STATIC, FREE-VIBRATION AND THERMAL-ANALYSIS OF COMPOSITE PLATES AND SHELLS USING A FLAT TRIANGULAR SHELL ELEMENT

Finite element static, free vibration and thermal analysis of thin lam inated plates and shells using a three noded triangular flat shell ele ment is presented. The flat shell element is a combination of the Disc rete Kirchhoff Theory (DKT) plate bending element and a membrane eleme nt derived from the Linear Strain Triangular (LST) element with a tota l of 18 degrees of freedom (3 translations and 3 rotations per node). Explicit formulations are used for the membrane, bending and membrane- bending coupling stiffness matrices and the thermal load vector. Due t o a strong analogy between the induced strain caused by the thermal fi eld and the strain induced in a structure due to an electric field the present formulation is readily applicable for the analysis of structu res excited by surface bonded or embedded piezoelectric actuators. The results are presented for (i) static analysis of(a) simply supported square plates under doubly sinusoidal load and uniformly distributed l oad (b) simply supported spherical shells under a uniformly distribute d load, (ii) free vibration analysis of (a) square cantilever plates, (b) skew cantilever plates and (c) simply supported spherical shells; (iii) Thermal deformation analysis of (a) simply supported square plat es, (b) simply supported-clamped square plate and (c) simply supported spherical shells. A numerical example is also presented demonstrating the application of the present formulation to analyse a symmetrically laminated graphite/epoxy laminate excited by a layer of piezoelectric polyvinylidene flouride (PVDF). The results presented are in good agr eement with those available in the literature.