scholarly journals Pre-Acting Control for Shock and Impact Isolation Systems

2005 ◽  
Vol 12 (1) ◽  
pp. 49-65 ◽  
Author(s):  
D.V. Balandin ◽  
N.N. Bolotnik ◽  
W.D. Pilkey
Keyword(s):  
Performance Index ◽  
Design Parameters ◽  
Control Force ◽  
Isolation System ◽  
Single Degree Of Freedom ◽  
Absolute Value ◽  
Single Degree ◽  
Shock Impact ◽  
Isolation Systems ◽  
Isolation Performance

Pre-acting control in shock/impact isolation systems is studied. With pre-acting control, the isolation system begins to respond to an impact before this impact has been applied to the base. The limiting performance of the isolator with pre-acting control is investigated for a single-degree-of-freedom system subject to an instantaneous impact. The isolation performance index is defined as the maximum of the absolute value of the displacement of the object to be isolated relative to the base, provided that the magnitude of the control force transmitted to the object does not exceed a prescribed value. It is shown that there is a substantial advantage in the use of pre-acting isolators over isolators without pre-action. Particular attention is given to a pre-acting isolator based on a passive elastic element (a spring) separating the object to be protected from the base. An example illustrates the calculation of the design parameters of such an isolator.

A Modular-Type Three-Axis Vibration Isolation System Using Negative Stiffness

2010 ◽  
Author(s):  
Md. Emdadul Hoque ◽  
Takeshi Mizuno ◽  
Yuji Ishino ◽  
Masaya Takasaki
Keyword(s):  
Vibration Isolation ◽  
Degree Of Freedom ◽  
Experimental Results ◽  
Negative Stiffness ◽  
Isolation System ◽  
Single Degree Of Freedom ◽  
Vibration Isolation System ◽  
Single Degree ◽  
In Series ◽  
Isolation Systems

A vibration isolation system is presented in this paper which is developed by the combination of multiple vibration isolation modules. Each module is fabricated by connecting a positive stiffness suspension in series with a negative stiffness suspension. Each vibration isolation module can be considered as a self-sufficient single-degree-of-freedom vibration isolation system. 3-DOF vibration isolation system can be developed by combining three modules. As the number of motions to be controlled and the number of actuators are equal, there is no redundancy in actuators in such vibration isolation systems. Experimental results are presented to verify the proposed concept of the development of MDOF vibration isolation system using vibration isolation modules.

scholarly journals Analysis and design of the power law damping based on the nonlinear vessel isolation system

2018 ◽  
Vol 10 (12) ◽  
pp. 168781401881719 ◽  
Author(s):  
You Wang ◽  
Xinghua Zhu ◽  
Rong Zheng ◽  
Zhe Tang ◽  
Bingbing Chen
Keyword(s):  
Resonant Frequency ◽  
Working Conditions ◽  
Power Law ◽  
Nonlinear Damping ◽  
Frequency Region ◽  
Isolation System ◽  
Analysis And Design ◽  
Force Transmissibility ◽  
Isolation Systems ◽  
Isolation Performance

In this study, the applications of the cubic power law damping in vessel isolation systems are investigated. The isolation performance is assessed using the force transmissibility of the vessel isolation system, which is simplified as a multiple-degree-of-freedom system with two parallel freedoms. The force transmissibilities of different working conditions faced in practice are discussed by applying the cubic power law damping on different positions of the vessel isolation system. Numerical results indicate that by adding the cubic power law damping to an appropriate position, the isolation system can not only suppress the force transmissibility over the resonant frequency region but also keep the force transmissibility unaffected at the nonresonant frequency region. Moreover, the design of the nonlinear vessel isolation system is discussed by finding the optimal nonlinear damping of the isolation system.

A genetic algorithm–based design approach for smart base isolation systems

2017 ◽  
Vol 29 (7) ◽  
pp. 1315-1332 ◽  
Author(s):  
Mohtasham Mohebbi ◽  
Hamed Dadkhah ◽  
Hamed Rasouli Dabbagh
Keyword(s):  
Genetic Algorithm ◽  
Optimization Problem ◽  
Base Isolation ◽  
Design Procedure ◽  
Design Parameters ◽  
Linear Quadratic ◽  
Isolation System ◽  
Isolation Systems ◽  
Magneto Rheological ◽  
Smart Base Isolation

This article presents a new approach for designing effective smart base isolation systems composed of a low-damping linear base isolation and a semi-active magneto-rheological damper. The method is based on transforming the design procedure of the hybrid base isolation system into a constrained optimization problem. The magneto-rheological damper command voltages have been determined using H2/linear quadratic Gaussian and clipped-optimal control algorithms. Through a sensitivity analysis to identify the effective design parameters, base isolation and control algorithm parameters have been taken as design variables and optimally determined using genetic algorithm. To restrict increases in floor accelerations, the objective function of the optimization problem has been defined as minimizing the maximum base drift while putting specific constraint on the acceleration response. For illustration, the proposed method has been applied to design a semi-active hybrid isolation system for a four-story shear building under earthquake excitation. The results of numerical simulations show the effectiveness, simplicity, and capability of the proposed method. Furthermore, it has been shown that using the proposed method, the acceleration of the isolated structure can also be incorporated into design process and practically controlled with a slight sacrifice of control effectiveness in reducing the base drift.

