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.

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.

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.

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.

A Non-Traditional Variant Nonlinear Energy Sink: Transient Responses

2019 ◽  
Author(s):  
Youzuo Jin ◽  
Kefu Liu ◽  
Deli Li ◽  
Liuyang Xiong ◽  
Lihua Tang
Keyword(s):  
Energy Harvester ◽  
Vibration Suppression ◽  
System Modeling ◽  
Nonlinear Energy Sink ◽  
Initial Energy ◽  
Transient Responses ◽  
Continuous Contact ◽  
Magnet Coil ◽  
Energy Sink ◽  
Nonlinear Energy

Abstract In this paper, a non-traditional variant nonlinear energy sink (NES) is developed for simultaneous vibration suppression and energy harvesting in a broad frequency band. The non-traditional variant NES consists of a cantilever beam attached by a pair of magnets at its free end, a pair of the so-called continuous-contact blocks, and a pair of coils. The beam is placed between the continuous-contact blocks. The constraint of the continuous-contact blocks forces the beam to deflect nonlinearly. Each of the magnet-coil pairs forms an electromagnetic energy harvester. Different from a traditional way that attaches the coils to the primary mass, the developed setup has the coils fixed to the base. First, the developed apparatus is described. Subsequently, the system modeling and parameter identification are addressed. The performance of the apparatus under transient responses is examined by using computer simulation. The results show that the proposed apparatus behaves similarly as the NES with the following features: 1:1 resonance, targeted energy transfer, initial energy dependence, etc.

scholarly journals Free Response of a Rotational Nonlinear Energy Sink: Complete Dissipation of Initial Energy for Small Initial Rectilinear Displacements

2020 ◽  
Vol 88 (1) ◽  
Author(s):  
Ke Ding ◽  
Arne J. Pearlstein
Keyword(s):  
Coupling Parameter ◽  
Equations Of Motion ◽  
Nonlinear Energy Sink ◽  
Initial Energy ◽  
Rectilinear Motion ◽  
Initial Condition ◽  
Free Response ◽  
Primary Mass ◽  
Energy Sink ◽  
Nonlinear Energy

Abstract For two combinations of a dimensionless rotational damping parameter and a dimensionless inertial coupling parameter, we consider free response of a rectilinearly vibrating linearly sprung primary mass inertially coupled to damped rotation of a second mass, for which Gendelman et al. (2012, “Dynamics of an Eccentric Rotational Nonlinear Energy Sink,” ASME J. Appl. Mech. 79(1), 011012) developed equations of motion in the context of a rotational nonlinear energy sink (NES) with no direct damping of the rectilinear motion. For dimensionless initial rectilinear displacements comparable with those considered by Gendelman et al., we identify a region in the motionless projection of the initial condition space (i.e., for zero values of the initial rectilinear and rotational velocities) in which every initial condition leads to a previously unrecognized zero-energy solution, with all initial energy dissipated by rotation. We also show that the long-time nonrotating, rectilinear solutions of the type found by Gendelman et al. are (orbitally) stable only in limited ranges of amplitude. Finally, we show how direct viscous damping of rectilinear motion of the primary mass affects dissipation, and that results with no direct rectilinear dissipation provide excellent guidance for performance when direct rectilinear dissipation occurs. Some applications are discussed.

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.

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.

A Variant Nonlinear Energy Sink for Vibration Suppression and Energy Harvesting

2018 ◽  
Author(s):  
Xiaolin Li ◽  
Kefu Liu ◽  
Liuyang Xiong ◽  
Lihua Tang
Keyword(s):  
Energy Harvesting ◽  
Vibration Suppression ◽  
System Modeling ◽  
Nonlinear Energy Sink ◽  
Initial Energy ◽  
Piezoelectric Energy ◽  
Thin Steel ◽  
Energy Sink ◽  
Thin Steel Plate ◽  
Nonlinear Energy

In this paper a variant nonlinear energy sink (NES) is developed for the purpose of simultaneous vibration suppression and energy harvesting in a broad frequency band. The NES consists of a cantilever beam attached by a mass at its free end and a pair of so-called double-stop blocks. The beam is formed by a piezoelectric energy harvester and a thin steel plate. It is placed between the double-stop blocks. The constraint of the double-stop blocks forces the beam to deflect nonlinearly. First, the developed apparatus is described. Subsequently, system modeling and parameter identification are addressed. The performance of the apparatus under transient responses is examined through both numerical simulation and experimental study. The results show that the proposed apparatus behaves similarly as the NES with the following features: 1:1 resonance, targeted energy transfer, initial energy dependence, etc.

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.

Free Response of a Rotational Nonlinear Energy Sink Coupled to a Linear Oscillator: Fractality, Riddling, and Initial-Condition Sensitivity at Intermediate Initial Displacements

2021 ◽  
pp. 1-59
Author(s):  
Ke Ding ◽  
Arne Pearlstein
Keyword(s):  
Initial Conditions ◽  
Nonlinear Energy Sink ◽  
Initial Energy ◽  
Linear Oscillator ◽  
Rectilinear Motion ◽  
Free Response ◽  
Time Harmonic ◽  
Wide Range ◽  
Energy Sink ◽  
Nonlinear Energy

Abstract Free response of a rotational nonlinear energy sink (NES) inertially coupled to a linear oscillator is investigated for dimensionless initial rectilinear displacements ranging from just above the smallest amplitude at which nonrotating, harmonically rectilinear motion is unstable absent direct rectilinear damping, up to the next-largest amplitude at which such motion is orbitally stable. With motionless initial conditions (MICs), i.e., initial velocity of the primary mass and initial angular velocity of the NES mass both zero, predicted behavior for two previously investigated combinations of the dimensionless parameters (characterizing rotational damping, and coupling of rectilinear and rotational motions) differs strongly from that found at smaller initial displacements (2021, J. Appl. Mech. 88, 011005). For both combinations, a wide range of MICs leads to solutions displaying transient chaos and depending sensitively on initial conditions, giving rise to fractality and riddling in the relationship between initial conditions and asymptotic solutions. Absent direct rectilinear damping of the linear oscillator, for one combination of parameters there exists a wide range of MICs with trajectories leading to time-harmonic, orbitally stable “quot;special”quot; solutions with a single amplitude, but no MICs are found for which all initial energy is dissipated. For the other combination, no such special solutions are found, but there exist MICs for which all initial energy is dissipated. With direct rectilinear damping, sensitivity extends to a measure of settling time, which can be extremely sensitive to initial conditions. A statistical approach to this sensitivity is discussed, along with implications for design and implementation.

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