Abstract
In the present paper a continuous Finite Element Analysis (FEA) simulation method of the ball indentation hardness test is introduced in order to describe the deformation behavior of nanosilica composites and with this to extract precisely the material's stress-strain behavior. The developed procedure demonstrate in particular the adequacy of this method to determine the nanocomposites' elastic modulus which is compared with Halpin-Tsai and Lewis-Nielsen models as well as with experimental measurements taken from uniaxial tensile tests. The fracture area of all the tensile specimens was examined using a scanning electron microscope (SEM). It is shown that the correlation between the experimental results, the semi-empirical models and the FEA computational models concerning the elastic modulus values was satisfactory with very small deviations.
Highlights
In recent years there are concentrated efforts on the development of advanced materials through the addition of nano-reinforcements on various matrices for higher mechanical, thermal and physical properties
The epoxy resin that has been used to form the nanocomposites was the SP115 supplied by Gurit, UK which is a standard diglycidyl ether of bis-phenol A/F (DGEBA/F) with a tensile modulus of 3.7 GPa and an epoxide equivalent weight (EEW) of 169,7 g/eq as given by the manufacturer
The homogeneous dispersion of these high stiffness nanofillers in the matrix enhanced the fracture toughness of the system as indicated by the larger area under stress-strain curve of the nanocomposite system
Summary
In recent years there are concentrated efforts on the development of advanced materials through the addition of nano-reinforcements on various matrices for higher mechanical, thermal and physical properties. Nanofiller aggregation introduces local stress concentration within the structure, while a weak particle-matrix adhesion reduces the capability of the load transfer mechanism between the nanofillers These lead to a premature failure of the polymer and reduce its strength and strain to failure. The presence of nanosilica improved ductility and promoted higher plastic hardening behavior after yielding in comparison with the unmodified resin system This result suggested that nanoparticles introduced additional mechanisms of energy absorption to enhance the compressive properties without reducing the deformation to failure. Despite the rigorous research on the effect of nanosilica particles on the mechanical behavior of the composite materials, there is a necessity for utilizing procedures using small samples to minimize the high costs involved with the preparation of samples that have embedded nanomaterials as compared to the standard tensile and compression test samples. The results obtained from the experimental tests and the elastic modulus was compared the Halpin-Tsai and Lewis-Nielsen models as well as with a developed finite element model simulating the ball indentation experiment
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