Piecewise Nonlinear Energy Sink

2015 ◽  
Author(s):  
Mohammad A. Al-Shudeifat
Keyword(s):  
Dead Zone ◽  
Linear Structure ◽  
Nonlinear Energy Sink ◽  
Viscous Damping ◽  
Nonlinear Stiffness ◽  
Flexible Design ◽  
Energy Inputs ◽  
Energy Sink ◽  
The Dead ◽  
Nonlinear Energy

Symmetric piecewise nonlinearities are employed here to design highly efficient nonlinear energy sink (NES). These symmetric piecewise nonlinearities are usually called in the literature as dead-zone nonlinearities. The proposed dead-zone NES includes symmetric clearance about its equilibrium position in which zero stiffness and linear viscous damping are incorporated. At the boundaries of the symmetric clearance, the NES is coupled to the linear structure by either linear or nonlinear stiffness components in addition to similar viscous damping to that in the clearance zone. By this flexible design of the dead-zone NES, we obtain a considerable enhancement in the NES efficiency at moderate and severe energy inputs. Moreover, the dead-zone NES is also found here through numerical simulations to be more robust for damping and stiffness variations than the linear absorber and some other types of NESs.

Enhanced Rotating Nonlinear Energy Sink

2016 ◽  
Author(s):  
Mohammad A. Al-Shudeifat ◽  
Adnan S. Saeed
Keyword(s):  
Radial Direction ◽  
Linear Structure ◽  
Nonlinear Energy Sink ◽  
Vertical Axis ◽  
Viscous Damping ◽  
Linear Coupling ◽  
Damping Coefficients ◽  
Wide Range ◽  
Energy Sink ◽  
Nonlinear Energy

An enhanced rotating nonlinear energy sink (NES) is numerically investigated in this study. The rotating NES in the literature is coupled with the associated linear structure by its nonlinear inertial coupling through a rigid arm that couples the rotating NES mass with the structure. Here, the coupling arm is assumed to be elastic. Consequently, the NES mass rotates about a fixed vertical axis and allowed to oscillate along the coupling arm in a radial direction. According to this modification, the rotating NES dissipates the transferred energy from the associated structure through its angular and radial viscous damping. Therefore, the modified rotating NES by elastic arm is found to absorb and dissipate more energy than the old one for a wide range of initial input energies induced into the associated linear structure. The arm length and the angular damping coefficient of the old rotating NES are optimized first by assuming a rigid coupling arm and later the stiffness and the damping coefficients in the radial direction are optimized accordingly. The obtained numerical results have shown a significant improvement in the rotating NES performance when the NES is allowed to oscillate through the coupling arm by a linear coupling restoring spring rather than locking the NES to a rigid arm.

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.

Asymmetric Magnet-Based Nonlinear Energy Sink

2014 ◽  
Vol 10 (1) ◽  
Author(s):  
Mohammad A. AL-Shudeifat
Keyword(s):  
Permanent Magnets ◽  
Nonlinear Energy Sink ◽  
Weakly Nonlinear ◽  
Strongly Nonlinear ◽  
Shock Mitigation ◽  
Energy Inputs ◽  
Energy Sink ◽  
Dynamic Structures ◽  
Nonlinear Energy ◽  
Weakly Linear

The nonlinear energy sink (NES) is a light-weighted device used for shock mitigation in dynamic structures through its passive targeted energy transfer (TET) mechanism. Here, a new design for the NES is introduced based on using an asymmetric NES force. This force is strongly nonlinear in one side of the NES equilibrium position, whereas it is either weakly nonlinear or weakly linear in the other side. This is achieved by introducing the asymmetric magnet-based NES in which the asymmetric nonlinear magnetic repulsive force is generated by two pairs of aligned permanent magnets. Consequently, this proposed design is found to provide a considerable enhancement in the shock mitigation performance compared with the symmetric stiffness-based NESs for broadband energy inputs.

