# Modelling of Failure Behaviour of 3D-Printed Composite Parts
## 4 Conclusions  
In this research work, we proposed two different computational methodologies for the failure modelling of 3D-printed parts. The computational models were then applied to investigate the nonlinear behaviour of 3D-printed parts subjected to tensile loading. The computational models based on CM-1 predicted higher values, and it is because the models employed the nonlinear material data of virgin material for modelling nonlinear behaviour. These computational models provided idealistic material behaviour of the parts. The computational models based on CM-2 predicted accurate damage behaviour of the printed parts, and this is because the models utilized the tensile testing data of uniaxially 3D-printed parts for the modelling of nonlinear behaviour. Computational models based on CM-2 provided realistic behaviour of the printed parts. The computational models were applied for 3D-printed parts and subjected to tensile loadings, only, to demonstrate the efficacy of the present computational models, and the models can be further applied to different mechanical loading cases. The following points are concluded from the research work:  
* The significant difference in the computational and experimental results indicates that the 3D-printed parts have inferior quality, and such parts can be further improved with proper selection of printing conditions and printing strategies.
* The material behaviour of 3D-printed parts with an ABS polymer displayed linear behaviour followed by nonlinear softening behaviour before fracture. In contrast, 3D-printed3D-printed composite parts exhibited linear behaviour followed by nonlinear hardening behaviour before the sudden fracture. The hardening behaviour is mainly attributed to sCF in the composite parts.
* Nonlinear behaviour in 3D-printed3D-printed composites is mainly attributed to matrix material (ABS polymer). Therefore, nonlinear data of ABS materials are considered for damage modelling, and the sCF reinforcements remain elastic during deformation.
* For realistic failure modelling of 3D-printed parts, it is recommended to use the mechanical testing data of unidirectionally 3D-printed parts in the computational models. Further, consider the mechanical testing data to replicate the predominant failure modes in the computational models.  
**Author Contributions:** Formal analysis, M.S. and A.C.; Investigation, M.S. and S.V.A.; Methodology, A.C.; Resources, A.C.; Validation, M.S.; Writing--original draft, M.S.; Writing--review & editing, A.C. and S.V.A. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was funded by Natural Sciences and Engineering Research Council (NSERC) of Canada for the financial support (Reference number PDF-557243-2021).  
**Acknowledgments:** M.S. would like to acknowledge the Natural Sciences and Engineering Research Council (NSERC) of Canada for the financial support (Reference number PDF-557243-2021).  
**Conflicts of Interest:** The authors declare no conflict of interest.  
\begin{table}
\begin{tabular}{l l l l l} \hline \hline  & **Experimental [16]** & **CLT and Tsai–Hill [16]** & \multicolumn{2}{c}{**Computational Modelling**} \\ \cline{3-5}  & & & **CM-1** & **CM-2** \\ \hline
**Cross-ply** & & & & \\ \(E_{x}\), in MPa & 2863.9 \(\pm\) 78.7 & 2125.9 & 3704.2 & 2974.5 \\ \(U_{t}\), in MPa & 23.5 \(\pm\) 0.5 & 26.0 & 61.6 & 33.6 \\ \(\epsilon_{t}\) & 0.0158 \(\pm\) 0.0006 & 0.0097 & 0.05 & 0.022 \\
**Angle-ply** & & & & \\ \(E_{x}\), in MPa & 2094.6 \(\pm\) 43.5 & 1733.3 & 2594.0 & 2053.9 \\ \(U_{t}\), in MPa & 21.7 \(\pm\) 0.5 & 22.7 & 43.52 & 24.3 \\ \(\epsilon_{t}\) & 0.0243 \(\pm\) 0.0011 & 0.0105 & 0.07 & 0.028 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Comparison of computational results with Tsai–Hill failure criterion results and experimental work for 3D-printed parts made of ABS + sCF composite material and subjected to uniaxial tensile loading.