Showing papers by "M. Ganapathi published in 2016"

Environmental effects on the free vibration of curvilinear fibre composite laminates with cutouts

Abstract: In this paper, we study the free vibration characteristics of curvilinear fibre composite laminates exposed to hygrothermal environment. The formulation is based on the transverse shear deformation theory and it accounts for the lamina material properties at elevated moisture concentrations and thermal gradients. A 4-noded shear flexible quadrilateral plate element based on extended finite element approach is employed for the spatial discretization. The effect of a centrally located cut-out, modelled within the framework of the extended finite element method, is also studied. A detailed parametric investigation by varying the curvilinear fibre angles at the centre and at the edge of the laminate, the plate geometry, the geometry of the cut-out, the moisture concentration, the thermal gradient and the boundary conditions on the vibration characteristics is numerically studied and it is hoped that this detailed study will help the designers in optimizing such structures under dynamic situation.

Dynamic snap-through buckling of CNT reinforced composite sandwich spherical caps

Abstract: This paper investigates the nonlinear dynamic buckling response of axisymmetric carbon nanotubes reinforced composite sandwich spherical caps subjected to suddenly applied pressure. To solve this problem, a finite element approach is adopted using an axisymmetric shear flexible shell element, free from spurious constraints causing shear and membrane locking especially for the case of thin shells. The geometric nonlinearity is accounted for in the formulation using von Karman’s strain-displacement relations. Newmark’s integration technique along with the modified Newton-Raphson iteration scheme is employed to solve the nonlinear governing equations. The critical dynamic pressure value is considered as the pressure load beyond which the maximum average displacement response shows instant growth in the time history of the shell structure. The obtained results are validated against the available analytical solutions for the case of isotropic spherical caps. A detailed parametric study is carried out to bring out the effects of shell geometry parameter, volume fraction of the CNT, core-to-face sheet thickness, temperature, boundary conditions and different types of pulse on the dynamic snap-through characteristics of spherical shells.