Issue 47

F. Moroni et alii, Frattura ed Integrità Strutturale, 47 (2019) 294-302; DOI: 10.3221/IGF-ESIS.47.22 301 Figure 13 : Example of force vs. opening behavior and fracture surface of CFRP-CFRP bonded joint DCB tests. Figure 14 : Mode I R-curve of CFRP-CFRP bonded joints. Figure 15 : Example of force vs. opening behavior and fracture surface of massive CFRP-CFRP bonded joint ENF tests. An example of Force vs. opening behavior and fracture surface of co-bonded ENF tests is shown in Fig. 15. Adhesive can be traced both at the beginning (fatigue precracking) and during the propagation phase. However, due to instability of the propagation phase of this test configuration, only one value of G IIc could be evaluated, that resulted 2.25 times higher than the value found in co-cured CFRP. Therefore, the adhesive yields a higher fracture toughness as expected since the crack is constrained within the adhesive layer differently from DCB test, where it jumps between the plies soon after the beginning of propagation. fatigue precrack fatigue precrack