Study On Dynamic Behavior Of A Class Of Single-sided Vibro-impact Nonlinear Energy Sinks

Structural vibration control is a topic of interest for engineers and scholars worldwide.In order to effectively reduce the structural response and protect the structure from the damage caused by extreme loads,such as impulse and blasting,a new type of passive control device,nonlinear energy sinks(NESs),have attracted extensive interest since they were proposed.NESs,like a pump,absorb energy from the structure to which it is attached and dissipates that energy locally.This transfer of energy to the NES can be irreversible under ideal conditions and can dramatically reduce the vibration of the primary structure.This one-way energy flow phenomenon exhibited by the NES is called targeted energy transfer(TET).Additionally,the NES can couple the vibration modes of the structure to realize the redistribution of the vibration energy with the transfer of energy from the low-frequency modes to the higher-frequency modes.This redistribution is usually beneficial in reducing the structural vibration response;the displacement amplitudes of higher-frequency modes are often smaller than those of the lower modes with the same energy level,and energy in higher-frequency modes is more easily dissipated by damping than energy in lower modes.The vibration energy transfer mechanism of the single-sided vibro-impact nonlinear energy sink(SSVI NES)is studied.The concept of impact mode is proposed and applied to the analysis of a single-degree-of-freedom(SDOF)vibration system with a SSVI NES.This analysis shows that the energy in the system can be redistributed between the different impact modes.More importantly,the mechanism of the SSVI NES to realize the local dissipation of energy is revealed.Then,the relationship between the energy in tne system and the energy free impact mode is investigated using the Hilbert transform.The effect of the SSVI NES parameters on the energy dissipation performance of the SSVI NES is discussed,and a satisfactory region for the SSVI NES design is proposed.A symmetric single-sided vibro-impact nonlinear energy sink(SSSVI NES)is proposed and applied to the vibration control of an Euler-Bernoulli beam.Consideration and theoretical analysis of the impact dynamics of the device is carried out by introducing the impact modes.This analysis shows that the proposed SSSVI NES has increased complexity in its modes of energy dissipation compared with the SSVI NES.A large number of simulations are conducted with a wide variety of impulse loads to determine the optimum parameters of the SSSVI NES.The optimized SSSVI NES is then compared with both the SSVI NES and the NES locked in the suppression of the beam response subject to an impulse load.When each of these devices is restricted to have the same total mass,the numerical results show that the SSSVI NES has superior vibration suppression performance.The vibration suppression performance of SSSVI NES is investigated when its location along this continuous beam is varied.The effect of the clearance between NES masses and the impact surface on the vibration suppression performance of the SSSVI NES and the device’s damping is also investigated.The efficacy of the SSSVI NES device for typical shock is investigated.The numerical results show that the optimized SSSVI NES can effectively suppress the vibration of the host cantilever beam,and can effectively protect the beam from damage.The single-sided vibro-impact track nonlinear energy sink(SSVI track NES)is studied.Optimization of the NES parameters is used to determine the NES mass and track shape.It is found that the optimized SSVI track NES can realize the dynamic coupling between the horizontal and vertical directions.The energy originally in the structure in the horizontal direction can be transferred to the vertical vibration of the structure where it can be dissipated.Considering that many 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 effects of the position of the impact surface and the ratio of the primary structure’s vertical to horizontal stiffness on the energy dissipation performance of the SSVI track NES are discussed.Numerical results show that the performance of the SSVI track NES remains stable over a wide range of stiffness ratios,showing strong robustness.A symmetric single-sided vibro-impact track nonlinear energy sink(SSSVI track NES)is proposed based on the SSVI track NES.The influence of the parameters of the SSSVI track NES on vibration suppression performance is discussed by numerical simulations.Optimal NES mass and track shape are obtained and applied to time domain and wavelet transform analysis.Energy transfer phenomenon from lower frequency vibration to higher frequency vibration is observed.Considering the practical application,the effect of SSSVI track NES design parameters difference on its performance is discussed.The results show that SSSVI track NES is robust to design parameters difference.The feasibility of using the SSVI track NES to vibration due to typical shock excitation was investigated,and the results demonstrated that the optimized SSVI track NES is effective.Finally,the response suppression performance of SSSVI NES on the beam under impulsive excitation is verified.The peak response in frequency domain is used as evaluation criteria to evaluate the response suppression performance of SSSVI NES.Both simulation and experimental results show that SSSVI NES can effectively suppress the vibration response of the beam.