The time history of each variable can be obtained directly by numerical integration. The response type of the system can be determined preliminarily by observing and analyzing the time history diagram. However, the properties of the nonlinear dynamic system that can be understood are generally few and need to be judged together with other methods.
Spectral analysis graph method can determine whether the system response is regular or irregular by analyzing the time history of the response and observing its amplitude spectrum.
Generally speaking, the amplitude spectrum of periodic motion is a discrete spectrum in the form of separate vertical lines, and each frequency is commonable. The height of each line indicates the vibration intensity of the corresponding frequency; the amplitude spectrum of quasi-periodic motion is also a discrete spectrum in the form of separate vertical lines, but there is no commonality between two or more frequencies; the amplitude spectrum of chaotic motion and transient motion is a table.It is now continuous over a wide frequency band.