Thermal Effect on Dynamics of Beam with Variable-Stiffness Nonlinear Energy Sink

2020 ◽  
Vol 21 (1) ◽  
pp. 1-10 ◽  
Author(s):  
J. E. Chen ◽  
W. Zhang ◽  
M. H. Yao ◽  
J. Liu ◽  
M. Sun
Keyword(s):  
Variable Stiffness ◽  
Nonlinear Energy Sink ◽  
Excitation Amplitude ◽  
Harmonic Excitation ◽  
Absorption Efficiency ◽  
Nonlinear Stiffness ◽  
Vibration Absorption ◽  
Low Stiffness ◽  
Energy Sink ◽  
Nonlinear Energy

AbstractIn this study, we investigate the targeted energy transfer (TET) from a simply supported beam that is subjected to thermal variations and external excitations to a local nonlinear energy sink (NES). We derive the governing equation of motion for the beam with an NES device and study the influences of NES parameters on the vibration-suppressing effect. We obtain the optimized parameters of the NES under constant-amplitude harmonic excitation at room temperature. The optimized NES gradually loses its vibration absorption efficiency as the excitation amplitude and temperature increase. We change the nonlinear stiffness of the NES to mitigate the influence of temperature variation and show that NES efficiency can be enhanced by reducing the nonlinear stiffness. We propose a variable-stiffness NES, and the results demonstrate this NES is best for maintaining efficiency over the whole temperature range. We also analyze the transient responses of the system under impulse loads. Results indicate that, like the performance of the system subjected to harmonic excitation, an NES with relatively low stiffness can better suppress vibration with increasing impulse amplitude and temperature.

Frequency-Energy Dependence of the Bistable Nonlinear Energy Sink

2017 ◽  
Author(s):  
Mohammad A. AL-Shudeifat ◽  
Adnan S. Saeed
Keyword(s):  
Stable Equilibrium ◽  
Initial Conditions ◽  
Energy Levels ◽  
Nonlinear Energy Sink ◽  
Nonlinear Stiffness ◽  
Targeted Energy Transfer ◽  
Simulation Techniques ◽  
Coupling Force ◽  
Energy Sink ◽  
Nonlinear Energy

Recently, the bistable attachment has been employed as a nonlinear energy sink (NES) for passive targeted energy transfer (TET) from linear structures. The bistable NES (BNES) has been coupled with a linear oscillator (LO) where the resulting LO-BNES system has been studied for passive TET. The nonlinear coupling force between the BNES and the associated LO comprises both negative and nonnegative linear and nonlinear stiffness components. Here, the dynamic behavior of the LO-BNES system on the frequency-energy plot is analyzed. The related FEP plot is obtained via numerical simulation techniques where the wavelet transform is imposed into the FEP for variety of initial conditions and damping content. It is found that the FEP has backbone branches at low energy levels associated with the oscillation of the bistable attachments about one of its stable equilibrium positions where passage through the unstable equilibrium position does not occur.

Simulation and Testing of a 6-Story Structure Incorporating a Coupled Two Mass Nonlinear Energy Sink

2012 ◽  
Author(s):  
Nicholas E. Wierschem ◽  
Jie Luo ◽  
Mohammad AL-Shudeifat ◽  
Sean Hubbard ◽  
Richard Ott ◽  
...  
Keyword(s):  
Linear Structure ◽  
Experimental Tests ◽  
Nonlinear Energy Sink ◽  
Degree Of Freedom ◽  
Nonlinear Element ◽  
Numerical Predictions ◽  
Wide Range ◽  
Modes Of Vibration ◽  
Energy Sink ◽  
Nonlinear Energy

The nonlinear energy sink (NES) is a passive device used to rapidly direct energy into higher modes of vibration and locally dissipate a significant portion of the impulsive shock energy induced in the primary, linear structure to which it is attached. The Type III NES is a two degree-of-freedom device comprised of two lightweight masses coupled together through an essentially nonlinear element. The lower mass in this two-mass arrangement is coupled to the linear structure through another essentially nonlinear element. This modification has been found to dramatically improve the performance of the NES to mitigate the shock when compared to a one degree-of-freedom NES device. The measure of effective damping of the linear structure indicates the ability of the NES to dissipate energy and reduce the response of the structure across a wide range of energies. Experimental tests have been performed to verify the numerical findings. Good agreement between numerical predictions and experimental observations validates the identified model of the NES.

scholarly journals Frequency Energy Plots of Dynamical Systems Attached to Piecewise Nonlinear Energy Sink

2021 ◽  
Author(s):  
Mohammed Ameen Ameen Al Shudeifat ◽  
Adnan Salem Saeed
Keyword(s):  
Normal Modes ◽  
Linear Structure ◽  
Nonlinear Energy Sink ◽  
Nonlinear Normal Modes ◽  
Dynamical Behaviour ◽  
Subharmonic Resonance ◽  
Numerical Continuation ◽  
Continuation Methods ◽  
Energy Sink ◽  
Nonlinear Energy

