J70%Pmax ¼ 81 2:1 e ð2Þ
Fig. 7 shows the obtained results of fracture toughness as a function of the biaxial pre-deformation, where the values of fracture
toughness of compact specimens with different thicknesses are included (CT20)JIc = 56 kJ/m2, CT15)JQ = 82 kJ/m2
and CT10)JQ = 118 kJ/m2).