Modeling and parametric analysis of multilayer piezocomposite actuators

Design space for morphing structures using single layer commercial piezocomposite actuators are often restricted due to limitations in actuation authority. Optimal designs are those in which the substrate-actuator composite is stiff enough to maintain shape when subjected to surface pressures but allow for the desired curvature under excitation. This trade-off limits substrate to actuator thickness ratios in applications where dynamic pressures are high. One way to improve actuation authority while maintaining stiffness is to use multiple piezocomposite actuators. This paper explores the benefits and drawbacks of using multilayer piezocomposite actuators. The actuators are modeled using the finite element method and are characterized using well-known free strain and blocked force conditions in a four-point loading condition. Material properties for substrate, piezocomposite, and glue layers are modeled based on previous experimental analysis of curvature over a range of thickness ratios for single element actuators. A parametric analysis is conducted on multilayer piezocomposites varying thickness ratio, substrate material and number of piezocomposite layers. Results for the parametric analysis are presented in the form of maximum curvature, work done, and work done normalized by number of layers. A discussion of new design space potential for multilayer actuators is provided.