ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

3aSA3. Active control of structural intensity in an elastic plate.

S. I. Hayek

M.-Y. Nam

Dept. of Eng. Sci. and Mech., Penn State Univ., University Park, PA 16801

S. Sommerfeldt

Penn State Univ, University Park, PA 16801

Active control of structural intensity (SI) in a finite elastic plate coupled to a point damper is achieved through the use of a judiciously located actuator. An algorithm was developed using the magnitude of the structural intensity vector to achieve local or global reduction of SI. The control algorithm showed that controlling each component of the intensity vector (I[sub x] or I[sub y]) generates a parabolic surface, which may or may not intersect the null plane. Under certain conditions based on the locations of the primary mechanical source and the error sensors, as well as the dynamic parameters of the plate, the surface intersects the null plane. If the surface intersects with the null plane, then the intersection generates a circle of possible actuator magnitudes and phases that will make either I[sub x]=0 or I[sub y]=0. If the circles exist for both I[sub x]=0 and I[sub y]=0, then inequalities were derived that will indicate when and if these circles will intersect. The intersection of these circles allows only two possible control solutions that will make the magnitude of the vector SI at the error sensor vanish. When the intersections do not occur, then minimization rather than extinction is achieved. These control strategies are explored and applied to an elastic simply supported plate coupled to a point damper and excited to vibration by a point force. The role of structural damping on control strategies is fully explored.