فهرست مطالب

  • Volume:12 Issue:3, 2019
  • تاریخ انتشار: 1398/06/10
  • تعداد عناوین: 10
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  • Mohammad Meghdad Fallah *, Seyyed Reza Hamzeloo Pages 1-8
    Reducing energy consumption is a demanding issue considering the limited available energy resources and increasing environmental pollution. On the other hand, industry consumes a huge amount of energy, and manufacturing processes are the most energy consuming portions of the industry. Machining issues including cutting tool geometry and process parameters affect the cutting forces and also production consuming energy. By increasing cutting forces, the tool life would be reduced and therewith cost of machining process increases. In this work, the effect of machining condition on cutting force and energy consumption studied in turning process during validated FE analysis using ALE method. So, the effect of rake angle, tool edge radius and cutting speed was investigated on the cutting force, plastic strain and plastic consuming energy. Results proved that these parameters are effective on plastic energy consumption in turning process among them cutting speed has more effect on the plastic energy. By increasing the cutting speed, the plastic energy decreases considerably. Rake angle is also effective on process energy consumption and the combination of increasing the rake angle and cutting speed, and choosing the optimal edge radius leads to the minimized plastic energy.
    Keywords: AISI, Cutting Parameters, FE Simulation, Plastic Energy, Turning Process, Tool Geometry
  • Mostafa Sayahbadkhor *, Ali Mozafari, Alireza Naddaf Pages 9-18

    Nowadays most of reciprocating compressors have one - way valves that act by difference pressure between behind and front of valves. In this article, experimental and numerical studying of one - way valves in reciprocating compressors was done. In this experimental tests, one – way valve with two different materials for rings; stainless steel with the material number 1.5022 and sign 38si6, and carbon-peek composite, were used. Numerical simulation for one-way valves with identical characteristics of experimental tests was done by CFX 5.7.1 and Ansys workbench 9.1. Experimental tests showed that life of carbon-peek composite ring was more than stainless steel. The most important cause of failure in the stainless steel ring was inappropriate distribution of forces due to the springs below the ring. Another common cause of failure in these valves was the stresses on walls in the location of springs that approved by numerical simulation. Difference in reaction of one - way valves in opening and closeing was another cause of failure because they were different in thermal expansion coefficient, thickness and diameter of carbon-peek composite and stainless steel rings. Appropriate thickness of rings determined by flow equation. The results obtained from numerical simulations have a good agreement with experimental tests.

