Experimental Investigation of a Rotational Nonlinear Energy Sink for Shock Mitigation

Rotational nonlinear energy sinks (NESs) have been proposed to mitigate the response of underlying primary structures subjected to shock loading. This type of NES, which is composed of a passive mass that is free to rotate, has the potential to be easier to realize and more compact than other types of NESs. Like other types of NESs, these devices engage in targeted energy transfer, which allows for the broadband transfer of energy from the primary structure to the NES where it can be rapidly dissipated. Additionally, these devices can couple the dynamics of the primary structure and facilitate the transfer of energy from lower modes to higher modes, where it can be dissipated at a faster rate. This paper experimentally investigates the performance of this type of NES by using the results from tests of a rotational NES attached to a small-scale two-story structure. For these experiments, a shock load is provided to the primary structure using a shake-table-produced impulse-like ground motion. Additionally, by varying the amplitude of the input ground motion, the energy dependency of the performance of these devices can be investigated. The results of these experiments show that this type of NES can attenuate the response of a structure by responding in a highly effective rotational mode.

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

Journal of Vibration and Control ◽

10.1177/1077546320919304 ◽

2020 ◽

Vol 26 (23-24) ◽

pp. 2261-2273 ◽

Cited By ~ 1

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.

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Nonlinear Energy Sinks With Nontraditional Kinds of Nonlinear Restoring Forces

Journal of Vibration and Acoustics ◽

10.1115/1.4035479 ◽

2017 ◽

Vol 139 (2) ◽

Cited By ~ 19

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.

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Numerical Study of a Single-Sided Vibro-Impact Track Nonlinear Energy Sink Considering Horizontal and Vertical Dynamics

Journal of Vibration and Acoustics ◽

10.1115/1.4044486 ◽

2019 ◽

Vol 141 (6) ◽

Cited By ~ 2

Author(s):

Wenke Li ◽

Nicholas E. Wierschem ◽

Xinhui Li ◽

Tiejun Yang ◽

Michael J. Brennan

Keyword(s):

Primary Structure ◽

Numerical Study ◽

Nonlinear Energy Sink ◽

Horizontal Direction ◽

Impact Surface ◽

Wide Range ◽

Quartic Polynomial ◽

Energy Sink ◽

The Impact ◽

Nonlinear Energy

Abstract In this paper, the single-sided vibro-impact track nonlinear energy sink (SSVI track NES) is studied. The SSVI track NES, which is attached to a primary structure, has nonlinear behavior caused by the NES mass moving on a fixed track and impacting on the primary structure at an impact surface. Unlike previous studies of the SSVI track NES, both the horizontal and vertical dynamics of the primary structure are considered. A numerical study is carried out to investigate the way in which energy is dissipated in this system. Assuming a track shape with a quartic polynomial, an optimization procedure that considers the total energy dissipated during a time period is carried out, to determine the optimum NES mass and track parameter. It is found that there is dynamic coupling between the horizontal and vertical directions caused by the SSVI track NES motion. The vibrational energy, originally in the structure in the horizontal direction, is transferred to the vertical motion of the structure where it is dissipated. Considering that many civil and mechanical systems are particularly vulnerable to extreme loads in the horizontal direction, this energy transformation can be beneficial to prevent or limit damage to the structure. The effect on energy dissipation of the position of the impact surface in the SSVI track NES and the ratio of the vertical to horizontal stiffness in the primary structure are discussed. Numerical results demonstrate a robust and stable performance of the SSVI track NES over a wide range of stiffness ratios.

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

Archive of Applied Mechanics ◽

10.1007/s00419-019-01622-0 ◽

2019 ◽

Vol 90 (3) ◽

pp. 495-521 ◽

Cited By ~ 4

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

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Numerical Investigation of Rotating Nonlinear Energy Sink for Shock Mitigation

Volume 8: 22nd Reliability, Stress Analysis, and Failure Prevention Conference; 25th Conference on Mechanical Vibration and Noise ◽

10.1115/detc2013-13177 ◽

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.

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Asymmetric Magnet-Based Nonlinear Energy Sink

Journal of Computational and Nonlinear Dynamics ◽

10.1115/1.4027462 ◽

2014 ◽

Vol 10 (1) ◽

Cited By ~ 27

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.

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EFFECT OF CHANGING THE COEFFICIENT OF RESTITUTION OF A SINGLE-SIDED VIBRO-IMPACT NONLINEAR ENERGY SINK IN A TWO-STORY STRUCTURE

Proceedings of the 7th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COMPDYN 2015) ◽

10.7712/120119.7268.19964 ◽

2019 ◽

Author(s):

Adnan S. Saeed ◽

Mohammad A. AL-Shudeifat

Keyword(s):

Nonlinear Energy Sink ◽

Coefficient Of Restitution ◽

Story Structure ◽

Energy Sink ◽

Nonlinear Energy

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Optimal Semiactive Damping Control for a Nonlinear Energy Sink Used to Stabilize Milling

Shock and Vibration ◽

10.1155/2020/8837753 ◽

2020 ◽

Vol 2020 ◽

pp. 1-11

Author(s):

Zhuo Chen ◽

Huancai Lu

Keyword(s):

Cutting Force ◽

Primary Structure ◽

Nonlinear Energy Sink ◽

Vibration Absorber ◽

Semiactive Control ◽

Vibration Absorbers ◽

Control Methods ◽

Damping Control ◽

Energy Sink ◽

Nonlinear Energy

Improving product quality of machining components has always met with problems due to the vibration of the milling machine’s spindle, which can be reduced by adding a vibration absorber. The tuned vibration absorber (TVA) has been studied extensively and found to have a narrow bandwidth, but the cutting force possesses wide bandwidth in the process of machining parts. Introducing nonlinearity into the dynamic vibration absorber can effectively increase the bandwidth of vibration suppression and can significantly improve the robustness of the vibration absorber. In addition, a semiactive TVA has proved to be more effective than a passive TVA for many applications, so the main purpose of this study is to find some appropriate semiactive control methods for a nonlinear energy sink (NES), a nonlinear vibration absorber, in structural vibration applications. Two semiactive control methods are considered in this study: continuous groundhook damping control based on velocity and on-off groundhook damping control based on velocity. To fairly compare these vibration absorbers, the optimal parameters of a passive TVA, a passive NES, and two semiactive NESs are designed using numerical optimization techniques to minimize the root-mean-square acceleration. Two cutting forces are introduced in this study, a periodic force and an aperiodic force, and the four vibration absorbers are compared. When the primary structure is excited with aperiodic cutting force, the amplitude of the primary structure decreased by 17.73% with the passive TVA, by 72.29% with the passive NES, by 73.54% with the on-off NES, and by 87.54% with the continuous NES. When the primary structure is excited with periodic cutting force, the amplitude of the primary structure decreased by 49.01% with a passive TVA, by 86.93% with a passive NES, by 96.38% with an on-off NES, and by 99.23% with a continuous NES. The results show that the passive NES is better than the passive TVA; the semiactive NES provides more effective vibration attenuation than the passive NES, and the continuous control is more effective than the on-off control.

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