Jump to content

Random Fatigue Analysis

Recommended Posts

Hello guys,

I'm trying to do a Random fatigue analysis thanks to Optistruct. So first of all, I know that 2017 version has its own module which does this kind of analysis, and I already did it. 
I'm now trying to compare Optistruct results with a VBA code I did.
So here are the step I did:

- FRF and Random Subcases (with RANDPS, TABLED1 etc)
- I ask for STRESS PSDF .Peak files for X to Z1, X to Z2, Y to Z1, Y to Z2, XY to Z1 and XY to Z2
 Here, I can already see the number of positive crossing (which allow me to calculate life). First Question, do I have to divide this number by 2PI?

My second question is, is it okay to create a derivated results on Hyperview, which does : RMS VELOCITY / (2*PI RMS DISPLACEMENT) in order to obtain the number of positive zero crossing directly on HyperView?
This whole zero crossing things is kind of getting me crazy, a lot of people use it but I do'nt really understand how it works.
(By the way, I can give you the files I have on my simple model if it is needed)

Thanks for your answers!

Share this post

Link to post
Share on other sites


Please forgive me I'm kind of new to this and I don't really know how to be sure to look at equivalent PSD stress.

here are My files, please tell me if anything is correct. By the way I did one different subcase for direction.

NB : I limited the study to one element, ID = 14 (the one taking most damage according to Optistruct).






Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now