Study on mode I dynamic fracture characteristics with a mini three-point bending specimen for the split Hopkinson bar technique

•A novel mode i dynamic fracture experimental technique is proposed based on the SHPB technique.•With the increase of loading rates, the crack initiation time decreases, but the maximum strain of the specimen increases.•The DFT of the two materials is positively correlated with the loading rate in different degrees.•The fracture of the two materials shows mixed characteristics of ductile and brittle fracture modes.•The crack initiation time is closely related to the material property, the geometry of the specimen, and the loading conditions.