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fluctuations and a supporting body (for example, between the machine and the foundation). The illustration shows a vibration isolator from the series «ВИ» (~"VI" in Roman characters), as used in shipbuilding in Russia, for example the submarine "St.Petersburg" (Lada). The depicted «ВИ» devices allow loadings ranging from 5, 40 and 300 kg. They differ in their physical sizes, but all share the same fundamental design. The structure consists of a rubber envelope that is internally reinforced by a spring. During manufacture, the rubber and the spring are intimately and permanently connected as a result of the vulcanization process that is integral to the processing of the crude rubber material. Under action of weight loading of the machine, the rubber envelope deforms, and the spring is compressed or stretched. Therefore, in the direction of the spring's cross section, twisting of the enveloping rubber occurs. The resulting elastic deformation of the rubber envelope results in very effective absorption of the vibration. This absorption is crucial to reliable vibration insulation, because it averts the potential for resonance effects. The amount of elastic deformation of the rubber largely dictates the magnitude of vibration absorption that can be attained; the entire device (including the spring itself) must be designed with this in mind. The design of the vibration isolator must also take into account potential exposure to shock loadings, in addition to the routine everyday vibrations. Lastly, the vibration isolator must also be designed for long-term durability as well as convenient integration into the environment in which it is to be used. Sleeves and flanges are typically employed in order to enable the vibration isolator to be securely fastened to the equipment and the supporting foundation.
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with a natural frequency of 0.5 Hz. The general shape of the curve is typical for passive systems. Below the natural frequency, transmissibility hovers near 1. A value of 1 means that vibration is going through the system without being amplified or reduced. At the resonant frequency, energy is transmitted efficiently, and the incoming vibration is amplified. Damping in the system limits the level of amplification. Above the resonant frequency, little energy can be transmitted, and the curve rolls off to a low value. A passive isolator can be seen as a mechanical
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six-degree-of-freedom systems with low natural frequencies. Practical systems with vertical and horizontal natural frequencies as low as 0.2 to 0.5 Hz are possible. Electro-mechanical auto-adjust mechanisms compensate for varying weight loads and provide automatic leveling in multiple-isolator systems, similar to the function of leveling valves in pneumatic systems. All-metal systems can be configured which are compatible with high vacuums and other adverse environments such as high temperatures.
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616:). Flexures are used in place of the hinged bars shown in Figure 1. A tilt flexure serves as the tilt-motion isolator. A vertical-stiffness adjustment screw is used to adjust the compression force on the negative-stiffness flexures thereby changing the vertical stiffness. A vertical load adjustment screw is used to adjust for varying weight loads by raising or lowering the base of the support spring to keep the flexures in their straight, unbent operating positions.
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have been used under washing machines and other items with some success. In fact, tennis balls became the de facto standard suspension technique used in DIY rave/DJ culture, placed under the feet of each record turntable which produces enough dampening to neutralize the vibrations of high-powered soundsystems from affecting the delicate, high-sensitivity mechanisms of the turntable needles.
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728:. The acceleration (vibration) signal is processed by a control circuit and amplifier. Then it feeds the electromagnetic actuator, which amplifies the signal. As a result of such a feedback system, a considerably stronger suppression of vibrations is achieved compared to ordinary damping. Active isolation today is used for applications where structures smaller than a
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large industrial equipment. Air tables consist of a working surface or optical surface mounted on air legs. These tables provide enough isolation for laboratory instrument under some conditions. Air systems may leak under vacuum conditions. The air container can interfere with isolation of low-amplitude vibration.
34:. Vibration is undesirable in many domains, primarily engineered systems and habitable spaces, and methods have been developed to prevent the transfer of vibration to such systems. Vibrations propagate via mechanical waves and certain mechanical linkages conduct vibrations more efficiently than others.