    Keywords: Experimental Test, Failure, Numerical Simulation, One–Way Valve, Reciprocating Compressor
  • Hossein Khorshidnia, Alireza Shirneshan * Pages 19-24
    The addition of nanoparticles to lubricant is effective for the reduction of wear and friction in the mechanical system. In this research, the effects of additions of copper oxide nanoparticle nanoparticles on lubrication behavior of biodiesel-diesel fuel blends were investigated by using a four-ball tester. Three fuel blends with the addition of 0, 25, 50 and 75 ppm nanoparticle were tested in steady-state conditions at four different rotational speed of 600, 1200 and 1500 rev/min. the results showed that the friction coefficient decreases with the increase in nanoparticles up to 50 ppm because of filling the friction surface with the nanoparticles and replacement of sliding friction with the rolling effect in the contact zone. On the other hand, the FC was enhanced significantly with 75 ppm nanoparticle addition in fuel blends B10 and B20. However, the results showed that the lubrication of fuel blend B50 with the 75 ppm nanoparticle is better than that of other fuel blends in the same situation. Moreover, it was found that with an increase in biodiesel concentration the friction coefficient was reduced due to free fatty acids, monoglycerides, and diglycerides as the components of biodiesel.
    Keywords: Biodiesel, Four-ball Tester, Friction, Nanoparticle
  • Sajjad Khaki, Ali Heidari *, Amin Kolahdooz Pages 25-33
    As a solid-state welding method, friction stir welding is widely employed for welding aluminium alloys. An important subject in this regard is the optimal adjustment of the parameters to maximize the ultimate tensile strength and the surface hardness. Four parameters have been selected for the multi-objective optimization of the 6061-T6 aluminium alloy, namely the rotational and the linear speed of the tool, the variation of the shoulder diameter with respect to the pin diameter (D⁄d ratio), and the shoulder base angle. The Taguchi's L9 Orthogonal Array has been employed for designing experiments. The experimental results have been examined using the Taguchi signal-to-noise (S/N) method, the analysis of variance, and regression. Optimization using the multi-objective Taguchi function revealed that a rotational speed of 800 rpm, a D⁄d ratio of 18/6, a shoulder base angle of 7°, and a linear speed of 80 mm/min yield both maximum strength and surface hardness. The results of the S/N analysis suggested the rotational speed of the tool and the linear tool speed have the most significant impact on the tensile strength with the average of 44.07 dB. On the other hand, the linear speed and the ratio of the diameters have the most significant impact on the surface hardness (around 36.91 dB). The results showed that using this optimization method, simultaneous improvement of tensile strength and surface hardness occurs. In fact, the tensile strength and hardness of the sheet surface were improved by 17.3% and 6.2%, respectively.
    Keywords: Aluminium Alloy, Friction Stir Welding, Hardness, Taguchi Technique, Strength
  • Afshin Lotfi, Davood Afshari *, Zuheir Barsoum Pages 35-41
    The purpose of this study is to investigate the effect of resistance spot welding (RSW) parameters on nugget size and ultimate strength of Magnesium alloy sheets AZ61 under tensile-shear test. In this study microstructural examination and hardness measurements were carried out on the welded samples. The results show that the weld nugget zone is divided into two separate parts: the equiaxed dendritic zone (EDZ) perched at the center of the weld nugget and the columnar dendritic zone (CDZ) situated around the fine-grained zone having it surrounded. The effect of the following three parameters: electric current, welding time and electrode force on the dimensions of the weld nugget and the welded ultimate strength is investigated. The response surface method (RSM) is employed to examine the effects of welding parameters and to attain optimum parameters. The analysis of variance (ANOVA) results of RSM model shows that however the tensile-shear strength and nugget size are improved with increasing the welding current and welding time, the welding current is the most influential parameter. In addition, the optimal values for the welding parameters are calculated to achieve the maximum nugget size and the ultimate strength of welded joint. Finally, a regression model is proposed in order to predict the peak load and the nugget size as function of the mentioned welding parameters.
    Keywords: AZ61 Mg Alloy, Optimization, Resistance Spot Weld, Response Surface Method
  • Saurabh Malpotra * Pages 43-50
    This paper discusses about the lapping process for both metallic and non-metallic materials. The experiments were carried out based on the RSM design of experiments (DOE) approach to investigate the effect of their parameters on the lapping quality of ball bearing, for predicting the new results. This study explored the modification for fine finishing of bearing balls through Biodegradable medium (Aloe Vera) and silicon carbide (SiC) powder as an abrasive in addition of conventional oil-based media having an advantage like Antioxidant, antibacterial, non–toxic, good compression, and shear stresses. Spindle speed (rpm), Time (minutes), Force (N), Abrasive concentration were considered as the input process variables while the PISF, MRR and surface Roundness was considered as the process response. The result shows the most significant parameter for maximum PISF of 82.3%, 7.6 mg/min MRR and 9.05μm roundness was achieved with 672 rpm at 7.5 N force, 37.5% abrasive concentration, 165 minutes experimental run time, was achieved.
    Keywords: Biodegradable Material, Design Expert, Lapping Process, Steel Ball Finishing
  • Jamaledin Binanejad, Amir Homayoon Meghdadi * Pages 51-62

    Despite the growing trend in the petrochemical industry in the country, the industry has faced challenges and accomplishments. One of the most important challenges in the petrochemical industry is energy management in the refinery. Fajr Jam refinery is designed to refine part of sour gas produced from Phase 6 of South Pars gas field in Iran and the nominal capacity of gas refining at this site, to determine the factors affecting energy consumption in the ophthalmic furnaces, 104 and 109 kilns were selected and the following were monitored scientifically: monitoring of furnace wall temperature with thermography, furnace feed analysis, steak gas analysis and energy efficiency of furnaces. The results of this study showed that in the furnace 104, the design efficiency and real efficiency was 92.98 and 84.67, respectively and for the furnace 109, the design efficiency and real efficiency was 94.98 and 71.18, respectively. As a result, the amount of energy loss is high and should save energy consumption in these furnaces and improve efficiency: replacement of refractory refractories is also a replacement of insulation.

