Nonlinear Energy Sinks With Piecewise-Linear Nonlinearities

2019 ◽  
Vol 14 (12) ◽  
Author(s):  
Mohammad A. AL-Shudeifat
Keyword(s):  
Vibration Suppression ◽  
Piecewise Linear ◽  
Linear Structure ◽  
Nonlinear Energy Sink ◽  
Mass System ◽  
Wide Range ◽  
Coupling Force ◽  
Negative Coupling ◽  
Stiffness And Damping ◽  
Nonlinear Energy

Abstract An efficient nonlinear energy sink (NES) is developed here by employing a symmetric piecewise nonlinear coupling force. The proposed piecewise NES has a symmetric clearance about its equilibrium position in which zero stiffness is assumed. However, at the boundaries of the symmetric clearance, the NES is coupled to the linear structure by either linear or nonlinear stiffness elements. The damping is assumed to be continuous linear viscous damping during the oscillation of the NES mass inside and outside the clearance zone. This design is further modified by incorporating a negative coupling stiffness within the clearance zone. Therefore, the performance of the proposed piecewise NESs in rapid vibration suppression is numerically investigated with two-degree-of-freedom spring-mass system and compared with existing NESs in the literature. Accordingly, significant improvement in vibration suppression has been achieved by the proposed piecewise NES compared with other types of existing NESs. Moreover, the numerical simulation results have shown more robustness in the piecewise NES performance for a wide range of stiffness and damping variations than the linear absorber and other types of NESs in the literature.

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.

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.

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.

Nonlinear Normal Modes of a Continuous Cantilever Beam with Nonlinear Energy Sink Absorber

2013 ◽  
Vol 325-326 ◽  
pp. 214-217
Author(s):  
Yong Chen ◽  
Yi Xu
Keyword(s):  
Cantilever Beam ◽  
Vibration Suppression ◽  
Normal Modes ◽  
Nonlinear Energy Sink ◽  
Nonlinear Normal Modes ◽  
Harmonic Excitation ◽  
Energy Sink ◽  
Nonlinear Normal ◽  
Nonlinear Energy ◽  
Good Agreement

Using nonlinear energy sink absorber (NESA) is a good countermeasure for vibration suppression in wide board frequency region. The nonlinear normal modes (NNMs) are helpful in dynamics analysis for a NESA-attached system. Being a primary structure, a cantilever beam whose modal functions contain hyperbolic functions is surveyed, in case of being attached with NESA and subjected to a harmonic excitation. With the help of Galerkins method and Raushers method, the NNMs are obtained analytically. The comparison of analytical and numerical results indicates a good agreement, which confirms the existence of the nonlinear normal modes.

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

2019 ◽  
Vol 141 (6) ◽  
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.

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 Application of Nonlinear Energy Sink for Rotor System Vibration Suppression

2020 ◽  
Vol 56 (15) ◽  
pp. 191
Author(s):  
YAO Hongliang ◽  
CAO Yanbo ◽  
ZHANG Qin ◽  
WEN Bangchun
Keyword(s):  
Vibration Suppression ◽  
Nonlinear Energy Sink ◽  
Rotor System ◽  
System Vibration ◽  
Energy Sink ◽  
Nonlinear Energy

Dynamic Analysis of 1-Dof and 2-Dof Nonlinear Energy Sink With Geometrically Nonlinear Damping and Combined Stiffness

2021 ◽  
Author(s):  
Yunfa Zhang ◽  
Xianren Kong ◽  
Chengfei Yue ◽  
Huai Xiong
Keyword(s):  
Bifurcation Analysis ◽  
Vibration Suppression ◽  
Harmonic Balance Method ◽  
Nonlinear Energy Sink ◽  
Nonlinear Damping ◽  
Linear Oscillator ◽  
Frequency Detuning ◽  
Incremental Harmonic Balance Method ◽  
Energy Sink ◽  
Nonlinear Energy

Abstract Nonlinear energy sink (NES) refers to a typical passive vibration device connected to linear or weakly nonlinear structures for vibration absorption and mitigation. This study investigates the dynamics of 1-dof and 2-dof NES with nonlinear damping and combined stiffness connected to a linear oscillator. For the system of 1-dof NES, a truncation damping and failure frequency are revealed through bifurcation analysis using the complex variable averaging method. The frequency detuning interval for the existence of the strongly modulated response (SMR) is also reported . For the system of 2-dof NES, it is reported in a similar bifurcation analysis that the mass distribution between NES affects the maximum value of saddle-node bifurcation. To obtain the periodic solution of the 2-dof NES system with the consideration of frequency detuning, the incremental harmonic balance method (IHB) and Floquet theory are employed. The corresponding response regime is obtained by Poincare mapping, it shows that the responses of the linear oscillator and 2-dof NES are not always consistent, and 2-dof NES can generate extra SMR than 1-dof NES. Finally, the vibration suppression effect of the proposed NES with nonlinear damping and combined stiffness is analyzed and verified by the energy spectrum, and it also shows that the 2-dof NES system demonstrates better performance.

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