scholarly journals Miura-ori, Basics for Designing its Folding Machines

2019 ◽  
Vol 2 ◽  
pp. 1-5
Author(s):  
Koryo Miura
Keyword(s):  
Basic Concept ◽  
High Speed ◽  
Geometric Property ◽  
Unique Property ◽  
Degree Of Freedom ◽  
Design Parameters ◽  
Geometric Properties ◽  
Single Degree Of Freedom ◽  
Single Degree

<p><strong>Abstract.</strong> The unique property of the Miura-ori map is due to the geometric property of “the single degree of freedom”. With this, one can open a map with a single pull motion. However, due to this property, the high-speed folding machine is difficult to realized. In this presentation, author investigates the natural geometric properties of Miura-ori in detail and proposes a basic concept for designing its folding machine. Though, the result does not provide a draft of a folding machine, the basics for the design parameters is beneficial for future works.</p>

Sliding-Mode Control Algorithm for a Hard-Mounted Isolation System

2007 ◽  
Author(s):  
Yung-Peng Wang ◽  
Jen-Chieh Tsao
Keyword(s):  
Sliding Mode Control ◽  
Control Algorithm ◽  
Sliding Mode ◽  
Isolation System ◽  
Mode Control ◽  
Active Isolation ◽  
Ultra Precision ◽  
Passive Isolation ◽  
Isolation Systems ◽  
Isolation Performance

It is well known that the trend of current technology development is microscopic and ultra-precision, especially in the areas of semiconductor manufacturing, ultra-precision machining, MEMS, microbiology and nanotechnology. Hence, vibration becomes a significant problem in those fields. There are two types of vibration control techniques. One is passive isolation system; the other is active isolation system. Passive isolation system can provide better performance for higher frequencies. Active isolation system is used to improve the isolation performance for lower frequencies. However, passive isolation system has bad performance around the natural frequency. In addition, it cannot eliminate the effects of onboard disturbances. Therefore, active isolation system becomes the major technology in the applications of microvibration control for precision equipment. In practice, all active isolation systems are based upon a hybrid concept, combining a passive isolator for higher frequencies and a servo control system for lower frequencies. This combination allows for two significantly different configurations, which can be categorized as: soft-mounted isolation systems and hard-mounted isolation systems. The soft-mounted systems are inherently insensitive to resonance in the main structure below the isolators. Yet, they are sensitive to resonances in the isolated platform. The hard-mounted systems are extremely stiff and allows for large onboard disturbance forces without excessive motion. However, the major drawback with a hard-mounted system is that vibration isolation performance suffers from the passive-active compromise and is unable to come up to the optimal performance. In this paper, a sliding-mode control algorithm is developed for a hard-mounted isolation system with a piezoactuator. Based on the bounds of environmental vibrations and onboard disturbances, the sliding-mode control algorithm can make the hard-mounted isolation system achieve the optimal and robust performance of low vibration transmissibility and high stiffness. The results are verified by the numerical simulations.

Displacement Transmissibility of a Four-Parameter Isolator with Geometric Nonlinearity

2020 ◽  
Vol 20 (08) ◽  
pp. 2050092
Author(s):  
Haiping Liu ◽  
Pengpeng Zhao
Keyword(s):  
Geometric Nonlinearity ◽  
Structural Vibration ◽  
Design Parameters ◽  
Engineering Practice ◽  
Base Excitation ◽  
Zener Model ◽  
Isolation System ◽  
Nonlinear Isolation ◽  
Isolation Performance ◽  
Steady State Solutions

This study is concerned with structural vibration reduction using a four-parameter isolator designed as a scissor-like structure, which can induce geometric nonlinearity during the deformation process. The displacement transmissibility of the isolator including the geometric nonlinearity under base excitations is thoroughly investigated. First, the dynamic model of the four-parameter isolator is presented. Then, by utilizing the harmonic balanced method (HBM), the steady-state solutions of the inertia mass and auxiliary spring of the proposed isolator are derived. The analytical solutions are validated by comparing with those obtained by the direct numerical integrating method. Besides, the natural frequency of the nonlinear isolation system is presented and investigated. Moreover, the isolation performance of the four-parameter isolator is assessed in terms of the relative and absolute displacement transmissibilities, and compared with that of the linear Zener model, by which the advantages of the present isolator have been clearly revealed. The effects of various design parameters on the displacement transmissibility of the isolator are also analyzed. Finally, a further comparison between the analytical and experimental results under base excitation also shows that the mechanical model used for the four-parameter isolator is accuracy enough. The present results may provide a useful theoretical basis for the design of the four-parameter isolator in engineering practice.

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