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دسترسی آزاد مقاله
1 - The experimental approach into the influence of external inductance on the discharge characteristic of HiPIMS
Saeed Ghasemi Pourya Seyfi Alireza Farhadizadeh Hamid GhomiAbstractThe main objective of the current paper is to describe the effect of external inductance (EI) on the current discharge waveforms of HiPIMS at different pulse-on time (Pon) and its relation with static deposition rate and topographical properties of deposited tit چکیده کاملAbstractThe main objective of the current paper is to describe the effect of external inductance (EI) on the current discharge waveforms of HiPIMS at different pulse-on time (Pon) and its relation with static deposition rate and topographical properties of deposited titanium thin films, which is investigated by scanning electron microscope and atomic force microscope. It has shown that the higher the EI, independent of the Pon, the higher the peak power is. The delay time also extensively increases when an EI is implemented into the circuit. However, the rise time does not have a linear dependency with the EI and its behavior changes to some extent at different Pon. By increasing the EI from zero to 30 mH at Pon = 60 μs, the peak power subsequently rises from 11 to 32 kW at constant time-average power. Meanwhile, the deposition rate decreases from 8.5 to 1.5 nm/min, which is mainly attributed to the metal ions return to the target surface and nonlinear dependency of sputtering yield with applied voltage. It was also revealed that the higher peak power has no special effect on the surface roughness of titanium thin films deposited by HiPIMS. پرونده مقاله -
دسترسی آزاد مقاله
2 - بررسی آزمایشگاهی اثر سازه راه ماهی V شکل بر تغییرات زبری راه ماهی
مریم شهابی جواد احدیان مرجان نری موسی مهدی قمشی حسین عزیزی نادیانزمینه و هدف: در این پژوهش اقدام به استفاده از سرریزی جدید با ساختاری شکل به‌عنوان مانعی در کالورت شد. به‌طوری‌که بررسی عملکرد آن بر تغییرات خصوصیات مقاومت جریان همانند جذر ضریب افت اصطکاک مودی سازه و ضریب زبری مانینگ هدف اصلی پژوهش حاضر قرار گرفتند.روش پژوهش: آزمایش‌های چکیده کاملزمینه و هدف: در این پژوهش اقدام به استفاده از سرریزی جدید با ساختاری شکل به‌عنوان مانعی در کالورت شد. به‌طوری‌که بررسی عملکرد آن بر تغییرات خصوصیات مقاومت جریان همانند جذر ضریب افت اصطکاک مودی سازه و ضریب زبری مانینگ هدف اصلی پژوهش حاضر قرار گرفتند.روش پژوهش: آزمایش‌های پژوهش حاضر در مدل فیزیکی موجود در آزمایشگاه هیدرولیک دانشکده مهندسی آب و محیط‌زیست دانشگاه شهید چمران اهواز صورت گرفت. این مدل فیزیکی شامل یک فلوم آزمایشگاهی به طول 10 متر، عرض 25/0 متر و ارتفاع 5/0 متر هست. در ابتدای هر آزمایش، سازه‌ها در فاصله‌های نسبی مشخص در بستر فلوم چسبانده می‌شد. در ادامه باگذشت 24 ساعت از چسباندن سازه‌ها اقدام به تنظیم دبی جریان و شیب فلوم می‌گردید. دبی‌های موردنظر از طریق سرریز مثلثی با زاویه 53 درجه واقع در پایین‌دست فلوم و شیب از طریق جک تنظیم می‌گردید. به‌منظور برداشت پروفیل سطح آب از پوینت گیج با دقت 1/0 میلی‌متر استفاده می‌گردیدیافته‌ها: با افزایش دبی بدون بعد در یک فاصله نسبی بین سازه‌ها و شیب مشخص، ضریب زبری مانینگ سازه کاهش می‌یابد. به‌طوری‌که در شیب 10%، فاصله نسبی بین سازه‌ها 3/1 مقدار ضریب زبری مانینگ سازه از دبی بدون بعد 20/0 به 43/0 به‌اندازه 30% کاهش یافت. با افزایش فاصله نسبی بین سازه‌ها در یک دبی مشخص، ضریب زبری مانینگ سازه کاهش می‌یابد که این روند همانند اثرگذاری فاصله نسبی بین سازه‌ها بر جذر ضریب افت اصطکاک مودی سازه است.نتایج: در بررسی روند اثرگذاری سازه راه ماهی V مشخص شد که دبی بدون بعد دارای اثر معکوس بر ضریب اصطکاک جریان و ضریب زبری مانینگ سازه است. از طرفی ارتباط معکوس عدد فرود بر ضریب اصطکاک جریان و ضریب مانینگ سازه مشخص شد. مشخص شد که فاصله نسبی بین سازه‌ها نیز دارای اثرگذاری معکوس بر ضریب اصطکاک جریان و ضریب مانینگ سازه است. اثرگذاری معکوس عدد رینولدز بر پارامترهای مقاومتی جریان نیز استخراج شد. بهترین حالت سازه راه ماهی با سرریز v شکل پژوهش حاضر در فاصله نسبی بین سازه‌ها 3/1 و شیب 10% رخ می‌دهد. پرونده مقاله -
دسترسی آزاد مقاله
3 - Optimization The High Speed Machining of Hardened AISI 4140 Steel Using Vapor Deposited Cutting Tools (Wear and Roughness)
Mehdi Jalali Azizpour Ata FardaghaieIn this study, the main cutting parameters of high speed machining (HSM) including cutting speed, feed rate, depth of cut as well as deposition method were optimized using genetic algorithm considering the average surface roughness (Ra) of work piece and flank wear (Vb) چکیده کاملIn this study, the main cutting parameters of high speed machining (HSM) including cutting speed, feed rate, depth of cut as well as deposition method were optimized using genetic algorithm considering the average surface roughness (Ra) of work piece and flank wear (Vb) of CVD and PVD coated tool criteria in high speed turning of hardened AISI 4140 Steel. Standard L18 orthogonal array has been used for the design of experiment (DOE) applying Taguchi approach. Multiple linear regression model applying Minitab, was used to determine the relationship and interaction between machining parameters and outputs. For genetic algorithm(GA) optimization, the average was applied as a functional output of design of experiments. The results of GA for smaller- the better quality characterization shows the optimum roughness of 1.107 mm and optimum flank wear of 0.461mm. The confirmation tests were carried out in order to validate the response of predicted optimum condition. The results of validation test show a good agreement between obtained optimum condition and the results of genetic algorithm. The analysis of variance was used in order to obtain the contribution of each factor on the output statistically. ANOVA results indicated that the cutting speed and cut depth are the most effective factors on the flank wear by 37.02 and 27.80 percent contribution respectively. The most effective factors on surface roughness were feed rate and cutting speed by 82.49 and 10.50 percent contribution respectively. Stereoscopy and Scanning electron microscopy was used to evaluate the wear mechanism and topography of worn surface. پرونده مقاله -
دسترسی آزاد مقاله
4 - Estimation of Surface Roughness in Turning by Considering the Cutting Tool Vibration, Cutting Force and Tool Wear
A. Salimi A. Ebrahimpour M. Shalvandi E. SeidiSurfacequality along with the low production cost, play significant role in today’s manufacturing market. Quality of a product can be described by various parameters. One of the most important parameters affecting the product quality is surface roughness of the ma چکیده کاملSurfacequality along with the low production cost, play significant role in today’s manufacturing market. Quality of a product can be described by various parameters. One of the most important parameters affecting the product quality is surface roughness of the machined parts. Good surface finish not only assures quality, but also reduces the product cost. Before starting any machining process, surface finish is predictable using cutting parameters and estimation methods. Establishing a surface prediction system on a machine tool, avoids the need for secondary operation and leads to overall cost reduction. On the other hand, creating a surface estimation system in a machining plant, plays an important role in computer integrated manufacturing systems (CIMS). In this study, the effect of cutting parameters, cutting tool vibration, tool wear and cutting forces on surface roughness are analyzed by conducting experiments using different machining parameters, vibration and dynamometers sensors to register the amount of tool vibration amplitude and cutting force during the machining process. For this, a number of 63 tests are conducted using of different cutting parameters. To predict the surface quality for different parameters and sensor variables, an ANN model is designed and verified using the test results. The results confirm the model accuracy in which the R2 value of the tests was obtained as 0.99 comparing with each other. پرونده مقاله -
دسترسی آزاد مقاله
5 - Experimental Study on Magnetic Abrasive Honing of Inner Surface of Tube AISI304
