PSI - Issue 52

Angela Russo et al. / Procedia Structural Integrity 52 (2024) 535–542 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

537

3

configuration), have been modelled in the finite element software Ansys Mechanical. The geometrical characteristics of the panel are reported in Figure 1.

200 mm

3.96 mm

32 mm

2.64 mm

400 mm

52mm

SS#1 80 mm / SS#2 120 mm

100 mm

a)

b)

Figure 1. Skin-stringer debonding geometry. The initially debonded region is shown in red. a) In-plane geometry; b) section sketch.

The numerical model has been discretized taking into account both solid and shell components, as illustrated in Figure 2. Specifically, the stringer and the underlying skin, which represent the area interested by the delamination propagation, have been modelled as solids (Ansys SOLID 186 elements [10]), while the remaining skin has been modelled as a shell component (Ansys SHELL281 elements [10]) to reduce the computational effort. The two domains have been connected each other with contact elements (Ansys CONTA174 and TARGE 170 [10]).

Figure 2. Shell and Solid domains.

Layered elements have been considered, adopting a single element in the thickness. This is due to the consideration that 20-node elements have been employed for the mesh, which possess a satisfactory bending behaviour; hence, it was deemed unnecessary to increase the density of the mesh along the thickness and consequently increase the computational cost. The resulting Finite element model is shown in Figure 3. Mesh sensitivity analysis has been avoided as the results obtained through the SMXB tool has proved to be independent from the mesh size. Indeed, the principal added value of the manuscript is the use of this methodology, due to its inherent characteristics, to study, specifically, the influence of the initial damage length on the delamination evolution under compressive load. A parametric procedure has been used to assign the properties, such as section, materials, thicknesses, and stacking sequences, as well as to place contact elements to interconnect the various regions of the panel. Information on the material properties and stacking sequence can be found in Tables 1 and 2, respectively.

Table 1. Mechanical properties of the material system.