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- Mixed-mode evaluation of ductile adhesive joints by the single-leg bending testPublication . Ribeiro, J.P.S.M.B.; Campilho, Raul D. S. G.; Rocha, R.J.B.In the design of adhesive structures, it is extremely important to accurately predict their strength and fracture properties (critical strain energy release rate in tension, GIC, and shear, GIIC). In most cases, the loads occur in mixed-mode (tension plus shear). Thus, it is of great importance the perception of fracture in these conditions, namely of the strain energy release rates in tension, GI, and shear, GII, relative to different crack propagation criteria or fracture envelopes. This comparison allows to determine the most suitable energetic propagation criterion to be used in cohesive zone models (CZM). The main objective of this work is to verify, by CZM, which is the power law parameter (Ī±) that best suits the energetic crack propagation criterion for CZM modelling, using single-lap joints (SLJ) and double-lap joints (DLJ) with aluminium adherends and bonded with a ductile adhesive. With this purpose, numerical simulations of the SLJ and DLJ are carried out, and the maximum load (Pm) is compared with experiments. For the tested materials and geometries, the energetic criterion resulting from the experimental work provided matching numerical results and, thus, the fracture envelope was validated.
- Geometrical parameter study of adhesively-bonded T-joints by cohesive modelsPublication . Lopes, J.P.M.; Campilho, R.D.S.G.; Rocha, R.J.B.; Silva, Francisco J. G.A wide variety of adhesive joints architectures is available, offering several options to the designers, although the most common are single-lap joints (SLJ), double-lap joints, and scarf joints. Additional designs, less used and studied are the stepped-lap, T-joints and tubular joints. T-joints find application in different types of industry, such as aircraft to bond stiffeners to skin and in the cars between the B-pillar and the rocker. This work numerically evaluates the performance of the structural adhesive AralditeĀ® 2015 in an aluminum T-joint, after validation with experimental results. A cohesive zone modelling (CZM) numerical study is carried out to capture the behavior of different T-joints geometrical configurations when subjected to peel loads. The work includes a parametric study, considering maximum load (Pm) and dissipated energy at failure (U) prediction, considering four geometrical parameters: flat adherend thickness (a), T-element thickness (t), overlap length (l) and T-element radius (r). A significant effect on Pm was found for the tested parameters, and the CZM method revealed to be a precious method for studying T joints with precision and accuracy.