Hamzeh Shahrajabian Masoud Farahnakian Payam SaraeianTo overcome the limitation of honing process, the present work proposes magnetic abrasive honing (MAH) process whereby abrasive stones are replaced by magnetic abrasives. This process is combination of magnetic abrasive finishing (MAF) and honing. MAF which is one of th چکیده کاملTo overcome the limitation of honing process, the present work proposes magnetic abrasive honing (MAH) process whereby abrasive stones are replaced by magnetic abrasives. This process is combination of magnetic abrasive finishing (MAF) and honing. MAF which is one of the finishing processes can improve the quality of workpiece surface with various geometries, removing the chips in micrometer scale by magnetic field forces. This study set to apply longitudinal vibration to the tube workpiece in MAF process; hence, this process is called MAH. The effects of rotary speed of workpiece, cross-hatch angle, and mesh number were investigated on the surface roughness of AISI 304. Magnetic abrasives were combination of SiC particles as abrasives and iron particles as ferromagnetic particles in lubricant of SAE 40 oil. The results revealed that the longitudinal movement of workpiece is effective on MAH, as the surface roughness decreased with increasing the cross-hatch angle. Surface roughness decreased with increase of rotary and mesh number. The major changes in surface roughness (58%) were obtained in cross-hatch angle of 45º rotary speed of 800 rpm and mesh size of 400. The microscopic picture showed that three-body wear mechanism is dominant for fine grits. پرونده مقاله -
دسترسی آزاد مقاله
6 - Experimental Study on Surface Roughness and Flatness in Lapping of AISI 52100 Steel
Masoud Farahnakian H. ُُShahrajabianLapping is one of the most important polishing processes which can be used to fabricate flat and smooth surfaces. In this paper, the effect of lapping characteristics and mesh number of abrasive particles are studied on the surface roughness and flatness for the machini چکیده کاملLapping is one of the most important polishing processes which can be used to fabricate flat and smooth surfaces. In this paper, the effect of lapping characteristics and mesh number of abrasive particles are studied on the surface roughness and flatness for the machining of hardened AISI 52100 rings. The most significant lapping characteristics are pressure, lap plate speed and time. Scanning electron microscopy and optical microscopy are used to investigate micro cracks and surface textures. Results showed that surface roughness increased by rising the lapping pressure and plate speed. Also, reduction of the lapping time and mesh number of abrasive particles led to lower surface roughness. Application of lapping process decreased the flatness to 1.2 µm and surface roughness (Ra) from 0.58 to 0.051 µm. The lapping pressure was a significant factor on the surface roughness; and the lapping time was a significant factor on flatness. However, surface roughness increased with rising of mesh number and lapping time, and increased with decreasing the lapping pressure. The minimum surface roughness was 0.051 μm which was obtained in lapping pressure of 7 kPa, lapping speed of 0.164 m/s, time of 15 min and mesh number of 600.The flatness decreased with lapping speed, and reduced with increasing the pressure, mesh number and lapping time. پرونده مقاله -
دسترسی آزاد مقاله
7 - Development of Process Model for Optimal Selection of Process Parameters for Geometric Tolerances and Surface Roughness in Stereolithography
Chockalingam Kunjan Jawahar N. Chandrasekhar U. Praveen J. Karthic M.The accuracy of stereolithography (SL) product is vital for meeting the intended functional applications. The parameters like layer thickness, hatch spacing, hatch overcure contribute significantly to the accuracy of the SL parts. In this paper an attempt has been made چکیده کاملThe accuracy of stereolithography (SL) product is vital for meeting the intended functional applications. The parameters like layer thickness, hatch spacing, hatch overcure contribute significantly to the accuracy of the SL parts. In this paper an attempt has been made to identify the process parameters that influences on the accuracy of the parts made with CIBA TOOL 5530 and optimize the process parameters. A standard test specimen is designed for this study. A process model between the geometric tolerance (parallelism, perpendicularity, angularity, radius fillet), surface roughness and the above mentioned process parameters (layer thickness, hatch spacing, hatch overcure) have been developed. It is found that parallelism, perpendicularity, angularity, radius fillet and surface roughness are influenced significantly by hatch spacing, layer thickness, hatch overcure, hatch spacing and layer thickness respectively. The percentage deviation between the experimental and process model values have also been calculated to validate the developed process model. پرونده مقاله -
دسترسی آزاد مقاله
8 - Influence of Vibratory Finishing Process by Incorporating Abrasive Ceramics and Glassy Materials on Surface Roughness of CK45 Steel
Payam Saraeian Mostafa Gholami Amir Behagh Omid Behagh Hamid Reza Javadinejad Mohammad MahdiehThe vibratory finishing is one of the important mass finishing processes. This can be applied for finishing many metallic and non- metallic components using abrasive materials such as steel, ceramic, natural materials and etc. The vibratory finishing process is used for چکیده کاملThe vibratory finishing is one of the important mass finishing processes. This can be applied for finishing many metallic and non- metallic components using abrasive materials such as steel, ceramic, natural materials and etc. The vibratory finishing process is used for some purposes such as surfaces polishing, deburring, oxide layer removing and rounding the edges. Evaluation of surface roughness changes with time that is one of the important parameters during the vibratory finishing process. In this study, the effects of the working time and abrasive materials are investigated on the surface roughness changes of CK45 steel samples. The ceramic, glass and mixed abrasive particles are used as the abrasive media. The experiments are performed at different time from 10 to 120 minutes in the dry environment. Finally, the surface roughness values of samples were measured and then fitted by a regression equation for description of the surface roughness changes with time. According to the results, the maximum surface finish was obtained after 120 minutes by using mixed abrasive materials. The surface roughness improved approximately 60%. پرونده مقاله -
دسترسی آزاد مقاله
9 - Investigating the Effect of Rotation Speed and Ultrasonic Vibrations in the Incremental Forming Process
Saeed Amini Farshad Nazari Mohammad Baraheni Amir Hossein GhasemiIncremental forming is one of the forming methods that is considered because of no need to specific die, especially for rapid prototyping. In this study, the incremental forming process is carried out by using a rotating tool and assisted ultrasonic vibration. Purpose o چکیده کاملIncremental forming is one of the forming methods that is considered because of no need to specific die, especially for rapid prototyping. In this study, the incremental forming process is carried out by using a rotating tool and assisted ultrasonic vibration. Purpose of this research is to investigate the effect of rotation speed and ultrasonic vibrations in the incremental forming process. According to the obtained results, mean and maximum values of forming force reduced by using a rotating tool and applying ultrasonic vibrations. The results of surface roughness tests demonstrated that by increasing rotational speed, the surface roughness improved 44% and applying ultrasonic vibrations with tool rotation can reduce surface roughness about 74%. Applying ultrasonic vibrations lead to increase micro-hardness up to 84%, but, by increasing rotational speed, surface hardness slightly reduces. Results of straight groove test determined ultrasonic vibrations with the rotating tool can increase stretching limit up to 41.79% due to the affect on the sheet plasticity behavior. پرونده مقاله -
دسترسی آزاد مقاله
10 - Effects of Abrasive Media on Surface Roughness in Barrel Finishing Process
Ali Vakili Sohrforozani Masoud Farahnakian Mohammad Sajjad Mahdieh Amir Masoud Behagh Omid BehaghBarrel finishing is a common technique for surface finishing of industrial parts. Many factors such as working time, abrasive media, initial roughness and machining parameters of rotary barrel affect the final surface roughness of workpieces. Analysing these input param چکیده کاملBarrel finishing is a common technique for surface finishing of industrial parts. Many factors such as working time, abrasive media, initial roughness and machining parameters of rotary barrel affect the final surface roughness of workpieces. Analysing these input parameters in order to obtain the least surface roughness as well as the least working time for barrel finishing of the specific samples, is not possible except by applying Design of Experiments method. Thus, the aim of the present paper is to improve the surface quality of the steel alloy CK45 samples in barrel finishing process, by investigating different combination of three abrasive particles including ceramics, steel balls and aluminium oxide as the abrasive media through design of experiments method. Initial roughness, working time and the combination of abrasive media are the input factors in the designed experiments, while the surface roughness is the output factor. Results show that the best surface roughness and working time have been achieved with the specific combination of steel balls and aluminium oxide particles as the abrasive media. پرونده مقاله -
