Improved inerter-based vibration absorbers

This paper presents improved inerter-based absorbers for vibration mitigation of structural systems. The driving innovative concept is to include a standard inerter-based device within a rhombus truss; specifically, the inerter-based device is connected to the two ends of one diagonal of the rhombus truss and activated by the motion of the structural system along the other diagonal. It is shown that, in this manner, a significant amplification of the inertance can be attained, depending on the diagonal ratio of the rhombus truss. The concept is presented for three typical inerter-based absorbers existing in the literature. The performances of the improved inerter-based devices are investigated and compared thoroughly, as applied to single-degree-of-freedom systems. The optimal tuning is implemented following a well-established procedure, entirely analytical, which makes the design of the improved inerter-based devices very straightforward. A further novelty, particularly appealing for design purposes, is that the improved inerter-based absorbers can be re-tuned over a certain frequency range by changing only the geometry of the rhombus truss, with considerable benefits in those cases where the structural system parameters may vary during the operational lifetime. For completeness, an application to a multi-degree-of-freedom system substantiates the effectiveness of the proposed concept.