Showing 4 results for Honarpisheh
Ahmad Reza Ghasemi, Mohammad Ali Moazam, Mohammad Honarpisheh,
Volume 17, Issue 4 (6-2017)
Abstract
Measurement of fracture toughness is one of the quality control parameter in rail manufacturing process. Fracture toughness value is needed for designing the rail lines, analysis of defects and other common prevalent works in mechanical engineering. The goal of this research is to introduce a relation for measuring fracture toughness of rail materials with grade R260 by Charpy V-notch number. At first the fracture toughness of rail material has been determined by 3-point bending technique according to ASTM E399 in ambient temperature. The fracture energies have been measured by Charpy impact test and it has been illustrated that fracture energies have no significant change in the tests temperature limit. Relations between the chemical analysis and mechanical properties have been studied and compared with results of the other researcher. Uniaxial tension test, analysis of chemical composite, metallography and hardness test have been carried out to better study of the process. Finally a relation to connect the Charpy V-notch number and fracture toughness has been introduced and the fracture toughness of the rails material over the impact test temperature limit has been calculated. Good agreement between calculated results and result of 3-pint bending test indicate appropriate accuracy of the introduced equation.
M. Honarpisheh , M.h. Tavajjohi , F. Nazari,
Volume 19, Issue 2 (February 2019)
Abstract
The Constrained Groove Pressing (CGP) process is one of the most effective and newest methods of the severe plastic deformation for production ultrafine-grain metal sheets. In this research, the effect of CGP on the microstructure and mechanical properties of pure copper sheets was investigated. In order to study the microstructure of the samples, the optical microscopy was used, and tensile and Vickers micro-hardness tests were utilized for the evaluation of the mechanical properties. Investigating the microstructure of CGPed sheets determined that the CGP process has caused intense grain refinement, especially at first pass. Also, the results of mechanical properties showed that this process has considerably increased strength and hardness of the copper samples. In the numerical investigation of constrained groove pressing, effective strain and forming force were evaluated, using finite element simulation and the results indicated that with increasing number of CGP passes, effective strain, and forming force increase. Also, distribution of effective strain illustrated that the center of samples are under more effective strain that causes increasing hardness inside the samples be more than increasing hardness of the surface. Finally, a method was presented for estimating the yield strength of material, using the hardness values, and it could calculate the yield stress in different passes of process with an acceptable error of 6%.
M. Aghaei, F. Nazari, M. Honarpisheh,
Volume 19, Issue 12 (December 2019)
Abstract
Quenching heat treatment is one of the most used processes in the industry, which has a great influence on the properties of materials. Accurate understanding of the effects of this process on the behavior of materials can be effective in better use of this process. In this research, the effect of quenching media on the mechanical behavior of wide used steel of AISI 1045 has been investigated and the residual stress created in the structure has been studied using the contour method. In this regard, three cooling environments of water, oil, and molten salt have been utilized, and after examining the strength and contour of hardness resulted by each cooling environment, the residual stresses have been investigated by the contour method. Also, the uncertainty of residual stresses in the environment with the most influencing factor has been evaluated. Investigation of the results shows that quenching in water can create higher hardness and strength, and more excessive compressive residual stress with greater penetration depth than the other environments. But cooling media of water creates more heterogeneous of the structure between the surface and the center of the piece, while quenching in a molten salt environment, with maintaining a structural homogeneity close to the annealing state, can increase the hardness and strength, and generate compressive residual stresses with a penetration depth of about 1.3 mm. Investigation of uncertainty for quenching in the water environment showed that the greatest error in the residual stresses was about 9%, and the error resulting from data smoothing had the most effect on the measurement of residual stresses by the cantor method.
Hamid Reza Ghahreman, Mohammad Honarpisheh, Mohammad Bagher Sarafrazi,
Volume 22, Issue 5 (May 2022)
Abstract
One of the forming pipes methods is the rotary draw bending process. Today, bending of thin-walled pipes with low radius of curvature is widely used in the automotive, military and aerospace industries, which is used to bend high-strength pipes. In this paper, at first the necessary models were created to simulate the bending process of the rotary pipe, and then the necessary mechanical and physical properties for stainless steel 304 and elastomers were determined. Then, experimental and numerical study of the forming force and changes in pipe wall thickness were performed. The process simulation was analytically performed using polyurethane elastomeric mandrels and nitrile rubber based on ABAQUS finite element software on 304 steel. The results show a good agreement between simulation and experimental results. Finally, the effects of process parameters including mandrel type, pipe diameter and bending radius were analyzed on the maximum forming force by factorial analysis. The results showed that the maximum forming force for both types of mandrel materials is obtained for pipes with small diameter and high curvature radius. Also, the bending forces increase 5 times by 30%increasing the bending radius, for pipes with smaller diameters. In addition, in equal diameter and radius of bending, the bending forces in the case of using polyurethane mandrel are 25% more than nitrile mandrel.
