AN ANALYTICAL MODEL FOR THE BRITTLE-DUCTILE TRANSITION IS DEVELOPED. THE PLASTIC ZONE AROUND THE CRACK IS CONSIDERED AS A CONTINUOUS DISTRIBUTION OF DISLOCATIONS AND ANALYTICAL EXPRESSIONS FOR THE TIME DEPENDENCE OF THE PLASTIC ZONE SIZE, NUMBER OF DISLOCATIONS EMITTED AND THE CRACK TIP SHIELDING ARE PRESENTED. THE RESULTS PREDICTED BY THE MODEL AGREES WITH THE MAIN FEATURES OF THE EXPERIMENTAL OBSERVATIONS AND COMPUTER SIMULATIONS. THE MODEL HIGHLIGHTS THE IMPORTANCE OF DISLOCATION MOBILITY IN CONTROLLING THE BRITTLE-DUCTILE TRANSITION.
PALAVRAS-CHAVE: BRITTLE-DUCTILE TRANSITION, PLASTIC ZONE, CRACK, DISLOCATIONS
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