Once the pre-notch was achieved, the SPT specimens could be
tested. The tests were conducted at room temperature using a
punch diameter of dp = 2.5 mm, the punch drop rate was
v = 0.5 mm/min and the hole in the lower die had a diameter of
Dd = 4 mm and a fillet radius of r = 0.5 mm (Fig. 3). For each specimen,
a load–displacement curve was obtained from which the area
under the curve was calculated corresponding to the total work of
fracture Wf.