DISCRETE CRACK-GROWTH ANALYSIS METHODOLOGY FOR THROUGH CRACKS IN PRESSURIZED FUSELAGE STRUCTURES

A methodology for simulating the growth of long through cracks in the skin of pressurized aircraft fuselage structures is described. Crack t rajectories are allowed to be arbitrary and are computed as part of th e simulation. The interaction between the mechanical loads acting on t he:superstructure and the local structural response near the crack tip s is accounted for by employing a hierarchical modelling strategy. The structural response for each cracked configuration is obtained using a geometrically non-linear shell finite element analysis procedure. Fo ur stress intensity factors, two for membrane behaviour and two for be nding using Kirchhoff plate theory, are computed using an extension of the modified crack closure integral method. Crack trajectories are de termined by applying the maximum tangential stress criterion. Crack gr owth results in localized mesh deletion, and the deletion regions are remeshed automatically using a newly developed all-quadrilateral meshi ng algorithm. The effectiveness of the methodology, and its applicabil ity to performing practical analyses of realistic structures, is demon strated by simulating curvilinear crack growth in a fuselage panel tha t is representative of a typical narrow-body aircraft. The predicted c rack trajectory and fatigue life compare well with measurements of the se same quantities from a full-scale pressurized panel test.