The optimal placement of piezoelectric ceramics in laminated composite structures

The cure cycle of thermoset composites can cause residual strains in laminated structure. The difference in the mechanical properties of a graphite/epoxy laminate and the piezoceramic can create large stresses in the piezoceramic. Accurate analysis of these stresses is critical. In the area of a laminate more than six ply thicknesses away from the edge, three-dimensional analysis and classical lamination theory provide comparable results. If the thermally induced strains are too great it is possible to modify the laminate's coefficient of thermal expansion by adding plies of a dissimilar material such as fiberglass/epoxy. This modification can relieve much of the thermal stress of the piezoceramic.