Material characteristic lengths to design 3D-printed notched titanium against fatigue

In the present paper, the Theory of Critical Distances (TCD) and the Strain Energy Density (SED) approach are attempted to be used to predict the fatigue lifetime of notched components made from additively manufactured titanium.

The reliability of these two methods was checked systematically by using a large number of experimental data we generated by testing notched specimens of 3D printed titanium containing different geometrical features and tested using various loading types and stress ratios. Our methods were seen to be successful, giving predictions falling always within the scatter band of the data from the un-notched material. These results are very interesting, especially considering that both the TCD and the SED are very easy to use because they require only a linear-elastic stress analysis.