PSI - Issue 71

Anoop Kumar A. et al. / Procedia Structural Integrity 71 (2025) 287–294

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Fig. 3. (a) FE model of injector head assembly; (b) Proof pressure with boundary conditions

In response to the applied internal pressure, high stresses are seen in the original configuration of the gas duct. The peak value of the Von Mises stress is 814N/mm 2 (see Fig. 4. (a)) is seen at the lower half of the gas duct, which is higher than its material (Nickel alloy) yield strength of 549N/mm 2 . As a result of this high stress considerable area on the gas duct experiences plastic strain, the peak value being 9.6%. Also, it is seen that there is a permanent plastic deformation of 13.5mm upon the removal of the pressure load, which will have a detrimental effect on its performance.

Fig. 4. (a) von Mises stress of injector head assembly at Proof condition – Existing config..; (b) Equivalent plastic strain of injector head assembly at Proof condition - Existing config.

Since stresses and strains were higher than allowable limits, it was proposed to increase the wall thickness of both the lower and upper halves of the gas duct. FE analysis was repeated for this modified configuration. Fig. 5. (a) and Fig. 5. (b) show the Von mises stress distribution and equivalent plastic strain in the injector head assembly modified configuration for proof pressure loads. Stresses and strains in the modified gas duct is within allowable limits when compared to the existing gas duct configuration.