Fatigue of Stiffened Panels with Multiple Interacting Cracks – an Experimental and Numerical Simulation Analysis

Fatigue crack propagation tests with cyclic stress of constant amplitude and frequency were carried out on stiffened panel specimens damaged with a single crack or an array of collinear cracks, until fracture occurred. A numerical simulation procedure for multiple propagating cracks which takes account of crack interaction was introduced. The Mode I stress intensity factors, KI, were calculated from finite element nodal displacements results. A bending effect due to the cut stiffeners has been taken into account in the stress intensity factor calculation. The experiment and numerical simulation showed a higher crack growth rate in the case of the stiffened panel with three cracks, which is due to cut cross sectional area and crack interaction.