A Novel Procedure for Measuring the Dynamic Fracture Toughness Using Direct Tension Hopkinson Bar

In this paper a technique for determining the dynamic fracture toughness is presented. The proposed experimental method is based on the use of the direct tension Hopkinson bar allowing accurate control of the generated tensile stress pulse and avoiding limitations showed by other similar configurations. The sample geometry investigated here is the circumferentially cracked bar in tension (CCB(T)). This geometry does not require special fixtures to be hold between the bars and does not suffer loss of contact during dynamic loading. Numerical simulation showed that, at least for high toughness materials, the relative displacement of the bars can be used to have a direct measure of the CTOD that can be used to derive the corresponding J-integral value.