Article
Mechanics
Wei Zou, Chun Cheng, Ran Ma, Yan Hu, Weiping Wang
Summary: A novel vibration isolation system with quasi-zero stiffness and nonlinear damping using geometric nonlinearity and scissor-like structures is proposed. This system can isolate low-frequency vibration, suppress high-amplitude vibration, and has minimal impact from increasing nonlinear damping at high frequencies. The theoretical results show that this system outperforms classical counterparts.
ARCHIVE OF APPLIED MECHANICS
(2021)
Article
Engineering, Mechanical
Srajan Dalela, P. S. Balaji, D. P. Jena
Summary: This paper introduces a metastructure-based vibration isolation model with high static and low dynamic stiffness properties to enhance isolation effectiveness of small-scale equipment under low-frequency excitations. The quasi-zero-stiffness (QZS) effect is achieved through the snap-through behavior of cosine beam systems and bending-dominated behavior of semicircular arches within each unit cell. Analytical and numerical studies as well as experimental validation confirm the static and dynamic characteristics of the proposed metastructure, showing lower transmissibility and wider isolation range compared to a linear model. The parametric study reveals that motion transmissibility decreases with decreasing damping ratio in the low-frequency region, while increasing damping ratio leads to wider effective isolation range. Stability analysis shows the unstable region in the frequency response curve reduces with higher damping ratio and is independent of excitation amplitude.
NONLINEAR DYNAMICS
(2022)
Article
Engineering, Multidisciplinary
Ze-Qi Lu, Dao Wu, Hu Ding, Li-Qun Chen
Summary: An electromagnetic Stewart platform with high static and low dynamic stiffness is explored to reduce vibration in six degrees of freedom (6-DOFs) and harvest energy simultaneously. The use of stiffness nonlinearity improves vibration isolation efficiency, leading to lower frequencies for vibration isolation and considerable power output. Analytical and numerical results both support the extension of vibration isolation frequency band and reduced vibration transmissibility with increased energy harvesting.
APPLIED MATHEMATICAL MODELLING
(2021)
Article
Physics, Applied
Hanxiao Wu, Zhi Tao, Haiwang Li, Tiantong Xu, Wenbin Wang, Jiamian Sun
Summary: This paper presents a systematic study on the output performance of nonlinear energy harvesters, using theoretical and numerical analysis. The study derives the general analytical expression for output power of systems with different combinations of nonlinear stiffness and damping. It is found that all nonlinear systems have a limit power determined by mass, acceleration, and damping. The results also reveal that asymmetrical damping has no effect on the output performance of symmetrical stiffness systems. Furthermore, the study investigates the influence of nonlinear coefficients on output power with matched load, and reveals a power function relationship between normalized power and matching resistance ratio. These findings provide valuable insights for the design and optimization of energy harvesters.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2022)
Article
Engineering, Mechanical
Yaohui Sun, Jiangping Hu, Rui Huang
Summary: This paper presents an impedance control method for lower limb exoskeleton robots driven by series elastic actuators (SEA). A negative stiffness structure (NSS) SEA is designed to achieve vibration isolation in the low-frequency excitation region. The dynamics model of the SEA-driven exoskeleton robot system is proposed and the impedance control strategy is integrated. Numerical responses in both time and frequency domains are given, and the stability of the system is demonstrated. Numerical simulations are carried out to show the effectiveness of the control method.
Article
Engineering, Civil
Peng Chen, Bin Wang, Kaoshan Dai, Tao Li
Summary: This study presents an innovative base isolation system using negative stiffness devices (NSDs) for seismic protection of structures. The theoretical dynamic solution is matched well with numerical simulation when the system nonlinearity is insignificant. Performance evaluation shows that the NSDs promote the isolation effect under minor and moderate earthquakes, reducing the large isolation deformation under major earthquakes, especially effective under near-field earthquakes.
ENGINEERING STRUCTURES
(2022)
Article
Engineering, Mechanical
Wen-Ju Han, Ze-Qi Lu, Mu-Qing Niu, Li-Qun Chen
Summary: An elliptical ring is used to implement a novel type of high-static-low-dynamic vibration isolation system, with force-displacement relation derived from mathematical theories and experimentally validated. Furthermore, a dynamic equation is established, revealing the high-static-low-dynamic stiffness of the elliptical ring isolator, and the displacement transmissibility can be predicted using the harmonic balance method.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2022)
Article
Acoustics
Ehsan Davoodi, Pedram Safarpour, Mahdi Pourgholi, Mostafa Khazaee
Summary: This article presents a seat suspension based on negative stiffness structure to reduce vibration transmitted to helicopter pilots. By studying the impact of parameters on system performance, design parameters are determined to make the system respond simultaneously as a negative stiffness structure in both directions.
