In many engineering applications, such as civil, mechanical and aerospace, large displacements and rotations may occur within the working composite structures, due to the extreme loading conditions that may occur during service. This afflicts the equilibrium states of the structures and could change them, eventually, in a catastrophic manner. Therefore, it may be necessary to predict the nonlinear stress conditions of the laminated structures through numerical simulation, in order to prevent the failure of the entire system.
To take into account these conditions, a geometrical nonlinear analysis has to be performed. The nonlinear framework proposed in this work is based on the Carrera Unified Formulation (CUF). CUF is a hierarchical formulation that considers the order of the structural model as an input of the analysis, so that no specific formulations are needed to obtain any refined model. The possibility to generate high-order structural elements makes possible to analyze any loading cases, including the post-buckling situation. Furthermore, this methodology allows to evaulate of the full three-dimensional stress tensor in laminated structures. In fact, as CUF is able to calculate the stiffness matrix in an automatic manner, there is no need to include any simplification to evaluate the out-of-plane components of the stress tensor.