Learning Forum

[omidrastkhiz]

Hi Again,nThanks for the response, I did what you said, and here is the close example of what I did, my final goal is to find a natural frequency of the this segment ( which is close to this one), and for the real experiment, we have to suspend the structure with crane to simulate free-free boundary condition, but since it is heavy , due to safety reasons, we can't so, we need to put it in 4 (set of springs) to simulate free-free boundary condition ( meaning put it on very soft place) , and then with a shaker and accelerometer find natural frequency(Modal part in ANSYS) and FRF function (Harmonic Response in Ansys), ( displacement 1 to 4 is for No movement in X and Y direction for edges in four corners)nso here as you can see the first 6 modes are translation and rotation modes, which we can ignore, but do you think, this is a right set up for the whole experiment to find natural frequency of the segment and FRF function?nThe reason that I am asking for, is because for the 7 mode, it just shows the segment goes up and down on spring like because it's own weight and almost no shaking or vibration is shown, but my goal is to let it go to the equilibrium point and then use shaker or impact hammer, and for the 8 to 10 modes shapes it doesn't show any movement at all.nThank you so much, I really appreciate your help n