the strain results taking into account nodal vs elemental results and type of strain. 

Thank you,
Tom

[albin.linderstam]

Hello Tom,

Thank you for your answer.
We use Ansys Workbench 2019 R3 and Ansys Sherlock 2021 R2 ; are these considered as updated versions? 
I'm not really sure I understand "follow the exact way Sherlock uses the strain results taking into account nodal vs elemental results and type of strain".
Do you have any recommendation of where I can read about this perhaps? 

Regards, Albin

[Tom David]

Hello Albin

On the Ansys help site, you can go into Sherlock->Sherlock theory guide-> Random vibration theory-> Random vibration strain 2021R2

From the name you canf see that 2021R2 is the version where your results should much up more nicely with your Mechanical simualtion.

note the differance between the strain reported in different windows and scenarios

I hope this helps,

Thank you,

Tom