AN EXPERIMENTAL INVESTIGATION INTO THE SEMIACTIVE AND ACTIVE CONTROL OF LONGITUDINAL VIBRATIONS IN A LARGE TIE-ROD STRUCTURE

An experimental study into the use of one semi-active and two active c ontrol devices employed to attenuate the transmission of longitudinal vibrations on a large tie-rod structure is described. A tie-rod struct ure similar to that found in marine machinery installations was assemb led in the laboratory. This type of structure was chosen because it is difficult to apply standard passive techniques due to the static stif fness requirement. A tunable pneumatic vibration absorber was used as the semi-active device, and an inertial electrodynamic exciter and a m agnetostrictive actuator were used as the active devices. The way in w hich these devices couple into and modify the dynamic behaviour of the tie-rod structure is discussed, and experimental results are presente d showing the effectiveness of the control measures in attenuating lon gitudinal vibrations. Significant reductions in transmitted vibrations were achieved by all the devices and the merits of each method are di scussed.