Additive manufacturing of cylindrical specimens with a central crack for fatigue crack growth analysis

Abstract Additive manufacturing is used to produce a new specimen geometry for fatigue crack growth (FCG) studies under plane strain conditions. There is a great influence of stress state in the FCG, directly on the damage mechanisms and indirectly through plasticity-induced crack closure. The proposed geometry allows the isolation of the plane strain state, which is not possible with standard through-thickness crack specimens. In fact, in the cylindrical geometry with central crack (CCC specimen), there are no corner points. The optional inclusion of a small-diameter longitudinal channel, which is also only possible with additive manufacturing, allows comparative studies under air-vacuum. However, different problems in the use of this geometry were identified and solved, namely the absence of internal defect, the misalignment of the loading, and the failure at the root of concordance. The final results proved the validity of the concept. Graphical abstract