    Keywords: Cracking, Energy Dissipation, Furnace Efficiency, Optimization, Steak, Thermography
  • Mohsen Rahmani, Younes Mohammadi* Pages 63-75

    For the first time, by applying a modified high order sandwich plates theory, vibration behaviour of two types of porous FG circular sandwich plates are investigated. In the first type, the face sheets and in the second one, the core is made of FGM which is modelled by power law rule that is modified by considering two types of porosity distributions. All materials are temperature dependent and uniform temperature distribution is used to model the effect of the temperature changing in the sandwiches. Governing equations are obtained by the Hamilton's energy principle and solved by Galerkin method for a clamped boundary condition. To verify the results, they are compared with FEM results obtained by Abaqus software and for special cases with the results in literatures.

    Keywords: FG Core, FG Face-Sheets, Porosity, Temperature Dependent, Vibration
  • Amir Vasei Moghadam, Hamid Reza Goshayeshi * Pages 77-84

    The enhancements in boiling heat transfer can bring immediate benefits to improve the efficiency and cost of heat energy transfer. In this study, heat transfer coefficient in pool boiling of single wall carbon nanotube-water (SWCNTs) at a concentration of 0. 05, 0. 1 and 0. 15 vol. % on smooth and grooved surfaces has been investigated experimentally at atmospheric pressure. The effect of some shapes namely circular groove, square groove and straight groove on the boiling heat transfer has been also investigated. The experimental results indicated that making different grooved surfaces and also using (SWCNTs)-water enhanced the boiling heat transfer coefficient. The highest increase in heat transfer coefficient was seen in circular grooved, which is 76% higher than the base fluid water on the smooth surface. The heat flux has been changed from 0 to 140 kW/m2. By comparing the results, the circular groove with 0.15% concentration of SWCNTs has higher heat transfer coefficient for the boiling heat transfer. Based on pool boiling surfaces, a new type of grooves pool pooling surface was designed and constructed, which is consisted of inclined circular groove at angle of 45°. Outcome of the present work definitely indicates that the inclination of the circular groove could be excellent option for the increasing of pool boiling heat transfer. Cornwel-Houston correlation has been modified to take care of the effect of grooved surfaces for correlating the Nusselt number as a function of Reynolds number and Prandtl number in pool boiling. This new correlation agrees with the experimental data from the augmented surface satisfactory.

    Keywords: Grooved Surface, Heat Transfer Coefficient, Pool Boiling, Single Wall Carbon Nanotube
  • Saeid Esmaeili, Mohsen Loh, Mousavi*, Sayyed Ali Eftekhari Pages 85-91

    Single point incremental forming (SPIF) and fused deposition modeling 3D printing (FDM) are two methods of rapid prototyping. Each method has its own pros and cons. using SPIF method can provide an accurate forming process to shape sheets fabricated by 3D printing with their special characteristics. In this study, single-point incremental forming of Poly Lactic Acid (PLA) sheets fabricated by FDM 3D printer was investigated by experiments. The formability process was evaluated by two different experiments. In the first experiment, a lubricant was used at ambient temperature and SPIF was investigated and for the second experiment hot air and lubrication were employed to achieve better formability. In addition, the effects of sheet thickness and strategy of layering of printed sheets by FDM were also studied on SPIF formability. The results showed that the incremental forming of printed PLA sheets in hot air is a more successful state to produce dome shapes parts and ruptures are less and this forming method can be used for some applications such as making partial curve of skull as a medicine solution in surgeries. Also, it was shown that the best layering strategy to print the PLA sheets used for better forming of SPIF is triangular pattern strategy against with rectangular strategy. It was found that thickness of 2mm printed sheet has better formability and less rupture versus 3mm of thickness.

    Keywords: 3D Printer, Formability, Incremental Forming, Orthopedic Appliance