Fatigue testing and analysis of steel plates manufactured by wire-arc directed energy deposition
Abstract
Wire-arc directed energy deposition (DED), also known as wire-arc additive manufacturing (WAAM), is a metal 3D printing technique that is recognised for its high efficiency, cost-effectiveness, flexibility in build scales and suitability for the construction sector. However, there remains a lack of fundamental data on the structural performance of WAAM elements, especially regarding their fatigue behaviour. A comprehensive experimental study into the fatigue behaviour of WAAM steel plates has therefore been undertaken and is reported herein. Following geometric, mechanical and microstructural characterisation, a series of WAAM coupons was tested under uniaxial high-cycle fatigue loading. A total of 75 fatigue tests on both as-built and machined coupons, covering various stress ranges and stress ratios (R = 0.1, 0.2, 0.3 and 0.4), have been conducted. The local stress concentrations in the as-built coupons induced by their surface undulations have also been studied by numerical simulations. The fatigue test results were analysed using constant life diagrams (CLDs) and S-N (stress-life) diagrams, based on both nominal and local stresses. The CLDs revealed that the fatigue strength of the as-built WAAM steel was relatively insensitive to the different stress ratios. The S-N diagrams showed that the surface undulations resulted in a reduction of about 35% in the fatigue endurance limit for the as-built WAAM material relative to the machined material, and a reduction of about 60% in fatigue life under the same load level. The as-built and machined WAAM coupons were shown to exhibit similar fatigue behaviour to conventional steel butt welds and S355 structural steel plates, respectively. Preliminary nominal stress-based and local stress-based S-N curves were also proposed for the WAAM steel. Show more
Permanent link
https://doi.org/10.3929/ethz-b-000624247Publication status
publishedExternal links
Journal / series
Additive ManufacturingVolume
Pages / Article No.
Publisher
ElsevierSubject
Directed energy deposition (DED); Experiments; Fatigue life; Geometric variability; metal 3D printing; Stress concentrationsOrganisational unit
03890 - Chatzi, Eleni / Chatzi, Eleni
09660 - Taras, Andreas / Taras, Andreas
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