PSI - Issue 50

Alexander Eremin et al. / Procedia Structural Integrity 50 (2023) 73–82 Alexander Eremin / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 2. Smoothed impact loading diagrams of [0/90] 5S CFRP specimens.

The integrated value of the loading curves from initial loading to the max deflection is equal to the impact energy. While the area between the deflective and rebound part of the curve is equal to absorbed energy.

Table 1. Results of impact testing of [0/90] 5S CFRP specimens.

Specimen 1 Specimen 2 Specimen 3

Impact energy, J

8.71 5.15 3.56

17.39

25.95 11.42 14.52

Residual kinetic energy, J

8.61 8.78

Absorbed energy, J

The size of the polygon outlined the defect revealed on the shearogram (refer Fig. 3) reach 14.9×26.9 mm after the 8.55 J impact. Two impacts of the higher energies result in formation of BVIDs sizing of 17.0×45.4 mm (17.1 J) and 18.7×52.4 mm (25.65 J). After a certain amount of energy the induced delamination area is not increased but the severity of the internal damage does. This is confirmed by the result of the following residual strength testing.

Specimen impacted by 8.55 J

Specimen impacted by 17.1 J

Specimen impacted by 25.65 J

Fig. 3. Damage detection using digital shearography of orthotropic [0/90] 5S CFRP specimens after the drop weight testing with different energies.