ON THE FEASIBILITY OF USING THERMAL-GRADIENTS FOR ACTIVE CONTROL OF INTERLAMINAR STRESSES IN LAMINATED COMPOSITES

In this paper, a method is proposed to actively control interlaminar s tresses near the free edges of laminated composites by through-thickne ss thermal gradients. Theoretical solutions are given for optimal stea dy-state through-thickness temperature distributions under uniaxial lo ading that are required to elmininate or reduce the interlaminar stres ses below a prescribed level. The optimal solutions are obtained by mi nimizing appropriate performance indices that are functions of the far -field properties, with respect to the through-thickness temperature d ifferences. In the second part, an experimental investigation is condu cted on a glass/epoxy cross-ply laminate with embedded piezoelectric s ensors and a thermal heater. Through the experiment, the feasiblity of the thermal control of interlaminar stresses is demonstrated.