Shock Characteristics of the Opposed Disc Springs (ODS) Shock Isolator with Pretightening under Boundary Friction Condition

In this study, to solve the problems of shock environment and shock isolation, about which there is still a lack of reasonable description, an isokinetic shock distinguishing method (ISDM), which can quantitatively distinguish between shock and forced vibration state, is presented. And the shock isolation performance of an opposed disc springs (ODS) shock isolator with pretightening under boundary friction condition is investigated. The static and dynamic stiffness properties of the ODS shock isolator are discussed. Relying on ISDM, a shock dynamic model of the ODS shock isolator with pretightening under boundary friction condition is established. The average method is adopted to solve the model theoretically. The shock acceleration ratio (SAR), shock displacement ratio (SDR), and relative displacement ratio (RDR) of the model are calculated using the numerical method and verified by experiments. Both numerical and experimental results show that ISDM is effective. And the effects on isolation efficiency of the number of disc springs, additional supporting force, pretightening force, load, and the shock velocity constant of the ODS shock isolator are discussed, which provide guidelines for its further practical application.

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Shock isolation characteristics of a bistable vibration isolator with tunable magnetic controlled stiffness

Journal of Vibration and Acoustics ◽

10.1115/1.4051850 ◽

2021 ◽

pp. 1-28

Author(s):

Bo Yan ◽

Peng Ling ◽

Yanlin Zhou ◽

Chuan-yu Wu ◽

Wen-Ming Zhang

Keyword(s):

Damping Ratio ◽

Excitation Amplitude ◽

Relative Displacement ◽

Vibration Isolator ◽

Maximum Acceleration ◽

Vibration Isolators ◽

Displacement Ratio ◽

Shock Isolation ◽

Maximum Relative Displacement ◽

Isolation Performance

Abstract This paper investigates the shock isolation characteristics of an electromagnetic bistable vibration isolator (BVI) with tunable magnetic controlled stiffness. The theoretical model of the BVI is established. The maximum acceleration ratio (MAR), maximum absolute displacement ratio (MADR) and maximum relative displacement ratio (MRDR) are introduced to evaluate the shock isolation performance of the BVI. The kinetic and potential energy are observed to further explore the performance of the BVI. The effects of the potential barrier, shape of potential well, damping ratio on the BVI are discussed compared to the linear vibration isolators (LVI). The results demonstrate that the intrawell oscillations and snap-through oscillations are determined by the excitation amplitude and duration time of main pulse. MADR and MRDR of the BVI are smaller than those of the LVI. The maximum acceleration peak amplitude of the BVI is far below that of the LVI, especially when the snap-through oscillation occurs. In brief, the proposed BVI has a better shock isolation performance than the LVI and has the potential to suppress the shock of space structures during the launch and on-orbit deploying process.

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Study on a Semi-Active Shock Isolation Technology with Magnetorheological Devices

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.26-28.770 ◽

2010 ◽

Vol 26-28 ◽

pp. 770-775

Author(s):

Yu Fei Wang ◽

Lin He ◽

Xue Yang

Keyword(s):

Active Control ◽

Control Strategy ◽

Control Algorithm ◽

Stable State ◽

Relative Displacement ◽

Shock Acceleration ◽

Passive Devices ◽

Simulation Results ◽

Shock Isolation ◽

Active Control Strategy

A semi-active shock isolation technology with magnetorheological devices was systematically studied. The magnetorheological devices consist of magnetorheological dampers (MRD) and magnetorheological elstomers (MRE) isolator. Based on the method of Lyapunov function, the semi-active control strategy and the control algorithm were developed to minimize the relative movement of the system. The simulation results show that, compared with the passive devices, the semi-active control technology in the paper is effective to reduce the relative displacement and the shock acceleration of protected equipment. And the system will go back to the stable state within ultrashort time.

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Repeatability, Reproducibility, and Calibration of the MyotonPro® on Tissue Mimicking Phantoms

Volume 1A: Abdominal Aortic Aneurysms; Active and Reactive Soft Matter; Atherosclerosis; BioFluid Mechanics; Education; Biotransport Phenomena; Bone, Joint and Spine Mechanics; Brain Injury; Cardiac Mechanics; Cardiovascular Devices, Fluids and Imaging; Cartilage and Disc Mechanics; Cell and Tissue Engineering; Cerebral Aneurysms; Computational Biofluid Dynamics; Device Design, Human Dynamics, and Rehabilitation; Drug Delivery and Disease Treatment; Engineered Cellular Environments ◽

10.1115/sbc2013-14622 ◽

2013 ◽

Author(s):

