Abstract
The goal of the present paper is to improve our understanding of the response of the in-plane loaded rectangular plates containing initial geometric imperfection. Besides the frequency responses and FFT curves, which were used as diagnostic tools in previous investigations, the temporal response and the phase diagram have been added to better study the transition zones between two kinds of vibration modes. The phase portrait shows that the plate response has a number of “unusual and perhaps chaotic” characteristics in the transition from one mechanism of vibration of another, which distinguished it from the more classical periodic response. Moreover, the effect of one particular spatial mode of imperfection on a different mode of vibration has been investigated for the first time. It was found that the maximum amplitude of forced vibrations is large when vibration and imperfection are in the same mode while the first mode of vibration is always excited whatever the mode of imperfection is.