Vibration isolation and energy harvesting integrated in a Stewart platform with high static and low dynamic stiffness

2021 ◽  
Vol 89 ◽  
pp. 249-267
Author(s):  
Ze-Qi Lu ◽  
Dao Wu ◽  
Hu Ding ◽  
Li-Qun Chen
Keyword(s):  
Energy Harvesting ◽  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Stewart Platform

Integrated vibration isolation and energy harvesting via a bistable piezo-composite plate

2019 ◽  
Vol 26 (9-10) ◽  
pp. 779-789 ◽  
Author(s):  
Ze-Qi Lu ◽  
Dong Shao ◽  
Zhi-Wei Fang ◽  
Hu Ding ◽  
Li-Qun Chen
Keyword(s):  
Energy Harvesting ◽  
Composite Plate ◽  
Output Voltage ◽  
Vibration Isolation ◽  
Virtual Work ◽  
Dynamic Stiffness ◽  
Nonlinear Phenomena ◽  
Approximate Analytical Solutions ◽  
Passive Vibration Isolation ◽  
Vibration Transmissibility

In passive vibration isolation, a bistable composite plate can be used to generate high-static low-dynamic stiffness, and in vibratory energy harvesting, when used with piezoelectric film flexing, the bistable composite plate can enhance the performance via snap-through motion. In the present work, we designed a bistable piezo-composite plate for both vibration isolation and energy harvesting. The analytical model for performance prediction is derived from the virtual work principle and the composite elasticity. Displacement transmissibility and output voltage generation were analytically determined for different mechanical and electrical parameters. The results illustrate that the bistable piezo-composite plate improves the feasibility and effectiveness of the integration design. Hardening and softening nonlinear phenomena coexist in both the displacement transmissibility and the output voltage plot. Approximate analytical solutions and numerical simulations are in good agreement. Both analytical and numerical results demonstrate that, at a certain frequency bands, enhanced energy harvesting is accompanied by a vibration transmissibility reduction. Compared with a linear system with the bistable piezo-composite plate removed, it achieved a reduction in the displacement transmissibility of about 13 dB at 100 Hz, simultaneously, and produced a considerable output voltage of about 0.05 V.

Design and analysis of a vibration isolation system with cam–roller–spring–rod mechanism

2021 ◽  
pp. 107754632110005
Author(s):  
Yonglei Zhang ◽  
Guo Wei ◽  
Hao Wen ◽  
Dongping Jin ◽  
Haiyan Hu
Keyword(s):  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Experimental Studies ◽  
Excitation Amplitude ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Stiffness Characteristic ◽  
Negative Stiffness Mechanism ◽  
Isolation Systems ◽  
Vibration Isolation Performance

The vibration isolation system using a pair of oblique springs or a spring-rod mechanism as a negative stiffness mechanism exhibits a high-static low-dynamic stiffness characteristic and a nonlinear jump phenomenon when the system damping is light and the excitation amplitude is large. It is possible to remove the jump via adjusting the end trajectories of the above springs or rods. To realize this idea, the article presents a vibration isolation system with a cam–roller–spring–rod mechanism and gives the detailed numerical and experimental studies on the effects of the above mechanism on the vibration isolation performance. The comparative studies demonstrate that the vibration isolation system proposed works well and outperforms some other vibration isolation systems.

Design of a Miniaturized Pneumatic Vibration Isolator With High-Static-Low-Dynamic Stiffness

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Yuhu Shan ◽  
Wenjiang Wu ◽  
Xuedong Chen
Keyword(s):  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Structure Design ◽  
Negative Stiffness ◽  
Vibration Isolator ◽  
Load Bearing Capacity ◽  
Compact Structure ◽  
Chamber Volume ◽  
Isolation Systems ◽  
Magnetic Rings

In the ultraprecision vibration isolation systems, it is desirable for the isolator to have a larger load bearing capacity and a broader isolation bandwidth simultaneously. Generally, pneumatic spring can bear large load and achieve relatively low natural frequency by enlarging its chamber volume. However, the oversized isolator is inconvenient to use and might cause instability. To reduce the size, a miniaturized pneumatic vibration isolator (MPVI) with high-static-low-dynamic stiffness (HSLDS) is developed in this paper. The volume of proposed isolator is minimized by a compact structure design that combines two magnetic rings in parallel with the pneumatic spring. The two magnetic rings are arranged in the repulsive configuration and can be mounted into the chamber to provide the negative stiffness. Then dynamic model of the developed MPVI is built and the isolation performances are analyzed. Finally, experiments on the isolator with and without the magnetic rings are conducted. The final experimental results are consistent with the dynamical model and verify the effectiveness of the developed vibration isolator.

