Issue 30

P.N.B. Reis et alii, Frattura ed Integrità Strutturale, 30 (2014) 431-437; DOI: 10.3221/IGF-ESIS.30.52 436 The G IIC results obtained with the ENF specimen show a stable increase up to the peak value observed for an effective crack length of about 43 mm. The maximum values obtained for G IIC is around 1800 J/m 2 . Figure 6 : G II versus crack length. C ONCLUSIONS he delamination of carbon-epoxy laminated composites was studied using mode I DCB specimen and mode II ENF specimens. Notched specimens were prepared, and tested under quasi-static loading, in order to obtain the load-displacement curves and energy release rate versus crack length. Significant instantaneous delaminations were observed particularly for all the DCB specimen independently initial crack delamination length. The mode I critical energy release rate showed some oscillatory behaviour, explained by the instantaneous delaminations. The maximum values obtained for G IC and G IIC were 281 and 1800 J/m 2 , respectively. R EFERENCES [1] Adams, R.D., Cawley, P.D., A Review of Defects Types and Non-Destructive Testing Techniques for Composites and Bonded Joints. NDT Int., 21 (1998) 208-222. [2] Amaro, A.M., Reis, P.N.B., de Moura, M.F.S.F., Santos, J.B., Damage Detection on Laminated Composite Materials Using Several NDT Techniques. Insight, 54 (2012) 14-20. [3] Caprino, G., Residual Strength Prediction of Impacted CFRP Laminates. J. Compos. Mater., 18 (1984) 508-518. [4] Davies, G.A.O., Hitchings, D., Zhou, G., Impact damage and residual strengths of woven fabric glass/polyester laminates. Compos. Part A-Appl. S., 27 (1996) 1147-1156. [5] de Moura, M.F.S.F., Marques, A.T., Prediction of low velocity impact damage in carbon-epoxy laminates. Compos. Part A-Appl. S., 33 (2002) 361-368. [6] Amaro, A.M., de Moura, M.F.S.F., Reis, P.N.B., Residual strength after low velocity impact in carbon-epoxy laminates. Mater. Sci. Forum, 514-516 (2006) 624-628. [7] Amaro, A.M., Reis, P.N.B., de Mouram M.F.S.F., Delamination effect on bending behaviour in carbon–epoxy composites. Strain, 47 (2011) 203-208. [8] Reis, P.N.B., Ferreira, J.A.M., Antunes, F.V., Richardson, M.O.W., Effect of Interlayer Delamination on Mechanical Behavior of Carbon/Epoxy Laminates. J. Compos. Mater., 43 (2009) 2609- 2621. T