Issue 47

F. Cucinotta et alii, Frattura ed Integrità Strutturale, 47 (2019) 367-382; DOI: 10.3221/IGF-ESIS.47.27 374 Figure 6 : Boundary conditions for four-points bending test. (a) (b) Figure 7 : Initial set up for the A sandwich (a) and B sandwich (b) . In the second experimental campaign, impact drop tests were conducted. These tests have been carried out by using a CEAST Fractovis Plus Machine (Fig. 8). The specimen is held between two steel plates, which present a central hole having a diameter of 70 mm, a thickness of 5 mm and connected through M5 bolts with no preload (Fig. 9). The plates holding the specimen are then placed on the machine basement without any additional constraint. The needed impact energy can be adjusted by choosing the mass of the striker and the impact speed. The measurement system of the machine allows to know the load of the striker during the impact as a function of time F(t). Furthermore, it was possible to know the velocity and the impact energy during the test by performing subsequent integrations [20]. A hemispherical striker having a diameter of 20 mm and a mass of 6.5 kg was used. Three energy levels were considered: 20 J, 40 J and 60 J. The tests were repeated twice for each energy level. (a) (b) Figure 8 : Drop test machine (a) and impact area detail (b) where it is possible to observe the indenter and the clamping rig