Influence of State-Switching Rotational Inertia Dampers on the Natural Frequencies and Response of Structures

Rotational inertia dampers have been proposed as passive vibration absorbers. Traditional rotational inertia dampers come in different configurations, but all feature a mechanical device called an inerter. The inerter is a two terminal device that can produce a large effective mass via the transformation of translational motion to the rotation of a flywheel. Despite the effectiveness of rotational inertia dampers at reducing the response of structures, there use has potential drawbacks. The inerter increases the effective mass of a system and, therefore, reduces the natural frequencies of that system; this shift in natural frequency is not always desirable. Furthermore, energy that is transferred to the inerter as rotational kinetic energy is transferred back to the structure when the structure’s motion slows, which can drive the response of the structure. To address these issues, one-way rotational inertia dampers have recently been proposed and investigated. In the one-way rotational damper, energy is transferred to a flywheel as rotational kinetic energy in a manner in which it cannot transfer back to the structure. In addition, the one-way rotational damper is not always engaged with the structure; thus, the effective mass of the system changes during its response. Due to these changes, also known as state-switching, it is not straightforward to evaluate the response of the system or its effective frequency. In this study, the effect of the one-way rotational inertia damper on the frequency and response of the base structure is investigated with numerical analyses.