PSI - Issue 49

Nataliya Elenskaya et al. / Procedia Structural Integrity 49 (2023) 43–50 Author name / Structural Integrity Procedia 00 (2023) 000–000

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structures was 30%. 3. Results and Discussion

Three-dimensional finite-element (FE) models of the developed structures were generated. Each structural model was discretised using solid tetrahedral elements in Wolfram Mathematica. The resulting model was then transferred to SIMULIA Abaqus for FE analysis of the effects of degradation process under quasi-static compression. Two auxiliary points connected to nodes at the top and bottom of the structure were used to apply loads and boundary conditions. The lower surface of the structure was rigidly and a uniformly distributed quasi-static load of 100 N was applied along the Y axis to the upper surface (Fig.1). The choice of the load type was determined by typical mechanical conditions for bone scaffold. The Young's modulus for PLA, according to the in-house experimental data, is 1682.4 MPa; the elastic limit of the material is 31.7 MPa, above which the scaffold demonstrates brittle fracture. The effect of the degradation process on mechanical performance of the basic unit cells was evaluated. In the case of SD, each degradation step resulted in a uniform thinning of the structure with the volume fraction of the material decreasing by the selected increment (Fig. 1). Diamond Gyroid I-WP Load

SD

0%

12.5%

25%

37.5%

50%

Fig. 1. Influence of surface degradation process on distribution of minimum principal stresses in different unit cells

In this case a significant increase in stress concentration was observed, making it possible to identify the scaffold zones that are most likely to fail. In the case of VD, a similar reduction was performed on the elastic modulus of the whole unit-cell model. On the basis of the obtained results, the effective moduli of the structures studied were been calculated for both degradation modelling techniques, and the obtained data were compared (Fig. 2).