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The equipment or other mechanical components are necessarily linked to surrounding objects (the supporting joint - with the support; the unsupporting joint - the pipe duct or cable), thus presenting the opportunity for unwanted transmission of vibrations. Using a suitably designed vibration-isolator
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A vertical-motion isolator is shown . It uses a conventional spring connected to an NSM consisting of two bars hinged at the center, supported at their outer ends on pivots, and loaded in compression by forces P. The spring is compressed by weight W to the operating position of the isolator, as shown
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In less sophisticated solutions, bungee cords can be used as a cheap isolation system which may be effective enough for some applications. The item to be isolated is suspended from the bungee cords. This is difficult to implement without a danger of the isolated item falling. Tennis balls cut in half
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The focus on negative-stiffness isolators has been on developing systems with very low resonant frequencies (below 1 Hz), so that low frequencies can be adequately isolated, which is critical for sensitive instrumentation. All higher frequencies are also isolated. Negative-stiffness systems can
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Not For Profit
Organizations such as ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) and VISCMA (Vibration Isolation and Seismic Control Manufacturers Association) provide specifications / standards for isolator types and spring deflection requirements that cover a
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Passive isolation operates in both directions, isolating the payload from vibrations originating in the support, and also isolating the support from vibrations originating in the payload. Large machines such as washers, pumps, and generators, which would cause vibrations in the building or room, are
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These are bladders or canisters of compressed air. A source of compressed air is required to maintain them. Air springs are rubber bladders which provide damping as well as isolation and are used in large trucks. Some pneumatic isolators can attain low resonant frequencies and are used for isolating
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These isolation systems enable vibration-sensitive instruments such as scanning probe microscopes, micro-hardness testers and scanning electron microscopes to operate in severe vibration environments sometimes encountered, for example, on upper floors of buildings and in clean rooms. Such operation
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Here is an example of a transmissibility curve. Transmissibility is the ratio of vibration of the isolated surface to that of the source. Vibrations are never eliminated, but they can be greatly reduced. The curve below shows the typical performance of a passive, negative-stiffness isolation system
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Every object on a flexible support has a fundamental natural frequency. When vibration is applied, energy is transferred most efficiently at the natural frequency, somewhat efficiently below the natural frequency, and with increasing inefficiency (decreasing efficiency) above the natural frequency.
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Passive vibration isolation is a vast subject, since there are many types of passive vibration isolators used for many different applications. A few of these applications are for industrial equipment such as pumps, motors, HVAC systems, or washing machines; isolation of civil engineering structures
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have to be produced or measured. A couple of companies produce active isolation products as OEM for research, metrology, lithography and medical systems. Another important application is the semiconductor industry. In the microchip production, the smallest structures today are below 20 nm, so
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Negative-Stiffness-Mechanism (NSM) vibration isolation systems offer a unique passive approach for achieving low vibration environments and isolation against sub-Hertz vibrations. "Snap-through" or "over-center" NSM devices are used to reduce the stiffness of elastic suspensions and create compact
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In general, for any given frequency above the natural frequency, an isolator with a lower natural frequency will show greater isolation than one with a higher natural frequency. The best isolation system for a given situation depends on the frequency, direction, and magnitude of vibrations present
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Relative costs of different isolation systems: Inexpensive shock mounts may need to be replaced due to dynamic loading cycles. A higher level of isolation which is effective at lower vibration frequencies and magnitudes generally costs more. Prices can range from a few dollars for bungee cords to
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often isolated from the floor. However, there are a multitude of sources of vibration in buildings, and it is often not possible to isolate each source. In many cases, it is most efficient to isolate each sensitive instrument from the floor. Sometimes it is necessary to implement both approaches.
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All mechanical systems in the real world contain some amount of damping. Damping dissipates energy in the system, which reduces the vibration level which is transmitted at the natural frequency. The fluid in automotive shock absorbers is a kind of damper, as is the inherent damping in elastomeric
50:"Passive vibration isolation" refers to vibration isolation or mitigation of vibrations by passive techniques such as rubber pads or mechanical springs, as opposed to "active vibration isolation" or "electronic force cancellation" employing electric power, sensors, actuators, and control systems.
