Fatigue crack growth of additively manufactured component under constant amplitude load

Abstract

Additive manufacturing is used to produce complex shapes and can give optimised components under bending and torsion loads. In additive manufacturing, 3D model of the component is created using the commercially available software and then physical part is obtained using the machine which links CAD model data to manufacturing machine. This method is ideal for batch production and Just in time production methods. The main drawback of additively manufactured components is presence of micro cracks which opens up when component is subjected to repeated axial, bending and torsional loads. It is important to estimate the behaviour of the material under these loading conditions. In this paper, delamination phenomenon in additively manufactured parts is investigated. Crack initiation and growth is modelled and simulated to evaluate the rate of crack growth and energy variation at the crack tip for mode 1 and mode 2 is investigated. Stress intensity factors are computed over the crack length. Stress intensity factors for various contours are investigated. Results indicate that for a given crack length stress intensity factors varies from positive to negative for different contours. For mode 1 crack, energy release increases as the length of the crack increases but decreases after 2.5 mm of the crack to balance the newly surface created due to crack opening new surfaces. Ideally energy release rate for mode 2 should be zero but practically some amount of sliding occurs therefore low values is observed for energy release rate in mode 2.