Thermal deformation and residual stress analysis of lightweight piezocomposite curved actuator device

Abstract

LIPCA (LIghtweight Piezo-composite Curved Actuator) is an actuator device which is lighter than other conventional piezoelectric ceramic type actuator. LIPCA is composed of a piezoelectric ceramic layer and fiber reinforced light composite layers, typically a PZT ceramic layer is sandwiched by a top fiber layer with low CTE (Coefficient of thermal expansion) and base layers with high CTE. LIPCA has curved shape like a typical THUNDER (Thin-layer composite unimorph ferroelectric driver and sensor), but it is lighter than THUNDER. Since the curved shape of LIPCA is from the thermal deformation during the manufacturing process of unsymmetrically laminated lay-up structure, and analysis for the thermal deformation and residual stresses induced during the manufacturing process is very important for an optimal design to increase the performance of LIPCA. To investigate the thermal deformation behavior and the induced residual stresses of LIPCA at room temperature, the curvatures of LIPCA were measured and compared with those predicted from the analysis using the classical lamination theory. A methodology is being studied to find an optimal stacking sequence and geometry of LIPCA to have larger specific actuating displacement and higher force. The residual stresses induced during the cooling process of the piezo- composite actuators have been calculated. A lay-up geometry for the PZT ceramic layer to have compression stress in the geometrical principal direction has been designed.