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is a part of a tube with elastic walls for reflection and absorption of waves of the oscillatory energy extending from the working pump over wall of the pipe duct. Is established between the pump and the pipe duct. On an illustration is presented the image a vibration-isolating branch pipe of a
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This is defined as a device that reflects and absorbs waves of oscillatory energy, extending from a piece of working machinery or electrical equipment, and with the desired effect being vibration insulation. The goal is to establish vibration isolation between a body transferring mechanical
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The theory of operation of NSM vibration isolation systems is summarized, some typical systems and applications are described, and data on measured performance is presented. The theory of NSM isolation systems is explained in
References 1 and 2. It is summarized briefly for convenience.
632:(absorber), vibration isolation of the supporting joint is realized. The accompanying illustration shows the attenuation of vibration levels, as measured before installation of the functioning gear on a vibration isolator as well as after installation, for a wide range of frequencies.
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Cost of providing isolation: Costs include the isolation system itself, whether it is a standard or custom product; a compressed air source if required; shipping from manufacturer to destination; installation; maintenance; and an initial vibration site survey to determine the need for
222:, the engines and alternators produce noise and vibrations. To solve this, the solution is a double elastic suspension where the engine and alternator are mounted with vibration dampers on a common frame. This set is then mounted elastically between the common frame and the hull.
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Damping is used in passive isolators to reduce the amount of amplification at the natural frequency. However, increasing damping tends to reduce isolation at the higher frequencies. As damping is increased, transmissibility roll-off decreases. This can be seen in the chart below.
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shows the force into the body for a subframe that is rigidly bolted to the body compared with the red curve that shows a compliantly mounted subframe. Above 42 Hz the compliantly mounted subframe is superior, but below that frequency the bolted in subframe is better.
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Negative-stiffness mechanisms are purely mechanical and typically involve the configuration and loading of components such as beams or inverted pendulums. Greater loading of the negative-stiffness mechanism, within the range of its operability, decreases the natural
691:, at the cost of introducing additional low frequency modes which may cause the low frequency behaviour to deteriorate. This is commonly used in the rear suspensions of cars with Independent Rear Suspension (IRS), and in the front subframes of some cars. The graph
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Amplitudes: The amplitudes of the vibration frequencies present can be compared with required levels to determine whether isolation is needed. In addition, isolators are designed for ranges of vibration amplitudes. Some isolators are not effective for very small
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Negative-stiffness isolators are less common than other types and have generally been developed for high-level research applications such as gravity wave detection. Lee, Goverdovskiy, and
Temnikov (2007) proposed a negative-stiffness system for isolating vehicle
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Vibration specifications of item to be isolated: Many instruments or machines have manufacturer-specified levels of vibration for the operating environment. The manufacturer may not guarantee the proper operation of the instrument if vibration exceeds the
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Acoustic noise: Some instruments are sensitive to acoustic vibration. In addition, some isolation systems can be excited by acoustic noise. It may be necessary to use an acoustic shield. Air compressors can create problematic acoustic noise, heat, and
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A horizontal-motion isolator consisting of two beam-columns is illustrated in Figure. 2. Each beam-column behaves like two fixed-free beam columns loaded axially by a weight load W. Without the weight load the beam-columns have horizontal stiffness
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series «ВИПБ». In a structure is used the rubber envelope, which is reinforced by a spring. Properties of an envelope are similar envelope to an isolator vibration. Has the device reducing axial effort from action of internal pressure up to zero.
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Base isolators made of layers of neoprene and steel with a low horizontal stiffness are used to lower the natural frequency of the building. Some other base isolators are designed to slide, preventing the transfer of energy from the ground to the
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Adjustment: Some isolation systems require manual adjustment to compensate for changes in weight load, weight distribution, temperature, and air pressure, whereas other systems are designed to automatically compensate for some or all of these
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Vacuum: Some isolators can be used in a vacuum environment. Air isolators may have leakage problems. Vacuum requirements typically include some level of clean room requirement and may also have a large temperature
997:, Camossi, "Device and process for the manufacture of vibration-damping and shockproof mountings incorporating at least one helically arranged metal cable and mounting thereby obtained", published 1983
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Size: The dimensions of the item to be isolated help determine the type of isolation which is available and appropriate. Small objects may use only one isolator, while larger items might use a multiple-isolator
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is basically the weight of the isolated object with low-amplitude vibration input. This is the environment of apparently stationary objects such as buildings (under normal conditions) or laboratory instruments.
