Active control of structural intensity in an elastic plate with a point damper

A structural intensity (SI) control algorithm was developed in order to minimize the SI at an error sensor in a damped, simply supported plate with an attached point damper. The objective was to prevent energy absorption at the point damper where the point damper represents an undesired structure-borne path that may exist in a practical control of power flow between connected structures.;Since the SI is a vector field, it was found that the magnitude of SI at the error sensor should be taken as the cost function, rather than its vector components. Minimizing the magnitude of SI results in the optimal control force. The optimal control force was evaluated through the use of a non-linear gradient search algorithm. Using the computed optimal control force, the intensity and displacement reduction at the damper were examined. The total input power injected into the plate by the primary force and the actuator was also calculated to evaluate the effectiveness of the SI control algorithm in minimizing the global energy.;Parametric studies were made to investigate the effect of actuator and error sensor locations on the optimal control force, near-field vs. far-field control, the influence of structural damping and the damping coefficient of the point damper, and on-resonance vs. off-resonance control of SI. When the actuator is located in the near-field of the primary source, the SI was controlled by attenuating the modal amplitudes of the uncontrolled modes for the required minimization, regardless of excitation frequency, i.e. it is a global control. Furthermore, the optimal control force minimizes the SI over the entire plate at resonance frequencies. If the actuator and the error sensor are in the far-field of the primary source, the SI control only minimizes SI near the damper, resulting primarily in a local control effect. As the structural damping or the point damper's coefficient increases, the total input power decreases. As a result, the SI control is more effective in a heavily damped structure. It is also established that SI control is more effective than displacement control in minimizing the SI at the damper.