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In this study, the authors performed a strength analysis of seven groups of commercially available materials based on SLS incremental technology. Test samples were made with Original PRUSA SL1S printers, with 10 samples of each type from 7 resins selected for testing. The tests were carried out on an MTS Bionix machine in a static tensile test, during which the basic mechanical properties were determined. This is also a preliminary study to determine material constants in the Johnson-Cook strength model. The authors then performed numerical simulations to mirror the experimental tests in order to tune the rheological model. In addition, a fracture criterion was determined based on a hybrid FEM/SPH numerical method. This allowed for the expansion of material libraries currently used in numerical simulations, as well as the sensitivity of the materials' models. In subsequent studies, in order to determine the nature of material destruction, analysis of fracture surfaces was performed using a scanning electron microscope (SEM). The final study was a biocompatibility test to assess the biological properties of the material. The conducted research made it possible to determine the strength properties of resins currently used in 3D printers, expand the libraries of material models in the computational environment (with an error rate of less than 5%), as well as observe the nature of the cracks formed and biocompatibility in the context of predicting the use of these materials for biomedical applications. [ABSTRACT FROM AUTHOR]

Polyetheretherketone (PEEK) is the leading high-performance thermoplastic biomaterial that can be processed through material extrusion (ME) additive manufacturing (AM), also known as three-dimensional (3D) printing, for patient-specific load-bearing implant manufacture. Considering the importance of cyclic loading for load-bearing implant design, this work addresses the high-cycle fatigue behaviour of 3D-printed PEEK. In this work, printed PEEK specimens are cyclically loaded under stress-controlled tension–tension using different stress levels between 75% and 95% of printed PEEK's tensile strength. The experimental results are used to document 3D-printed PEEK's fatigue behaviour using Basquin's power law, which was compared with previous fatigue research on bulk PEEK and other 3D-printing materials. As a pioneering study on its fatigue behaviour, the results from this work show that 3D-printed PEEK exhibits an above-average fatigue strength of 65 MPa, corresponding to about 75% of its tensile strength. Fracture surface analysis suggests that a transition can occur from ductile to brittle fracture with maximum stresses between 85% and 95% of the tensile strength. Evidence of crack propagation features on fracture surfaces under scanning electron microscope (SEM) observation suggests crack initiation in void defects created by printing deposition that propagates longitudinally through line bonding interfaces along layers. Considering this, 3D-printed PEEK's fatigue behaviour can be strongly related to printing conditions. Further research on the fatigue behaviour of 3D-printed PEEK is necessary to support its use in load-bearing implant applications. [ABSTRACT FROM AUTHOR]