دسترسی آزاد مقاله
11 - Thermal Loads and Surface Quality Evaluation in Machining of Hardened Die Steel under Dry and Cryogenic Machining
Farshid Jafarian Emad MohseniAISI H13 die steel is widely used in different industries because of its especial properties. During the machining of hard materials, some of the mechanical properties of the material are changed due to the generation of intensive thermo-mechanical loads and plastic def چکیده کاملAISI H13 die steel is widely used in different industries because of its especial properties. During the machining of hard materials, some of the mechanical properties of the material are changed due to the generation of intensive thermo-mechanical loads and plastic deformation into the workpiece. Controlling these intensive changes in machined surfaces is an important task and significantly affects the performance of the machined part. In addition, surface roughness is one of the aspects of surface texture and affects the fatigue life of the material. Since machining of hard materials is a difficult procedure and it is confronted with several limitations, new methods in machining processes are essential to be developed. One of these methods is using cryogenic coolant where the machining temperature may be considerably reduced by spraying liquid nitrogen on the cutting region. Based on this, at the present study, the variation of thermal loads and surface roughness at different machining parameters were evaluated under dry and cryogenic conditions. To do this, a thermal infrared camera and liquid nitrogen delivery system was used during the machining of hardened AISI H13 steel. Compared with dry condition, the effectiveness of the cryogenic coolant on surface roughness and thermal loads were analysed and discussed at different cutting speed, feed rate, and depth of cut. Finally, it was found that, applying cryogenic coolant in machining of AISI H13 die steel can be very effective to enhance performance and quality of the machined component in terms of surface roughness and thermal loads. پرونده مقاله -
دسترسی آزاد مقاله
12 - Evaluation of Fatigue Behavior and Surface Characteristics of Novel Machining Process: Rotary Chemical Machining (RCM)
Pooya Bahrami Ali Khoshanjam Abdolhamid AziziIn this study, Rotational Chemical Machining (RCM) as a novel machining process is introduced. The properties such as surface roughness and residual stress as well as fatigue strength of the RCM process are evaluated, discussed and compared to the conventional turning p چکیده کاملIn this study, Rotational Chemical Machining (RCM) as a novel machining process is introduced. The properties such as surface roughness and residual stress as well as fatigue strength of the RCM process are evaluated, discussed and compared to the conventional turning process. In this sense, Scanning Electron Microscope (SEM) and Atomic Force Microscope (AFM) were utilized. The results show the superiority of the RCM method over the conventional method and eliminate limits of process such as low surface quality and improve fatigue strength. The Amplitude Distribution Curve has a balanced Gaussian shape in RCM indicating the balanced distribution of peaks and valleys on machined surface. Due to the absence of machining force in the RCM process, in comparison to the turning process, maximum residual stress is significantly decreased from 363Mpa to 71Mpa; surface roughness reduced from 3.1µm to 1.5 µm as well as the fatigue strength improved 20% approximately. پرونده مقاله -
دسترسی آزاد مقاله
13 - Multi-Objective Optimization of Shot-Peening Parameters Using Modified Taguchi Technique
M Hassanzadeh S. E Moussavi TorshiziShot-peening is a surface treatments utilized extensively in the industry to enhance the performance of metal parts against fatigue. This paper aimed to find the optimal parameters of the shot-peening process based on the finite elements model and the Taguchi method. Th چکیده کاملShot-peening is a surface treatments utilized extensively in the industry to enhance the performance of metal parts against fatigue. This paper aimed to find the optimal parameters of the shot-peening process based on the finite elements model and the Taguchi method. The effects of three peening parameters (shot diameter, shot velocity, coverage percentage) are investigated on residual stress and roughness using Taguchi method. A new Taguchi technique is proposed by combining it with desirability function to optimize the shot-peening parameters that simultaneously provide two or more responses in an optimal mode. The results show that the coverage percentage has the most influence on the surface stress and maximum compressive stress whereas the velocity and diameter of the shot are the most effective parameters on the depth of compression stress. The shot velocity is the main factor of the surface roughness due to the shot peening. Through the proposed structure, optimal conditions can be obtained for surface stress and roughness simultaneously with high-coverage and low-velocity. Eventually, results reveal the effectiveness of the proposed strategy in stand point of saving time and cost. پرونده مقاله -
دسترسی آزاد مقاله
14 - Prediction of Vegetation Cover Effect on Bank and Bed Hydraulic Roughness Coefficient in Shiraz Khoshk River
محمدرضا نیک منشSoil and water resources management of rivers has an important role because of direct relation withdifferent systems such as earth, life, social and people. Although the use of vegetation cover inbioengineering and biological stabilization and also soil and water resour چکیده کاملSoil and water resources management of rivers has an important role because of direct relation withdifferent systems such as earth, life, social and people. Although the use of vegetation cover inbioengineering and biological stabilization and also soil and water resources management projects hasmany advantages, but improper methods of design and implementation cause hydraulic specificationsof river alter. The vegetation cover in river reach decreases flow mean velocity, river's width andincreases sedimentation in river bed and therefore discharge capacity be reduced. In this paper, we willinvestigated different projects of retrieval vegetation cover and bioengineering in Shiraz Khoshk Riveras an influential element in Shiraz city and their effects on hydraulic specifications of river. Also,advantages and disadvantages of bioengineering and biological stabilization projects of the river arediscussed. Also problematic river reach caused by improper biological stabilization was identified andthe inappropriate implementation effects of vegetation cover on increase of hydraulic roughnesscoefficient and reduction of discharge capacity were investigated. Based on results, although erosionrate of Khoshk River’s banks in sections without vegetation cover was more than sections withvegetation cover, sometimes vegetation cover caused a significant increase of hydraulic roughnesscoefficient and significant reduction of section area and discharge capacity. The Khoshk River’ssections such as upstream and downstream of Chamran Boulevard Bridge, upstream of Ghadir Bridgeand downstream of Fazilat Bridge were analyzed by HEC-RAS. In these sections for stream flowvalues of 100 to 250 m3/sec, reduction of 10 to 28.5% was obtained. پرونده مقاله -
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15 - Simulation of hydraulic jump on bed with gravel roughness using FLOW- 3D software
