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In this paper an investigation of shape evolution of fatigue crack isexposed. A numerical model able to foresee the local growth of a border crack is firstpresented. The numerical model is based on 3D FEM calculation of singular stress fieldalong the crack boundary, obtained by a dedicated pre-processor able to insert anarbitrary shaped crack in the analysed component. The crack evolution is simulated bymeans of a step by step basis advancing model. The crack growth is governed by adriving force dependent by the local fracture parameters and taking into accounteventual plasticity induced by a notch. To assess the reliability of the presented modelan experimental evaluation was conducted inserting an artificial starting crack in thespecimens. The use of non destructive testing procedures made possible to follow thecrack evolution during fatigue life. Crack extent and shape, and its evolution at differentstep of fatigue life are measured by means of radiographic method and penetrant liquid.