Bending behaviors of both a piezoelectric curved bi-morph actuator and a functional gradient piezoelectric curved actuator are studied and compared. The exact solutions of both mechanical and electrical fields of the actuators are obtained based fully on the theory of elasticity. It is found that non-zero normal stresses exist in the gradient piezoelectric curved actuator when the actuator is subjected to an external voltage, which is different from the results obtained in our previous works on the gradient piezoelectric flat actuator. It is also proved that the internal stresses are drastically reduced although the deflection of the gradient curved actuator is quite small. The present analytical solutions are compared with the FEM results and a good agreement is found. (Some figures in this article are in colour only in the electronic version)

The bond decay at the bar–concrete interface under variable fatigue loads is investigated in this paper. Two kinds of loading paths are considered: low- and high-amplitude cycles. Based on the shear-lag model, the governing equations of the problem are established and solved with reference to three different interfacial degradation models. By the aid of Paris formula, the interfacial debonding rate, the debonded length, and the pull-out force are studied. The effect of the amplitude of the middle applied load and of several material parameters on bond decay is discussed. It is found that the power-degradation model is suitable for short embedment lengths, while both the linear-degradation model and the modified power-degradation model are advantageous in study of bond in long embedment length. It is also found that interfacial friction plays an important role in resisting interfacial debonding, in spite of the effects of Poisson's contraction.

Both multi-layer piezoelectric cantilevers and multi-layer piezoelectric composite cantilevers are studied based on 2D linear theory of elasticity and piezoelectricity. Both the piezoelectric coefficient and the thickness for different layers are taken as variables. As opposed to traditional investigations based on the elementary theory of elasticity, the present investigation gives exact solutions for the variation of these parameters by introducing several recurrence formulae. The solutions obtained in the present paper are compared with numerical results and the results obtained by other investigators; good agreement is found. (Some figures in this article are in colour only in the electronic version)

Two different kinds of heterogeneous elastic hollow cylinders are studied herein. One is a cylinder with multi-layers and another is a cylinder with continuously graded properties. A simple and convenient method is obtained to find the exact solutions of a N-layered elastic hollow cylinder submitted to uniform pressures on the inner and outer surfaces. For the hollow cylinder with continuously graded properties, the displacement method is used. A hyper-geometric equation is derived and solved, and then the exact solutions are found. The results obtained in the present paper are compared with both the numerical solutions and other findings provided by some references and good agreements are found. At the end of the present paper, some inherent properties of these two different kinds of heterogeneous graded hollow cylinders are presented and discussed.

Based on the general theory of elasticity, the static behavior of 2-2 multi-layered piezoelectric curved composites is investigated. The exact solutions of the mechanical and electrical fields of the curved composites are obtained by utilizing Airy stress function method. Both the piezoelectric coefficient and the thickness for different layers are taken as variables. Different from other investigations based on the elementary theory of elasticity, the present investigation gives exact solutions for these variables by introducing several recurrence formulas, which make the present results very useful. The theoretical results obtained in the present paper are compared with the numerical results and good agreements are found.