ناهید پورعبدالله تورج هنر شهاب انصاریHydraulic jump control in open channels to reduce energy and damage to downstream constructions has always been a topic of researchers’ interests. One of the most important cases in this field is the build of various types of stilling basin considering economic fa چکیده کاملHydraulic jump control in open channels to reduce energy and damage to downstream constructions has always been a topic of researchers’ interests. One of the most important cases in this field is the build of various types of stilling basin considering economic factors and ease of construction. For this reason, jump simulations are often performed before deciding to construct a stilling basin to predict jump behavior in different conditions. One of the new methods of jump control in channels is the construction of a stilling basin with gravel roughness. Therefore, in this research, jump simulation on a non-sloped bed with gravel roughness in the initial Froude numbers of 4.9 to 7.8 and four different roughness’s diameters of zero, 1, 4 and 10 mm was performed using FLOW-3D software and results were compared with experimental results. Results showed that the maximum and minimum errors in estimating the initial depth were determined on the bed without roughness and with diameter roughness of 4 mm and the highest and lowest errors in estimating the sequent depth were determined on the bed with diameter roughness of 4 mm and the bed without roughness, respectively. Moreover, the highest and lowest errors in estimating the jump length occurred in the bed with a diameter roughness of 4 mm and the bed without roughness, respectively. پرونده مقاله -
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16 - محاسبه انتقال جرم خودرو ناشی از ناهمواری های جاده ای در مانورهای شتاب گیری و ترمز گیری
کاظم رضاکاشی زاده علی اسفندی سید مجید عطایی اردستانی حسن غفوری ورزنهدر مقاله حاضر، هدف اصلی محاسبه انتقال جرم خودرو ناشی از ناهمواری های جاده ای در مانورهای مختلف اعم از شتاب گیری و ترمزگیری است. برای دستیابی به این هدف مدل فنربندی شده یک خودروی کامل بصورت 10 درجه آزادی و در حالت کلی بر اساس مشخصات ارتعاشاتی آن در محیط سیمولینک نرم افزا چکیده کاملدر مقاله حاضر، هدف اصلی محاسبه انتقال جرم خودرو ناشی از ناهمواری های جاده ای در مانورهای مختلف اعم از شتاب گیری و ترمزگیری است. برای دستیابی به این هدف مدل فنربندی شده یک خودروی کامل بصورت 10 درجه آزادی و در حالت کلی بر اساس مشخصات ارتعاشاتی آن در محیط سیمولینک نرم افزار متلب شبیه سازی شد. جابجایی عمودی چرخ ها ناشی از ناهمواری ها بر روی جاده های مختلف بر اساس کلاسه بندی استاندارد ایزو با سرعت ثابت 70 کیلومتر بر ساعت و مسیر کلی حرکت خودرو برابر با 1000 متر بدست آمد. در ادامه با استفاده از تحلیل دینامیکی معکوس مدل ارائه شده در سیمولینک متلب، نیروهای وارد شده به هر یک از چرخ های خودرو در طی مانورهای مختلف بدست آمد. در نهایت با استفاده از تاریخچه نیرویی بدست آمده در چرخ ها در اثر عبور از ناهمواری های جاده ای و نیز تحت اثر عمل شتاب گیری و ترمزگیری، میزان انتقال جرم از عقب به جلوی خودرو در مانور ترمزگیری و میزان انتقال جرم از جلو به عقب خودرو در مانور شتاب گیری بدست آمد. پرونده مقاله -
دسترسی آزاد مقاله
17 - بررسی ارتعاشات وارده به بدنه خودرو ناشی از ناهمواری های جاده ای در طی حرکت شتابدار
کاظم رضاکاشی زاده سید محمد صالح موسوی بفروئی صالح عربدر مقاله حاضر، هدف اصلی بدست آوردن ارتعاشات وارده به بدنه خودرو و سرنشینان آن ناشی از ناهمواری های جاده ای در طی یک حرکت شتاب دار با شتاب ثابت است. برای دستیابی به این هدف از مدل ¼ خودرو جداگانه برای چرخ جلو و عقب یک خودروی سواری استفاده شده است. بدین ترتیب که در چکیده کاملدر مقاله حاضر، هدف اصلی بدست آوردن ارتعاشات وارده به بدنه خودرو و سرنشینان آن ناشی از ناهمواری های جاده ای در طی یک حرکت شتاب دار با شتاب ثابت است. برای دستیابی به این هدف از مدل ¼ خودرو جداگانه برای چرخ جلو و عقب یک خودروی سواری استفاده شده است. بدین ترتیب که در ابتدا ناهمواری های جاده ای بر اساس کلاسه بندی انجام شده توسط استاندارد ایزو بدست آمده است. سپس مدل ¼ خودرو با شرایط حرکت با سرعت ثابت و نیز حرکت شتابدار در جاده کلاس D بر اساس استاندارد ISO8606 در نرم افزار المان محدود آباکوس شبیه سازی شده است. ارتعاشات وارده بر بدنه خودرو و نیز نیروهای وارد شده بر بدنه خودرو تحت اثر همزمان حرکت شتابدار و ناهمواری های جاده ای برای چرخ عقب و جلوی خودرو استخراج شده است. پرونده مقاله -
دسترسی آزاد مقاله
18 - بررسی اثر قطر نازل و فشار آب بر کیفیت برش فولاد CK45 در فرآیند جت آب
یونس انامرادی مهرداد عضو امینیانیکی از مزایای استفاده ازبرش با جت آب ساینده، خاصیت برشکاری سرد می باشد که ایجاد گرما نمی‌کند و مانع از ذوب شدن و یا ترک برداشتن و یا تاب برداشتن و سخت شدن سطح روی قطعات می‌شود. در این پژوهش، تأثیر قطر نازل در دو اندازه و فشار آب در دو مقدار متفاوت در میزان زبری سطح برش چکیده کاملیکی از مزایای استفاده ازبرش با جت آب ساینده، خاصیت برشکاری سرد می باشد که ایجاد گرما نمی‌کند و مانع از ذوب شدن و یا ترک برداشتن و یا تاب برداشتن و سخت شدن سطح روی قطعات می‌شود. در این پژوهش، تأثیر قطر نازل در دو اندازه و فشار آب در دو مقدار متفاوت در میزان زبری سطح برش فولاد CK45 به وسیله روش جت آب به صورت تجربی بررسی شده است. نتایج نشان می‌دهد که با افزایش قطر نازل از mm0.76 به mm1.1، زبری سطح برش افزایش یافته است. همچنین با افزایش فشار آب از 2500 بار به 3000 بار، اگر چه تغییر محسوسی در کیفیت سطحی مشاهده نمی‌شود ولی با افزایش فشار آب در روش برش با جت آب، زبری سطح کاهش یافته و کیفیت برش افزایش می‌یابد. پرونده مقاله -
دسترسی آزاد مقاله
19 - تاثیر تغییر پارامترهای عمق بار، قطر ابزار و نرخ پیشروی در فرآیند فرزکاری 4 محورۀ پره توربین بر روی زبری و شکل بافت سطح
امیر علی نقی زاده بهروز نوروزی علی فرهمندیهمواره در فرآیند تولید پره های توربین سعی شده از عملیات ثانویه ای همچون پرداختکاری که در قبال افزایش کیفیت سطح از درستی هندسی سطح می کاهد کمتر استفاده شود. بر این اساس در مقاله حاضر، بهبود زبری و شکل بافت سطح پره توربین مستقیما با استفاده از بهینه سازی پارامترهای ماشینک چکیده کاملهمواره در فرآیند تولید پره های توربین سعی شده از عملیات ثانویه ای همچون پرداختکاری که در قبال افزایش کیفیت سطح از درستی هندسی سطح می کاهد کمتر استفاده شود. بر این اساس در مقاله حاضر، بهبود زبری و شکل بافت سطح پره توربین مستقیما با استفاده از بهینه سازی پارامترهای ماشینکاری مورد بررسی قرار گرفته است. پارامترهای متغیر این تحقیق قطر ابزار، عمق بار ونرخ پیشروی بوده اند. کار آزمایشی با استفاده از ماشین فرز CNC4 محور بر روی پره توربین آلومینیومی انجام گرفته است.طراحی آزمایشات به صورت فول فاکتوریل بوده وتمامی جایگشت های سطح های پارامترهای متغیر به اجرا در آمده است.زیری سطح مناطق ماشینکاری شده با استفاده از زبری سنج وشکل بافت سطح آنها با بهره گیری از میکروسکوپ استریو مورد بررسی قرار گرفته است و در نهایت با مقایسه داده های بدست آمده بهترین حالت معرفی شده است. پرونده مقاله -
دسترسی آزاد مقاله
20 - پیش بینی عمر خستگی توپی چرخ خودرو تحت بارگذاری ارتعاشات تصادفی ناشی از ناهمواری های جاده ای
کاظم رضاکاشی‌زاده محمد جعفر استاد احمد قرابی علیرضا ارغوان -
دسترسی آزاد مقاله
21 - آنالیز حساسیت ضریب زبری مانینگ رودخانه ها در مدل HEC-RAS جهت تعیین پهنه های سیلاب (مطالعه موردی: رودخانه کر- استان فارس)
وحید سهرابی فرشید هاشمی پور پتکوئی حمید شیخ پور شاهیرودخانه ها یکی از معدود پدیده های طبیعی می باشند که علیرغم خسارات و زیانهای بیشماری که از دیرباز به انسانها وارد نموده اند ، بدلیل تأثیر ویژه در زندگی بشر و شکل گیری تمدنها همواره انسان ها را به اراضی حاشیه رودخانه فراخوانده اند . در ایران نیز بدلیل وسعت زیاد ، اقلیم مت چکیده کاملرودخانه ها یکی از معدود پدیده های طبیعی می باشند که علیرغم خسارات و زیانهای بیشماری که از دیرباز به انسانها وارد نموده اند ، بدلیل تأثیر ویژه در زندگی بشر و شکل گیری تمدنها همواره انسان ها را به اراضی حاشیه رودخانه فراخوانده اند . در ایران نیز بدلیل وسعت زیاد ، اقلیم متعدد و تراکم زمانی و مکانی بارش ها در اکثر حوضه های آبخیز ، همه ساله شاهد سیلاب های عظیمی در اکثر مناطق کشور بوده که بسیاری از آنها ، خسارات جانی و مالی فراوانی را به بار می آورند. این تحقیق بازهای به طول حدود 10 کیلومتر از رودخانه کر (پایین دست ایستگاه هیدرومتری چمریز) انتخاب شد و پس از تهیه آمار حداکثر دبی لحظهای رودخانه در دو حالت قبل و بعد از احداث سد ملاصدرا، اثر احداث سد بر روی جریان رودخانه بررسی شد. سپس با در نظر گرفتن دبی رودخانه به ازای دبی با دوره بازگشت 25 سال برای دو حالت قبل و بعد از احداث سد مدل جریان ماندگار رودخانه مذکور توسط نرم افزار HEC-RAS تهیه و سپس با یکدیگر مقایسه شدند. در ادامه بر اساس دبی با دوره بازگشت 25 سال بعد از احداث سد اقدام به تغییر ضریب زبری مانینگ به میزان 50 درصد از مقدار اولیه گردید و مجدداً مدل HEC-RAS اجرا گردید.احداث سد نقش بسزایی در کاهش سیلاب رودخانه کر داشته است، بطوری که احداث سد مذکور باعث شده است که برخی از پارامترها مانند تراز سطح آب، سرعت جریان آب، مساحت جریان آب، میزان دبی در رودخانه و همچنین سیلاب دشتهای آن کاهش یابد.نتایج آنالیز حساسیت برخی از پارامترها نسبت به ضریب زبری مانینگ نشان دادکه باکاهش ضریب زبری مانینگ،برخی ازپارامترها نظیرترازسطح آب و مساحت جریان نیزکاهش و پارامترهای نظیر سرعت جریان آب، دبی رودخانه، دبی رودخانه در ساحل سمت راست و چپ افزایش یابد و بالعکس. پرونده مقاله -
دسترسی آزاد مقاله
22 - Optimizing Surface Roughness of Nylon6/CaCO3 Nano-Composites Using Harmony Search Algorithm
