Demonstration of Dynamic Tailoring for Gossamer Structures

A structure for demonstrating dynamic tailoring for gossamer structures is presented. This demonstration structure consists of a torus with stiffening “dimples” and an attached central membrane. As a performance metric for evaluating the tailoring approaches, three reaction mass actuators were used to drive the torus while the velocity of the central membrane was measured with a laser vibrometer. Four types of dynamic tailoring were demonstrated. Inert masses were attached to the torus at the disturbance input locations and random locations to increase the effective impedance of the structure. Lightweight tuned mass dampers were attached to the torus in an attempt to reduce the vibration in a narrowband region. Because the central membrane is only attached to the torus at a discrete number of points and all disturbance energy must pass through these junctions, piezoelectric polymer patches were attached to the membrane at these locations. Passive shunting of these piezoelectric patches with resistors was implemented to show broadband vibration attenuation of the membrane. Finally, along with nearly collocated piezoelectric strain sensors, these piezoelectric patches were used as actuators in an active feedback control system using three controllers of increasing complexity. A fourth controller was implemented using the laser vibrometer measurement of a single spot in the center of the membrane as the feedback sensor. Experimental data is presented for each of these dynamic tailoring approaches.