Application of split Hopkinson tension bar technique to the study of dynamic fracture properties of materials

A novel method is proposed to determine dynamic fracture toughness (DFT) of materials using the split Hopkinson tension bar (SHTB) technique, in conjunction with self-designed specimen and fixture. The incident and transmitter bars have threaded grip ends and can be screwed into the fixtures. The specimen, with a fatigue precrack at the center, is dog-bone shaped tension plate, which is connected between the fixtures with pin constraints. With these apparatus, DFT of high strength steels, 40Cr and 30CrMnSiA, are determined. For comparison purpose, three-point bend specimens of the same materials are also tested using the revised Hopkinson pressure bar (HPB) technique. For the both testing systems, the dynamic stress intensity factor history is evaluated using a hybrid experimental-numerical method, and the fracture initiation time is measured by strain gage on the specimen. The results show that the present testing method in tension is effective compared with the compression tests.