a b s t r a c tIn this study, a new theory for the accurate simulation of the shear-mode behaviour of thin or thick piezoelectric sandwich composite beams is developed. The effects of transverse normal stress and transverse flexibility of layers are considered in the development of the proposed formulation. In order to increase the computational accuracy, all kinematic and stress continuity conditions are satisfied at layer interfaces. Moreover, for the first time, both the electrically induced strain components and the transverse flexibility are taken into account in the proposed formulation. Despite the fact that the number of unknown mechanical parameters in this theory is only one degree higher than the first order shear deformation theory, the accuracy is surprisingly more pronounced for the thicker beams. (S.B. Beheshti-Aval).[10], Kogl and Bucalem [11,12] Chee et al. [13], Jiang and Li[14], Shu [15], Thornburgh and Chattopadhyay [16], Fukunaga et al. [17] and Mitchell and Reddy [18]used equivalent single layer theories (ESLT) for the analysis of extension-mode piezoelectric beams/plates structures. The idea of layer-wise theory (LWT) or discrete-layer theory was presented and developed by Heyliger and Saravanos [19], Saravanos and Heyliger [20], Saravanos et al.[21], Kusculuoglu et al. [22], Garcia Lage et al. [23,24] Robaldo et al. [25], and Tzou and Ye [26]. Beheshti-Aval and Lezgy-Nazargah[27,28] used a sinus zigzag (ZZ) model for analyzing and controlling of smart laminated piezoelectric beams. Kapuria [29], Kapuria et al. [30], and Kapuria and Alam [31] presented an efficient coupled ZZ theory for static and dynamic analysis of extension-mode piezoelectric laminated/sandwich beams based on third order ZZ approximations. introduced a computationally low cost FE model for the static analysis of extension-mode piezoelectric multilayered/sandwich beams based on global-local theory. For an overview on the modeling of extension-mode piezoelectric laminates, readers can refer to Benjeddou [33].The use of a shear-mode piezoelectric actuator was first proposed by Sun and Zhang [34]. In their work, they employed thickness-shear piezoelectric patches to create transverse deflection in sandwich beams. Moreover, they demonstrated that shear-mode actuators can offer many advantages over the extension-mode actuators. The analysis of this study was carried out using the ANSYS finite-element package. Furthermore, Zhang and Sun [35] developed an analytical model to predict the static, as well as the dynamic behavior of a sandwich beam which comprises of a core layer of shear-mode piezoelectric. The model relies on the assumptions that the face layers obey the Euler-Bernoulli theory, while the core piezoelectric layer follows the Timoshenko theory. Moreover, closed-form solutions of a static cantilever beam with shear-mode actuators were presented. Benjeddou et al. [36] proposed a finite element model of a sandwich beam with extension and shear piezoelectric segments. To verify their model, they compared their finite e...

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The horizontal kinetic energy of the fluid flow, from on-land wind to ocean tidal stream, is one of the most promising sources of the energy. In the field of renewable energies, power extraction from Flow Induced Vibration (FIV) of bluff bodies is a fast growing research area which has seen a great advancement over the last decade. In this study, the FIV energy harvesting potential of a sharp edge square cylinder in two different flow incidences is investigated. The square cylinder, depending on its orientation with respect to the incident flow, demonstrates VIV or galloping types of responses. The results indicate that the square cylinder with a flat side perpendicular to the flow has a galloping type of response. In contrast, the same cylinder with a sharp vertex pointing the flow (diamond configuration) shows a VIV type of response. The hydroelastic efficiency of the resonating square cylinder is significantly higher than that with the galloping type of response. This shows the great advantages of diamond VIV excavators over square galloping harvesters.

The relative incompetency of rectangular galloping excavators against conventional circular VIV harvesters is already known. In this experimental study, the hydroelastic energy performances of new right-angle isosceles triangular cylinder against circular, square and diamond cross-sections are investigated. The triangular cylinder displays VIV or galloping type of response in four different symmetrical and unsymmetrical configurations tested. The results show the distinct higher overall galloping energy performance of the triangular cylinder in Config. 2 among other VIV and galloping harvesters. The Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) is employed to order the remaining tested cross-sections using the averaged and maximum values of the mechanical power and efficiency as criteria. The TOPSIS algorithm shows that the VIV diamond and circular harvesters stay at the second and third places of the energy performance, respectively. The preference value of the diamond and circular cross-sections are almost comparable but are less than half of that in Config. 2. In general, the sharp-edge cylinders display superior energy performance over circular cross-section. However, the axisymmetric circular cylinders, because of their omnidirectional performances, are more efficient in places with the varying flow direction.