ACTIVE PLATE AND MISSILE WING DEVELOPMENT USING DIRECTIONALLY ATTACHED PIEZOELECTRIC ELEMENTS

The properties of directionally attached piezoelectric (DAP) elements and a low aspect ratio DAP torque-plate wing are investigated. Tests show that isotropic piezoceramic elements exhibit orthotropic behavior when directionally attached using any of three methods: 1) partial attachment, 2) transverse shear lag, and 3) differential stiffness bonding. Closed-form expressions of DAP strains based on laminated plate theory are presented. The models demonstrate that DAP elements can generate pure extension, bending, or twist deflections in beams and plates. Activation sequences and balancing strains for DAP and conventionally attached piezoelectric (CAP) elements based on laminated plate theory are presented. Experimental beam specimens were constructed to verify the models. Tests show that 0.030-in. (0.0762-cm) thick aluminum beams with antisymmetrically laminated DAP elements produce twist rates of 0.23 deg/in. (9 deg/m) and bending rates in excess of 0.36 deg/in. (14 deg/m) with theory and experiment in close agreement. A DAP torque-plate was constructed of 8.0-mil-thick piezoceramic elements bonded antisymmetrically on a 5-mil steel substrate. The torque plate was then used to induce pitch deflections in a subsonic missile fin with a NACA 0012 profile and an aspect ratio of 1.4. The wing demonstrated a break frequency in excess of 80 Hz and static pitch deflections of 8.5 deg, showing excellent correlation with theory.