An experimental methodology to determine damage mechanics parameters for phase-field approach simulations using material extrusion-based additively manufactured tensile specimens

The 3D printing or material extrusion-based additive manufacturing has evolved from a promising fabrication technology to a mature method that can be integrated into numerous applications. However, this technique involves a large number of variables that significantly affect the resulting structure. In addition, this dependence hinders the development of numerical models to estimate the mechanical behaviour of 3D-printed components with different printing configurations. Hence, the phase-field approach is presented to predict crack propagation through a relatively simple energy balance minimisation problem. Nevertheless, this computational method requires specific parameters to be determined. Therefore, an experimental methodology based on tensile tests is proposed to mechanically characterise the material and analytically define the necessary fracture parameters, including strength and critical energy release rate, from the experimental results. Unnotched and notched specimens, fabricated via material extrusion using a sustainable thermoplastic, are studied under different configurations to analyse fracture mechanisms while addressing strategies to minimise printing defects. Additionally, an open-source numerical predictive tool by means of the phase-field fracture modelling is developed, along with the assessment of the essential length scale parameter. The combination of experimental and numerical studies validates the proposed methodology, and also demonstrates the ease of reproducing for further case studies.