Abstract
The purpose of this study is to investigate the characteristics of vibration isolation system with a single degree-of-freedom (SDOF) and a two-degree-of-freedom (2DOF) respectively based on the high-static-low-dynamic-stiffness (HSLDS). This model consists of a simple configuration connecting a vertical spring and a pair of oblique springs. The restoring force of the isolation system is approximated to linear and cubic stiffness by applying the Maclaurin series expansion. The dynamic equations of the SDOF and 2DOF are established for the harmonic force excitation. The frequency-amplitude response equation of the SDOF is obtained by employing the harmonic balance method (HBM) and is demonstrated in the classical Runge-Kutta method. The solution stability is ensured by applying the Floquet theory. Effects on the frequency response curves (FRCs) for the damping ratio and excitation amplitude are explored and discussed. The force transmissibility (FT) is defined to evaluate the vibration suppression capability. Effects on the FT of the SDOF and 2DOF for the excitation amplitude, mass ratio, and damping ratio are investigated. An experimental investigation of the SDOF is carried out to evaluate the actual attenuation performance in comparison with the equivalent linear system (ELS). The simulation and experimental results show that the HSLDS system with harmonic force excitation demonstrates hardening stiffness with multi-valued solutions. The occurrence of jump phenomenon is observed and explained by the stiffness variation. The system response and resonance frequency are affected by the excitation amplitude and damping ratio. The HSLDS system outperforms the ELS in a low frequency range if an appropriate mass is mounted. It is excited by a proper force and owns a suitable damper, which offers a theoretical guidance for the design and application of a novel HSLDS isolator.
Highlights
Undesirable vibration is a harmful effect that affects practical equipment, high-precision machinery and human health
The aim of this paper is to develop a single degree-of-freedom (SDOF)-HSLDS and two-degree-of-freedom (2DOF)-HSLDS system experimentally and theoretically that can be useful for the elimination of line spectra of noise radiated from a submarine
The vibration isolation performance is assessed by the force transmissibility (FT), which is defined as the ratio of the root mean square (RMS) value of the force transmitted to the base, and as of the RMS value of the excitation force
Summary
Undesirable vibration is a harmful effect that affects practical equipment, high-precision machinery and human health. It is evident that the bandwidth of vibration isolation is often limited by the mounted stiffness element required to support a static load To overcome this limitation, the High-static-low-dynamic-stiffness (HSLDS) mechanism was put forward, what results in low a natural frequency with a small static displacement. Carrella and Wu investigated vibration isolators with the HSLDS property via a combination of a mechanical spring and magnets [3, 4]. CHARACTERISTIC ANALYSIS OF VIBRATION ISOLATION SYSTEM BASED ON HIGH-STATIC-LOW-DYNAMIC STIFFNESS. Liu developed a quasi-zero-stiffness by connecting the Euler buckled beam mechanism and a linear spring [8]. The effects of the excitation amplitude, mass ratio and damping ratio on frequency response curves (FRCs) and force transmissibility (FT) of the HSLDS vibration isolation system were investigated analytically and experimentally as compared with that of the equivalent linear system (ELS)
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