JOURNAL OF VIBRATION AND CONTROL
(2022)
Article
Engineering, Mechanical
N. Menga, F. Bottiglione, G. Carbone
Summary: The paper evaluates the effectiveness of nonlinear viscoelastic damping in controlling base-excited vibrations. It investigates the robustness of nonlinear base isolation performance in controlling system response to a wide set of possible excitation spectra, showing that tuned nonlinear RLRB provides loads isolation in a wider range of excitation spectra.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2021)
Article
Green & Sustainable Science & Technology
Cindy S. Barrera, Janice L. Tardiff
Summary: The use of eggshells as replacements for carbon black in rubber composites for automotive applications can achieve comparable reinforcement and improved isolation performance. It can also enhance the processing of the material and increase the renewable fraction while reducing energy consumption.
JOURNAL OF CLEANER PRODUCTION
(2022)
Article
Engineering, Mechanical
Yuanhao Xiong, Fengming Li, Yu Wang
Summary: This article proposes a novel nonlinear quasi-zero-stiffness (QZS) vibration isolation system with high load carrying capacity. By connecting an X-shaped structure with a platform, the quasi-zero-stiffness vibration isolation system with additional X-shaped structure (X-QZS) is designed. The relationships of system restoring force and stiffness related to displacement are obtained by static modelling and the influences of the parameters on the system stiffness are analyzed. In the dynamic analysis, the amplitude-frequency characteristics and transmissibility curves are calculated. Numerical simulations and vibration experiments verify the accuracy of the calculation results. The designed X-QZS system exhibits a wide QZS interval, a small unstable interval, a low jump-down frequency, and a high load carrying capacity.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2022)
Article
Engineering, Mechanical
Xiao Feng, Xingjian Jing, Yingqing Guo
Summary: This study presents a novel way to achieve superior passive vibration isolation using a specially designed and compact linkage mechanism, with beneficial nonlinear inertia and an adjustable nonlinear stiffness system. The proposed system shows significantly reduced resonant frequency and enhanced damping effect in a beneficial nonlinear way, resulting in excellent vibration isolation performance.
NONLINEAR DYNAMICS
(2021)
Article
Engineering, Mechanical
Yongheng Yu, Fengming Li, Guo Yao
Summary: To achieve broad-range vibration isolation, an X-shaped structure is integrated into a two-stage vibration isolation system. The Lagrange equation is used to establish the nonlinear equation of motion for the proposed X-shaped two-stage isolator, considering both rotational and vertical displacements. The effects of key parameters on frequency response characteristics and vibration isolation frequency bands are examined using the incremental harmonic balance method. The investigation validates the correctness and feasibility of the analytical approach, and reveals the possibility of low-frequency isolation and the influence of softening nonlinearity.
NONLINEAR DYNAMICS
(2023)
Article
Engineering, Civil
Huan Li, Kaiming Bi, Hong Hao
Summary: Recently, the tuned negative stiffness inerter damper (TNSID), which combines negative stiffness and inerter elements, has been proven effective in controlling structural vibration. This paper investigates the influence of the nonlinearity of negative stiffness on the performances of two different TNSID configurations. The study introduces the working mechanisms and optimal parameters of TNSIDs with simplified linear negative stiffness, and then analyzes the dynamic responses and unstable behaviors caused by different nonlinear negative stiffness. Parameter studies and structural optimization are also conducted to evaluate the effects and mitigate the negative impacts of the nonlinearity.
ENGINEERING STRUCTURES
(2023)
Article
Engineering, Mechanical
Xiaoying Hu, Chunyan Zhou
Summary: In this study, a nonlinear quasi-zero-stiffness (QZS) vibration isolation system with nonlinear hysteretic damping is investigated. The effects of nonlinear damping on the bounded response and isolation performance are verified through numerical simulations and vibration tests.
NONLINEAR DYNAMICS
(2022)
