Abstract
The vibration isolator equipped with a negative stiffness corrector (NSC) excels at vibration isolation, but its stiffness often presents complex nonlinearity which needs to be approximated in calculation. To avoid the harmful effects of approximate stiffness, the NSC formed by the cam-roller mechanism with a quadratic polynomial trajectory (QCRM) is proposed to construct the vibration isolation system. From the inherent geometrical relationship in the structure, the generation mechanism of high-static-low-dynamic stiffness is analyzed, and the quasi-zero stiffness (QZS) condition of the system is derived. Based on the dynamic model of the QZS vibration isolator, the functions of response characteristics are solved by the harmonic balance method. Then, the absolute displacement transmissibility with different parameter values, and the vibration isolation performance under sinusoidal, multi-frequency wave, and random excitations are discussed. The simulated results show that the stiffness expression of the proposed QZS vibration isolator is directly a quadratic function, which removes the calculation error caused by approximate stiffness at large displacement and broadens the available isolation displacement range. Introducing the QCRM-NSC can significantly suppress the low-frequency vibration and resonance response without changing the load-bearing capacity of the vibration isolator. Under various excitations, the vibration isolation performance of the QZS vibration isolator all outperforms the linear counterpart.
Highlights
This paper proposes an negative stiffness corrector (NSC) formed by the cam-roller mechanism with a quadratic polynomial trajectory
For the quasi-zero stiffness (QZS) vibration isolator equipped with the novel NSC, its static and dynamic models are established to investigate the high-static-low-dynamic stiffness and the dynamic characteristics under QZS condition
The vibration isolation performance of the QZS vibration isolator is discussed under various excitations
Summary
Sci. 2020, 10, 3573 type of nonlinear vibration isolator, the static stiffness is high, but the dynamic stiffness drops to extremely low and can even realize the quasi-zero stiffness (QZS). This means that introducing an NSC will reduce the natural frequency without increasing the static deflection of the original system, which is beneficial to vibration isolation. When the response of the vibration isolation system is small enough, it is reliable to adopt the Taylor series expansion with low order to simplify the stiffness of the system. In order to avoid the above approximation error problem in dynamic analysis of nonlinear vibration isolators, a novel cam-roller type negative stiffness corrector is proposed in this paper.
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