The applicability of a recently proposed test specimen named the edge‐notched diametrically compressed (ENDC) disc was assessed for mixed mode I/III fracture toughness studies. The specimen benefits from simple geometry and does not require complicated test configuration. The finite element analyses of this specimen revealed that pure modes I and III, as well as various intermediate mixed mode I/III deformations, are easily achieved by changing the direction of edge crack relative to the applied diametral compressive load. The modes I and III stress intensity and geometry factors were numerically computed in the midsection of the ENDC specimen using several 3D finite element analyses for different crack depths and inclination angles. Pure mode III angle was also obtained for each crack depth ratio. These assessments showed that the ENDC specimen can be a suitable candidate for studying mixed mode I/III fracture toughness.

Crack growth and brittle fracture is one of the major failure modes in bone materials and therefore understanding the fracture behavior and affecting parameters on the crack growth resistance of bone is necessary for biomechanics researchers. In this paper, mode I fracture toughness value for the left and right femur bones of same bovine were measured experimentally using several single edge notch bend beam specimens (SENB) subjected to three-point bend loading in dry condition. The SENB specimens were cut along the longitudinal axis of bone but from different hoop directions. Fracture toughness results of sample prepared from the frontal part of bone were higher than the back or side sections. Depending on the location of sample, the fracture toughness of femur bone was varied from 5 to 10 MPa m. Furthermore, the results obtained for similar location of both left and right femur bones were nearly identical. The fracture energy (Gf) of the tested specimens was also measured and it was found that a linear relation can be fitted to the (K Ic) 2 versus G f results of the tested bovine bone.