Evaluation of stiffeners effects on buckling and post-buckling of laminated panels

In aerospace applications, panel structures are bounded by stiffeners that enforce the loaded edge a constant load or displacement. Depending on the type of these attachments and stiffeners, the real boundary condition could be a combination of loads or displacements. Therefore, the accurate assessment of the effects of these boundary conditions on the mechanical behavior of the plate structures is vital for designers and engineers. In this research, those effects are investigated. Stiffeners with various material properties are modeled, and the post-buckling behaviors of pamel structures are evaluated. The Carrera unified Formulation is recalled and, according to it, the structural theory approximation order and the strain-displacement assumptions, opportunely. Thus, in this paper different nonlinear strain assumptions are considered in the CUF with the total Lagrangian framework. In this regard, the Newton-Raphson linearization scheme is employed with the path-following method based on the arc-length constraint. Several numerical assessments of post-buckling in composite plates are conducted. The von Kármán theory and some modified strain-displacement relationships with various nonlinear terms are compared with the full Green-Lagrange nonlinear model based on the CUF plate model. A number of interesting conclusions regarding the efficiency of the presented model are highlighted. The findings of this research also demonstrate that the full Green-Lagrange nonlinear model based on the CUF plate model can predict the nonlinear behavior of laminated composite plates efficiently and accurately that can be a basis to evaluate the effectiveness of different structural theory approximation orders and strain-displacement assumptions.