PSI - Issue 42

V. Shlyannikov et al. / Procedia Structural Integrity 42 (2022) 714–721 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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Thus, as a result of a series of experiments, the plastic deformation zones were obtained for all investigated materials. Fig. 4 shows of the contours of the plastic deformation zones for Steel P2M. The first two figures illustrate the typical shapes and dimensions of the respective plastic deformation zones formed by the loadings of pure mode I and initial pure mode II. Next picture represent Point 7 along curvilinear crack path corresponds to the state before the final fracture under initial mode II. The main feature Point 7 is that, despite the fact that an inclined curvilinear crack has already formed in the CTS specimen loaded by shear forces, a pseudo-mode I scenario is realized at its tip.

Pure mode I Point 1

Initial pure mode II Point 1

Mixed mode with initial pure mode II Point 7

Fig. 4. Crack tip plastic deformation zones along crack paths for Steel P2M.

3. Numerical study As a complement to the DIC experimental results are represented as contours strain distributions near the crack tip, FE modelling of the displacement and strain fields around the crack tip in the CTS specimen was performed. Numerical calculations were performed using the experimental set of forces F (Table 2) for each tested specimen subjected to tension or shear loading manufactured from steel, aluminum and titanium alloys. In this numerical study, we used the classical HRR and gradient plasticity theories to acquire more detailed information about the local displacement and strain ahead of the crack tip and the crack opening. The modeling of the calculation schemes was carried out using the commercial finite element software package ANSYS 2021R1 using a user subroutine to study displacement-strain fields along the experimental crack paths for CTS specimens (Fig. 5).

Fig. 5. (a) Crack path and (b) crack tip finite element meshes.