Shahab Mohammadi Reza Farshbaf Zinati MohammadReza RazfarNowadays, polymer-based Nano-composites are of special importance in industry considering their mechanical properties including high strength to weight ratio. On another hand, since Nano-composites produced by methods such as extrusion are at simple cross sections, it i چکیده کاملNowadays, polymer-based Nano-composites are of special importance in industry considering their mechanical properties including high strength to weight ratio. On another hand, since Nano-composites produced by methods such as extrusion are at simple cross sections, it is necessary to machine them in order to reach geometrically complex figures. Surface roughness is a parameter affecting mechanical specifications of the machined part. Thus, it is necessary to study surface roughness of the machined parts to reach optimized cutting parameters and optimized surface roughness. The present paper tries to experimentally test milling of Nylon 6/ CaCo3 Nano-composites and measure surface roughness of the milled surfaces using the obtained data. The obtained data were used to model surface roughness to obtain an appropriate model for its milling. Finally, the obtained model was optimized using harmony search algorithm to reach optimized surface roughness and cutting parameters. پرونده مقاله -
دسترسی آزاد مقاله
23 - Statistical Analysis and Optimization of Factors Affecting the Surface Roughness in UVaSPIF Process Using Response Surface Methodology
Mehdi Vahdati Ramezanali Mahdavinejad Saeid Amini Mahmoud MoradiUltrasonic vibration assisted single point incremental forming (UVaSPIF) is based on localized plastic deformation in a sheet metal blank. It consists to deform gradually and locally the sheet metal using vibrating hemispherical-head tool controlled by a CNC milling mac چکیده کاملUltrasonic vibration assisted single point incremental forming (UVaSPIF) is based on localized plastic deformation in a sheet metal blank. It consists to deform gradually and locally the sheet metal using vibrating hemispherical-head tool controlled by a CNC milling machine. The ultrasonic excitation of forming tool reduces the vertical component of forming force. In addition, application of ultrasonic vibration reduces the surface roughness of the specimen. Surface roughness is one of the quantitative and qualitative parameters, which is used to assess the quality of the final product. In the present paper, a statistical analysis and optimization of effective factors on this parameter is performed in the UVaSPIF. For this purpose, response surface methodology (RSM) is selected as the experiment design technique. The controllable factors such as vertical step size, sheet thickness, tool diameter, wall inclination angle, and feed rate is specified as input variables of the process. The obtained results from analysis of variance (ANOVA) and regression analysis of experimental data confirm the accuracy of mathematical model. Furthermore, it is shown that the linear, quadratic, and interactional terms of the variables are effective on the surface roughness parameter. To optimize the surface roughness parameter, the finest conditions of the experiment are determined using desirability method, and statistical optimization is subsequently verified by conducting the confirmation test. پرونده مقاله -
دسترسی آزاد مقاله
24 - واکاوی شرایط همدید رخداد تند باد و توفان گرد و غبار شیراز اسفند 1399
اشرف اسدیبا نزدیک شدن به فصول گذار در انتهای فصل زمستان ، تغییر در شرایط الگوهای حرکت و تندی باد در عرض های میانه پدیده ای اجتناب ناپذیر است که گاهاً می تواند مدیریت بحران و رفت و آمد در معابر شهری را با مشکل مواجه کند . هدف این پژوهش بررسی شرایط همدید شکل گیری تند باد و توفان گ چکیده کاملبا نزدیک شدن به فصول گذار در انتهای فصل زمستان ، تغییر در شرایط الگوهای حرکت و تندی باد در عرض های میانه پدیده ای اجتناب ناپذیر است که گاهاً می تواند مدیریت بحران و رفت و آمد در معابر شهری را با مشکل مواجه کند . هدف این پژوهش بررسی شرایط همدید شکل گیری تند باد و توفان گرد و غبار در شهر شیراز در روز در 22 اسفند 1399 می باشد. برای رسیدن به این هدف با رویکرد محیطی به گردشی از داده های روزانه بارش ، سرعت باد و گرد و غبارِ سازمان هواشناسی و داده های دمای هوا، ارتفاع ژئوپتانسیل ، فشار تراز دریا ، باد مداری، باد نصف النهاری، رطوبت ویژه و اُمگا از پایگاه داده NCEP/NCAR جهت بررسی تراز فوقانی جو استفاده شده است. نتایج نشان داد که قرار گیری منطقه مورد مطالعه در زیر ناحیه فرارفت تاوایی مثبت در شرق ناوه بادهای غربی که منجر به واگرایی بالایی و همگرایی پایینی می گردد ، برقراری شیو دما و جبهه زایی و به ویژه فرود رودباد جبهه قطبی تا ترازهای پایین جو ، شرایط همدید برای رخداد صعود شدید هوا و شکل گیری تندباد های شدید ناشی از آن را در روز مورد مطالعه فراهم کرده است. این پژوهش می تواند با شناسایی عوامل تاثیر گذار بر رخداد تند بادها مبنای علمی مطلوبی، برای حفاظت و بهبود شرایط سکونت گاه های انسانی باشد. پرونده مقاله -
دسترسی آزاد مقاله
25 - اندازه‌گیری و سهم ساقاب تولیدی درتک درختان بلندمازو و پلت درناحیه رویشی جنگل‌های هیرکانی
سیوان نیکخواه سید محسن حسینی عبدالواحد خالدی درویشان امید فتحی زادهپژوهش حاضر با هدف برآورد میزان ساقاب تک درختان بلندمازو Quercus castaneifolia C.A.M)) و پلت (Acer velutinum Boiss) طی دوره قبل خزان و خزان در دانشکده منابع طبیعی دانشگاه تربیت مدرس شهرستان نور مازندران انجام شد. ساقاب با استفاده از جمع‌آوری کننده‌های مارپیچی که در ارتفا چکیده کاملپژوهش حاضر با هدف برآورد میزان ساقاب تک درختان بلندمازو Quercus castaneifolia C.A.M)) و پلت (Acer velutinum Boiss) طی دوره قبل خزان و خزان در دانشکده منابع طبیعی دانشگاه تربیت مدرس شهرستان نور مازندران انجام شد. ساقاب با استفاده از جمع‌آوری کننده‌های مارپیچی که در ارتفاع برابر سینه درختان نمونه ساقاب نصب شده بود جمع‌آوری و مقدار بارندگی کل نیز با استفاده از 5 جمع‌آوری‌کننده باران در نزدیک‌ترین فضای باز نسبت به درختان اندازه‌گیری شد. اندازه‌گیری بارندگی و ساق‌آب در 4 بارندگی دوره قبل خزان مجموع 114 میلی‌متر و 7 بارندگی دوره خزان مجموع 119 میلی‌متر انجام شد. متوسط ساقاب درختان بلندمازو و پلت به‌ترتیب 62/0 و 7/5 درصد بارندگی کل دوره قبل خزان و 64/0 و 65/7 درصد بارندگی کل دوره خزان بدست آمد. نتایج نشان داد طی دوره مطالعه، بین ساقاب و مقدار بارندگی کل رابطه مثبت و معنی‌داری وجود داشت. همچنین بر طبق نتایج پژوهش حاضر رابطه بین نسبت ساقاب به بارندگی کل گونه بلندمازو دوره خزان (85/0=2R) قوی‌تر از دوره قبل خزان (35/0=2R) بود حال آن‌که گونه پلت تقریباً در هر دو دوره قبل خزان (92/0=2R) و خزان (67/0=2R) رابطه نسبتاً قوی بین نسبت ساقاب به بارندگی مشاهده شد. به‌طور کلی بر طبق نتایج پژوهش حاضر گونه بلندمازو به‌دلیل داشتن پوست شیاردار و زبر ، سهم ساقاب از بارندگی به‌طور متوسط 9 برابر بیشتر از گونه پلت بود. این مطالعه نشان داد که پلت ساقاب بیشتری نسبت به بلندمازو تولید میکند و دلیل آن پوست صاف پلت و وجود ظرفیت نگهداری آب پوست کم پلت است. پرونده مقاله -
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26 - Investigation of Parameters Affecting Surface Integrity and Material Removal during Electrical Discharge Machining of HARDOX-400 Steel
Hesam Motevasseli Ahmad Afsari Ali KhosravifardHardox-400 with an extra-high yield strength of ~1000 MPa and excellent abrasion resistance is a good candidate for several industrial applications including automotive parts, working tools, barges, loaders, etc. Due to high dimensional precision and to avoid mechanical چکیده کاملHardox-400 with an extra-high yield strength of ~1000 MPa and excellent abrasion resistance is a good candidate for several industrial applications including automotive parts, working tools, barges, loaders, etc. Due to high dimensional precision and to avoid mechanical abrasion of the work-piece, electrical discharge machining (EDM) is a proper machining technique for such steel. The influences of important process parameters, i.e. discharge current and spark pulse cycle on the electrode wear, material removal, surface roughness, and integrity of the machined material is investigated. It was observed in this work that as the discharge current increased, the electrode wear also increased but this occurred with a gradually decreasing rate. On the other hand, increasing the ratio of pulse-on to pulse-off time decreased material removal. Furthermore, it was observed that increasing both the discharge current and the pulse-on time led to a thicker solidified so-called white layer which is more susceptible to cracking and thus is detrimental to the material integrity. پرونده مقاله -
دسترسی آزاد مقاله
27 - Predicting the Influence of Electrical Discharge Machining (EDM) Parameters on the Finished Work Surface in CK45 Steel
