Πλοήγηση ανά Συγγραφέας "Tselepidou, Sofia"

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  • Μικρογραφία εικόνας
    Τεκμήριο
    Three-Dimensional printing of intelligent composite polymer materials with sandwich panel structures
    (ΕΛΜΕΠΑ, Πολυτεχνική Σχολή, Τμήμα Μηχανολόγων Μηχανικών, 2026-03-16) Tselepidou, Sofia; Τσελεπίδου, Σοφία; Tzounis, Lazaros; Τζούνης, Λάζαρος
    This thesis presents a comprehensive experimental investigation of cellular and three-dimensional lattice structures, including diamond lattice, rhombicuboctahedron, and honeycomb cores, as well as composite sandwich panels with CFRP facings bonded using epoxy adhesives. The study aimed to evaluate the mechanical performance of these architectures under flexural, compressive, and adhesive shear loads, following relevant ASTM standards for each test. Diamond lattice specimens (30×30 surface, polyamide material) with a unit cell size of 0.6 and wall thicknesses of 0.8 and 1.2 were tested, showing that increased wall thickness significantly enhanced stiffness and collapse load, highlighting the importance of geometric parameters in controlling relative density and mechanical properties. Rhombicuboctahedron cores (38×38×38) with varying filling ratios demonstrated different load transmission mechanisms, from interior concentration at low ratios to interlayer and inclined transmission at higher ratios. Flexural tests on rhombicuboctahedron samples of various sizes confirmed that bending response strongly depends on geometry and scale. Honeycomb structures, particularly hexagonal configurations, exhibited bending-dominated stiffness with moderate bending strength and lower in-plane compressive stiffness, while providing higher energy absorption compared to other simple hierarchical geometries. CFRP facings were fabricated using a hand lay-up process with epoxy resins, and cores were bonded to the facings using epoxy adhesive following ASTM D5868. Material selection included ABS, PLA, and Polyamide (PA) cores. ABS was primarily used for lattice and rhombicuboctahedron cores, while PLA and PA were mainly employed for honeycomb structures. UD CFRP layers (12×15 cm) were applied in six layers per sample, pressed five times per layering. The total cost of materials and laboratory work amounted to approximately €1,179. This work demonstrates the critical role of systematic design, material selection, and standardized testing in developing lightweight, reliable composite structures. The findings provide valuable guidance for the optimization of lattice cores and sandwich panels and lay the groundwork for future studies on full-scale applications, environmental durability, and fatigue performance.