I am a student from Poland, who is finishing study. My last project is to prepare modal analyse for one element from some vehicle. I choosen FEMAP for this project. The instruction of this software are really helpfull and clearly but I have got one problem. I try to make a Random Response Analyse and I can't find any information about solution frequencies tab. I know that I need 2 sections (it depends on my PSD function, which I made corretly) but I don't know which FREQ should I'll use. I supose it should be FREQ4 or FREQ5 but if I try, then it won't work and I'll get wrong chart.
I would like to ask more more experienced people for the definition od those function. In which situations shall I use it. Maybe has anybody got some materials about this thema?
Information regarding the Solution Frequencies tab can be found in the FEMAP Help under section 188.8.131.52 "NASTRAN Modal Frequency Analysis"
Which FREQ you specify depends on what range of frequencies you want NASTRAN to analyze for you. FREQ4 would analyze a specified range of values around each of your modes using a spread percentage (FSPD %). For example, you could specify to analyze 5 frequencies at +/- 3% of each of your natural modes within a specified range of frequencies. FREQ5 is similar, but requests a proportion instead of a percent (ie. 0.9, 1.0, and 1.1 times each mode within range).
All of this information and more can be found in the help seciton I referenced. Additionally, the FEMAP Help includes an example for setting up a similar analysis, Example 18 "Random Response of the Hinge Model"
Hope this helps!