Mohan, Turup PanduranganKanny, KrishnanAjayi, Ayodele Abraham2025-09-082025-09-082025https://hdl.handle.net/10321/6217A thesis submitted for the degree of Doctor of Engineering: Mechanical Engineering, Durban University of Technology, Durban, South Africa, 2025.Selection of appropriate materials for composite design is very crucial in critical engineering applications such as aerospace, marine and automobile industries. This study focused on developing lightweight hybrid-filled foam composite panels with enhanced mechanical and thermal properties. Hollow glass microspheres (HGM) and nanoclay were the fillers used in the foam core. The HGM content was varied from 1wt.% to 3wt.% in foam composites panel while nanoclay content was varied from 1wt.% to 5wt.% in each of the HGM-filled series of foam composites panel, these foam composite panels were fabricated using a conventional resin casting method. These hybrid-filled foam panels were also reinforced with banana fibres as facesheet in the sandwich composites. Comprehensive characterization was carried out on the foam composite panels, this involve investigating their physical properties. The results obtained showed that tensile and flexural strength improved by 12% and 23.1% respectively with the infusion of hybrid fillers content of 3%wt.HGM+1%wt.clay and 1%wt.HGM+1%wt.clay into the epoxy when compared to neat epoxy. Thermal strength was optimum with infusion of 1%wt.HGM+5%wt.clay into the epoxy while the buoyancy results revealed that the sample with 3%wt. hollow glass microspheres concentration has the highest buoyancy due to the low density of the HGM used which is 0.19 g/cm3 and because sample 3%wt.HGM has the highest concentration of HGM with the respect to series of samples considered in this study. Similar trend of improvement in mechanical properties and physical properties was observed when the fabricated hybrid-filled foam panels was used as core in the sandwich composites developed which resulted to 22.11% and 29.53% improvement as flexural strength and tensile strength while there was 32.26% improvement in the impact energy. Also, there was 8.61% reduction in the water uptake. Furthermore, the tensile and flexural results was validated numerically by using finite element method and abaqus® 6.13 software and this revealed that most of the modelled samples are stronger than the experimental tested samples with up to 9% increase from experimental values obtained because of limitation in some parameter estimation of the numerical model such as the thermal properties, perfect contact and linear failure criteria. Since the improvement in mechanical and thermal properties has been established, the composite panels developed are suitable for applications in manufacturing ship propellers. Future studies aims to improve the fire retardation of sandwich composites for marine applications183 penEpoxy-based foam compositesSandwiched compositesCritical engineeringBuoyancy applicationsComposite materialsSandwich constructionEpoxy compoundsFoamed materialsThesis