Static and free vibration analyses of stiffened folded plates using a cell-based smoothed discrete shear gap method (CS-FEM-DSG3)

Recently, a cell-based smoothed discrete shear gap method (CS-FEM-DSG3) based on the first-order shear deformation theory (FSDT) was proposed for static and free vibration analyses of Mindlin plates. The CS-FEM-DSG3 uses three-node triangular elements that can be easily generated automatically for arbitrary complicated geometric domains. In this paper, the CS-FEM-DSG3 is further extended for static and free vibration analyses of stiffened folded plates, by combining the original CS-FEM-DSG3 with an Allman's plane stress triangular element and with a stiffener modeled by Timoshenko beam element. The model of a stiffened folded plate is formed by (1) regarding the plate and the stiffener separately in which the stiffeners can be placed anywhere on the plate and need not be placed along the mesh lines, (2) imposing displacement compatible conditions between the plate and the stiffener so that displacement fields of the stiffener can be expressed in terms of the mid-surface displacement of the plate, (3) superimposing the strain energy of plate and stiffener, and (4) using a transformation of degrees of freedom from a local system to a global system. The accuracy and reliability of the proposed method are verified by comparing its numerical solutions with those of other available numerical methods.