ANALYTICAL STUDY OF SHEAR ACTUATION MECHANISM IN A SAND-WICH BEAM

Abstract

For more than ten years, intelligent systems and structures have created great interest in the research community because of their enormous possibility in vibration and acoustic control, shape control, and health monitoring. A smart structure involves distributed actuators and sensors and one or more microprocessors analyze the responses from the sensors and use distributed-parameter control theory to command the actuator to apply localized strains to minimize system response. The extension actuation achieved by applying voltage in same direction as they have poled, producing axial stresses or strains, whereas shear actuation is obtained by applying voltage in thickness direction of longitudinally poled actuators producing shear stresses or strains. In the present work, a finite element formulation is presented to model the static response of sandwich beam containing induced strain actuators subjected to only electrical loading. The actuation performance of smart beams with extension and shear mode segments is studied and both mechanisms are compared. Beam is modeled with 3-D solid structural and coupled field elements of ANSYS 5.4 finite element code. Static deflection characteristic of both mechanisms is compared for various parameters (structure/actuator stiffness ratio, thickness of actuator, actuator position and length). The obtained results are _valided by comparison with existing results documented in the literature. Results show that the shear actuation mechanism presents several promising feature over the conventional extension actuation mechanism.