ACTIVE POWER MINIMIZATION AND POWER ABSORPTION IN A PLATE WITH FORCE AND MOMENT EXCITATION

This paper presents a comparison of the active control strategies of m inimizing the total power supplied to a plate and maximizing the power absorbed by the secondary source. Force and moment excitations of inf inite and finite plates are considered. For an infinite plate analytic solutions can be obtained for the total power supplied ro the plate b y the primary and secondary actuator arrays when using the two control strategies. Minimizing the power supplied by a primary force or momen t with a secondary force or moment can produce large attenuation provi ded that the two sources are close together compared with a flexural w avelength. Minimizing the power supplied by a primary force with a sec ondary moment can also give attenuation of up to 5 dB when the spacing between the sources is about 0.3 times the flexural wavelength. In co ntrast to the acoustic case, for the infinite plate the total power su pplied is generally reduced when the power absorbed by the secondary s ource is maximized. On a finite panel, however, maximizing the power a bsorbed by the secondary source can significantly increase the total p ower supplied. The strategy of minimizing the total power supplied can give considerably larger values of attenuation for finite rather than infinite plates, particularly at higher frequencies. This is because the structural modes can be actively controlled. A particularly effici ent secondary actuator for total power minimisation appears to be an i ndependently adjustable,lt collocated, force and moment pair. (C) 1997 Academic Press Limited.