The Study Of Dynamic Property Analysis Of The Vibration Isolation System With Inerter

Invention of the inerter and design of the ISD vibration isolation system make it possible for the further development of mechanical vibration system. This paper analyzes mechanical dynamic characteristics of single-stage, two-stage and multi-stage vibration isolation system and studies the influence of inerter on natural frequency and transmissibility of these systems. And a kind of ball-screw inerter is designed for the basis of single-stage vibration isolation system, while damping property of the system has been developed with relevant experiment. Research above provides a theoretical basis and experimental reference for inerter devices used in complex vibration system. Contents and innovations are as follows:Firstly, this paper elaborates technology development of vibration isolation, research background and significance of inerter on the basis of domestic and foreign research literatures, and makes a summary of research methods, present situation and development of vibration isolation system. According to electro-mechanical analogy with inerter,concept of the inerter and its mechanical impedance are introduced and kinds of inerter device model are studied, such as the design of the inerter with leverage formula, which provide a theoretical foundation for the following research.Secondly, application of inerter in single-stage vibration isolation system has been explored in this article. By designing two kinds of ISD vibration isolation system, some useful analytical formulas are derived to investigate the dynamic influence of inerter on vibration isolation system. Yet there are specific damping effects of application of inerter by experimental verification. Test results show that the natural frequency of the vibration system moves to a lower frequency and its vibration amplitude at the natural frequency also decreases. As expected, the damping effect of ISD vibration system is better than spring-damping vibration system in low frequency. However, the damping effect increases with the decrease of the inertance when transmissibility of the ISD vibration isolation system tends to become a fixed value. Transmissibility of the ISD vibration isolation system falls in between spring-damping vibration system and isolation system of an inerter and a spring in parallel.At last, based on a single-staged vibration isolation system with inerter, the dynamic properties of double-staged and multi-staged vibration isolation system are analyzed bycalculation example. Meanwhile, transmissibility formula of two-stage vibration isolation system is brought forward. Test results show that the installation of inter device either in upper layer or lower layer reduces the natural frequency, especially high order natural frequencies. When inerter device is installed in upper layer, it has greater influence on vibration isolation system and decreases the space between two adjacent natural frequencies. When inerter device is installed in lower layer, it could be considered to increase intermediate mass which would improve vibration isolation performance of two-stage vibration isolation system. In other words, inerter device installed in lower layer could maintain the vibration isolation performance of multi-stage vibration isolation system with less intermediate mass. However, the ungrounded inerter will decrease the high-frequency attention.Study in this dissertation has contributed to the understanding of vibration isolation system with inerter, revealing the function of inerter in single-staged, double-staged and multi-staged isolation systems and providing a theoretical basis and experimental reference for inerter devices used in the complex vibration system. In practical application, inerter devices installed in upper layer decrease the natural frequency in vertical direction, as well as the space between two adjacent natural frequencies, which contribute to avoid perturbation frequency. However, the damping effect increases with the decrease of the inertance when transmissibility of the ISD vibration isolation system tends to become a fixed value. Since inerter device installed in lower layer could be considered increasing intermediate mass which would improve vibration isolation performance of vibration isolation system, it solves the quality controlling problem. Research results in this paper would be conducive to the application of inerter on vibration isolation both in ships and warships.