FRONT DEVELOPMENT OF A LONG FATIGUE-CRACK DURING ITS GROWTH

A 3-D elastic-plastic finite element analysis has been developed to si mulate the deformation development along the front of a long mode I si ngle edge crack in plates subjected to either monotonic or cyclic load ing. Idealisations having both equal and unequal layers through the th ickness of the plate were involved. Plane stress and plane strain 2-D finite element analyses were also performed and compared with the pres ent 3-D solutions. The development of the monotonic and cyclic crack t ip plastically deformed zones and opening displacements were traced an d correlated to accommodate the effect of the plate thickness and the profile of the crack front. A previously developed crack tip deformati on parameter was invoked to predict the effect of the specimen thickne ss on mode I fatigue crack growth and the associated change of crack f ront profile. Comparison of such a prediction and the experimental fin dings of the present work reflected the capability of that parameter i n modelling fatigue crack growth through the plate thickness.