Evaluation of dynamic fracture toughness KId by Hopkinson pressure bar loaded instrumented Charpy impact test

Abstract A novel method for measuring the dynamic fracture toughness, K Id , using a Hopkinson pressure bar loaded instrumented Charpy impact test is presented in this paper. The stress intensity factor dynamic response curve ( K I ( t )− t ) for a fatigue-precracked Charpy specimen is evaluated by means of an approximate formula. The onset time of crack initiation is experimentally detected using the strain gauge method. The value of K Id is determined from the critical dynamic stress intensity factor at crack initiation. A K Id value for a high-strength steel is obtained using this method at a stress-intensity-factor rate ( K Id ) greater than 10 6 MPa  m / s .