Dears,
I am modeling a foundation for a screw compressor machine. I already calculated the 6 springs (3 translational (units kN/m) and 3 rotational (units kNm/deg)) to be included in the center of the base area. Also, I already calculated manually the natural frequencies. After the analysis in staad, the translational frequencies are close to those manually calculated, but the rotational frequencies are pretty far. Manually, I use the formula: frequecy=sqrt(K_rot/M), where K is the spring stiffness and M is the Mass moment of Inertia. The rotational modes frequencies from staad are too low, normally the rotational frequencies shall be greater than translational frequencies. Could you please check?.
DYN_6DOF.STD
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