Targeted Energy Transfer by New Nonlinear Energy Sinks

Abstract

During the past two decades, there has been an increasing interest in targeted energy transfer (TET) for passive shock mitigation and energy harvesting purposes. Therefore, extensive investigations for employing different kinds of nonlinearly coupled dynamical attachments known as nonlinear energy sinks (NESs) to primary linear structures have been conducted in different related engineering applications. One such design is the rotary NES consisting of a small mass inertially coupled to the primary structure through a rigid arm; another is the vibro-impact NES with non-smooth nonlinearities and inelastic collisions with the primary structure. In the first contribution of the thesis, the rotary NES is enhanced by replacing the rigid coupling arm by an elastic one, with a linear coupling radial stiffness element to provide the NES with the added capacity for radial oscillation. Secondly, a hybrid NES design is proposed based on the synergetic synthesis of the rotary and impact-based NESs in a single rotary-impact NES (RINES) which incorporates a fixed rigid barrier attached to the top floor of the primary structure to generate impacts between its rotating mass and the top floor. Thirdly, we investigate improvements to the impact-based NESs by studying the effect of the coefficient of restitution in increasing the TET efficiency. The fourth part of the thesis presents a numerical comparison of the NES types for energy transfer and dissipation when employed to a large-scale dynamical structure subject to an impulsive excitation. Finally, most investigations have focused on employing dynamical absorbers to suppress vibrations in structures that oscillate in only one-dimension. However, most real life dynamical structures are subject to different excitations that could induce multi-dimensional oscillations. Consequently, we numerically investigate the application of a two-dimensional nonlinear energy sink (2D-NES) to suppress induced vibrations associated with impulsive and seismic excitations into a structure that oscillates in two-dimensions.

Date of Award	Dec 2019
Original language	American English
Supervisor	Mohammad Alshudeifat (Supervisor)