On the notch fatigue strength of additively manufactured polylactide (PLA)

•Notch fatigue strength of 3D-printed PLA is investigated experimentally.•Notched 3D-printed PLA is modelled as a linear-elastic, homogenous, and isotropic material.•Critical distance methods are used to assess notch fatigue strength of 3D-printed PLA.•The proposed design methods can be used along with commercial FE codes. The strength and cracking behaviour under fatigue loading of additively manufactured polylactide (PLA) was investigated experimentally to quantify and model the role of notches. These tests were run under load ratios equal to −1 and to 0. Being supported by the experimental evidence, 3D-printed PLA was treated as a linear-elastic, isotropic, and homogenous material. This allowed the use of the Theory of Critical Distances to be extended also to the fatigue assessment of notched 3D-printed PLA. This theory was seen to return accurate estimates. This confirms that it can be used also to estimate fatigue lifetime of notched 3D-printed polymers.