Abstract
Abstract
Sandwich composites are lightweight structures comprising stiff, thin face sheets, often carbon or glass, bonded to a low-density core, delivering high strength-to-weight ratios, superior bending stiffness, and excellent energy absorption. These properties make them ideal for aerospace, automotive, and marine applications. Their performance hinges on core material selection, face sheet composition, and interfacial bonding, prompting research into optimized designs for improved mechanical behavior. This study investigates the optimization of face-sheet configurations in glass fiber-reinforced sandwich composites with PVC cores, fabricated via vacuum infusion. The research evaluates the flexural performance of composites with varying layer configurations (2/2, 2/4, and 4/2 layers at top/bottom) and fiber orientations (transverse and longitudinal) through mechanical, thermal, and chemical analyses. Flexural testing under 4-point bending revealed that asymmetric layer configurations (2/4 and 4/2) exhibited superior strength compared to symmetric (2/2) layouts, The 4/2 longitudinal configuration achieved the highest load-bearing capacity, reaching a maximum peak force of 1,103.3 N and an average breaking force of 1,098.4 N (30.4 MPa). Conversely, transverse orientations demonstrated lower capacities, with the 2/2 baseline averaging 401.2 N (11.7 MPa) and the 4/2 layout peaking near 690 N (18.9 MPa). Differential Scanning Calorimetry revealed a distinct exothermic curing reaction for the epoxy resin, identifying a glass transition temperature (
T
g
) of 99.17 °C and a substantial total enthalpy of 439.7 J/g, indicating highly efficient cross-linking. SEM confirmed consistent individual glass fiber diameters ranging from 14.2 µm to 17.33 µm. Energy-Dispersive X-ray Spectroscopy (EDS) verified the silicate composition of the fibers, detecting 13.8–14.3 wt% silicon and 43.8–48.1 wt% oxygen in rupture regions, alongside a carbon-dominated surface layer (78.1–80.7 wt%) suggesting potential environmental or organic residues. These findings provide valuable insights for designing high-performance sandwich composites in aerospace, automotive, and civil engineering applications, balancing strength, weight, and durability.