An experimental and numerical study on the effects of nanoadditives and material extrusion parameters on the mechanical and flexural characteristics of ABS/PVC blend polymer core sandwich panels

This thesis investigates the effects of different core structures on the flexural response of composite core shell structures fabricated using fused deposition modeling (FDM). The study explores the influence of various FDM parameters and the composition of the base matrix material on the mechanical properties of the structures. Regression modeling with artificial neural networks (ANN) is employed to predict the mechanical variables of the 3D printed samples, such as in-plane and out-of-plane modulus of elasticity and ultimate strength. Optimization techniques using ant colony optimization (ACO) are applied to optimize the FDM parameters and material composition, resulting in improved mechanical performance. The obtained regression models are used to analyze variations in mechanical properties, visualized through bar-charts and surface responses, and optimization algorithms determine the material extrusion parameters that maximize the response variables individually and cumulatively. Insights are provided into the influence of material extrusion parameters and the compatibility of additives, such as PVC and carbon nanofibers (CNFs), on the mechanical characteristics of 3D printed samples and composite core shell sandwich panel (CCSSP) specimens. The study highlights the potential for tailoring the mechanical properties of 3D printed materials for specific applications through careful selection and optimization of material extrusion parameters. Furthermore, the research demonstrates the potential of FDM as a viable manufacturing technique for producing composite core shell structures with tailored mechanical properties. By optimizing the core structures and FDM parameters, the flexural response and overall performance of the fabricated structures can be enhanced. The outcomes of this research contribute to the advancement of additive manufacturing, particularly in the context of composite core shell structures. The findings offer valuable knowledge for engineers and researchers in optimizing FDM processes and material compositions to achieve desired mechanical properties for specific applications. Key findings of this study include the analysis of mechanical properties of 3D printed samples fabricated at different orientations of principal axes, with the addition of PVC improving in-plane stiffness, particularly at lower extrusion rates and printing orientations. The presence of CNFs has a limited effect on stiffness at different printing orientations. Investigation of ultimate strength reveals that PVC alone does not effectively enhance it, but the inclusion of CNFs counteracts the reduction caused by increased extrusion rates, particularly for samples with a raster orientation of [0/90°]. The addition of CNFs creates a load-carrying network through mechanical interlocking, improving the compatibility between ABS and PVC molecules and the ultimate strength of the samples. The response surface analysis of CCSSPs with hybrid circular/triangular corrugated cores (HCTC) elucidates the influence of material extrusion parameters and polymer composition on the flexural response. PVC addition improves flexural stiffness, while CNF presence can reduce stiffness, especially at higher extrusion rates. The optimization process indicates that optimal parameter combinations often involve samples without CNF in the matrix, although the addition of CNF can positively influence the mechanical and flexural response of 3D printed samples for compositions with higher PVC concentrations. Considering CNF concentration, PVC ratio, and extrusion parameters is crucial for achieving desired mechanical properties and tailoring the performance of 3D printed structures.