Esmaeil Jafari Ahmad Afsari Sina AbedpourCK45 steel is a suitable material for the manufacturing of forging dies. This paper investigates the influence of electrical discharge machining (EDM) parameters including voltage, current, on-time and off-time on the microstructure of the machined surface of this mater چکیده کاملCK45 steel is a suitable material for the manufacturing of forging dies. This paper investigates the influence of electrical discharge machining (EDM) parameters including voltage, current, on-time and off-time on the microstructure of the machined surface of this material. The process induces thermal stresses that in turn result in the generation of widespread micro-cracks on the surface of the part subjected to spark EDM. The influence of EDM parameters on the quality of the machined surface is explored by performing an extensive experimental program. The impact of EDM parameters on the surface roughness and the intensity of micro-cracks have been evaluated quantitatively using the test results and regression analysis. Predicting the relationship between EMD parameters and the surface quality provides practical means to appropriately decide on the adjustment of process control parameters to their optimum values and hence to achieve the desired surface quality at reasonable manufacturing times and cost. پرونده مقاله -
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28 - Experimental Investigation of the Effects of the Roller Burnishing Parameters on the Surface Roughness and Micro-hardness of Ti6Al4V Alloy
Mohammad Asadbeiki Reza NosouhiIn this research, the effects of three important input parameters of roller burnishing process, namely burnishing speed, feed rate and the number of passes on the surface integrity (surface roughness and surface micro-hardness) of Ti-6Al-4V alloy are investigated. The d چکیده کاملIn this research, the effects of three important input parameters of roller burnishing process, namely burnishing speed, feed rate and the number of passes on the surface integrity (surface roughness and surface micro-hardness) of Ti-6Al-4V alloy are investigated. The design of the experiment is carried out using a full factorial method. Measurement of process outputs is carried out with precise methods and the results are recorded and examined. The results showed that the parameters studied have a very significant effect on the surface roughness and micro-hardness of Ti6Al4V alloy. The feed rate is the most effective parameter on the surface roughness and the burnishing speed is the most effective parameter on the surface micro-hardness. Generally concluded, the roller burnishing process improves the final surface quality and increases surface micro-hardness. It also concluded that increasing the number of the burnishing passes from 1 to 2 would excel both of the output parameters while increasing of this parameter further has no significant effect or; in certain cases; an inverse effect on the surface roughness and surface micro-hardness. پرونده مقاله -
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29 - Experimental Study of Germanium Dry Machining with Various Rake Angles and Different Feed Rates of Tool
Mohammad Reza Safavipour Masoud FarahnakianToday, germanium single-crystals are used as an infrared and semiconductor material in the manufacturing of infrared optical lenses and windows (thermal vision), gamma-ray detectors, and substrates for optoelectronic and electronic applications. Given that germanium is چکیده کاملToday, germanium single-crystals are used as an infrared and semiconductor material in the manufacturing of infrared optical lenses and windows (thermal vision), gamma-ray detectors, and substrates for optoelectronic and electronic applications. Given that germanium is an optically brittle material with high brittleness and brittle failure that mainly affects the surface integrity of the machined part on this material; In this experimental study, by changing the rake angle and feed rate of the cutting tool, experiments were performed to determine the appropriate rake angles and suitable feed rates and their effects on the surface roughness and texture of the relevant surface for germanium turning in the dry state. The results show that with increasing the rake angle and decreasing the feed rate of the cutting tool, the surface roughness decreases, which reduces the surface damage to a considerable extent. The purpose of this experimental study is to create a surface with the desired quality in the machining process of the germanium optical part using ductile mode machining and to change the parameters of this process to control the configuration and dimensions of microstructures, micro-cracks, micro craters, and Surface pits. پرونده مقاله -
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30 - Comparing and Investigating the Effect of Input Parameters on External Parameters in Parts of Different Materials in EDM Operation Using Taguchi Method
Seyed Mohammad Reza Nazemosadat Ahmad Afsari Najwan Nejah Adnan Jeddeh Alireza BahramkiaThe correct selection of input parameters in the electric discharge machining (EDM) process leads to improvements in the material removal rate (MRR), dimensional accuracy of the parts, quality of the surface finish, and reduction of tool wear. The main goal of the resea چکیده کاملThe correct selection of input parameters in the electric discharge machining (EDM) process leads to improvements in the material removal rate (MRR), dimensional accuracy of the parts, quality of the surface finish, and reduction of tool wear. The main goal of the research was to investigate the type and extent of the influence of input on output parameters in EDM operations. Experimental data and the contribution of parameters were obtained using the Taguchi test design with three levels. The tool used was made of copper. Samples were selected from three types of alloy steel: 4340, Ti6Al-4V, and AISI D2 steel. The test variables included maximum current (Ip), gap voltage (Vg), and duty factor (DF). In these experiments, Ip values of 5, 10, and 15 amps, Vg values of 25, 50, and 75 volts, and DF values of 0.3, 0.6, and 0.9 were selected. The number of machining operations was 81 tests, and the L9 orthogonal array related to the Taguchi approach used for Design of Experiments (DOE) reduced the number of machining operations from 81 to 27 tests. The results indicated that the current parameter of 5 amps had the highest effect on surface roughness (SR) in samples of AISI4340 steel. The current of 15 amps had the greatest impact on MRR, while the duty factor (DF) of 0.6 played the highest role in electrode wear rate (EWR). Maximum Ip contributed 36.77%, Vg contributed 31.03%, and DF contributed 32.18% to EWR. پرونده مقاله -
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31 - Analysis of Surface Roughness and Micro-hardness in Roller Burnishing of Aluminum Alloy 6061
Amin PoursafarBurnishing is a chip-less finishing process, in which a hard roller or ball presses the surface layer of part to perform plastic deformation in the surface layer and produce improved finish, enhanced hardness and compressive residual stresses on the surface of special m چکیده کاملBurnishing is a chip-less finishing process, in which a hard roller or ball presses the surface layer of part to perform plastic deformation in the surface layer and produce improved finish, enhanced hardness and compressive residual stresses on the surface of special materials such as Aluminum and Brass. In the following research, the effect of input parameters such as feed rate, cutting speed, number of passes , burnishing force and cooling system which is applying by minimum quantity of lubrication (MQL) on surface roughness and micro-hardness in roller burnishing of Aluminum alloy 6061 has been investigated. Taguchi method is used for design of experiments and special burnishing tool is used for this research. The optimization results show that the effect of feed rate and burnishing speed is significant on surface roughness and burnishing force and the number of passes plays important role in micro-hardness. The minimum surface roughness in burnishing of aluminum alloy 6061 was 0.138 μm and the maximum was 0.475 μm. The maximum micro-hardness in roller burnishing Aluminum alloy 6061was found 122 HB and the minimum was 100 HB. پرونده مقاله -
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32 - Experimental Investigation of the Effect of Deionized Water on Surface Roughness of Near Dry Electro Discharge Machining of AISI D2 Steel
