PSI - Issue 52

Satrio Wicaksono et al. / Procedia Structural Integrity 52 (2024) 438–454 Satrio Wicaksono et al./ Structural Integrity Procedia 00 (2023) 000 – 000

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model that can capture pressure-dependent failure strength. Delamination was captured by inserting cohesive interface elements between skin and foam of the T-joint composites. First, the accuracy of the proposed model was validated against the existing experimental data. Additionally, various parametric study was performed to understand the effect of material properties variations with respect to the failure modes. 2. Finite Element Modelling The finite element model of the foam core sandwich T-joints followed the experimental specimen of low-speed impact on foam-core sandwich T-joint constructed by Caliskan et al. [14]. By following the dimensions of adhesively bonded sandwich T-joint configuration made for the referred experimental test, the numerical model of T-joint was successfully remade, as depicted in Figure 1. The T-joint model consists of horizontal and vertical sandwich panels, and cleats holding those two sandwich panels together, as presented in Figure 2. The sandwich structures, which consist of cores and skins, were modelled as solid geometry. Meanwhile, the cohesive layers were in the form of 3D thin plate. The other parts, such as cleats, clamps, block support and impactor were also modelled as solid geometry.

Block support

Sandwich panels

Cleats

Clamps

Clamps

Impactor

Figure 1 Model and dimensions of T-joint structure.

Figure 2 Major components of the T-joint model.

In the T-joint model, the interactions between the cohesive layers and the other surfaces were modelled using tie constraint method. This interaction ensured that the nodes on the cohesive parts were connecting to the nodes on the skin and core components. The surfaces of cohesive layers were always treated as the slave surfaces to make sure that the interaction would be working properly. To define the contact during the impact in the simulation, the model was assigned with general contact interaction with friction coefficient of 0.3 and hard contact model. For the interaction between clamp components and sandwich structures, surface-to-surface interaction was utilized. The skins of the sandwich structures and cleat components were assigned with the material properties of Aluminium 1050-H14. These material properties were obtained from several references, as gathered in Table 1. The modelling of material properties for skins and cleats used the elastic-plastic assumption along with damage initiation for ductile metals.