Nonlinear Dynamics - Quasi-zero-stiffness (QZS) vibration isolator seeks better isolation performance by lowering the natural frequency while maintaining the same static load bearing capacity as... 相似文献
A newly-developed numerical algorithm, which is called the new Generalized-α (G-α) method, is presented for solving structural dynamics problems with nonlinear stiffness. The traditional G-α method has undesired overshoot properties as for a class of α-method. In the present work, seven independent parameters are introduced into the single-step three-stage algorithmic formulations and the nonlinear internal force at every time interval is approximated by means of the generalized trapezoidal rule, and then the algorithm is implemented based on the finite difference theory. An analysis on the stability, accuracy, energy and overshoot properties of the proposed scheme is performed in the nonlinear regime. The values or the ranges of values of the seven independent parameters are determined in the analysis process. The computational results obtained by the new algorithm show that the displacement accuracy is of order two, and the acceleration can also be improved to a second order accuracy by a suitable choice of parameters. Obviously, the present algorithm is zero-stable, and the energy conservation or energy decay can be realized in the high-frequency range, which can be regarded as stable in an energy sense. The algorithmic overshoot can be completely avoided by using the new algorithm without any constraints with respect to the damping force and initial conditions.The English text was polished by Keren Wang. 相似文献
Nonlinear Dynamics - This paper deals with periodic motions and their stability of a flexible connected two-body system with respect to its center of mass in a central Newtonian gravitational field... 相似文献
Nonlinear Dynamics - A typical quasi-zero stiffness (QZS) vibration isolator composed of two lateral springs and a vertical spring has been widely studied previously, aiming to widen the frequency... 相似文献
An eight-legged vibration isolation platform (ELVIP) with dual-pyramid-shape (DPS) struts is proposed in this paper to achieve six-degree-of-freedom vibration isolation. The DPS strut has higher static stiffness and lower dynamic stiffness than the equivalent linear strut due to geometric nonlinearity, and therefore the ELVIP with DPS struts possesses high-static–low-dynamic-stiffness characteristic which is desirable for widening the frequency range of isolation. The layout of the ELVIP legs is conducive to vibration decoupling and has higher reliability than six-legged platforms. Firstly, the stiffness characteristics of the DPS strut are derived; then the dynamic model of the ELVIP with DPS struts is established and the steady-state responses are obtained analytically; finally, the isolation performance is studied and the effects of damping and excitation amplitudes are investigated. It is shown that the ELVIP with DPS struts, as a passive approach, can achieve good isolation performance in all six directions with a small static deflection.