Nonlinear Energy Sinks With Nontraditional Kinds of Nonlinear Restoring Forces

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
Mohammad A. AL-Shudeifat
Keyword(s):  
Energy Transfer ◽  
Nonlinear Energy Sink ◽  
Nonlinear Coupling ◽  
Closed Loops ◽  
Strong Resonance ◽  
Shock Mitigation ◽  
Restoring Forces ◽  
Initial Shock ◽  
Energy Sink ◽  
Nonlinear Energy

The nonlinear energy sink (NES) is usually coupled with a linear oscillator (LO) to rapidly transfer and immediately dissipate a significant portion of the initial shock energy induced into the LO. This passive energy transfer and dissipation are usually achieved through strong resonance captures between the NES and the LO responses. Here, a nontraditional set of nonlinear coupling restoring forces is numerically investigated to introduce enhanced versions of the NESs. In this new set of nonlinear coupling restoring forces, one has a varying nonlinear stiffness that includes both of hardening and softening stiffness components during the oscillation, which appear in closed-loops under the effect of the damping. The obtained results by the numerical simulation have shown that employing this kind of the nonlinear restoring forces for passive targeted energy transfer (TET) is promising for shock mitigation.

Numerical Investigation of Rotating Nonlinear Energy Sink for Shock Mitigation

2013 ◽  
Author(s):  
Mohammad A. Al-Shudeifat ◽  
Lawrence A. Bergman ◽  
Alexander F. Vakakis
Keyword(s):  
Energy Transfer ◽  
Linear Structure ◽  
Nonlinear Energy Sink ◽  
Initial Energy ◽  
Shock Mitigation ◽  
Nonlinear Targeted Energy Transfer ◽  
Primary Test ◽  
Energy Sink ◽  
Two Degree Of Freedom ◽  
Nonlinear Energy

Passive nonlinear targeted energy transfer (TET) is addressed here by investigating a lightweight rotating nonlinear energy sink (NES). The rotating sink mass has an essentially nonlinear inertial coupling with the two degree-of-freedom linear system (the primary test structure). The proposed rotating NES is numerically investigated where it is found to passively absorb and rapidly dissipate a considerable portion of the initial energy induced by impulse to the linear structure. The parameters of the rotating NES are optimized for the best performance in the vicinity of intermediate and high loads. The fundamental mechanism for significant energy transfer to the NES is its rotational mode; the oscillatory mode of the NES dissipates far less energy. The frequency-energy dependences are investigated through the frequency-energy plot (FEP). Early and strong resonance capture at the lowest modal frequency is observed between the rotator and the structure, at which a significant portion of the induced energy is transferred and dissipated by the rotator. The performance of this device is found to be comparable to existing, stiffness-based NES designs. However, this device is less complicated and more compact.

Nonlinear Energy Sink With a Non-Traditional Kind of Nonlinear Restoring Force

2015 ◽  
Author(s):  
Mohammad A. Al-Shudeifat
Keyword(s):  
Nonlinear Energy Sink ◽  
Initial Energy ◽  
Type I ◽  
Nonlinear Coupling ◽  
Restoring Force ◽  
Nonlinear Restoring Force ◽  
Coupling Force ◽  
Restoring Forces ◽  
Energy Sink ◽  
Nonlinear Energy

Enhanced nonlinear energy sink (NES) is addressed here by employing a non-traditional kind of a nonlinear restoring force. The usual nonlinear coupling element between the NES and the linear oscillator (LO) in the literature generates essentially nonlinear restoring force between the NES and the LO. Unlike Type I NES, here the nonlinear coupling force has varying components during the oscillation which appear in closed loops under the effect of damping terms. This NES attachment with the LO rapidly absorbs and immediately dissipates significant portion of the initial energy induced into the LO through a strong resonance capture between the NES and LO responses. The proposed design could also be promising for energy harvesting purposes. The obtained results by numerical simulation show that employing this type of nonlinear restoring force for passive targeted energy transfer (TET) is more promising than some other types of NESs in which purely cubic stiffness restoring forces have been incorporated.

Targeted Energy Transfer to a Rotary Nonlinear Energy Sink

2010 ◽  
Author(s):  
Sean A. Hubbard ◽  
D. Michael McFarland ◽  
Alexander F. Vakakis ◽  
Lawrence A. Bergman
Keyword(s):  
Finite Element ◽  
Energy Transfer ◽  
Finite Element Model ◽  
Nonlinear Energy Sink ◽  
Element Model ◽  
Targeted Energy Transfer ◽  
Discrete Equations ◽  
Resonant Interactions ◽  
Energy Sink ◽  
Nonlinear Energy

We study computationally the passive, nonlinear targeted energy transfers induced by resonant interactions between a single-degree-of-freedom nonlinear energy sink and a uniform-plate model of a flexible, swept aircraft wing. We show that the nonlinear energy sink can be designed to quickly and efficiently absorb energy from one or more wing modes in a completely passive manner. Results indicate that it is feasible to use such a device to suppress or prevent aeroelastic instabilities like limit-cycle oscillations. The design of a compact nonlinear energy sink is introduced and the parameters of the device are examined. Simulations performed using a finite-element model of the wing coupled to discrete equations governing the energy sink indicate that targeted energy transfer is achievable, resulting, for example, in a rapid and significant reduction in the second bending mode response of the wing. Finally, the finite element model is used to simulate the effects of increased nonlinear energy sink stiffness, and to show the conditions under which the nonlinear energy sink will resonantly interact with higher-frequency wing modes.