John Dougherty ◽

Emily Schaefer ◽

Kalyani Nair ◽

Joseph Kelly ◽

Alfonse Masi

Keyword(s):

Data Collection ◽

Dynamic Stiffness ◽

Correlation Study ◽

Living Tissue ◽

Polymeric Gel ◽

Stiffness Properties ◽

Tissue Phantoms ◽

Repeatability And Reproducibility ◽

Living Tissues

The MyotonPro® (Myoton AS, Tallinn, Estonia) is commonly used to quantify stiffness properties of living tissues in situ. Current studies quantify the dynamic stiffness properties of living tissues, but do not validate or compare these measurements to a standardized method. Additionally, living tissue, being dynamic in nature, presents much variability in data collection. To address these issues this study focuses on the repeatability and reproducibility of the MyotonPro® on polymeric gel-based tissue phantoms. In addition, a correlation study is also performed to translate dynamic stiffness to a more standardized property, Young’s modulus. Such studies help to confirm the reliability of the measurements obtained in situ.

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Improving Low Frequency Isolation Performance of Optical Platforms Using Electromagnetic Active-Negative-Stiffness Method

Applied Sciences ◽

10.3390/app10207342 ◽

2020 ◽

Vol 10 (20) ◽

pp. 7342

Author(s):

Yamin Zhao ◽

Junning Cui ◽

Junchao Zhao ◽

Xingyuan Bian ◽

Limin Zou

Keyword(s):

Root Mean Square ◽

Dynamic Stiffness ◽

Low Frequency ◽

Laser Interferometry ◽

Relative Displacement ◽

Negative Stiffness ◽

Mean Square ◽

Electromagnetic Actuators ◽

Micro Vibration ◽

Isolation Performance

To improve the low-frequency isolation performance of optical platforms, an electromagnetic active-negative-stiffness generator (EANSG) was proposed, using nano-resolution laser interferometry sensors to monitor the micro-vibration of an optical platform, and precision electromagnetic actuators integrated with a relative displacement feedback strategy to counteract the positive stiffness of pneumatic springs within a micro-vibration stroke, thereby producing high-static-low-dynamic stiffness characteristics. The effectiveness of the method was verified by both theoretical and experimental analyses. The experimental results show that the vertical natural frequency of the optical platform was reduced from 2.00 to 1.37 Hz, the root mean square of displacement was reduced from 1.28 to 0.69 μm, and the root mean square of velocity was reduced from 14.60 to 9.33 μm/s, proving that the proposed method can effectively enhance the low frequency isolation performance of optical platforms.

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Design and Analysis of a Magnetorheological Fluid Mount Featuring Uni-Directional Squeeze Mode

Volume 2: Integrated System Design and Implementation; Structural Health Monitoring; Bioinspired Smart Materials and Systems; Energy Harvesting ◽

10.1115/smasis2015-8813 ◽

2015 ◽

Cited By ~ 2

Author(s):

Xian-Xu Bai ◽

Peng Chen ◽

Li-Jun Qian ◽

Ping Kan

Keyword(s):

Dynamic Stiffness ◽

Magnetorheological Fluid ◽

Relative Displacement ◽

Bottom Surface ◽

Damping Properties ◽

Damping Force ◽

Equivalent Damping ◽

Engine Vibration ◽

Coil Winding ◽

Stiffness And Damping

A magnetorheological fluid (MRF) mount featuring unidirectional squeeze mode for vehicle engine mounting system is proposed and designed to attenuate the engine vibration with characteristics of broadband and small amplitude. The MRF mount is comprised of upper and lower bases for installation, a main rubber for static load, a bobbin for electromagnetic coil winding and a squeeze plate. The bottom surface of the bobbin and the top surface of the squeeze plate form the polar plates, between which the MRF is squeezed during the rebound of the MRF mount. Combining dynamic stiffness property of passive hydraulic mounts without fluid and adjustable damping force of MRF at squeeze mode, the MRF mount could provide a unique variable dynamic stiffness and damping properties, by adjusting the exciting current. To evaluate the performance of the MRF mount, a mathematical model considering the behavior of MRF at squeeze mode is derived to theoretically analyze and numerically simulate the dynamic stiffness and equivalent damping properties of the MRF mount. Further, the MRF mount based quarter vehicle mounting system model considering suspension system is constructed to analyze the force transmissibility of engine mounting system in frequency domain and simulate the relative displacement response in time domain.

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MAPPING OF DYNAMIC STIFFNESS PROPERTIES OF CARTILAGE ON THE HUMAN PATELLA

Journal of Biomechanics ◽

10.1016/s0021-9290(12)70158-6 ◽

2012 ◽

Vol 45 ◽

pp. S157 ◽

Cited By ~ 1

Author(s):

Sarah Ronken ◽

Markus P. Arnold ◽

Sebastian Hoechel ◽

A.U. Daniels ◽

Magdalena Müller-Gerbl ◽

...

