Papers by Author: M. Ghazinejad

Abstract: Monodispersed nanometer-sized particles proved to be very important and advantageous in many industrial applications. One of the notable groups of these particles is silica (SiO2) nanoparticles which are widely utilized in developing numerous products such as electrical and thermal insulators, humidity sensors, varnish, etc. Since the quality of some of these products depends highly on the purity and size distribution of the silica particles, it is necessary to produce silica nanoparticles of narrow size distribution and very high purity. In this research silica nanoparticles, with a relatively narrow size distribution, have been synthesized via the hydrolysis reaction of tetraethoxisilane (TEOS) in the solution of deionized water and ethanol (C2H5OH), and in the presence of ammonia (NH3) as a catalyst. The nature, morphology and the size of the silica particles has been studied using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and X-ray diffraction. Results indicate that the morphology, structure and the diameter of silica particles depend strongly on the molar ratios of the reactants.

Abstract: In this paper the effect of stress induced phase transformation on the vibration response of SMA structures has been studied. To this end, a Ni-Ti clamped-free rod in the superelastic range which is subjected to axial harmonic loading has been considered. Subsequently, the dynamic behavior of the superelastic rod has been analyzed using Auricchio’s superelastic model, which can reproduce the superelastic behavior of the sample during stress induced phase transformation, and Finite Element Method. Obtained Results show that due to the phase transformation the dynamic behavior of superelastic rod is highly nonlinear. Also, it can be deduced that superelastic components with large hysteresis loop has the potential for use in vibration attenuation of structures.