PSI - Issue 51

P.A.R. Ferreira et al. / Procedia Structural Integrity 51 (2023) 115–121 P.A.R. Ferreira et al. / Structural Integrity Procedia 00 (2022) 000–000

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4. Conclusions This study aimed to investigate the effect that several geometric parameters have on joint strength ( P max ). The joints analyzed are representative of those employed in aircraft fuselages; thus, composite substrates and a structural adhesive were used for the study. Although the increase in substrate thickness ( t P ) is often associated with stronger joints while under traction, the curved joints studied here were more prone to interlaminar failure, mostly in the vicinity of the knee region. On the contrary, those joints with the thinnest substrate ( t P =1.2 mm) were able to sustain higher loads until failure of the bond line, in which case was cohesive, regardless of the overlap length ( L O ); hence, being more predictable. Similarly, in flat joint configurations, the increase in L O is also proportional to P max ; however, in the joint configuration and load solicitation studied here, it was found that L O ≥50 mm provided no significant improvement in P max . In addition, shorter L O allow for a better load transmission along the bond line; however, the joint geometry causes a stress concentration near the knee region, which negatively influences P max . The curvature radii explored here, although representative of those employed in aircraft fuselages, had no significant influence on P max . In this regard, the joints with larger radii were slightly stronger than those with shorter ones. Nevertheless, the joints with a larger curvature showed a more uniform stress transference along the bond line. Finally, the joints with thinner substrates and overlap lengths from short to medium showed the best performance under internal pressure (1 MPa). Although the performance slightly improved on larger curvature radius, the latter has more influence on the stress distributions than in P max . This study could be the base for analyzing other joint configurations under pressure. Furthermore, the numerical approach chosen allowed for studying a joint configuration otherwise difficult to study experimentally. References Abdelfattah, I., Ferreira, F., Nasr Saleh, M., Reis, P.N., Teixeira De Freitas, S., 2022. Flexural performance of squared one-sided CFRP patches: modelling and experimental study. The Journal of Adhesion 1–19. Campilho, R.D.S.G., Banea, M.D., Neto, J.A.B.P., 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 Adhesive 44, 48–56. Campilho, R.D.S.G., Pinto, A.M.G., Banea, M.D., Silva, R.F., da Silva, L.F.M., 2011. Strength Improvement of Adhesively-Bonded Joints Using a Reverse-Bent Geometry. Journal of Adhesion Science and Technology 25, 2351–2368. Correia, J.M.C., Campilho, R.D.S.G., Rocha, R.J.B., Liu, Y., Ramalho, L.D.C., 2020. Parametric study of composite curved adhesive joints. The International Journal of Advanced Manufacturing Technology 111, 2957–2970. Hart-Smith, L.J., 2011. Adhesively bonded joints in aircraft structures, in: da Silva, L.F.M., Öchsner, A., Adams, R.D. (Eds.), Handbook of Adhesion Technology. Springer Berlin Heidelberg, pp. 1101–1147. Liu, Y., Lemanski, S., Zhang, X., 2018. Parametric study of size, curvature and free edge effects on the predicted strength of bonded composite joints. Composite Structures 202, 364–373. Nunes, S.L.S., Campilho, R.D.S.G., da Silva, F.J.G., de Sousa, C.C.R.G., Fernandes, T.A.B., Banea, M.D., da Silva, L.F.M., 2016. Comparative Failure Assessment of Single and Double Lap Joints with Varying Adhesive Systems. The Journal of Adhesion 92, 610–634. Sforza, P.M., 2014. Commercial Airplane Design Principles, Commercial Airplane Design Principles. Elsevier Inc. Taib, A.A., Boukhili, R., Achiou, S., Boukehili, H., 2006. Bonded joints with composite adherends. Part II. Finite element analysis of joggle lap joints. The International Journal of Adhesion and Adhesives 26, 237–248.