Showing 6 results for Asghari
M. Rezaiee-Pajand and H. Asghari,
Volume 15, Issue 2 (1-1997)
Abstract
This paper is on the elasto-plastic analysis of plane stress problems. A five-parameter yield surface is presented. This yield criterion uses associate flow along with mixed hardening rule. The analytical formulations are written and related computer program for non-linear analysis is prepared. Finally, based on the formulations, numerical examples are solved.
M. Salimi and S. Asghari,
Volume 24, Issue 1 (7-2005)
Abstract
In this paper an analytical model for cold rolling of strip has been described. This model is developed based on the slab method of analysis and the hydrodynamic lubrication. The characteristics of rolling are obtained from the equations of equilibrium and the plate was allowed to strain harden assuming that the lubricant behaves as a Newtonian fluid. The shear stress to the plate is obtained by calculating the thickness of the lubricant film by employing a viscosity-pressure-temperature relation. The governing equations are obtained by composing these relations and the final differential equations have been solved. From the solution of the final equation, the rolling force، torque and shear stress to the plate are calculated. To verify the validity of
the proposed model, these values are compared with experimental and analytical results of other investigators. It was also noted that by employing the proposed analytical model, a large amount of computation time and costs are saved
R. Lotfi Orimi, V. Asghari , M. Lashkarbolouki,
Volume 30, Issue 1 (Jun 2011)
Abstract
ZnS nanoparticles were synthesized by chemical precipitation method. As-prepared ZnS nanoparticles were found to be stabilized in the form of cubic phase. Cubic to hexagonal structural transformation was studied using X-ray diffraction (XRD). The effect of annealing temperature (100-700 ) on the band gap, particle size, and structural phase was investigated. Photoluminescence studies indicated two strong and narrow emission peaks in blue and orange regions. These two strong and narrow emission peaks were shifted to blue and red regions by increasing the annealing temperature..
S. Yousefi, B. Ghasemi, M. Tajalli, A. Asghari,
Volume 36, Issue 4 (Journal of Advanced Materials-Winter 2018)
Abstract
In this paper, high purity magnesium hydroxide nanoplates were successfully synthesized by using brine rich in magnesium ions as precursor and NaOH as precipitating agent without using dispersant agent in the room temoerature. The study and characterization of various properties of obtained nanopowder was carried out by X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-ray Fluorescence Spectrometer (EDX), Fourier Transform Infrared Spectrophotometer (FTIR) and Ultraviolet–visible spectroscopy (UV-Vis). The FESEM and XRD analysis results showed that magnesium hydroxide powder had nanoplates with the average crystallite size 17.1nm and no impurity; that was in agreement with the result of EDX and FTIR perfectly. Furthermore, optical characteristics of magnesium hydroxide nanoplates by UV-Vis spectroscopy showed an optical band gap of 5.5 eV. This wide band gap can be a useful innovation in optoelectronic sub-micron devices.
M. R. Pakmanesh, M. Shamanian, S. Asghari,
Volume 36, Issue 4 (Journal of Advanced Materials-Winter 2018)
Abstract
In the present study, the optimization of pulsed Nd:YAG laser welding parameters was done on a lap-joint of a 316L stainless steel foil in order to predict the weld geometry through response surface methodology. For this purpose, the effects of laser power, pulse duration, and frequency were investigated. By presenting a second-order polynomial, the above-mentioned statistical method was managed to be well employed to evaluate the effect of welding parameters on weld width. The results showed that the weld width at the upper, middle and lower surfaces of weld cross section increases by increasing pulse durationand laser power; however, the effects of these parameters on the mentioned levels are different. The effect of pulse duration in the models of weld upper, middle and lower widths was calculated as 76, 73 and 68%, respectively. Moreover, the effect of power on theses widths was determined as 18, 24 and 28%, respectively. Finally, by superimposing these models, optimum conditions were obtained to attain a full penetration weld and the weld with no defects.
S. Asghari, A. M. Eslami, A. Taheri Zadeh, N. Saeidi,
Volume 39, Issue 3 (Journal of Advanced Materials-Fall 2020)
Abstract
In this study, the effect of welding heat input on microstructure and mechanical properties of dissimilar joints of API-X42 and API-B pipeline steels was investigated. Evaluation of the microstructures showed that increasing the welding heat input decreased acicular ferrite in weld metal microstructure, while amount of Widmanstatten ferrite, polygonal ferrite and grain boundary ferrite increased. Also, results of microhardness test showed that by increasing the heat input, hardness of weld metal and the heat affected zone decreased. Tensile test results showed that as the heat input increased, fracture transferred from base metal of API-B to the heat affected zone. Impact test results also showed that increasing the welding heat input could sharply drop the impact energy of the heat affected zone for both base metals due to extensive grain growth.
