The buckling and postbuckling behaviors were investigated numerically and experimentally for laminated cylindrical panels with a cutout.
In the finite element analysis, the nonlinear finite element method adopted an improved arc-length method and the updated Lagrangian scheme based on the second Piola-Kirchhoff stress tensor and the Green strain tensor. For the finite element modeling of cylindrical panels with a cutout, the eight-node degenerated shell element was used. This model can also represent geometrical nonlinear behavior by considering large displacements and large rotations. For the large displacement and large rotation shell problems, the incremental equations are derived using a quadratic approximation for the increment of the reference vectors in terms of the nodal rotation increment. For the progressive failure analysis, the maximum stress criterion and complete unloading failure model were adopted. The effects of the cutout shape and the radius of curvature on buckling and postbuckling behaviors were investigated.
In the experiments, the shadow moire technique was used to monitor the out-of-plane deformations of the panels during tests. The major finding in experiments was that local disturbances caused mode shape changes in postbuckling range. Experimental results showed good agreement with the analytical results for the buckling load and postbuckling compression strength.
