Laminated composite materials have been increasingly employed in the engineering industries, due to their high stiffness-to-weight ratio, high strength-to-weight ratio, high corrosion resistance, and high chemical stability. These materials have become prevalent in the aircraft manufacturing, vehicle industries, medical fields, and even sport equipment industries. However, there exist undesirable large interlaminar peeling stresses due to the mismatch of elastic properties between the adjacent layers. Because of these highly concentrated peeling stresses, failures such as delamination or crack may occur near the free edges, and that further lead to the damage of structures. The concentrated free edge peeling stresses are critical issue in the design of laminated composite structures.
In this study, piezoelectric actuator was used to reduce free edge peeling stresses of laminated composite structure. Owing to their electromechanical coupling nature, piezoelectric actuators have potential to generate stress which has opposite sign of those peeling stress generated by mechanical bending load. A stress function based approach was proposed to analyze the reduction of free edge peeling stress using piezoelectric actuators. Governing equations are obtained using the principle of stationary complementary virtual work. Generalized plain strain was assumed and Lekhnitskii stress functions were introduced to satisfy pointwise equilibrium equations automatically. These stress functions can be divided into the in-plane and out-of-plane functions. The thickness of the composite layer and the piezoelectric actuator is assumed to be the same for convenience. The proposed method was verified using the finite element method. The peeling stress show positive magnitude near the free-edge and decrease in interior in the smart composite laminate. This peeling stress generated by mechanical bending load were reduced by applying an electric field. The present method could serve as an efficient tool for reducing the free edge peeling stresses and extending the service life of smart composite laminate.