Air mounts can provide the highest degree of isolation of any type vibration isolator. Soft-mounting, and thus high level of low-frequency isolation, with system natural frequency as low as 1 Hz can be achieved. Due to their construction, air mounts have negligible damping. Although, this almost undamped nature of air mounts enhances the high-frequency isolation, provisions should be made to address the lack of isolation resulting in excessive body displacements around the resonant frequencies, especially when the system is exposed to shock inputs. While the addition of viscous damping to the air mount is proposed in the literature but it is not recommended in most applications. This is because it deteriorates the mount’s high-frequency isolation performance. Instead, it would be highly desirable to add tuned damping to the mounted system at its resonant frequency (ies). The challenge in doing so, is realizing a damper tunable to a very low frequency and yet not be prohibitively large. A novel tuned damping mechanism is proposed in this paper. It adds damping to an air mount only at the resonant frequency (ies), via a bi-fluid Helmholtz resonator. In an illustrative example the mechanics and mathematics (modeling) of a one and three degree of freedom air mounted systems equipped with a tuned damper, as well as the tuning of such damper are discussed. The example also demonstrates the effectiveness of the air mount with the tuned damper.
Super harmonic nonlinear lateral vibrations of a segmented driveline incorporating a tuned damper excited by non-constant velocity joints