PSI - Issue 68

Saeid Hadidimoud et al. / Procedia Structural Integrity 68 (2025) 788–794 Saeid Hadidimoud et al. / Structural Integrity Procedia 00 (2025) 000–000

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• Loading (1): The uncracked cylinder was subjected to internal pressure to a level that induced plastic deformation through 80% of the cylinder thickness from the inner wall. • Unloading (2): The uncracked cylinder was unloaded by removing the internal pressure. • Residual stresses redistribution (3): The boundary conditions were modified, and a crack of desired configuration was introduced into the model. • Applying internal pressure (4): Internal pressure is applied to the cracked cylinder. • Applying additional axial tension (5): Axial tension was applied in addition of internal pressure to th 3. Modeling Results Gao (1992) solution (for internally pressurized open-end cylinders) was verified through FEM analysis. This was not explicit and required solving a nonlinear equation to calculate p L . The proposed solution was limited to radius ratio . The solutions were compared with the FEM data, and through curve fitting, an explicit relationship for was obtained. As shown in figure 2, the comparison exhibits negligible error. • ! <

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Fig. 2. (a) comparison of analytical solutions and FEM results for an internally pressurized open-end thick-walled cylinder; (b) second-degree polynomial fit to FEM results.

In this study, the limit load of closed-end cylinders is presented using sequential loading in ABAQUS for different radius ratios and compared to the analytical solutions provided for combined loading in both thick-walled and thin walled cylinders. No analytical solution for open-end cylinders under combined loading conditions was available. Therefore, yield curves for open-end cylinders were presented based on FE analyses performed in ABAQUS that covered a range of radius ratios in both thin-walled and thick-walled vessels. The results for yield pressure and axial tension were then normalized as described in equation 1:

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Additionally, the influence of strain-hardening was examined by assuming a linear strain-hardening response (Gao 2007). The effect of strain-hardening on the limit load of thick-walled cylinders under combined loading was also investigated using FEM by similarly considering a linear strain-hardening material response in ABAQUS. Results are summarized in Figure 3.