PSI - Issue 25

F.J.C.F.B. Loureiro et al. / Procedia Structural Integrity 25 (2020) 63–70 Loureiro et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 5. Tensile (a) and shear (b) cohesive laws obtained by the direct method for the Araldite® 2015.

4. Conclusions

The main aim of this work was the evaluation of the mixed-mode fracture properties of Araldite ® 2015 by the SLB test, including the R -curve, fracture envelope, and CZM laws by the direct method. In particular, the fracture envelope (and  exponent of the mixed-mode power-law failure criterion) and the CZM laws are valuable information for further use of the CZM technique for general purpose strength prediction. The J -integral analysis revealed consistent J I and J II data between specimens and confirmed the expected behavior of the adhesive, showing the ductile nature of the Araldite ® 2015. Fracture envelope with typical exponents of the mixed-mode power law was constructed, and placement of the experimental data points marked a clear tendency for the behavior of the adhesive. It was concluded that the Araldite ® 2015 could be represented by a mixed-mode power-law failure criterion with  =1/2. To conclude, the mixed-mode data obtained in this work can be used for the fracture or CZM analysis of bonded joints under mixed mode loadings in the adhesive, which is the most common scenario in real-world applications, although proper data validation should be performed beforehand due to different factors affecting CZM results. Barenblatt, G. I., 1962. The Mathematical Theory of Equilibrium Cracks in Brittle Fracture. Advances in Applied Mechanics 7, 55-129. Campilho, R. D. S. G., Banea, M. D., Neto, J. A. B. P. and da Silva, L. F. M., 2013. Modelling adhesive joints with cohesive zone models: effect of the cohesive law shape of the adhesive layer. International Journal of Adhesion and Adhesives 44, 48-56. Campilho, R. D. S. G., Banea, M. D., Pinto, A. M. G., da Silva, L. F. M. and de Jesus, A. M. P., 2011. Strength prediction of single- and double lap joints by standard and extended finite element modelling. International Journal of Adhesion and Adhesives 31(5), 363-372. da Silva, L. F. M. and Campilho, R. D. S. G. (2012). Advances in Numerical Modelling of Adhesive Joints. Advances in Numerical Modeling of Adhesive Joints, Springer Berlin Heidelberg : 1-93. Dugdale, D. S., 1960. Yielding of steel sheets containing slits. Journal of the Mechanics and Physics of Solids 8(2), 100-104. Ji, G., Ouyang, Z. and Li, G., 2012. On the interfacial constitutive laws of mixed mode fracture with various adhesive thicknesses. Mechanics of Materials 47, 24-32. Petrie, E. W. (1999). Handbook of adhesives and sealants. New York, McGraw-Hill. Rice, J. R., 1968. A path independent integral and the approximate analysis of strain concentration by notches and cracks. Journal of applied mechanics 35(2), 379-386. Santos, M. A. S. and Campilho, R. D. S. G., 2017. Mixed-mode fracture analysis of composite bonded joints considering adhesives of different ductility. International Journal of Fracture 207(1), 55-71. Szekrényes, A. and Uj, J., 2004. Beam and finite element analysis of quasi-unidirectional composite SLB and ELS specimens. Composites Science and Technology 64(15), 2393-2406. Wu, E. M. and Reuter, R. C. J. (1965). Crack extension in fiberglass reinforced plastics. Urbana, Illinois, T&AM Report No. 275, Department of Theoretical and Applied Mechanics, University of Illinois. Yoon, S. and Hong, C., 1990. Modified end notched flexure specimen for mixed mode interlaminar fracture in laminated composites. International Journal of Fracture 43(1), R3-R9. References Barenblatt, G. I., 1959. The formation of equilibrium cracks during brittle fracture. General ideas and hypothesis. Axisymmetrical cracks. Journal of Applied Mathematics and Mechanics 23, 622-636.