THEORETICAL AND EXPERIMENTAL EVIDENCE OF SYMMETRIC RESPONSE INSTABILITY IN THE FINITE, PLANAR DYNAMICS OF A CIRCULAR ARCH

摘要

The contemporaneous analysis of an experimental and an analytical models of a double hinged circular arch gave a complete understanding of the dynamical behavior concerning the problem of the dynamic instability of the simple unimodal symmetric solution under the action of a concentrated, vertical load applied on its tip. Preliminary experimental tests furnished hints for a correct analytical modeling. Then, a systematic analysis conducted on the two models on wide ranges of the forcing parameters showed a good qualitative and quantitative agreement between the two models: while in the cases of periodic evolutions the comparison was done on the basis of the modal components, when complex motion arise, the comparison was done on the basis of synthetic complexity indicators like the correlation dimension and the maximum Lyapunov exponent (delay map technique). Eventually, because theoretical results concerning strangeness and chaoticity could be related more to the analytical modeling than to the real behavior of structures, in the case of complex time evolutions the help of a companion experimental model is crucial for furnishing an actual mechanical framework to the understanding and interpretation of strange phenomena.