Mojtaba Taghizadeh Sayed Ali MosaviThe electro discharge machining (EDM), one of the methods used in the machining industry and a non-traditional manufacturing method, the electro erosion process does not depend on the hardness of material and offers a way to process materials of very complex geometry wi چکیده کاملThe electro discharge machining (EDM), one of the methods used in the machining industry and a non-traditional manufacturing method, the electro erosion process does not depend on the hardness of material and offers a way to process materials of very complex geometry with very fine and high precision by using cheap electrode materials, which make it a preferred method. In this study, effect of wet and near dry EDM has been investigated. Design of the experiment was chosen as full-factorial. Experimental data has been statistically analyzed and then appropriate model was extracted. The experimental results show that surface roughness decreases by increase of peak current and also pulse on-time; it should be mentioned that effect of peak current on surface roughness is greater than pulse on-time. Also by using near dry machining (NDM), surface roughness decreased about 1µm and approximately 15 percent. These indicate the good performance of NDM. پرونده مقاله -
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33 - Investigation of the Effective Parameters on Surface Roughness in Magnetic Abrasive Finishing Process Using Design of Experiments
Yahya Choopani Mohammad Reza RazfarIn this article, the effect of parameters like working gap, work piece rotational speed and material removal mechanism(injection of the SiC Abrasive slurry and Al2O3, use of diamond paste as abrasive tool) in Magnetic Abrasive Finishing process using designing of experi چکیده کاملIn this article, the effect of parameters like working gap, work piece rotational speed and material removal mechanism(injection of the SiC Abrasive slurry and Al2O3, use of diamond paste as abrasive tool) in Magnetic Abrasive Finishing process using designing of experiments on the external surface of Cylindrical work pieces of Stainless steel AISI 440C to get minimum surface roughness has been investigated. For implementation of tests, a mechanism was designed and after carrying out the tests, the obtained data was analyzed using Minitab software. Using response surface method the predicted model, the value of surface roughness was represented. Input parameters to produce optimum have also been reached using the predicted model and desirable surface roughness. Also, results show that the surface roughness has been improved by 50% with the working gap of 2 mm and work piece rotational speed of 355 rpm and using diamond paste. پرونده مقاله -
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34 - Micro Machining of AISI 440C Stainless Steel using Magnetic Field and Magnetic Abrasive Particles
Yahya Choopani Mohammad Reza RazfarMagnetic abrasive finishing (MAF) is a micromachining process that uses magnetic field and magnetic abrasive particles to conduct the mechanism of material removal in micro-nanometer scales. In this paper, by an experimental method and statistical analysis, the effects چکیده کاملMagnetic abrasive finishing (MAF) is a micromachining process that uses magnetic field and magnetic abrasive particles to conduct the mechanism of material removal in micro-nanometer scales. In this paper, by an experimental method and statistical analysis, the effects of parameters like working gap, work-piece rotational speed and material removal mechanism (injection of abrasive slurry of Al2O3) in the MAF process, on the external surfaces of cylindrical pieces of stainless steel (AISI 440C)were investigated on surface roughness. To do the experiments, a mechanism was designed and constructed. The results of this research show that the working gap and work-piece rotational speedhave a significant effect on the improvement of the surface roughness. It has been indicated that in vitro surface roughness improved 20% as a result of the gap working of 2 mm, workpiece rotational speed of 355 rpm, using the injection of abrasive slurry of Al2O3. پرونده مقاله -
دسترسی آزاد مقاله
35 - Investigation of Magnetic Abrasive Finishing on Inner Surface of AL 6061 Tube
Hamzeh Shahrajabian Masoud Farahnakian Seyed Alireza Mousavi Hasan SoltaniIn magnetic abrasive finishing (MAF), abrasive grains as a tool move on surface and can remove chip from surface of work piece. In this study AL 6061 tube was considered as the work piece and the effect of finishing parameters such as gap distance between tube and poles چکیده کاملIn magnetic abrasive finishing (MAF), abrasive grains as a tool move on surface and can remove chip from surface of work piece. In this study AL 6061 tube was considered as the work piece and the effect of finishing parameters such as gap distance between tube and poles, rotational speed of tube, abrasive ration and finishing time on surface roughness was investigated. The mixture of ferromagnetic grits (Fe) and Al2O3 grains was considered as the abrasives. The result showed increasing in rotational speed, finishing time and abrasive grains up to certain value decreases surface roughness and increasing in air gap increases surface roughness. پرونده مقاله -
دسترسی آزاد مقاله
36 - Machinability Investigation of Inconel 657 in High-speed Turning
Amir Hossein Khoei Hasan Fathi Masoud Farahnakian Mohammad Reza RazfarA high strength nickel chromium alloy (50Cr-50Ni-Nb alloy), commonly referred to as IN-657, is specifically used for components in furnaces which are fired by low grade fuel oils containing high levels of vanadium, sodium and sulphur. The purpose of this study is to exp چکیده کاملA high strength nickel chromium alloy (50Cr-50Ni-Nb alloy), commonly referred to as IN-657, is specifically used for components in furnaces which are fired by low grade fuel oils containing high levels of vanadium, sodium and sulphur. The purpose of this study is to experimentally investigatethe effect of machining parameters on machinability in turning of Inconel 657. The considered parameters were cutting speed, feed and tool material. Cutting force components, tool flank wear and surface roughness were measuredbased on design of experiments, and then analysis of variance was performed. Experimental results show that tool wear of CBN tools is 50 %lower than that of carbide tools. The Tool material with percentage contribution of 48% and 56% is the main parameter that influencesthe cutting forces and the flank wear, respectively. Also, the cutting speed with percentage contribution of 48% is the main parameter that effects the surface roughness. The lowest surface roughness is attained by the cutting speed of 250 m/min and the feed of 0.05 mm/rev by the CBN tool. پرونده مقاله -
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37 - Experimental Investigation of the Surface Roughness in Grinding of BK7 Optical Glass in Brittle Mode
Vahid Barahimi Masoud FarahnakianSurface roughness is a significant parameter which determines the efficiency of optical components. Surface damages induced by grinding strongly influence the mechanical strength and optical quality of optical glasses. It is meaningful to rapid evaluate the surface roug چکیده کاملSurface roughness is a significant parameter which determines the efficiency of optical components. Surface damages induced by grinding strongly influence the mechanical strength and optical quality of optical glasses. It is meaningful to rapid evaluate the surface roughness through the measurement of different grinding parameters. In this study, a cup diamond wheel (D64) is used in grinding process of the specimens made of BK7optical glass to investigate the influences of grinding parameters on the surface roughness. The grinding parameters used in this study are depth of cut, cutting speed, tables speed and feed rate; and effects of these parameters are studied. The dependence of surface roughness on grinding parameters was systematically analyzed. The experimental results indicate that feed rate, depth of cut and cutting speed have the most significant effect on surface roughness, respectively. By increasing feed rate and depth of cut, the surface roughness increases and increasing cutting speed results in a decrease in surface roughness. پرونده مقاله -
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38 - The Effectiveness of Ceramic Wiper Tool in Turning of Monel K500
