چكيده به لاتين
The main purpose of this study is to simulate the Nanoindentation test on dental nanocomposite material, Filtek Z350 XT, and to compare the obtained mechanical properties by the experimental data. Nanoindentation is a suitable method to determine mechanical properties of relatively small samples and surface characteristics.
To determine mechanical properties in the ranges mentioned in references for each of the phases which the nanocomposite material is made of, compression test is simulated on a RVE in three different directions, and the results are compared to the experimental results of this test. Moreover, efforts have been made to reach to a model close to real conditions, including using random distribution of particles in RVE space and utilizing periodic boundary conditions. Due to Nanoindentation test being local, it was decided to increase the simulation cases for more RVEs.
At the end of the study, comparing Nanoindentation test and simulation results, the necessary conditions for suitable RVEs were studied. The results showed that to determine the physical properties (elasticity modulus, hardness, etc), the RVEs are more suitable in which convergence to target volume fraction is achieved in radial distances less than that of the tip of indentor.
The analysis of Nanoindentation test was done by the modified Oliver-Pharr method, while, in numerical simulation of this test, the analysis was done by real contact area of the indentor and sample, in addition to Oliver-Pharr method. All of the results showed occurrence of rigid body motion of sink in Nanofiller clusters in matrix space. Finally, comparison of the results corresponding to compression test and Nanoindentation test is presented.
It should be noted that this is the first research to simulate the nanoindentation test on several RVEs with random particle distribution and periodic boundary conditions. Previously, simulations in this field were performed on simple RVEs consisting of a single particle or a limited number of particle with manual distribution and the application of simple symmetric boundary conditions. In addition, it is the first research to compare the simulation results of macro compression test with simulation results of nanoindentation test in different areas.