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Temperature: In general, isolators are designed to be used in the range of temperatures normal for human environments. If a larger range of temperatures is required, the isolator design may need to be modified.
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Corrosive/non-corrosive: Some indoor environments may present a corrosive danger to isolator components due to the presence of corrosive chemicals. Outdoors, water and salt environments need to be considered.
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Weight: The weight of the object to be isolated is an important factor in choosing the correct passive isolation product. Individual passive isolators are designed to be used with a specific range of loading.
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With the weight load the lateral bending stiffness is reduced by the "beam-column" effect. This behavior is equivalent to a horizontal spring combined with an NSM so that the horizontal stiffness is
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reduce the effects of harmonic vibration in buildings or other structures. A relatively small mass is attached in such a way that it can dampen out a very narrow band of vibration of the structure.
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is the magnitude of a negative-stiffness which is a function of the length of the bars and the load P. The isolator stiffness can be made to approach zero while the spring supports the weight W.
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would not be practical with pneumatic isolation systems. Similarly, they enable vibration-sensitive instruments to produce better images and data than those achievable with pneumatic isolators.
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Platus PhD, David L., SPIE International
Society of Optical Engineering - July 1999, Optomechanical Engineering and Vibration Control Negative-Stiffness-Mechanism Vibration Isolation Systems
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Another technique used to increase isolation is to use an isolated subframe. This splits the system with an additional mass/spring/damper system. This doubles the high frequency attenuation
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Elastomer pads, dense closed cell foams and laminate materials are often used under heavy machinery, under common household items, in vehicles and even under higher performing audio systems.
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Maintenance: Some isolation systems are quite durable and require little or no maintenance. Others may require periodic replacement due to mechanical fatigue of parts or aging of materials.
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Frequencies: If possible, it is important to know the frequencies of ambient vibrations. This can be determined with a site survey or accelerometer data processed through FFT analysis.
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A six-DOF NSM isolator typically uses three isolators stacked in series: a tilt-motion isolator on top of a horizontal-motion isolator on top of a vertical-motion isolator. Figure 3 (
612:) shows a schematic of a vibration isolation system consisting of a weighted platform supported by a single six-DOF isolator incorporating the isolators of Figures 1 and 2 (
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Magnetism: Some experimentation which requires vibration isolation also requires a low-magnetism environment. Some isolators can be designed with low-magnetism components.
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A basic understanding of how passive isolation works, the more common types of passive isolators, and the main factors that influence the selection of passive isolators:
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Movement: Machines or instruments with moving parts may affect isolation systems. It is important to know the mass, speed, and distance traveled of the moving parts.
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is the magnitude of the beam-column effect. Horizontal stiffness can be made to approach zero by loading the beam-columns to approach their critical buckling load.
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involves accelerations and larger amplitude shock and vibration. This environment is present in vehicles, heavy machinery, and structures with significant movement.
163:. The mass and spring stiffness dictate a natural frequency of the system. Damping causes energy dissipation and has a secondary effect on natural frequency.
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These are heavy-duty isolators used for building systems and industry. Sometimes they serve as mounts for a concrete block, which provides further isolation.
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Semiactive vibration isolators have received attention because they consume less power than active devices and controllability over passive systems.
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Size
Constraints: The isolation system may have to fit in a restricted space in a laboratory or vacuum chamber, or within a machine housing.
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Subframe vibration isolation graph: force transmission on suspended body vs. frequency for rigidly and compliantly mounted subframes.
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Direction: Knowing whether vibrations are horizontal or vertical can help to target isolation where it is needed and save money.