Design of mechanical metamaterials for simultaneous vibration isolation and energy harvesting

2017 ◽  
Vol 111 (25) ◽  
pp. 251903 ◽  
Author(s):  
Ying Li ◽  
Evan Baker ◽  
Timothy Reissman ◽  
Cheng Sun ◽  
Wing Kam Liu
Keyword(s):  
Energy Harvesting ◽  
Vibration Isolation ◽  
Mechanical Metamaterials

On the Effects of Mistuning a Force-Excited System Containing a Quasi-Zero-Stiffness Vibration Isolator

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Ali Abolfathi ◽  
M. J. Brennan ◽  
T. P. Waters ◽  
B. Tang
Keyword(s):  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Low Frequency ◽  
Vibration Isolator ◽  
Linear Vibration ◽  
Vibration Isolators ◽  
Zero Dynamic ◽  
Low Frequency Vibration ◽  
Excited System ◽  
Better Than

Nonlinear isolators with high-static-low-dynamic-stiffness have received considerable attention in the recent literature due to their performance benefits compared to linear vibration isolators. A quasi-zero-stiffness (QZS) isolator is a particular case of this type of isolator, which has a zero dynamic stiffness at the static equilibrium position. These types of isolators can be used to achieve very low frequency vibration isolation, but a drawback is that they have purely hardening stiffness behavior. If something occurs to destroy the symmetry of the system, for example, by an additional static load being applied to the isolator during operation, or by the incorrect mass being suspended on the isolator, then the isolator behavior will change dramatically. The question is whether this will be detrimental to the performance of the isolator and this is addressed in this paper. The analysis in this paper shows that although the asymmetry will degrade the performance of the isolator compared to the perfectly tuned case, it will still perform better than the corresponding linear isolator provided that the amplitude of excitation is not too large.

Experimental Investigations on the Contour Generation of a Reconfigurable Stewart Platform

2013 ◽  
pp. 291-301
Author(s):  
G. Satheesh Kumar ◽  
T. Nagarajan
Keyword(s):  
Error Analysis ◽  
Natural Frequency ◽  
Vibration Isolation ◽  
Stewart Platform ◽  
Design Tool ◽  
Experimental Investigations ◽  
Variable Geometry ◽  
Optimum Geometry ◽  
Complete Set

Reconfiguration of Stewart platform for varying tasks accentuates the importance for determination of optimum geometry catering to the specified task. The authors in their earlier work (Satheesh et al., 2008) have indicated the non availability of an efficient holistic methodology for determining the optimum geometry. Further, they have proposed a solution using the variable geometry approach through the formulation of dimensionless parameters in combination with generic parameters like configuration and joint vector. The methodology proposed provides an approach to develop a complete set of design tool for any new reconfigurable Stewart platform for two identified applications viz., contour generation and vibration isolation. This paper details the experimental investigations carried out to validate the analytical results obtained on a developed Stewart platform test rig and error analysis is performed for contour generation. The experimental natural frequency of the developed Stewart platform has also been obtained.

scholarly journals Analysis and optimal design of a vibration isolation system combined with electromagnetic energy harvester

2019 ◽  
Vol 30 (16) ◽  
pp. 2382-2395
Author(s):  
Uchenna Diala ◽  
SM Mahdi Mofidian ◽  
Zi-Qiang Lang ◽  
Hamzeh Bardaweel
Keyword(s):  
Energy Harvesting ◽  
Energy Conversion ◽  
Conversion Efficiency ◽  
Vibration Isolation ◽  
Energy Conversion Efficiency ◽  
Isolation System ◽  
Magnetic Components ◽  
Energy Harvesting System ◽  
Response Function Method ◽  
Conversion Efficiencies

This work investigates a vibration isolation energy harvesting system and studies its design to achieve an optimal performance. The system uses a combination of elastic and magnetic components to facilitate its dual functionality. A prototype of the vibration isolation energy harvesting device is fabricated and examined experimentally. A mathematical model is developed using first principle and analyzed using the output frequency response function method. Results from model analysis show an excellent agreement with experiment. Since any vibration isolation energy harvesting system is required to perform two functions simultaneously, optimization of the system is carried out to maximize energy conversion efficiency without jeopardizing the system’s vibration isolation performance. To the knowledge of the authors, this work is the first effort to tackle the issue of simultaneous vibration isolation energy harvesting using an analytical approach. Explicit analytical relationships describing the vibration isolation energy harvesting system transmissibility and energy conversion efficiency are developed. Results exhibit a maximum attainable energy conversion efficiency in the order of 1%. Results suggest that for low acceleration levels, lower damping values are favorable and yield higher conversion efficiencies and improved vibration isolation characteristics. At higher acceleration, there is a trade-off where lower damping values worsen vibration isolation but yield higher conversion efficiencies.