Keyword(s):

Dynamic Stiffness ◽

Stiffness Properties

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Analysis of Frequency and Damping Ratio on the Shock Isolation Efficiency

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.791-793.835 ◽

2013 ◽

Vol 791-793 ◽

pp. 835-838

Author(s):

Shi Jie Wu ◽

Lin He ◽

Xi Zhi Zhao

Keyword(s):

Damping Ratio ◽

Relative Displacement ◽

Displacement Amplitude ◽

Vibration Isolator ◽

Isolation System ◽

Single Degree Of Freedom ◽

Absolute Acceleration ◽

Single Degree ◽

Acceleration Amplitude ◽

Shock Isolation

The traditional shock isolation system is only designed in stiffness regardless of damping, which causes acute contradiction between absolute acceleration amplitude and relative displacement amplitude. Based on the single degree of freedom negative shock isolation system, numerical analysis demonstrates that relative little amplitude of absolute acceleration and relative displacement could be attained within a certain range of damping and frequency ratio. Selecting appropriate damping and stiffness of vibration isolator can resolve contradiction between absolute acceleration amplitude and relative displacement amplitude and consequently improve shock isolation efficiency.

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Optimal fluid passageway design methodology for hydraulic engine mounts considering both low and high frequency performances

Journal of Vibration and Control ◽

10.1177/1077546319870036 ◽

2019 ◽

Vol 25 (21-22) ◽

pp. 2749-2757

Author(s):

Yuan Li ◽

Jason Zheng Jiang ◽

Simon A Neild

Keyword(s):

High Frequency ◽

Dynamic Stiffness ◽

Low Frequency ◽

Relative Displacement ◽

Wide Frequency Range ◽

Performance Criteria ◽

Frequency Model ◽

Engine Mounts ◽

Engine Mount ◽

And Performance

This paper investigates the potential for improving the performance of hydraulic engine mounts through fluid passageway designs. In previous studies, a few simple inertia track designs have been investigated with moderate improvements obtained. However, there are countless alternative design possibilities existing; while analyzing each one of them in turn is impracticable. To this end, this paper introduces a systematic methodology to optimize fluid passageway designs in a hydraulic engine mount. First, beneficial fluid passageway configurations are systematically identified using a linearized low-frequency model that captures the relative displacement transmissibility. A nonlinear model is then used to fine-tune the fluid passageway designs for the low-frequency transmissibility improvement, and also for the assessment of high-frequency dynamic stiffness performance. The obtained beneficial designs present performance advantages over a wide frequency range. The design approach introduced in this study is directly applicable to other engine mount models and performance criteria.

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Theoretical and Experimental Investigation of Molecular Spring Isolator

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.764-765.388 ◽

2015 ◽

Vol 764-765 ◽

pp. 388-392 ◽

Cited By ~ 2

Author(s):

Mu Chun Yu ◽

Qian Chen ◽

Xue Gao

Keyword(s):

Dynamic Stiffness ◽

External Pressure ◽

Hydraulic Pressure ◽

Periodic Excitation ◽

Large Numbers ◽

Stiffness Properties ◽

Working Medium ◽

Hydrophobic Pore ◽

Static Experiment ◽

Force Equilibrium

A molecular spring isolator which consists of water and hydrophobic zeolites as working medium is investigated. When the isolator undergoes periodic excitation, water intrudes into hydrophobic pores of zeolites depending on the external pressure and extrudes from the pores as hydraulic pressure decreases. As a result, molecular spring absorbs, releases and dissipates mechanism energy. To obtain the stiffness properties of molecular spring isolator, the mechanics modal of water column intruding into a hydrophobic pore is established utilizing force equilibrium. Subsequently, the process of water infiltrating large numbers of hydrophobic pores is explored. Then the quasi-static experiment is carried out to validate the theoretical modal. It is found that the molecular spring exhibits high static and low dynamic stiffness. Finally, the effect of quantity of zeolites and temperature on stiffness of molecular spring is investigated experimentally.

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An experimental nonlinear low dynamic stiffness device for shock isolation

Journal of Sound and Vibration ◽

10.1016/j.jsv.2015.02.006 ◽

2015 ◽

Vol 347 ◽

pp. 1-13 ◽

Cited By ~ 21

Author(s):

Diego Francisco Ledezma-Ramirez ◽

Neil S. Ferguson ◽

Michael J. Brennan ◽

Bin Tang

Keyword(s):

Dynamic Stiffness ◽

Shock Isolation

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