PSI - Issue 66

G. Cricrì et al. / Procedia Structural Integrity 66 (2024) 282–286 Author name / Structural Integrity Procedia 00 (2025) 000–000

286

5

constitutive relationship of the adhesive layer with only two parameters: mode II fracture energy and maximum shear stress. The model provides, in closed form, the maximum load carriable by the joint, which is coincident with the onset of failure, as a function of five parameters: the axial stiffnesses of the two adherends, the two adhesive parameters, and the overlap length. Furthermore, it provides the lap-joint load-displacement curve related to the crack growth phase from the onset of failure up to the complete detachment.

Fig. 4 – Lap-joints load-elongation curves.

The FE validation campaign shows that this model can provide very good approximation of the failure loads, with errors less than 10%. Also, the load-displacement curves are well approximated by the analytical model, at least for not too short initial overlaps. This information is very useful for the joints design, since it is related to the ability of dissipate energy during the detachment process. It is worth noting that the FE models contain much more details than the analytical ones, that are: the bending capability, the nonlinear kinematics, the mixed mode fracture capability of the cohesive zone model. The ability of the analytical model to provide, nevertheless, very sound results shows that the main failure mechanism of the single lap-joint is correctly taken into account by the few parameters of this model, whereas the other effects are apparently less important for its overall behaviour. Hence it seems useful using the analytical model for the preliminary or draft design and apply the detailed FE analyses for possible refinements.

References

Tserpes, K., Barroso-Caro, A., Carraro, P. A., Beber, V. C., Floros, I., Gamon, W., ... & Rajčić, V. (2022). A review on failure theories and simulation models for adhesive joints. The Journal of Adhesion, 98(12), 1855-1915. da Silva, L. F., das Neves, P. J., Adams, R. D., & Spelt, J. K. (2009). Analytical models of adhesively bonded joints—Part I: Literature survey. International Journal of Adhesion and Adhesives, 29(3), 319-330. Xu, X.P., Needleman, A., Numerical simulations of fast crack growth in brittle solids, Journal of the Mechanics and Physics of Solids, Vol. 42, 1397-1434, 1994.