Time frequency analysis of the system?

It is the Time -frequency (pspectrum) graph of vibration of one of the system, placed in a shaking table, where natural frequncy of the body reduces over time.

Can you please tell me what does the following graph demonstrate?

Answer 1

[Jyotish Kumar]

Hi,

As I can see from the plot attached, this is a time vs frequency plot presented in terms of power(dB). Such plot gives information about the spectrum of frequency components with respect to time. Color map shows the amount of frequency components at given time. For example, in the given plot, frequency component of 4 Hz is higher (shown in yellow) at near 1.5 and 2.5 minutes. One can understand with this representation that, at 1.5 and 2.5 minutes 4Hz frequency was more prominent than other frequency components. In simple words, Power of frequency represents the dominance of given frequency components.

Hope it helps you.