Issue 47

F. Cucinotta et alii, Frattura ed Integrità Strutturale, 47 (2019) 367-382; DOI: 10.3221/IGF-ESIS.47.27 371 E-Glass Carbon Kevlar w f 0.50 0.59 0.50 w m 0.50 0.41 0.50 v f 0.32 0.49 0.45 v m 0.68 0.51 0.55 Table 4 : Weight and Volume percentage of fibres and resin. Unidirectional lamina σ R11 [N/mm 2 ] σ R22 [N/mm 2 ] E1 [N/mm 2 ] E2 [N/mm 2 ] G12 [N/mm 2 ] ν 12 ν 21 E-Glass 553.62 62.04 25420 4890 1880 0.27 0.05 Carbon 2048.92 47.07 123160 6580 2530 0.25 0.01 Kevlar 1699.43 51.25 61180 6080 2340 0.32 0.03 Table 5 : Mechanical properties of unidirectional laminas. The mechanical properties of a single cross-ply laminate are function of the orientation and stacking sequence of the plies inside the laminate. It is possible to calculate these mechanical properties and to know the main engineering characteristics along all possible orientation of the laminate by exploiting the lamination theory. Fig. 4 from (a) to (h) shows the differences between the mechanical properties of the unidirectional fibres and the resulting properties of the obtained cross-ply laminates inside the A sandwich. In the case of a specimen A, Tab. 6 resumes the mechanical properties for each oriented cross-ply laminate. The second sandwich, called B sandwich, has been produced with different plies of carbon, as shown in Fig. 5, having a symmetric distribution of the plies along the thickness. The core material is the same typology of the A sandwich but with slightly different density. The general characteristics of each laminate inside the sandwich are shown in Tab. 7. The total thickness of the specimen B is 33 mm. Cross-ply laminate σ R11 [N/mm 2 ] σ R22 [N/mm 2 ] E1 [N/mm 2 ] E2 [N/mm 2 ] G12 [N/mm 2 ] ν 12 E-Glass [0/90] 307.8 307.8 15250 15250 1880 0.09 Carbon [-45/45] 801.2 801.2 9400 9400 31700 0.68 Carbon [0/-45/90/45] 924.6 924.6 45260 45260 17120 0.44 Kevlar [0/90] 875.3 875.3 33800 33800 2340 0.06 Table 6 : Mechanical properties for each laminate in A sandwich. Ply Orientation [°] Wet thickness [mm] Dry mass density Carbon -45/+45 0.50 4.07E-07 [kg/mm 2 ] Carbon 0/90 0.50 4.07E-07 [kg/mm 2 ] Carbon -45/+45 0.50 4.07E-07 [kg/mm 2 ] Core M100 Gurit-M100 30.00 1.07E-07 [kg/mm 3 ] Carbon -45/+45 0.50 4.07E-07 [kg/mm 2 ] Carbon 0/90 0.50 4.07E-07 [kg/mm 2 ] Carbon -45/+45 0.50 4.07E-07 [kg/mm 2 ] Table 7 : General characteristics of B sandwich.