Issue 31

R.D.S.G. Campilho et alii, Frattura ed Integrità Strutturale, 31 (2015) 1-12; DOI: 10.3221/IGF-ESIS.31.01 11 C ONCLUDING REMARKS his work dealt with the determination of G n c of adhesive joints with different configurations, considering either the adhesive or adherend material. The J -integral was used to measure G n c , given the large adhesive plasticity. With this purpose, an optical measurement and data analysis method was built in Matlab ® to extract  o to obtain G n , and  n to build the CZM laws. The complete tensile CZM law of the adhesive was derived by the direct method in some cases, on account of the available G n -  n curve that was differentiated to provide the t n -  n (or CZM) law. For configuration 1, an average value of G n c =1.182 N/mm was obtained for the adhesive Sikaforce ® 7888 between jute-epoxy composite adherends. This value can be compared to the average of G n c =1.095 N/mm estimated in configuration 2 for h =4 mm aluminium adherends. These values agree quite well, although it should be considered that both configurations differ in the values of h and E of the adherends. A direct analogy cannot be formed between configuration 3 and configurations 1 and 2, because a different adhesive was considered. As output of this work, G n c data was given for the strength prediction of bonded joints for different adhesives and joint conditions. Additionally, a methodology was presented to accurately estimate G n c for ductile adhesives, as well as the CZM law, which can be used for strength predictions of bonded structures by CZM modelling. R EFERENCES [1] Lee, M.J., Cho, T.M., Kim, W.S., Lee, B.C., Lee, J.J., Determination of cohesive parameters for a mixed mode cohesive zone model, Int. J. Adhes. Adhes., 30 (2010) 322-328. [2] Pinto, A.M.G., Magalhães, A.G., Campilho, R.D.S.G., de Moura, M.F.S.F., Baptista, A.P.M., Single-lap joints of similar and dissimilar adherends bonded with an acrylic adhesive, J. Adhesion, 85 (2009) 351-376. [3] Campilho, R.D.S.G., Pinto, A.M.G., Banea, M.D., Silva, R.F., da Silva, L.F.M., Strength improvement of adhesively- bonded joints using a reverse-bent geometry, J. Adh. Sci. Technol., 25 (2011) 2351-2368. [4] Deng, J., Lee, M.M.K., Effect of plate end and adhesive spew geometries on stresses in retrofitted beams bonded with a CFRP plate, Compos: Part B, 39 (2008) 731-739. [5] Kim, T.H., Kweon, J.H., Choi, J.H., An experimental study on the effect of overlap length on the failure of composite-to-aluminum single-lap bonded joints, J. Reinf. Plast. Compos. 27 (2008) 1071-1081. [6] Volkersen, O., Die nietkraftoerteilung in zubeanspruchten nietverbindungen konstanten loschonquerschnitten, Luftfahrtforschung, 15 (1938) 41-47. [7] Chai, H., Shear fracture, Int. J. Fract., 37 (1988) 137-159. [8] Campilho, R.D.S.G., de Moura, M.F.S.F., Barreto, A.M.J.P., Morais, J.J.L., Domingues, J.J.M.S., Fracture behaviour of damaged wood beams repaired with an adhesively-bonded composite patch, Compos. Part A 40 (2009) 852-859. [9] Campilho, R.D.S.G., de Moura, M.F.S.F., Ramantani, D.A., Morais, J.J.L., Domingues, J.J.M.S., Buckling behaviour of carbon-epoxy adhesively-bonded scarf repairs, J. Adhes. Sci. Technol., 23 (2009) 1493-1513. [10] Yoshihara, H., Simple estimation of critical stress intensity factors of wood by tests with double cantilever beam and three-point end-notched flexure, Holzforschung, 61 (2007) 182-189. [11] Suo, Z., Bao, G., Fan, B., Delamination R -curve phenomena due to damage, J. Mech. Phys. Solids, 40 (1992) 1-16. [12] Campilho, R.D.S.G., de Moura, M.F.S.F., Pinto, A.M.G., Morais, J.J.L., Domingues, J.J.M.S., Modelling the tensile fracture behaviour of CFRP scarf repairs. Compos: Part B, 40 (2009) 149-157. [13] Carlberger, T., Stigh, U., Influence of layer thickness on cohesive properties of an epoxy-based adhesive-an experimental study, J. Adhesion, 86 (2010) 814-833. [14] Ji, G., Ouyang, Z., Li, G., Ibekwe, S., Pang, S.S., Effects of adhesive thickness on global and local mode-I interfacial fracture of bonded joints, Int. J. Solids Struct., 47 (2010) 2445-2458. [15] Wambua, P., Ivens, J., Verpoest, I., Natural fibres: can they replace glass in fibre reinforced plastics?, Compos. Sci. Technol., 63 (2003) 1259-1264. [16] Ku, H., Wang, H., Pattarachaiyakoop, N., Trada, M., A review on the tensile properties of natural fiber reinforced polymer composites, Compos.: Part B, 42 (2011) 856-873. [17] Herrera-Franco, P.J., Valadez-González, A., A study of the mechanical properties of short natural-fiber reinforced composites, Compos: Part B, 36 (2005) 597-608. [18] Campilho, R.D.S.G., Banea, M.D., Pinto, A.M.G., da Silva, L.F.M., de Jesus, A.M.P., Strength prediction of single- and double-lap joints by standard and extended finite element modelling, Int. J. Adhes. Adhes., 31 (2011) 363-372. T