Numerical Simulation and Testing of a Composite-Stiffened Structure Under Combined Buckling Loads

Prediction of the buckling behavior of structures is of great interest in the aerospace industry, and extensive research is taking place worldwide in that area. The current work concerns numerical simulation of the collapse test of a closed stiffened composite box subjected to compression followed by torsion. Numerical simulation is performed and the results are correlated with experimental findings. The objective is to validate the numerical model and detect any deficiencies of the modeling procedure. For this purpose, a series of quantities numerically predicted are directly compared with experimental ones: strains, displacements, deformation plots and load-displacement curves. The physical test article also contains artificial stringer-skin debondings realized via Teflon film inserts. The energy release rates are calculated at the debonding front using the virtual crack closure technique. The FE model is slightly stiffer than the actual structure but the numerical results are at a reasonable level of agreement with the experimental data.