Abstract The frequency-energy plots (FEPs) of two-degree-of-freedom linear structures attached to piecewise nonlinear energy sink (PNES) are generated here and thoroughly investigated. This study provides the FEP analysis of such systems for further understanding of nonlinear targeted energy transfer (TET) by the PNES. The attached PNES incorporates a symmetrical clearance zone of zero stiffness content about its equilibrium position where the boundaries of the zone are coupled with linear structure by linear stiffness elements. In addition, linear viscous damping is selected to be continuous during PNES mass oscillation. The underlying nonlinear dynamical behaviour of the considered structure-PNES systems is investigated by generating the fundamental backbone curves of the FEP and the bifurcated subharmonic resonance branches using numerical continuation methods. Accordingly, interesting dynamical behaviour of the nonlinear normal modes (NNMs) of the structure-PNES system on different backbones and subharmonic resonance branches has been observed. In addition, the imposed wavelet transform frequency spectrums on the FEPs have revealed that the TET takes place where it is dominated by the nonlinear action of the PNES.

Numerical and Experimental Investigation of a New Nonlinear Energy Sink for Passive Shock Mitigation

2012 ◽  
Author(s):  
Mohammad A. AL-Shudeifat ◽  
Nicholas Wierschem ◽  
Alexander F. Vakakis ◽  
Lawrence A. Bergman ◽  
Billie F. Spencer
Keyword(s):  
Linear Structure ◽  
Nonlinear Energy Sink ◽  
Initial Energy ◽  
Numerical Results ◽  
New Device ◽  
Numerical Predictions ◽  
Energy Sink ◽  
Experimental Findings ◽  
High Level ◽  
Nonlinear Energy

A new device functioning as an efficient nonlinear energy sink (NES) is explored here. The device consists of a mass coupled to a two-story linear test structure through a single-sided vibro-impact (VI) nonlinearity in one direction and a weak linear spring in both directions. This design is found to be more efficient for passive targeted energy transfer (TET) than existing NESs. It absorbs and rapidly dissipates a significant amount of the impulsive energy induced in the linear structure. In addition, some of this initial energy is pumped to higher modes of the structure and efficiently dissipated there. The numerical results have verified that the proposed single-sided VI NES maintains high level of performance over a broad range of high input energies. It performs near to its optimum even for severe induced shocks. Moreover, the numerical results have been experimentally verified; good agreement between numerical predictions and experimental findings was observed.

scholarly journals Dynamics of Nonlinear Primary Oscillator with Nonlinear Energy Sink under Harmonic Excitation: Effects of Nonlinear Stiffness

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Min Sun ◽  
Jianen Chen
Keyword(s):  
Averaging Method ◽  
Nonlinear Energy Sink ◽  
Excitation Amplitude ◽  
Harmonic Excitation ◽  
Nonlinear Stiffness ◽  
Frequency Range ◽  
Steady State Responses ◽  
Energy Sink ◽  
State Responses ◽  
Nonlinear Energy

The dynamics of a system consisting of a nonlinear primary oscillator, subjected to a harmonic external force, and a nonlinear energy sink (NES) are investigated. The analytical solutions for the steady-state responses are obtained by the complexification-averaging method and the analytical model is confirmed by numerical simulations. The results indicate that the introduction of the NES can effectively suppress the vibrations of the primary oscillator. However, as the excitation amplitude increased, the NES may lose its efficiency within certain frequency range due to the appearance of the high response branches. Following the results analysis, it is concluded that this failure can be eliminated by reducing the nonlinear stiffness of the NES properly. The effects of nonlinear stiffness of the primary oscillator on the corresponding responses are also studied. The increase in this nonlinear stiffness can reduce the response amplitude and alter the frequency band where the high branches exist.

Comments on Energy Harvesting on a 2:1 Internal Resonance Portal Frame Support Structure, Using a Nonlinear-Energy Sink as a Passive Controller

2016 ◽  
Vol 10 (3) ◽  
pp. 147 ◽  
Author(s):  
Rodrigo Tumolin Rocha ◽  
Jose Manoel Balthazar ◽  
Angelo Marcelo Tusset ◽  
Vinicius Piccirillo ◽  
Jorge Luis Palacios Felix
Keyword(s):  
Energy Harvesting ◽  
Internal Resonance ◽  
Nonlinear Energy Sink ◽  
Support Structure ◽  
Portal Frame ◽  
Energy Sink ◽  
Nonlinear Energy
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