Sine on Random Vibrations

Question

Hello everyone,

I have a structure which requires Operational sine on Random vibrations. What should i do,

Should I perform Random vibrations and Sine sweep analysis in different subcases and combine them in damage calculation,

"https://2025.help.altair.com/2025/hwsolvers/os/topics/solvers/os/sine_on_random_fatigue_analysis_r.htm"

I dont see any Harmo option in FATLOAD

is there any other method

If possible gimme a setup with sine on random

Urgent

Thank you

solon · Answer

In the spectral moment calculation, the sine contribution must be based on the resulting stress amplitude generated through the FRF, not on the excitation amplitude specified in the HARMO card. The amplitude entered in the spectral moment equation should be the stress response amplitude after applying the structural transfer function (FRF) at each sine frequency.

Mintu · Answer

Hello Solon,

Thanks for the reply, I ran the SOR,

I calculated the moments as per this guide

"https://help.altair.com/hwsolvers/os/topics/solvers/os/sine_on_random_fatigue_analysis_r.htm"

When i used TDAMP or global damping usimg PARAM,G,V1 in MFRA Sine the moments and damage aren't matching, I tried doing without damping the moments and damage matched.

solon · Answer

Hello,

The HARMO option is not yet supported in the Hypermesh GUI. You have to add it manually in the .fem deck under FATLOAD.