Showing 5 results for Hom
K. Mazaheri and H. Assadollahi,
Volume 21, Issue 2 (1-2003)
Abstract
One of the basic equations to analyze the detonation of high explosives is the equation of state of the detonation products. Due to the very high pressure of the product, the direct measurement of the thermodynamic variables such as pressure or temperature is not possible. In this research, the parameters of BKW and HOM equations of state of detonation products are determined via experimental measurement of the detonation velocity. Comparing the calculated parameters show good agreement with the published results for a vast range of explosives.
It is also shown that the curve fitting of the enthalpy of the products in standard states to a forth degree polynomial of temperature improves the results with respect to entropy fitting used by Mader.
Keywords: BKW, HOM, Equation of state, Detonation product, Explosion simulation
M. Kamalian and A. Sohrabi Bidar,
Volume 24, Issue 2 (1-2006)
Abstract
This paper presents the complete algorithm of site response analysis of nonhomogeneous topographic structures using transient two-dimensional boundary element method (BEM). Seismic behaviour of various topographic features including canyon, half plane, sedimentary filled valley and ridge sections, subjected to incident SV and P waves are analysed. The analysis shows the efficiency of the proposed algorithm and its advantage over common transformed domains methods in forming a basis for extension to non-linear behaviour.
A. Samadi, A. Abdollah-Zadeh, S.h. Razavi , H. Assadi,
Volume 29, Issue 1 (6-2010)
Abstract
The initial stages of the precipitation in a dilute Ni-Al binary alloy, Ni-11.6 at.%Al, were studied using differential
scanning calorimetry (DSC), X-ray diffraction (XRD), electron diffraction and electron microscopy (FEG-SEM and TEM) techniques. Three samples were similarly solution treated and then cooled to room temperature under different cooling rates, 170، 25 and 0.03oCs-1. The results indicate a clearly homogenous nucleation during rapid quenching which takes place via simultaneous ordering and phase separation. However, by decreasing the cooling rate to 25oCs-1 the nucleation mechanism changes to heterogeneous on the preferred nucleation sites. The capability of the mentioned empirical techniques for studying the initial stages of the γ′ is another subject which is studied in this article.
M. Etminan, M. Morakabati, S. M. Qazi Mir Saeid,
Volume 39, Issue 2 (8-2020)
Abstract
The aim of this study was to investigate the effect of temperature and time of homogenization treatment on the microstructure, distribution of alloying elements and hardness of the novel Co-based superalloy Co-7Al-7W-4Ti-2Ta. For this purpose, the specimens were first homogenized at 1250 and 1300 °C for 2, 4, 6 and 8 hours and then water-cooled. Subsequently, the specimens were subjected to hardness testing and microstructural examinations by optical and electron microscopy. The results showed that by increasing the homogenization temperature to 1300 °C, the porosity created by Ti oxidation and local melting of the Co-Al-Ti eutectic compounds led to a decrease in hardness to 90 Vickers. This phenomenon was due to high segregation of alloying elements in the cast structure. The intensity and destructive effects of this segregation were reduced by remelting of alloy. However, by homogenization at 1250 °C, no local melting of eutectic zones or porosity were observed in the specimens and a more uniform structure was obtained with increasing time. Minimum and maximum hardness values after homogenization at 1250°C were 348 and 406 Vickers, respectively. Moreover, the microstructure became more homogenous by increasing the homogenization treatment time at this temperature.
F. Fareghdeli, M. Karimi, A. Novin, M. Solati-Hashjin,
Volume 40, Issue 3 (11-2021)
Abstract
One challenge in preparing polymer/ceramic composites is non-uniform ceramic particles distribution in a polymer matrix. This research evaluated the effect of stirring time and temperature on hydroxyapatite (HA) distribution through (polylactic acid) PLA matrix. Therefore, to mix the ceramic suspension with the polymer solution, three temperatures, namely 25, 37, and 45°C and four times including 6, 12, 24 and, 48 h were examined. Fourier-transform infrared spectroscopy (FTIR) analysis was used to investigate the bonds, which showed physical bond formation such as carboxyl-calcium-carboxyl between HA and polymer matrix, influenced on particles distribution. Scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDS) were used to observe particles distribution and determine samples homogeneity. To fulfill this goal, each obtained photograph representing the calcium presentation was split into nine equal sections, and a method based on the newly defined index called dispersion factor “α” was used to analyze the distribution. Results showed that the sample prepared at 37°C and 48 h had the topmost homogeneity properties.
