Dependency of fatigue resistance on roughness in WAAM printed carbon steel components
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The fatigue resistance of rough components produced by wire-arc additive manufacturing (WAAM) is highly sensitive to geometric discontinuities as surface undulations contribute to stress concentration where fatigue cracks initiate. This research investigates the fatigue resistance of WAAM plates made of S355 carbon steel by combining fatigue experiments on samples characterised by different roughness and finite element (FE) models. The experiments evaluated the fatigue lives of a range of rough specimens under constant amplitude cyclic loading. The as-deposited surfaces were measured with high precision three-dimensional laser scanning. A generalised notch stress (GNS) approach estimating the fatigue resistance of as-deposited specimens is then developed. Based on parametric FE assessment, different surface roughness is studied and their influence on the fatigue resistance is computed, highlighting key correlations between the ten-point roughness height and the fatigue strength.