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ABSTRACT. ONE SHORT FATIGUE CRACK IS CHARACTERIZED BY GROWING WITH MAJOR VELOCITY THAN A LONG CRACK SUBJECTED TO THE SAME CRACKING LOAD, FOR EXAMPLE IDENTICAL VARIATION OF STRESS INTENSITY FACTOR DELTAK. THE LINEAR ELASTIC FRACTURE MECHANICS AND THE ELASTIC PLASTIC FRACTURE MECHANICS DO NOT MODEL ADEQUATELY THE BEHAVIOR OF THE THREE TYPES OF SHORT CRACKS: MICROSTRUCTURAL, PHYSICALLY SMALL AND OF HIGH STRESS. THIS WORK STUDY THE BEHAVIOR OF SHORT CRACKS UNDER FATIGUE LOADS. PLASTIC FATIGUE STANDARD SPECIMENS OF VARIABLE SECTION FOR LOW NUMBER OF CYCLES WERE USED, OF AISI 316L, SUBJECTED TO PLASTIC DEFORMATION AMPLITUDES, DEP/2, EQUAL TO 0,0040, 0,0087, 0,0135 AND 0,0183. SINCE DA/DN PROPAGATION VELOCITY VS. DELTAK CURVES, IT RESULTS THAT EXPERIMENTAL SHORT CRACKS GROWING VELOCITIES WERE EFFECTIVELY FASTER THAN CORRESPONDING LONG CRACKS UNDER IDENTICAL DELTAK. BESIDES, IT WAS OBSERVED A DESACCELERATION AND NON GROWING TIME OF THE INITIATED SHORT CRACKS, DURING AN IMPORTANT PERIOD OF ITS PROPAGATION IN STAGE I, THAT PROMOTES SOME OTHER PROPAGATION MODEL FOR USING IN SHORT CRACKS.
KEY-WORDS: FRACTURE MECHANICS, FATIGUE, SHORT CRACKS
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