Percorrer por autor "Ferreira, J. A. Martins"
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- Notch fatigue analysis and crack initiation life estimation of maraging steel fabricated by laser beam powder bed fusion under multiaxial loadingPublication . Branco, R.; Prates, P. A.; Costa, J. D.; Ferreira, J. A. Martins; Capela, C.; Berto, F.This paper deals with the notch fatigue behaviour and crack initiation life estimation in maraging steel fabricated by laser beam powder bed fusion under multiaxial loading. Tests are conducted in tubular geometries with lateral holes considering different normal stress to shear stress ratios and multiaxial loading levels. The cyclic stress–strain response at the notch-controlled process zone is simulated numerically using two alternative approaches: a generalised isotropic plasticity model with mixed isotropic-kinematic hardening, and a linear-elastic model. Both approaches demonstrated to be suitable for predicting the crack initiation sites, the directions of crack growth, and the fatigue life. Fatigue life was calculated from a SWT-based model combined with the Theory of Critical Distances. Elastic-plastic predictions led to smaller errors but slightly shifted to the non-conservative side.
- Prediction of multiaxial fatigue life of notched maraging steel components manufactured by selective laser meltingPublication . Branco, R.; Costa, J. D.; Jesus, J.; Berto, F.; Ferreira, J. A. Martins; Capela, C.This paper aims at predicting the fatigue crack initiation life in maraging steel manufactured by selective laser melting under in-phase bending-torsion loading. Three relationships between the bending moment and the torsion moment were studied, namely B/T=2, B/T=1, and B/T=2/3. The tested geometries consisted of hollow cylindrical specimens with lateral holes. The crack initiation and the crack paths were detected in-situ using a high-resolution digital camera. The local stress-strain states at the notch region were accounted for using two alternative numerical models developed within linear-elastic frameworks: (1) a parametric structured mesh; and (2) an automatic unstructured mesh. Fatigue crack initiation sites and fatigue crack initiation lives were successfully predicted using both numerical models.