2001 Volume 50 Issue 3 Pages 229-234
An impact fracture test method has been developed to measure fracture toughness under mixed mode I/II loading using an edge-cracked half-disk specimen. Using this method, dynamic and quasi-static tests were performed and mixed-mode fracture toughness for graphite was measured. The results were compared with those that the authors had obtained using center-notched disk specimens. It was found that fracture toughness measured with edge-cracked half-disk specimens was comparatively good agreement with MHS (maximum hoop stress) or MERR (maximum energy release rate) criteria. On the other hand, using center-notched disk specimens, mode II components of mixed mode fracture toughness were estimated larger. It seems that one reason of this was the effect of the second order, nonsingular term in the series solution for the crack-tip stress field.
