Flexural Properties of Functionally Graded Silica Nanoparticles

Abstract

In the present research, layered-functionally graded polymer nanocomposites were made via the silica (SiO2) nanoparticles (14-36 nm in diameter) distributed in the epoxy matrix throughout the ultra-sonication by hand lay–up technique. The change in volume fraction (Vf.) of the nanoparticles was given in the direction of thickness to reach the gradation. Layers having a thickness of (1.2 mm) with different nanoparticles concentrations were consecutively casted in acrylic molds to fabricate the graded composite sheet having a thickness of (6 mm). To fabricate the functionally graded layers, different concentrations of nanoparticles were taken (0, 0.5, 1, 1.5, 2 and 2.5 %Vf) and tested by tensile test. The improvement in the properties of composite samples included the all ratios up to 2% Vf. of the adding filler, and the properties were then decreased. The mechanical property that was studied was the flexural resistance. Flexural properties of three types of FGMs (FGM1, FGM2 and FGM3), isotropic nanocomposite (1% SiO2) and pristine epoxy in order to evaluate their mechanical property, such as Stress–Strain criteria and flexural Young’s modulus, were obtained by 3-point bending test, with loading from pure and composite side for FGM1 and at one side of FGM2 and FGM3 isotropic nanocomposite (1% SiO2) and pristine epoxy. The results manifested that the flexural strength and Young’s modulus loaded from the pure epoxy side was higher than when samples loaded from the composites side for FGM1. The mechanical properties of the epoxy resin and nanocomposites (tensile and compression) and the density for each layer were determined and could be useful for the finite element analysis of the 3-point bending test for FGMs specimens by using Design Modeler (ANSYS Workbench). Experimental results were validated by developing a detailed three-dimensional finite element model. Results of the progressive deformation from the finite element model agreed well with the experimental results.