Analysis and design of passive low-pass filter-type vibration isolators considering stiffness and mass limitations

The aim of this paper is to design stiff and lightweight uniaxial passive vibration isolators that have low stop-band frequency. In order to make fair comparisons, stop-band frequencies of various isolator designs are formulated in a general framework. Two new n-degree-of-freedom (n-dof) isolator designs are introduced. The first design has n - 1 anti-resonance frequencies (zeros), which are generated by n - 1 single-degree-of-freedom (sdof) dynamic vibration absorbers (DVAs). It is shown that this system offers lower stop-band frequency than an equivalent mass-spring chain, which just uses resonance frequencies to achieve isolation. The second design is synthesized using n lever-type anti-resonant vibration isolators in series, so it has n zeros. It is shown that this design attains lowest stop-band frequency when all the isolator mass is concentrated on lever tips. Finally, comparative numerical examples are presented. (c) 2005 Elsevier Ltd. All rights reserved.