Stress amplification in a topology-optimized maraging steel 300 connecting rod due to as-built SLM deviations: a case study

Abstract This study investigates how as-built dimensional deviations in a topology-optimized connecting rod manufactured by selective laser melting (SLM) affect structural response. A maraging steel 300 connecting rod was fabricated on a Renishaw 500 S Flex system and digitized using a low-cost structured-light 3D scanner. The scan-derived mesh was aligned to the nominal CAD geometry using principal component analysis initialization and point-to-plane iterative closest point refinement. Full-field deviations were then quantified using signed nearest-neighbor distance and bidirectional Hausdorff distance. The as-built part showed a 3.10% volume increase (73,014 mm 3 vs. 70,822 mm 3 in CAD), with most deviations ranging from approximately − 0.20 to + 0.30 mm and localized hotspots up to 1.746 mm in support-affected and curvature-critical regions. Both geometries were converted into simulation-ready STEP models and analyzed in ANSYS under identical static loading. Mesh-converged analyses gave maximum von Mises stresses of 757.78 MPa for the CAD model and 890.39 MPa for the as-built geometry, corresponding to approximately 17.5% stress amplification. The study presents a deviation-aware scan-to-FEA workflow that quantifies how as-built geometry modifies structural response relative to the nominal CAD model.