Experimental analysis of epoxy-based functionally graded composite materials

Functionally graded materials (FGMs) are crucial in the mechanical and aerospace industries for improving material quality by combining distinct qualities to create composite substances with desired properties. Using the layer-by-layer hand-laying technology in the casting process, samples with dimensions calculated according to international standards (ASTM) were created in a glass mold. Several fine fillers, such as alumina (Al2O3) and silicon carbide (SiC) microparticles, were added to the epoxy resin. Tensile, bending, and impact tests were performed on samples from the five layers of FGM. The experimental test results showed that the fracture toughness of functionally graded samples slightly improved, with the highest value reaching 13.63865 MNm3/2 in the Al2O3-reinforced epoxy sample. The ultimate tensile stress of the functionally graded epoxy sample reinforced by Al2O3 is 15.572 MPa, and the ultimate value of tensile stress of the functionally graded epoxy sample fortified with SiC is 19.4198 MPa. In comparison, the ultimate value of tensile stress of the pure epoxy sample is 21.247 MPa. The results show that pure epoxy samples have high stress levels. The increase in SiC percentage in the functionally graded sample enhanced the mechanical properties in the bending tests, giving the best results. The pure epoxy sample has the ultimate bending stress of 1.974 MPa, while the ultimate bending stress in the functionally graded material sample of Al2O3-reinforced epoxy is 1.9558 MPa. The ultimate bending stress of the functionally graded sample of SiC-reinforced epoxy is 2.924 MPa, and the ultimate bending stress value in the SiC-reinforced epoxy sample was 2.924 MPa. The functionally graded sample of epoxy and SiC yielded the best result in terms of durability. The maximum load applied on the sample of epoxy and SiC was 150 N; this indicates that the functionally graded material has significantly reduced the material's deformation and increased the mechanical properties of the material in terms of strength, durability, and resistance. It was found that the maximum load applied on the pure epoxy sample was 91 N, while the maximum load applied on the functionally graded sample of epoxy and Al2O3 was 126 N.