Daily Archives: December 10, 2024

This dissertation investigated the effect arrangement of layers in glass and carbon composites, focusing on the effects of longitudinal fiber orientation, thickness, and the addition of SiO₂ nanoparticles. Three batches of composite plates were produced. The first category comprised unidirectional glass fiber sheets arranged in a stacking sequence of 0° [G/G/G/G]s  with and without 2% silica dioxide nanoparticles and carbon fiber sheets arranged in a stacking sequence of 0° [C/C/C/C]s with and without 2% silica dioxide nanoparticles. These sheets were specifically designed to assess the mechanical properties, namely the modulus of elasticity in the longitudinal and transverse directions E₁ and E₂, shear modulus (G₁₂), and Poisson's ratio (ν₁₂) for glass/epoxy and carbon/epoxy composites.

The second group, characterized by quasi-isotropic-balanced distinct stacking sequences, comprised three primary unidirectional fiber orientations: 0°, 45°, and 90°. These sequences varied in thickness, consisting of eight layers (2 mm), ten layers (2.5 mm), and twelve layers (3 mm). Additionally, SiO₂ nanoparticles were utilized as a reinforcing agent within the epoxy matrix. The third group consisted of cross-layer configurations, with various stacking sequences examined. These sequences involved two primary unidirectional fiber orientations: 0° and 90°, and they exhibited different thicknesses. Specifically, the group included eight layers (2 mm), twelve layers (3 mm), sixteen layers (4 mm), and twenty layers (5 mm).

Furthermore, SiO₂ nanoparticles were employed as a reinforcing agent within the epoxy matrix. The vacuum-assisted resin infusion process was utilized to fabricate fourteen combinations of fiber-reinforced epoxy composites, including those with and without the addition of 2% silicon dioxide nanoparticle composites, designated as QS1, QS1N, QS2, QS2N, QS3, QS3N, CS1, CS1N, CS2, CS2N, CS3, CS3N, CS4, and CS4N. The quasi-static mechanical properties (tensile and three-point bending test) and dynamic (axial and flexural fatigue test) behaviors of the material were examined through experimental analysis and validated using numerical simulations via the finite element method (ANSYS 2019/R3 Workbench).

The modulus of elasticity (E₁) and maximum stress for QS3 and QS3N increased by 20.97% and 18.65%, respectively. In comparison to CS1, which lacks SiO₂ nanoparticles, CS1N exhibited increases in E₁ and maximum stress of 2.5% and 12.7%, respectively. The incorporation of SiO₂ nanoparticles significantly enhanced the performance of glass/carbon hybrid composite materials. Axial fatigue tests demonstrated that the number of cycles of the hybrid composites (CS1 and CS1N), (CS2 and CS2N), and (CS3 and CS3N) increased by approximately 55%, 27%, and 58%, respectively, at a load level of 70%. In flexural fatigue testing, there was a stress increase of 17.4% between CS1 and CS₁N, and a similar increase of 13.11% between CS2 and CS2N. The sample pairs CS3 and CS3N showed a comparable percentage increase of 17.1%, while CS4 and CS4N exhibited an increase of 13.61%.