PSI - Issue 61

G.J.C. Pinheiro et al. / Procedia Structural Integrity 61 (2024) 71–78 Pinheiro et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 6 shows the P m comparison between different damage propagation exponents (exponential law) and experimental data, considering the same three adhesives. For all adhesives, a large disparity is found between the numerical and experimental P m , with the numerical values being much higher than the experimental ones. This difference shows that the exponential model overpredicts P m by excess, for the same overall characteristics of the adhesives, compared to the triangular law. Moreover, the differences increase for higher  . Besides, the horizontal portion of the curves for all adhesives and lower values of  indicates a modification of failure mode towards failure in the adherents (at P m =24.3 kN), which is not representative of reality. 4. Conclusions The main aim of this study was to validate different XFEM criteria to predict P m of scarf joints. The experimental data highlighted the high dependence of the joint behavior on the adhesive type and  . The numerical analysis using XFEM showed that it is possible to accurately predict P m of scarf joints using the QUADS and MAXS initiation criteria. The results obtained with the QUADS initiation criterion were the closest to the experimental results. On the other hand, the QUADE, MAXE, MAXPE and MAXPS initiation criteria did not provide satisfactory results for all  values and adhesives used. Studying the effect of the propagation law led to the conclusion that, in the case of brittle adhesives, the triangular propagation law with power law 1 gives the best results. The more ductile the adhesive, the less the influence of the power law parameter, and the three values tested (0.5, 1 and 2) give identical predictions of P m . The exponential propagation law, regardless of the power law value, does not allow an accurate P m prediction of the strength of the evaluated joints. Overall, the XFEM proved to be suitable for P m prediction of scarf joints using the QUADS and MAXS criteria, in which case it provides very accurate results. It can therefore be concluded that it was possible to assess the potential of XFEM to predict joint strength and to clarify the effect of different adhesives and  on the tensile performance of scarf joints, aiming to the maximum strength. References Abaqus ® (2013). Documentation. D. Systèmes, Vélizy-Villacoublay. Barbosa, N. G. C., Campilho, R. D. S. G., Silva, F. J. G. and Moreira, R. D. F., 2018. Comparison of different adhesively-bonded joint types for mechanical structures. Applied Adhesion Science 6(1), 15. Belytschko, T. and Black, T., 1999. Elastic crack growth in finite elements with minimal remeshing. International Journal for Numerical Methods in Engineering 45(5), 601-620. Campilho, R. D. S. G., Banea, M. D., Chaves, F. J. P. and Silva, L. F. M. d., 2011a. eXtended Finite Element Method for fracture characterization of adhesive joints in pure mode I. Computational Materials Science 50(4), 1543-1549. 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., 2011b. 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. Campilho, R. D. S. G., Pinto, A. M. G., Banea, M. D. and da Silva, L. F. M., 2012. Optimization study of hybrid spot-welded/bonded single-lap joints. International Journal of Adhesion and Adhesives 37, 86-95. Faneco, T., Campilho, R., Silva, F. and Lopes, R., 2017. Strength and fracture characterization of a novel polyurethane adhesive for the automotive industry. Journal of Testing and Evaluation 45(2), 398-407. Fernandes, T. A. B., Campilho, R. D. S. G., Banea, M. D. and da Silva, L. F. M., 2015. Adhesive selection for single lap bonded joints: Experimentation and advanced techniques for strength prediction. The Journal of Adhesion 91(10-11), 841-862. Kumar, S. B., Sivashanker, S., Bag, A. and Sridhar, I., 2005. Failure of aerospace composite scarf-joints subjected to uniaxial compression. Materials Science and Engineering: A 412(1-2), 117-122. Moës, N., Dolbow, J. and Belytschko, T., 1999. A finite element method for crack growth without remeshing. International Journal for Numerical Methods in Engineering 46(1), 131-150. Mohammadi, S. (2008). Extended Finite Element Method: for Fracture Analysis of Structures, Wiley. Moreira, R. D. F. and Campilho, R. D. S. G., 2015. Strength improvement of adhesively-bonded scarf repairs in aluminium structures with external reinforcements. Engineering Structures 101, 99-110. Mubashar, A., Ashcroft, I. A. and Crocombe, A. D., 2014. Modelling damage and failure in adhesive joints using a combined XFEM-cohesive element methodology. The Journal of Adhesion 90(8), 682-697. Neto, J. A. B. P., Campilho, R. D. S. G. and da Silva, L. F. M., 2012. Parametric study of adhesive joints with composites. International Journal of Adhesion and Adhesives 37, 96-101. Pike, M. G. and Oskay, C., 2015. XFEM modeling of short microfiber reinforced composites with cohesive interfaces. Finite Elements in Analysis and Design 106, 16-31.