Targeted energy transfers in vibro-impact oscillators for seismic mitigation

Abstract

In the field of seismic protection of structures, it is crucial to be able to diminish 'as much as possible' and dissipate 'as fast as possible' the load induced by seismic (vibration-shock) energy imparted to a structure by an earthquake. In this context, the concept of passive nonlinear energy pumping appears to be natural for application to seismic mitigation. Hence, the overall problem discussed in this paper can be formulated as follows: Design a set of nonlinear energy sinks (NESs) that are locally attached to a main structure, with the purpose of passively absorbing a significant part of the applied seismic energy, locally confining it and then dissipating it in the smallest possible time. Alternatively, the overall goal will be to demonstrate that it is feasible to passively divert the applied seismic energy from the main structure (to be protected) to a set of preferential nonlinear substructures (the set of NESs), where this energy is locally dissipated at a time scale fast enough to be of practical use for seismic mitigation. It is the aim of this work to show that the concept of nonlinear energy pumping is feasible for seismic mitigation. We consider a two degree-of-freedom (DOF) primary linear system (the structure to be protected) and study seismic-induced vibration control through the use of Vibro-Impact NESs (VI NESs). Also, we account for the possibility of attaching to the primary structure additional alternative NES configurations possessing essential but smooth nonlinearities (e.g., with no discontinuities). We study the performance of the NESs through a set of evaluation criteria. The damped nonlinear transitions that occur during the operation of the VI NESs are then studied by superimposing wavelet spectra of the nonlinear responses to appropriately defined frequency -energy plots (FEPs) of branches of periodic orbits of underlying Conservative systems.

Vibro-impact attachments as shock absorbers

“…This is expected, as the effectiveness of the linear attachment as shock absorber is narrowband and, as a result, its performance deteriorates away from the condition of linear resonance with the primary system. In contrast, the performance of the VI attachment is broadband [19,20], so that its effectiveness to passively absorb and dissipate shock energy extends over wider parameter ranges. With respect to the performance of the VI shock absorber (cf.…”

“…In an additional series of articles [10][11][12][13][14][15][16][17], VI dampers were considered to reduce the vibration levels of structures under periodic or stochastic excitation. In other works, VI devices have been applied to the problem of shock/seismic mitigation [18][19][20] and TET from structures to attached VI oscillators has been studied. In these words, it was shown that VI attachments are capable of absorbing broadband energy from a linear system at a fast time scale; this is critical in applications in which energy dissipation must occur at the initial phase of the motion where the energy is the highest.…”

Targeted energy transfer and modal energy redistribution in automotive drivetrains

“…Some of the excess energy is retained within the NES itself [23]. This action leads to a reduction in the vibration amplitudes of the primary system in a broadband manner, which is due to the strong nonlinearity of the NES [24][25][26]. The energy dissipation rate of the primary structure can be controlled by adjusting the damping content of the NES [27].…”

Vibratory energy exchanges between a system with a chain of Saint-Venant elements and a nonlinear energy sink

“…Non-smooth nonlinear systems due their efficiency and feasibilities in fabrications and design are of highly interests in industrially [3]. Some research works have been carried to show the effectiveness of non-smooth NES devices in control of main structures [4][5][6][7][8]. However, some researches are carried to analyze and to consider the energy pumping phenomenon between a main non-smooth systems and coupled NES (essentially nonlinear or non-smooth) [9][10][11][12].…”