A study of a nonlinear vibration isolator with a quasi-zero stiffness characteristic

Force and displacement transmissibility of a nonlinear isolator with high-static-low-dynamic-stiffness

On the force transmissibility of a vibration isolator with quasi-zero stiffness

In this paper, we present a nonlinear electromagnetic energy harvesting device that has a broadly resonant response. The nonlinearity is generated by a particular arrangement of magnets in conjunction with an iron-cored stator. We show the resonant response of the system to both pure-tone excitation and narrow-band random excitation. In addition to the primary resonance, the superharmonic resonances of the harvester are also investigated and we show that the corresponding mechanical upconversion of the excitation frequency may be useful for energy harvesting. The harvester is modeled using a Duffing-type equation and the results are compared with the experimental data.

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Energy Harvesting From Vibrations With a Nonlinear Oscillator

Recent advances in micro-vibration isolation

Static analysis of a passive vibration isolator with quasi-zero-stiffness characteristic

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

On the jump-up and jump-down frequencies of the duffing oscillator

The frequency range over which a mount can isolate a mass from a vibrating base (or vice versa) is often limited by the mount stiffness required to support the weight of the mass. This compromise can be made more favourable by employing non-linear mounts with a softening spring characteristic such that small excursions about the static equilibrium position result in small dynamic spring forces and a correspondingly low natural frequency. This paper concerns the force-displacement characteristic of a so-called quasi-zero-stiffness (QZS) mechanism which is characterised by an appreciable static stiffness but very small (theoretically zero) dynamic stiffness. The mechanism studied comprises a vertical spring acting in parallel with two further springs which, when inclined at an appropriate angle to the vertical, produce a cancelling negative stiffness effect. Analysis of the system shows that a QZS characteristic can be obtained if the system’s parameters (angle of inclination and ratio of spring stiffnesses) are opportunely chosen. By introducing the additional criterion that the displacement of the system be largest without exceeding a desired (low) value of stiffness an optimal set of parameter values is derived. Under sufficiently large displacements the stiffness of the QZS mechanism can eventually exceed that of the simple mass-spring system and criteria for this detrimental scenario to arise are presented.

A. Carrella

Papers

Static analysis of a passive vibration isolator with quasi-zero-stiffness characteristic

On the force transmissibility of a vibration isolator with quasi-zero stiffness

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

On the jump-up and jump-down frequencies of the duffing oscillator

Optimization of a Quasi-Zero-Stiffness Isolator