Geometrically nonlinear analysis of sandwich FGM and laminated composite degenerated shells using the isogeometric finite strip method

Abstract

Isogeometric analysis (IGA) has become a strong tool for analysis of shell structures, which can be considered as a powerful alternative to the standard finite element method (FEM). Besides several advantages of IGA over FEM in geometric nonlinear analysis of the shells, it has some drawbacks corresponding to tensor-product of B-spline and NURBS surfaces. One of the solutions to eliminate or at least reduce the effects of the mentioned shortcomings is to combine IGA with the other methods, such as FEM. In the present paper, a novel version of the finite strip method (FSM) is developed to carry out the geometric nonlinear analysis, which employs a combination of FEM and IGA in the transversal and longitudinal directions, respectively and is named isogeometric B-spline finite strip method (IG-SFSM). The strip elements have been formulated based on the Degenerated-Shell method for Updated-Lagrangian (UL) approach. Then, it is examined by some examples incorporating various geometries, boundary conditions (BCs), and material properties, such as laminated composites and sandwich FGMs. The results exhibited that, to achieve the complicated nonlinear equilibrium paths of the shells, IG-SFSM requires a lower number of degrees of freedom (DOFs) and, consequently, computational efforts comparing to the other common methods, such as finite element and mesh-free methods.