Fluid-structure interaction analysis and fatigue life prediction of additively manufactured nickel-based superalloy centrifugal compressor impeller

บทคัดย่อ

A fluid–structure interaction (FSI) approach was developed in this study to evaluate fatigue life of a centrifugal compressor impeller fabricated from an additively manufactured nickel-based superalloy Inconel 718. First, pressure fields of impeller blades under a pre-defined service load obtained from computational fluid dynamics (CFD) simulations were calculated and applied as boundary conditions in another finite element (FE) model, incorporating a nonlinear isotropic–kinematic hardening law. As a result, local stress and strain distributions on the impeller response were determined. The highest stress concentration occurred near the root of trailing edge, which corresponded to likely fatigue crack initiation site, whereas the largest deformation was observed along the leading edge. Subsequently, fatigue analysis was performed to predict service life of the impeller blades using the Smith-Watson-Topper criterion, in which influences of surface defects inherent to laser powder bed fusion (LPFB) additive manufacturing process were also considered. Hereby, as-built surface and ground surfaces, representing condition with reduced unmelt particles on the surface, were analyzed. The results demonstrated that fatigue life of the compressor impeller improved by 13% when the surface roughness (R_a) was reduced by 6%, while maintaining the same R_v value, highlighting the significant benefit of post-processing treatments to reduce unmelt particles.