By Miriam Chillemi
How to increase a mass without using mass!
The most used passive vibration control systems are mass-dependent devices like Tuned Mass Dampers (TMDs) or Tuned Liquid Column Dampers (TLCDs). Increasing their mass would definitely lead to better performance at the expense of practical design issues. One possible way to produce an apparent mass without any physical addition is by means of the so-called inerter. In this study, the dynamic performance of a fluid inerter is analyzed experimentally. In a first step, the dry configuration, i.e. without fluid, is investigated, revealing a nonlinear dissipation force. This force is represented by a variant of the well-known Stribeck effect. Subsequent experiments on the complete configuration, i.e. with fluid, reveal a further nonlinear effect. This effect is attributed to the compressibility of the working fluid as well as air trapped in the system. Once the parameters of the mechanical model are retrieved, comparative studies are carried out. These show a remarkable agreement between numerical and experimental outcomes, proving that it was possible to generate a fictitious mass (inertance) of about 160 kg with only 50 g of working fluid. This underlines the large potential of fluid inerters when applied to vibration control in civil structures.
For more information: doi.org/10.1016/j.ymssp.2022.109986