An evaluation of the chevron V-notched bend bar fracture toughness specimen

The chevron V-notched bend bar specimen recently proposed as a practical approach to the fracture toughness testing of brittle materials has been further evaluated. The accuracy of the stress intensity expression has been improved through experimental analysis. The applicability of this specimen for determining the environment induced cracking threshold, K_Iscc was also investigated. Fracture toughness results developed for Pyroceram 9606, 7079-T6 aluminum and the apparent K_Iscc value of AISI 4340 steel exposed to hydrogen sulfide gas show that the chevron V-notched bend bar specimen can yield data essentially identical to that developed with more conventional fatigue precracked specimens. However, results also show that when catastrophic failure of a specimen occurs rather than the expected stable crack growth, the test is invalid. Further work is required to resolve this complication.