Hi, I am new to COMSOL, and would like to know if there is an expression/operation or function I can apply or plot in COMSOL that will return the Time Period / Frequency / Wavelength information from the following Displacement/Time Graph attached below?
The 3 coloured displacement components are w, u & v, z, x and y componenets respectively displaced due to pressure and shear waves.
I wish to find the difference in the time period and frequency response of various structures to an induced earthquake.
Thank you,
MM
quick&dirty field analysis ;-) : the blue signal is a pretty clean ~3.3 Hz sine (~30 peaks/9 sec). the red one contains at the first sight the 3.3 Hz component and a second frequency pretty close to it (3.3+/- 0.2Hz), you can see the resulting interference (beating T~5 sec). the green has a baseline, as Claudio said, get rid of it, and FFT to find the harmonics. My stomach feeling tells me you'll find a mix of the ~3.3Hz main and another 2 relevant additional frequencies, each with significantly smaller amplitude... regards
Claudio Pedrazzi
, thank you for that, COMSOL does indeed have those options! Looking through them now.And thank you for noticing the drifting as well! I originally attributed that to the permamnent deformation of the soil block underneath the structure being shook. Please have a look at the screenshot attached below. The green signal is a measure of the displacement in the x direction measured at the bottom of the soil block, at the centre of the structure. Originally it should return to 0, but I have truncated the duration of the earthquake before it normalises due to lack of computational power. But I will look into what you have sugessted as well. If you have any more thoughts, please do share, and thank you for pointing me in the right direction! Much appreciated.
PS. The prescribed acceleration is also in the x direction.
Andreas Näßl, brilliant, that is close to my calculations as well, thank you! I will reply with my findings later on.
Regards,
MM
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