On the design of a high-static–low-dynamic stiffness isolator using linear mechanical springs and magnets

Carrella, A.; Brennan, M.J.; Waters, T.P.; Shin, Kihong

doi:10.1016/j.jsv.2008.01.046

Cited by 305 publications

(132 citation statements)

References 7 publications

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“…The mechanical springs consist of three types of coil springs, symbolized by 11 , 12 , and 13 separately. One mechanical spring denoted by 12 and four mechanical springs all denoted by 13 are employed to maintain the active cell at the desired position when no electric power is applied and no additional isolated mass is added. The mechanical coil springs symbolized by 11 , placed between the plate and the cylinder body, are only used to balance the additional mass and provide positive vertical stiffness in future application.…”

Section: Basic Configuration Of the Evimentioning

confidence: 99%

“…Furthermore, permanent magnets can also be utilized to obtain negative stiffness. The negative stiffness mechanism presented in [13] was conducted by using three permanent magnets arranged in an attracting configuration. In addition, another two types of negative stiffness mechanism made by permanent magnets can be found in [14,15].…”

Section: Introductionmentioning

confidence: 99%

“…Zhou and Liu [18] and Francisco LedezmaRamirez et al [19,20] have presented a series of papers in which the negative stiffness is obtained by using two electromagnets and one (or two) permanent magnet. It works like the mechanism proposed by [13], but the negative stiffness can be changed by adjusting the input current. However, the characteristic of the magnet is very sensitive to the temperature and the demagnetization phenomenon will occur at high temperature.…”

Section: Introductionmentioning

confidence: 99%

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A New Approach to Achieve Variable Negative Stiffness by Using an Electromagnetic Asymmetric Tooth Structure

Han

Liu

et al. 2018

Shock and Vibration

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Traditional passive nonlinear isolators have been paid much attention in recent literatures due to their excellent performance compared to linear vibration isolators. However, they are incapable of dealing with varying conditions such as changing excitation frequency due to the nonadjustable negative stiffness. To solve this drawback, a new approach to achieve variable negative stiffness is proposed in this paper. The negative stiffness is realized by an electromagnetic asymmetric magnetic tooth structure and can be changed by adjusting the magnitude of the input direct current. Analytical model of the electromagnetic force is built and simulations of magnetic field are conducted to validate the negative stiffness. Then the EATS is applied to vibration isolation and an electromagnetic vibration isolator is designed. Finally, a series of tests are conducted to measure the negative stiffness experimentally and confirm the effect of the EATS in vibration isolation.

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Section: Basic Configuration Of the Evimentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A New Approach to Achieve Variable Negative Stiffness by Using an Electromagnetic Asymmetric Tooth Structure

Han

Liu

et al. 2018

Shock and Vibration

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“…This configuration causes the stiffness to be the summation of a linear and cubic component. While linear stiffness hinders the system's adaptivity and robustness to 75 different excitation spectra, Carrella et al [23] describe how the effective linear stiffness component can be reduced by counteracting it with a negative stiffness component using magnets arranged in an attracting configuration. In another study, Kovacic et al [24] demonstrate that a negative stiffness can be implemented using oblique pre-stressed springs.…”

Section: Introductionmentioning

confidence: 99%

Robust energy harvesting from walking vibrations by means of nonlinear cantilever beams

Kluger

Sapsis

Slocum

2015

Journal of Sound and Vibration

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In the present work we examine how mechanical nonlinearity can be appropriately utilized to achieve strong robustness of performance in an energy harvesting setting. More specifically, for energy harvesting applications, a great challenge is the uncertain character of the excitation. The combination of this uncertainty with the narrow range of good performance for linear oscillators creates the need for more robust designs that adapt to a wider range of excitation signals. A typical application of this kind is energy harvesting from walking vibrations. Depending on the particular characteristics of the person that walks as well as on the pace of walking, the excitation signal obtains completely different forms. In the present work we study a nonlinear spring mechanism that is comprised of a cantilever wrapping around a curved surface as it deflects. While for the free cantilever, the force acting on the free tip depends linearly with the tip displacement, the utilization of a contact surface with the appropriate distribution of curvature leads to essentially nonlinear dependence between the tip displacement and the acting force. The studied nonlinear mechanism has favorable mechanical properties such as low frictional losses, minimal moving parts, and a rugged design that can withstand excessive loads. Through numerical simulations we illustrate that by utilizing this essentially nonlinear element in a 2 degrees-of-freedom (DOF) system, we obtain strongly nonlinear energy transfers between the modes of the system. We illustrate that this nonlinear behavior is associated with strong robustness over three radically different excitation signals that correspond to different walking paces.To validate the strong robustness properties of the 2DOF nonlinear system, we perform a direct parameter optimization for 1DOF and 2DOF linear systems as well as for a class of 1DOF and 2DOF systems with nonlinear springs similar to that of the cubic spring that are physically realized by the cantilever-surface mechanism. The optimization results show that the 2DOF nonlinear system presents the best average performance when the excitation signals have three possible forms. Moreover, we observe that while for the linear systems the optimal performance is obtained for small values of the electromagnetic damping, for the 2DOF nonlinear system optimal performance is achieved for large values of damping. This feature is of particular importance for the the system's robustness to parasitic damping.

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“…To overcome this problem, a high-static-low-dynamic stiffness (HSLDS) spring can be used. The HSLDS isolator is capable of supporting a large static load while possessing a low natural frequency [6,7].…”

Section: Introductionmentioning

confidence: 99%

Characterization of an Electromagnetic Vibration Isolator

Zhou¹,

Liu²

2011

JEMAA

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On the design of a high-static–low-dynamic stiffness isolator using linear mechanical springs and magnets

Cited by 305 publications

References 7 publications

A New Approach to Achieve Variable Negative Stiffness by Using an Electromagnetic Asymmetric Tooth Structure

A New Approach to Achieve Variable Negative Stiffness by Using an Electromagnetic Asymmetric Tooth Structure

Robust energy harvesting from walking vibrations by means of nonlinear cantilever beams

Characterization of an Electromagnetic Vibration Isolator

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