Abstract:A negative stiffness element is always employed to generate high-static–low-dynamic stiffness characteristic of the vibration isolator, reduce the resonance frequency of the isolator, and improve the vibration isolation performance under low and ultra-low frequency excitation. In this paper, a new compact negative stiffness permanent magnetic spring (NSPMS) that is composed of two axial-magnetized permanent magnetic rings is proposed. An analytical expression of magnetic negative stiffness of the NSPMS is dedu… Show more
“…Although a small deviation of magnitude between the designed and the anticipated is observed, it is completely acceptable in engineering applications. And comparing the designed LNS with results proposed by our previous work Zhou et al (2019) and Dong et al (2017), the linear range of the LNS in these two references is about 2.5 mm. Obviously, a larger range of the LNS was obtained in this work.Figure 8.The negative stiffness with the proposed designing procedure.…”
Section: Analysis and Design Of The Lnsmentioning
confidence: 60%
“…Dong et al proposed a negative stiffness magnet spring (NSMS) that composed of a pair of coaxial ring radial magnetization permanent magnets to obtain the LNS in a narrow displacement range (Dong et al, 2017). Using axial magnetized permanent rings to get the LNS was also put forward by Zhou et al (2019). Unfortunately, the range of the LNS is so narrow that the operation point cannot be changed.…”
Vibration isolator with high-static low-dynamic stiffness property has been researched extensively, but the isolator’s stability and performance will be deteriorated with the operation point variation. In this article, a vibration isolator that operation point can be variable was proposed, and it was constructed by combining a coil spring and flexible leaf springs with a negative stiffness magnet spring in parallel. Unlike previous studies, this article focuses on the realization of the high-static low-dynamic stiffness characteristic of the isolator, and the operation point of the vibration isolator can be varied in a certain range. The effects of configuration parameters on the negative stiffness are investigated in detail. Furthermore, the designing procedure to realize the linear negative stiffness with the expected magnitude and range was also developed. A prototype was installed and the vibration transmissibility of the system at different operation points was measured, the experimental results indicated that the isolator can be kept stable in different operation points, and the performance does not deteriorate with the variation of the operation point. The effectiveness of the designing procedure of the realization of linear negative stiffness with the expected magnitude and range and the variable of the operation point of the isolator was validated.
“…Although a small deviation of magnitude between the designed and the anticipated is observed, it is completely acceptable in engineering applications. And comparing the designed LNS with results proposed by our previous work Zhou et al (2019) and Dong et al (2017), the linear range of the LNS in these two references is about 2.5 mm. Obviously, a larger range of the LNS was obtained in this work.Figure 8.The negative stiffness with the proposed designing procedure.…”
Section: Analysis and Design Of The Lnsmentioning
confidence: 60%
“…Dong et al proposed a negative stiffness magnet spring (NSMS) that composed of a pair of coaxial ring radial magnetization permanent magnets to obtain the LNS in a narrow displacement range (Dong et al, 2017). Using axial magnetized permanent rings to get the LNS was also put forward by Zhou et al (2019). Unfortunately, the range of the LNS is so narrow that the operation point cannot be changed.…”
Vibration isolator with high-static low-dynamic stiffness property has been researched extensively, but the isolator’s stability and performance will be deteriorated with the operation point variation. In this article, a vibration isolator that operation point can be variable was proposed, and it was constructed by combining a coil spring and flexible leaf springs with a negative stiffness magnet spring in parallel. Unlike previous studies, this article focuses on the realization of the high-static low-dynamic stiffness characteristic of the isolator, and the operation point of the vibration isolator can be varied in a certain range. The effects of configuration parameters on the negative stiffness are investigated in detail. Furthermore, the designing procedure to realize the linear negative stiffness with the expected magnitude and range was also developed. A prototype was installed and the vibration transmissibility of the system at different operation points was measured, the experimental results indicated that the isolator can be kept stable in different operation points, and the performance does not deteriorate with the variation of the operation point. The effectiveness of the designing procedure of the realization of linear negative stiffness with the expected magnitude and range and the variable of the operation point of the isolator was validated.
“…Equation ( 14) is substituted into Equation (8), and the left side of Equation ( 8) is simply integrated to sort out: 4 (1 )…”
Section: B Mathematical Model Of the Dual-chamber Flexible Bellows Is...mentioning
confidence: 99%
“…In recent years, for the lightweight, high-speed and comfortable requirements of the vehicle increase, air spring is often used as an elastic component in the suspension system of the vehicle [3]. The design of air springs may vary according to the application, and the design differences will affect the performance of air springs, which can be divided into two main types: rolling vane type and bellows type [4].…”
To achieve an effective and versatile solution for reducing vibrations and reducing maintenance costs, the dual-chamber flexible bellows isolator (D-CFBI) of rubber material is designed. The outer chamber of D-CFBI is used as an actuator to change its own variable stiffness and control the feedback force by filling negative pressure gas. The inner chamber is used as a rubber air spring to work as the main vibration isolation element. Under different loads and sinusoidal excitation forces, the damping characteristics and damping effects of the D-CFBI with different stiffness are investigated. By exciting the isolator, the frequency sweep experiment is carried out, the dynamic flexibility in the initial state is studied, and a preload of the D-CFBI is given to change the stiffness of the D-CFBI, and the changing trend between restoring force and amplitude and frequency is found out. Conclusions can be summarized that increasing the preload of the D-CFBI leads to increased stiffness and better damping effect. For compression amounts of 20% and frequencies higher than 7Hz or amplitudes lower than 2mm, the damping effect is also better. Consequently, this D-CFBI offers satisfactory damping and increased safety at low amplitudes and frequencies. To achieve optimal damping, it is recommended to adjust the stiffness of the driver.
“…For example, pre-stressed bars or beams [2,3], inclined springs with axial preload [4][5][6], cam-roller-spring mechanisms [7,8], and scissor-like structures [9] combined with a vertical spring in parallel, can produce high-static-low-dynamic stiffness. In addition, cubic permanent magnets in attractive [10,11], repulsive [12,13], or a combination of attractive and repulsive configuration [14,15], permanent magnet rings magnetized axially [16,17] or radially [18,19] were well proposed to produce negative stiffness with non-contact characteristics. The negative stiffness of the above vibration isolators was not easy to adjust, so their optimal performance can only be achieved when they are with a certain payload and geometric parameters.…”
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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