PSI - Issue 71

Karthik K R. et al. / Procedia Structural Integrity 71 (2025) 210–217

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In our study, 3D FE simulations are carried out to find out the J value at the crack tip for all the specimens. ANSYS Workbench Mechanical is used to perform the simulation. FE model of the specimen is made using quadratic hexahedral and tetrahedral elements. The fracture tool available in the workbench is used to create semi elliptical crack in the FE model as shown in Figures 6a and 6b. One end of the specimen is arrested axially and applied force on the other end, which are shown in Figure 6c.

Figure 6: FE model of surface crack (a) surface view (b) section view (c) loading and boundary conditions

Plasticity is modelled in FE simulation using the multilinear kinematic hardening model. Stress-strain curve of AA2219 parent material shown in Figure 7 is used as input for the material model. For the weld material, parent material curve is modified with 40% of weld efficiency.

Figure 7: Typical tensile stress-strain response for AA2219-T87 at room temperature (MMPDS-13 (2018))

3. Results Since crack initiation is important, J values are extracted around the crack front from simulation for the nominal break-through stress as shown in Figure 8. It was observed that the maximum value of J is developed either near to surface or at the deepest point, depending upon the crack aspect ratio. This behaviour is similar to what NASA has reported in their studies.