Research on dynamic stiffness of the damping element in bellows-type fluid viscous damper by a simplified model

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Xiaolei Jiao ◽  
Jinxiu Zhang ◽  
Hongchao Zhao ◽  
Yong Yan
Keyword(s):  
Frequency Domain ◽  
Analytical Model ◽  
High Frequency ◽  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Simplified Model ◽  
Viscous Damper ◽  
Content Type ◽  
Fluid Viscous Damper ◽  
Frequency Domains

Purpose Bellows-type fluid viscous damper can be used to isolate micro vibration in high-precision satellites. The conventional model cannot describe hydraulic stiffness in the medium- and high-frequency domain of this damper. A simplified analytical model needs to be established to analyze hydraulic stiffness of the damping element in this damper. Design/methodology/approach In this paper, a bellows-type fluid viscous damper is researched, and a simplified model of the damping element in this damper is proposed. Based on this model, the hydraulic stiffness and damping of this damper in the medium- and high-frequency domains are studied, and a comparison is made between the analytical model and a finite element model to verify the analytical model. Findings The results show that when silicone oil has low viscosity, a model that considers the influence of the initial segment of the damping orifice is more reasonable. In the low-frequency domain, hydraulic stiffness increases quickly with frequency and remains stable when the frequency increases to a certain value; the stable stiffness can reach 106 N/m, which is much higher than the main stiffness. Excessive dynamic stiffness in the high-frequency domain will cause poor vibration isolation performance. Adding compensation bellows to the end of the original isolator may be an effective solution. Practical implications A model of the isolator containing the compensation bellows can be derived based on this analytical model. This research can also be used for dynamic modeling and vibration isolation performance analysis of a vibration isolation platform based on this bellows-type fluid viscous damper. Originality/value This paper proposed a simplified model of damping element in bellows-type fluid viscous damper, which can be used to analyze hydraulic stiffness in this damper and it was found that this damper showed stable hydraulic stiffness in the medium- and high-frequency domains.

scholarly journals Dynamically variable negative stiffness structures

2016 ◽  
Vol 2 (2) ◽  
pp. e1500778 ◽  
Author(s):  
Christopher B. Churchill ◽  
David W. Shahan ◽  
Sloan P. Smith ◽  
Andrew C. Keefe ◽  
Geoffrey P. McKnight
Keyword(s):  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Low Frequency ◽  
Variable Stiffness ◽  
Negative Stiffness ◽  
Load Bearing ◽  
Vibration Isolators ◽  
Wide Range ◽  
Engineered Systems ◽  
Tunable Stiffness

Variable stiffness structures that enable a wide range of efficient load-bearing and dexterous activity are ubiquitous in mammalian musculoskeletal systems but are rare in engineered systems because of their complexity, power, and cost. We present a new negative stiffness–based load-bearing structure with dynamically tunable stiffness. Negative stiffness, traditionally used to achieve novel response from passive structures, is a powerful tool to achieve dynamic stiffness changes when configured with an active component. Using relatively simple hardware and low-power, low-frequency actuation, we show an assembly capable of fast (<10 ms) and useful (>100×) dynamic stiffness control. This approach mitigates limitations of conventional tunable stiffness structures that exhibit either small (<30%) stiffness change, high friction, poor load/torque transmission at low stiffness, or high power active control at the frequencies of interest. We experimentally demonstrate actively tunable vibration isolation and stiffness tuning independent of supported loads, enhancing applications such as humanoid robotic limbs and lightweight adaptive vibration isolators.

Vibration Energy Harvesting of a Hydraulic Engine Mount Using a Turbine

2010 ◽  
Author(s):  
Omid Mohareri ◽  
Siamak Arzanpour
Keyword(s):  
Energy Harvesting ◽  
Vibration Isolation ◽  
Vibration Suppression ◽  
Low Cost ◽  
Dissipated Energy ◽  
Vibration Energy ◽  
Vibration Energy Harvesting ◽  
Engine Mounts ◽  
Harvesting Technique ◽  
Engine Mount

The hydraulic engine mount (HEM) has been designed to provide a vibration isolation characteristic to control road and engine induced vibrations in vehicles by using two fluid passages known as decoupler and inertia track. These types of engine mounts are known for their best noise, vibration, and harshness (NVH) suppression performance among other different types of engine mounts. However, a low cost technique to recycle the dissipated energy of the system in the process of vibration suppression is significantly advantageous. A novel design structure in which the decoupler is replaced with a water turbine to capture and restore the vibration energy of the system is presented in this paper. The turbine design and selection has been done based on the upper and lower chamber pressures and the fluid flow rates in the system’s resonant frequency. The mount vibration isolation and energy generation performance is studied in both frequency and time domains. The simulation results demonstrate that a considerable amount of energy can be harvested from the engine vibration sources. This recent study demonstrates a novel energy harvesting technique in vehicles that require minimum design modifications of conventional hydraulic mounts.

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