ASA 126th Meeting Denver 1993 October 4-8

3aSA17. Adaptive control of bending wave intensity in a finite beam.

David C. Swanson Cassandra Gentry Sabih I. Hayek Scott D. Sommerfeldt

Graduate Program in Acoust., Penn State Univ., University Park, PA 16802

Adaptive control of the bending wave field in a finite beam is simulated using a classical Euler--Bernoulli analytical model and a dual-actuator filtered-x feedforward controller. Three different intensity-based error signal strategies are compared for multiple locations on the beam in and out of the near field of the actuators. The goal is to actively minimize the propagating bending wave power where the five-element error sensor array may be located in the near field of the actuators. Since the error array must be effective in the near field, the idea of simultaneously minimizing all five accelerometer signals was rejected. Reults from using an instantaneous intensity error estimate were ineffective due to the nonlinearity in the adaptive control error gradient. Results from minimizing the intensity (rather than intensity-squared) were acceptable and consistent with the experimental results of Sommerfeldt [Sommerfeldt et al., J. Acoust. Soc. Am. 93, 2370 (A) (1993)]. A new error method based on an intensity transfer function plant also produced acceptable simulation results. [Work supported by the GEM Fellowship Program.]