Realization of three-port spring networks with inerter for effective mechanical control

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Minimal realizations of three-port resistive networks

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Investigation on semi-active control of vehicle suspension using adaptive inerter

The analysis of passive control with inerter in suspension system has been well studied in previous work by employing different configurations and optimizing the spring stiffness, damping coefficient and inertance simultaneously. In this paper, we study the suspension performance with semi-active control under the assumption that the inertance may be adjusted in real-time. The suspension system is designed to attenuate the vertical acceleration of the sprung mass. A quarter-car model is considered, and the inerter is installed parallel to the spring and damper. First, an analysis is provided on the influence of a fixed inerter to a given suspension system. Then, a state-feedback H2 controller for active suspension system is designed. The active force is approximated by an inerter with adaptive inertance. Simulation results show that comparing with the passive suspension with a fixed inerter, the designedH2 controller realized by adaptive inerter can achieve good improvement of ride comfort at the sprung mass natural frequency at the expense of a relatively small deterioration at the unsprung mass natural frequency. Copyright © (2014) by the International Institute of Acoustics & Vibration All rights reserved.postprin

KDamping: A Stiffness Based Vibration Absorption Concept

© 2016, © The Author(s) 2016. The KDamper is a novel passive vibration isolation and damping concept, based essentially on the optimal combination of appropriate stiffness elements, which include a negative stiffness element. The KDamper concept does not require any reduction in the overall structural stiffness, thus overcoming the corresponding inherent disadvantage of the “Quazi Zero Stiffness” (QZS) isolators, which require a drastic reduction of the structure load bearing capacity. Compared to the traditional Tuned Mass damper (TMD), the KDamper can achieve better isolation characteristics, without the need of additional heavy masses, as in the case of the T Tuned Mass damper. Contrary to the TMD and its variants, the KDamper substitutes the necessary high inertial forces of the added mass by the stiffness force of the negative stiffness element. Among others, this can provide comparative advantages in the very low frequency range. The paper proceeds to a systematic analytical approach for the optimal design and selection of the parameters of the KDamper, following exactly the classical approach used for the design of the Tuned Mass damper. It is thus theoretically proven that the KDamper can inherently offer far better isolation and damping properties than the Tuned Mass damper. Moreover, since the isolation and damping properties of the KDamper essentially result from the stiffness elements of the system, further technological advantages can emerge, in terms of weight, complexity and reliability. A simple vertical vibration isolation example is provided, implemented by a set of optimally combined conventional linear springs. The system is designed so that the system presents an adequate static load bearing capacity, whereas the Transfer Function of the system is below unity in the entire frequency range. Further insight is provided to the physical behavior of the system, indicating a proper phase difference between the positive and the negative stiffness elastic forces. This fact ensures that an adequate level of elastic forces exists throughout the entire frequency range, able to counteract the inertial and the external excitation forces, whereas the damping forces and the inertia forces of the additional mass remain minimal in the entire frequency range, including the natural frequencies. It should be mentioned that the approach presented does not simply refer to discrete vibration absorption device, but it consists a general vibration absorption concept, applicable also for the design of advanced materials or complex structures. Such a concept thus presents the potential for numerous implementations in a large variety of technological applications, whereas further potential may emerge in a multi-physics environment.status: publishe