OBJECTIVE – Use cases of FREQi card required to define frequencies for Frequency Response (FRF) Analysis.
Topic description: FREQi card defines the range of Frequencies in which response needs to be extracted in FRF Analysis. To create this, it is required to first create a Load collector with card image as FREQi and then select any of the 6 FREQ available cards in Optistuct to define the Frequency range.
Below is the detailed explanation of these cards and their use cases.
By this FREQ crad response can be calculated at a single frequency or N no. of frequencies defined by user. Only for those frequency output will be generated.
For the above defined frequency, response will be calculated at 36.77Hz.
File used for this study is Freq.fem.
F1 – Lower Frequency Bound DF – Frequency Increment
NDF–No. of Frequency Increment
fi = F1 + DF * (i 1) 
Where i = 1 to (NDF + 1) 
File used for this study is Freq1.fem.
F1 – Lower Frequency Bound F2 – Upper Frequency Bound
NF – No. of Logarithmic Increments

File used for this study is Freq2.fem.
F1 – Lower Frequency Bound F2 – Upper Frequency Bound
NEF – No. of Increment in subset of frequency, CLUSTER – Position of calculation point
In FREQ3 frequency will form a subset (i.e) from F1 to 1^{st} Natural Frequency will form a set, similarly 1^{st} Natural frequency to 2^{nd} Natural frequency will form another subset, like this subset are formed till the F2 Frequency.
File used for this study is Freq3.fem.
F1 – Lower Frequency Bound F2 – Upper Frequency Bound
File used for this study is Freq4.fem.
F1 – Lower Frequency Bound F2 – Upper Frequency Bound
FR – Fraction of frequency
If FR = 1 then calculation will be
Fi = FR* Natural Frequency
Here in table, we have given FR as 0.5, So 39.33*0.5=19.66
File used for this study is Freq5.fem.