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Static or dynamic loads: This distinction is quite important as isolators are designed for a certain type and level of loading.
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Laboratory: Labs are sometimes troubled by specific building vibrations from adjacent machinery, foot traffic, or HVAC airflow.
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These are often used as machinery (such as engines) mounts or in vehicles. They absorb shock and attenuate some vibration.
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These isolators are durable and can withstand extreme environments. They are often used in military applications.
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Industrial: This generally entails strong vibrations over a wide band of frequencies and some amount of dust.
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from earthquakes (base isolation), sensitive laboratory equipment, valuable statuary, and high-end audio.
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Large high-load applications where isolation of medium to high frequency noise and vibration is required
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Pads or sheets of flexible materials such as elastomers, rubber, cork, dense foam and laminate materials.
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involves sensors and actuators that produce disruptive interference that cancels-out incoming vibration.
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This can be seen in the transmissibility curve, which is a plot of transmissibility vs. frequency.
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be made with low stiction, so that they are effective in isolating low-amplitude vibrations.
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makes use of materials and mechanical linkages that absorb and damp these mechanical waves.
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Electron microscopes, sensitive instruments, optics and laser systems, cryogenic systems
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A.Kolesnikov «Noise and vibration». Russia. Leningrad. Publ.«Shipbuilding». 1988
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wide array of industries including electrical, mechanical, plumbing, and HVAC.
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1016:, Gilbert, LeKuch, Ferri, "Isolator Apparatus", published 1988
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from one component of a system to others parts of the same system, as in
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the machines which produce and check them have to oscillate much less.
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1034:"MasterSounds and TPI aim to end turntable feedback with new isolator"
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is realized in the device named branch pipe a of isolating vibration.
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White Paper on Active
Vibration Isolation for Lithography and Imaging
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Active vibration isolation systems contain, along with the spring, a
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Clean room: Some isolators can be made appropriate for clean room.
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Factors influencing the selection of passive vibration isolators
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Base isolators for seismic isolation of buildings, bridges, etc.
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Molded and bonded rubber and elastomeric isolators and mounts
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and the desired level of attenuation of those frequencies.
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1.5 – 3 Hz, large systems customized to 0.5 Hz
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Large industrial equipment, some optics and instruments
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Earthquakes and
Engineers: An International History
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1094:Harris Shock and Vibration Handbook, Fifth Edition
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439:Depends on type of cord and the mass they support
395:3 – 40 Hz, depending on size of pad and load
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490:in Figure 1. The stiffness of the isolator is K=K
322:Nature of vibrations to be isolated or mitigated
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307:millions of dollars for some space applications.
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425:Machinery, instruments, vehicles, aviation
403:Machinery, instruments, vehicles, aviation
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657:Vibration isolation of unsupporting joint
652:Vibration isolation of unsupporting joint
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604:Six-degree-of-freedom (six-DOF) isolation
461:Any, but usually used at low frequencies
1122:Passive Isolation of Harmonic Excitation
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901:(2 ed.). Oxford University Press.
895:Escudier, Marcel; Atkins, Tony (2019).
831:Noise and vibration on maritime vessels
627:Vibration isolation of supporting joint
458:Buildings, large structures, aerospace
231:Characteristics of item to be isolated
16:Prevention of transmission of vibration
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898:A Dictionary of Mechanical Engineering
155:A passive isolation system, such as a
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468:Negative-stiffness vibration isolator
73:Mechanical springs and spring-dampers
22:is the prevention of transmission of
907:10.1093/acref/9780198832102.001.0001
668:Branch pipe a of isolating vibration
663:Branch pipe a of isolating vibration
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190:negative-stiffness transmissibility
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1066:. 2020. p. 19. Archived from
970:Assembly of a T Series HA DS Mount
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400:Molded or bonded elastomer mounts
210:Damping effect on transmissibility
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1127:Vibration Control for Microscopy
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381:Heavy loads, pumps, compressors
61:Common passive isolation systems
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826:Noise, vibration, and harshness
599:Beam column vibration isolation
447:Buildings and large structures
347:Comparison of passive isolators
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558:{\displaystyle K=K_{S}-K_{N}}
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411:Negative-stiffness isolators
1060:Solutions for generator sets
737:Sensors for active isolation
91:Negative-stiffness isolators
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930:Reitherman, Robert (2012).