Reliability analysis of the hysteretic nonlinear energy sink in shock mitigation considering uncertainties

2020 ◽  
Vol 26 (23-24) ◽  
pp. 2261-2273 ◽  
Author(s):  
George C Tsiatas ◽  
Dimitra A Karatzia
Keyword(s):  
Reliability Analysis ◽  
Nonlinear Energy Sink ◽  
System Response ◽  
Primary System ◽  
Dissipation Energy ◽  
Linear Elastic ◽  
Shock Mitigation ◽  
Energy Sink ◽  
Elastic Spring ◽  
Nonlinear Energy

The reliability of the hysteretic nonlinear energy sink in shock mitigation is investigated herein. The hysteretic nonlinear energy sink is a passive vibration control device which is coupled to a primary linear oscillator. Apart from its small mass and a nonlinear elastic spring of the Duffing oscillator, it also comprises a purely hysteretic and a linear elastic spring of potentially negative stiffness. The Bouc–Wen model is used to describe the force produced by both the purely hysteretic and linear elastic springs. The hysteretic nonlinear energy sink protects the primary system through the energy pumping mechanism which transfers energy from the primary system and dissipates it in the hysteretic nonlinear energy sink. Three nonlinear equations of motion describe the resulting two-degree-of-freedom system response. The parameters of the system to be considered as uncertain are the natural frequency of the primary system and the hysteretic nonlinear energy sink linear elastic spring, which follow a normal distribution. A reliability analysis is then performed to evaluate the robustness of the coupled system in the presence of uncertainty. Specifically, the reliability index is calculated based on first passage probabilities of distinct dissipation energy level crossings using the Monte Carlo method. Several examples are examined considering various levels of initial input energy, and useful conclusions are drawn concerning the influence of uncertainty in the system robustness.

Targeted energy transfer in mechanical systems by means of non-smooth nonlinear energy sink

2011 ◽  
Vol 221 (1-2) ◽  
pp. 175-200 ◽  
Author(s):  
Claude-Henri Lamarque ◽  
Oleg V. Gendelman ◽  
Alireza Ture Savadkoohi ◽  
Emilie Etcheverria
Keyword(s):  
Energy Transfer ◽  
Mechanical Systems ◽  
Nonlinear Energy Sink ◽  
Targeted Energy Transfer ◽  
Energy Sink ◽  
Nonlinear Energy

Targeted energy transfer in stochastically excited system with nonlinear energy sink

2018 ◽  
Vol 30 (5) ◽  
pp. 869-886
Author(s):  
P. KUMAR ◽  
S. NARAYANAN ◽  
S. GUPTA
Keyword(s):  
Energy Transfer ◽  
Equations Of Motion ◽  
Nonlinear Energy Sink ◽  
Flow Dynamics ◽  
Slow Flow ◽  
Targeted Energy Transfer ◽  
Optimal Regime ◽  
Excited System ◽  
Energy Sink ◽  
Nonlinear Energy

This study investigates the phenomenon of targeted energy transfer (TET) from a linear oscillator to a nonlinear attachment behaving as a nonlinear energy sink for both transient and stochastic excitations. First, the dynamics of the underlying Hamiltonian system under deterministic transient loading is studied. Assuming that the transient dynamics can be partitioned into slow and fast components, the governing equations of motion corresponding to the slow flow dynamics are derived and the behaviour of the system is analysed. Subsequently, the effect of noise on the slow flow dynamics of the system is investigated. The Itô stochastic differential equations for the noisy system are derived and the corresponding Fokker–Planck equations are numerically solved to gain insights into the behaviour of the system on TET. The effects of the system parameters as well as noise intensity on the optimal regime of TET are studied. The analysis reveals that the interaction of nonlinearities and noise enhances the optimal TET regime as predicted in deterministic analysis.

Rotary-impact nonlinear energy sink for shock mitigation: analytical and numerical investigations

2019 ◽  
Vol 90 (3) ◽  
pp. 495-521 ◽  
Author(s):  
Adnan S. Saeed ◽  
Mohammad A. AL-Shudeifat ◽  
Alexander F. Vakakis ◽  
Wesley J. Cantwell
Keyword(s):  
Nonlinear Energy Sink ◽  
Numerical Investigations ◽  
Shock Mitigation ◽  
Energy Sink ◽  
Nonlinear Energy

Dynamics of an Eccentric Rotational Nonlinear Energy Sink

2011 ◽  
Vol 79 (1) ◽  
Author(s):  
O. V. Gendelman ◽  
G. Sigalov ◽  
L. I. Manevitch ◽  
M. Mane ◽  
A. F. Vakakis ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Nonlinear Energy Sink ◽  
Experimental Investigations ◽  
Primary System ◽  
Targeted Energy Transfer ◽  
Energy Sink ◽  
Nonlinear Energy

The paper introduces a novel type of nonlinear energy sink, designed as a simple rotating eccentric mass, which can rotate with any frequency and; therefore, inertially couple and resonate with any mode of the primary system. We report on theoretical and experimental investigations of targeted energy transfer in this system.

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