Irina Koroleva (Kikot)

The results of an experimental and numerical investigation of the dynamics of a string with three uniformly distributed discrete masses are presented. This system can be used as a resonant energy sink for protecting structural elements from the effects of undesirable dynamic loads over a wide frequency range. Preliminary studies of the nonlinear dynamics of the system under consideration showed its high energy capacity. In this paper, we present the results of an experimental study in which a shaker’s table mounted cantilever beam was being protected. As a result, the efficiency of the sink was confirmed, and data were also obtained to refine the mathematical model. It was shown that the experimental data obtained are in good agreement with the results of computer simulation.

We present results of analytical and numerical investigation of the nonstationary planar dynamics of a string with uniformly distributed discrete masses without preliminary tension and taking into account the bending stiffness. Each mass is coupled to the ground by lateral springs without tension which have (effectively) a characteristic that is nonlinearizable in the case of planar motion. The most important limiting case corresponding to low-energy transversal motions is considered taking into account geometrical nonlinearity. Since such excitations are described by approximate equations where cubic elastic forces contribute the most, oscillations take place under conditions close to the acoustic vacuum. We obtain an adequate analytical description of resonant nonstationary processes in the system under consideration, which correspond to an intensive energy exchange between its parts (clusters) in the domain of low frequencies. Conditions of energy localization are given. The analytical results obtained are supported by computer numerical simulations. The system considered may be used as an energy sink of enhanced effectiveness.

In this work we investigate dynamics of a string with uniformly distributed discrete masses without tension both analytically and numerically. Each mass is also coupled to the ground through lateral spring which provides effect of cubic grounding support. The most important limiting case of low-energy transversal oscillations is considered accounting for geometric nonlinearity. Since such oscillations are governed by motion equations with purely cubic stiffness nonlinearities, the chain behaves as a nonlinear acoustic vacuum.We obtained adequate analytical description of resonance non-stationary processes in the system which correspond to intensive energy exchange between parts (clusters) of the chain in low-frequency domain. Conditions of energy localization are given. Obtained analytical results agree well with results of computer simulations. The considered system is shown to be able to be used as very effective energy sink.

A weightless string without preliminary tension with two symmetric discrete masses, which are influenced by elastic supports with cubic characteristics, is investigated both by numerical and analytical methods. The most important limit case corresponding to domination of resonance lowenergy transversal oscillations is considered. Since such oscillations are described by approximate equations only with cubic terms (without linear ones), the transversal dynamics occurs n the conditions of acoustic vakuum. If there is no elastic supports nonlinear normal modes of the system under investigation coincide with (or are close to) those of corresponding linear oscillator system. However within the presence of elastic supports one of NNM can be unstable, that causes formation of two another assymmetric modes and a separatrix which divides them. Such dynamical transition which is observed under certain relation between elastic constants of the string and of the support, relates to stationary resonance dynamics. This transition determines also a possibility of the second dynamical transition which occurs when the supports contribution grows. It relates already to non-stationary resonance dynamics when the modal approach turns out to be inadequate. Effective description of both dynamical transitions can be attained in terms of weakly interacting oscillators and limiting phase trajectories, corresponding to complete energy echange between the oscillators.