Number vs size of electro-mechanical tuneable vibration absorbers for aeronautical applications: a case study

This paper presents a case study on the tuning and flexural vibration control effects generated either by many-small-scale or few-large-scale electromagnetic tuneable vibration absorbers on a model section of an aircraft fuselage structure. The absorbers are formed by a coil-magnet seismic transducer connected to a tuneable resistive-inductive shunt. The control of both tonal and broad-band disturbances is investigated with reference to the number, and thus the size, of the units. The principal aim of the paper is to address the key question on whether, for a fixed total weight of the absorbers, it would be preferable to have a small number of comparatively larger and heavier units or a greater number of comparatively smaller and lighter units. To this end, the first part of the paper presents a comprehensive scaling analysis based on fundamental principles of the physical properties and tuning laws of the electromagnetic tuneable vibration absorbers. Then, the second part of the paper presents a simulation study on the optimal-tuning and the vibration control effects of setups with 4, 8, 16, 32 electromagnetic tuneable vibration absorbers whose total weight is kept equal to 6% of the weight of a model fuselage structure. The study shows that arrangements with many small-scale units produce larger vibration control effects than setups formed by comparatively fewer, larger scale, units. However, the operation frequency range of the EM-TVAs tends to shift to higher frequencies with downsizing. Moreover, the size of the optimal shunt inductance that would guarantee the tuning of the EM-TVAs tends to grow as the unit is downscaled such that an artificially large inductor may be required.