Passive vibration control via unusual geometries: Experiments on model aerospace structures

In a previous paper [1], one of the present authors described a method whereby passive vibration isolation could be designed into a lightweight aerospace structure by the adoption of unusual geometric configurations. This was achieved by the use of Genetic Algorithm methods to optimize the isolation characteristics of the structure. The current brief paper follows on from that work and describes an experimental investigation into the performance of the structures designed in the earlier study. It is shown that, although the detailed behaviour of the experimental models is somewhat different from that predicted theoretically, the same broadband vibration isolation characteristics shown by the theory exist in practice. It is seen to be possible to achieve an average of 50 dB isolation in the vibrational energy transfer between the ends of a network of beams over a 100 Hz bandwidth in an essentially undamped structure. These experimental results are sufficiently encouraging that work is now underway to apply Genetic Algorithm based design methods to more complex structural vibration problems.