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

3pSA2. Broadband control of multi-mode power flow in beams using wave vector sensors.

G. P. Gibbs

M. Bronzel

C. R. Fuller

J. D. Blotter

D. E. Montgomery

R. L. West

Dept. of Mech. Eng., Virginia Polytechnic Inst. and State Univ., Blacksburg, VA 24061-0238

Recent work has demonstrated the use of wave filtering techniques to estimate traveling waves in the time domain. These techniques use PVDF surface mounted sensors in conjunction with a digital filter network to estimate the traveling flexural and extensional waves in beams for band-limited spectra. The traveling wave estimates are proportional to the power flow in the beam, and thus can be used as the cost function of an active control system. In this paper, experimental results are presented which demonstrate the broad band active control of flexural and extensional power flow in beams using surface mounted piezoceramic control actuators, surface mounted PVDF wave vector filters, and a TMS320C30 based adaptive controller. The results demonstrate flexural and extensional power flow attenuations of 5 to 20 dB for band-limited excitation. Independent verification of the total beam response before and after control (three dimensional) is found via a technique called experimental spatial dynamics modeling (ESDM). Velocity measurements from a scanning laser vibrometer are processed using the ESDM technique to produce a full 3-D velocity response field. These data can be further reduced using a method termed experimental spatial structural intensity (ESSI) to determine the complex intensity over the beam. Contour plots are presented showing flexural and extensional power flow in the beam for both uncontrolled and controlled cases. [Work supported by NASA Langley Research Center.]