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718:piezoelectric accelerometer
614:Figures 1 and 2 are missing
510:Horizontal-motion isolation
170:Passive Vibration Isolation
151:How passive isolation works
36:Passive vibration isolation
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936:. Reston, VA: ASCE Press.
846:Passive heave compensation
378:Springs or spring dampers
362:Typical Natural Frequency
356:Type of Passive Isolation
66:Pneumatic or air isolators
40:Active vibration isolation
1092:Harris, C., Piersol, A.,
485:Vertical-motion isolation
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142:Do it Yourself Isolators
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436:Laboratory, home, etc.
389:Elastomer or cork pads
1142:Mechanical engineering
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636:The vibration isolator
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246:Operating Environment
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585:{\displaystyle K_{N}}
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422:Wire rope isolators
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455:Tuned Mass Dampers
417:0.17 - 2.5 Hz
161:harmonic oscillator
110:Wire rope isolators
20:Vibration isolation
841:Package cushioning
811:Bushing (isolator)
752:MEM accelerometers
720:or a geophone), a
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137:Tuned mass dampers
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32:mechanical systems
916:978-0-19-883210-2
876:Vibration control
762:Proximity sensors
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47:
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15:
9:
6:
4:
3:
2:
1159:
1148:
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1139:
1137:
1128:
1125:
1123:
1120:
1118:
1115:
1114:
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1103:
1102:0-07-137081-1
1099:
1095:
1091:
1088:
1087:
1073:on 2021-06-07
1069:
1062:
1061:
1054:
1039:
1035:
1032:Smith, Mark.
1028:
1015:
1009:
996:
990:
976:
972:
971:
964:
950:on 2012-07-26
949:
945:
943:9780784410714
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866:Soundproofing
864:
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849:
847:
844:
842:
839:
837:
834:
832:
829:
827:
824:
822:
821:Damping ratio
819:
817:
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802:
799:
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790:
787:
785:
782:
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779:Linear motors
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760:
758:
755:
753:
750:
747:
744:
743:Piezoelectric
741:
740:
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731:
727:
723:
719:
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705:
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672:
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611:
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37:
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25:
21:
1093:
1075:. Retrieved
1068:the original
1059:
1053:
1041:. Retrieved
1037:
1027:
1008:
989:
979:, retrieved
969:
963:
952:. Retrieved
948:the original
932:
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513:
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428:10 - 40+ Hz
406:10 - 20+ Hz
350:
217:
213:
201:
197:
193:
177:
173:
154:
56:
52:
49:
39:
35:
19:
18:
856:Shock mount
836:Oscillation
816:Damped wave
610:Ref. needed
329:amplitudes.
220:Superyachts
157:shock mount
1136:Categories
1077:2021-06-07
1014:US4783038A
995:US4397069A
981:2021-06-16
954:2012-07-10
882:References
861:Sorbothane
730:micrometer
722:controller
303:isolation.
107:frequency.
1043:14 August
871:Vibration
757:Geophones
724:, and an
543:−
130:building.
28:buildings
24:vibration
975:archived
795:See also
726:actuator
313:factors.
275:airflow.
689:rolloff
498:where K
235:system.
1100:
1020:
1001:
940:
913:
565:, and
299:Cost:
268:range.
95:seats.
1071:(PDF)
1064:(PDF)
338:spec.
1098:ISBN
1045:2020
938:ISBN
911:ISBN
903:doi
218:In
30:or
1138::
1036:.
973:,
909:.
494:-K
1080:.
1047:.
957:.
919:.
905::
578:N
574:K
551:N
547:K
538:S
534:K
530:=
527:K
517:S
515:K
504:N
500:S
496:N
492:S
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