Mohammad Lotfi Saeid Amini Sayed Ali Sajjady Adil Hussein JuaiferIn this study, turning operation of Monel K500 copper-nickel super-alloy was evaluated. Ceramic cutting tools with two different cutting noses (conventional and wiper) were utilized. At first, the experimental tests were designed by using central composite design method چکیده کاملIn this study, turning operation of Monel K500 copper-nickel super-alloy was evaluated. Ceramic cutting tools with two different cutting noses (conventional and wiper) were utilized. At first, the experimental tests were designed by using central composite design method. After implementation of the tests, the statistical models for output data (surface roughness, cutting force, and flank wear) have been developed. Furthermore, the effect of cutting parameters on output data was taken into account with help of analysis of variance. In third step, the optimal cutting condition was introduced for both cutting tools by using response surface method. In total, it was revealed that low depth of cut and feed rate coupled with high cutting speed is an optimal condition for turning of Monel super-alloy when ceramic tools are selected. In particular, the positive effect of wiper tool on output data was more when depth of cut has been lower than the length of wiper edge. پرونده مقاله -
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39 - Machining of Makrana White Marble Surfaces by Abrasive Water Jet Machining
Vishal Gupta M.P. Garg Garg N.K. Batra Arjun S. WadwaIn the present study, experimental investigations were conducted to find out the effect of abrasive water jet machining (AWJM) process parameters on the surface roughness (Ra) of white Makrana Marble. The approach was based on Taguchi’s method and analysis of vari چکیده کاملIn the present study, experimental investigations were conducted to find out the effect of abrasive water jet machining (AWJM) process parameters on the surface roughness (Ra) of white Makrana Marble. The approach was based on Taguchi’s method and analysis of variance (ANOVA) to optimize the AWJM process parameters for effective machining. Nozzle transverse speed, water pressure, and stand of distance were selected as the input parameters while the other was kept constant. It was found that the water pressure and nozzle transverse speed were significant control factors and the stand of distance was the insignificant control factor in controlling the surface roughness (Ra). پرونده مقاله -
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40 - بررسی آزمایشگاهی اثر تغییرات زبری و ارتفاع سرریز لبه پهن بر ضریب دبی جریان
ابراهیم نوحانی امین محبی زادهدر بسیاری از پروژههای تامین آب و انرژی، همچون سدها، رهاسازی یک دبی مشخص و ایجاد یک سازه برای تخلیهی ظرفیت مازاد در مدت زمان معین، امری ضروری است. این وظیفه را سازههایی به نام سرریز به عهده دارند. سرریزها آنچنان دارای پیچیدگی و تنوع هستند که بررسی و تحلیل پارامترهای هیدر چکیده کاملدر بسیاری از پروژههای تامین آب و انرژی، همچون سدها، رهاسازی یک دبی مشخص و ایجاد یک سازه برای تخلیهی ظرفیت مازاد در مدت زمان معین، امری ضروری است. این وظیفه را سازههایی به نام سرریز به عهده دارند. سرریزها آنچنان دارای پیچیدگی و تنوع هستند که بررسی و تحلیل پارامترهای هیدرولیکی آنها، بخصوص با استفاده از مدلهای فیزیکی و هیدرولیکی، کاری بسیار مهم و مهندسی است. سرریزهای لبهپهن به علت اقتصادی بودن و سادگی در ساخت، به طور گسترده در سیستم های انتقال آب و به عنوان ابزاری برای اندازه گیری شدت جریان و کنترل تراز سطح آب مورد استفاده قرار می گیرند. با توجه به کاربردهای فراوان سرریزهای لبه پهن، اگر ابعاد مقطع آن بهینه شود، منجر به اقتصادی شدن طرح گردد. در این تحقیق با انجام مطالعات آزمایشگاهی بر روی مدلهای مختلف بهینه ضریب دبی جریان آنها محاسبه گردید. همچنین با استفاده از مدل فیزیکی یک سرریز لبه پهن ساخته شده در آزمایشگاه هیدرولیک و تغییر ارتفاع سرریز و نصب زبری روی سطح تاج و تغییرات ضریب دبی، عدد فرود، عمق آب بالادست و دیگر پارامترهای هیدرولیکی مورد شبیهسازی قرارگرفت. تعداد کل آزمایشات انجام داده شده 75 مورد بود و نتایج نشان داد که با افزایش زبری سطح تاج سرریز، ضریب دبی تا 10 درصد کاهش پیدا میکند. پرونده مقاله -
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41 - بررسی آزمایشگاهی تاثیر همزمان زبری تیز گوشه و شیب مثبت بر روی طول پرش هیدرولیکی در حوضچه های آرامش کلاسیک
روزبه آقا مجیدی امیر حسین نوذریسازههای هیدرولیکی نظیر حوضچه‌های آرامش عمدتاً به منظور استهلاک انرژی در پائین دست سرریزها، تندآب‌ها و دریچه‌ها از این خاصیت مهم پرش هیدرولیکی استفاده می‌نمایند.در این تحقیق میزان و نحوه تاثیر پرش هیدرولیکی با انجام آزمایش‌های آزمایشگاهی مشخص می‌گردد. با این هدف آزمایش چکیده کاملسازههای هیدرولیکی نظیر حوضچه‌های آرامش عمدتاً به منظور استهلاک انرژی در پائین دست سرریزها، تندآب‌ها و دریچه‌ها از این خاصیت مهم پرش هیدرولیکی استفاده می‌نمایند.در این تحقیق میزان و نحوه تاثیر پرش هیدرولیکی با انجام آزمایش‌های آزمایشگاهی مشخص می‌گردد. با این هدف آزمایش‌های متعددی(60 آزمایش) برای اعداد فرود ورودی در محدوده 4 تا 12 در فلوم به عرض 35 سانتی متر انجام گرفت. در این آزمایش‌ها زبری تیز گوشهنصب و همچنین با تغییر شیب کف از 0 تا 3/0 درصد، مورد آزمایش قرار گرفت و پارامترهایی چون، دبی جریان، عمق اولیه، عمق ثانویه، طول پرش پروفیل سطح آب، هد آب روی تاج سرریز و هد آب قبل از سرریز با دقت اندازه گیری شد. تجزیه و تحلیل داده‌ها نشان داد که زبری تیز گوشهمی‌توانند نسبت طول پرش به عمق ثانویه را تا 35.5% کاهش دهد.برای زبری تیز گوشهبا افزایش عدد فرود نسبت y2/y1 به طور میانگین 6.5 % افزایش می یابد.برای یک عدد فرود با نصب زبری تیز گوشهنسبت Lj/y2 به طور میانگین 1.2 % کاهش می یابد پرونده مقاله -
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42 - Application of orthogonal array technique and particle swarm optimization approach in surface roughness modification when face milling AISI1045 steel parts
Masoud Azadi Moghaddam Farhad KolahanFace milling is an important and common machining operation because of its versatility and capability to produce various surfaces. Face milling is a machining process of removing material by the relative motion between a work piece and rotating cutter with multiple cutt چکیده کاملFace milling is an important and common machining operation because of its versatility and capability to produce various surfaces. Face milling is a machining process of removing material by the relative motion between a work piece and rotating cutter with multiple cutting edges. It is an interrupted cutting operation in which the teeth of the milling cutter enter and exit the work piece during each revolution. This paper is concerned with the experimental and numerical study of face milling of AISI1045. The proposed approach is based on statistical analysis on the experimental data gathered using Taguchi design matrix. Surface roughness is the most important performance characteristics of the face milling process. In this study the effect of input face milling process parameters on surface roughness of AISI1045 steel milled parts have been studied. The input parameters are cutting speed (v), feed rate (fz) and depth of cut (ap ). The experimental data are gathered using Taguchi L9design matrix. In order to establish the relations between the input and the output parameters, various regression functions have been fitted on the data based on output characteristics. The significance of the process parameters on the quality characteristics of the process was also evaluated quantitatively using the analysis of variance method. Then, statistical analysis and validation experiments have been carried out to compare and select the best and most fitted models. In the last section of this research, mathematical model has been developed for surface roughness prediction using particle swarm optimization (PSO) on the basis of experimental results. The model developed for optimization has been validated by confirmation experiments. It has been found that the predicted roughness using PSO is in good agreement with the actual surface roughness. پرونده مقاله -
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43 - On the use of back propagation and radial basis function neural networks in surface roughness prediction
Angelos P. Markopoulos Sotirios Georgiopoulos Dimitrios E. ManolakosVarious artificial neural networks types are examined and compared for the prediction of surface roughness in manufacturing technology. The aim of the study is to evaluate different kinds of neural networks and observe their performance and applicability on the same pro چکیده کاملVarious artificial neural networks types are examined and compared for the prediction of surface roughness in manufacturing technology. The aim of the study is to evaluate different kinds of neural networks and observe their performance and applicability on the same problem. More specifically, feed-forward artificial neural networks are trained with three different back propagation algorithms, namely the adaptive back propagation algorithm of the steepest descent with the use of momentum term, the back propagation Levenberg–Marquardt algorithm and the back propagation Bayesian algorithm. Moreover, radial basis function neural networks are examined. All the aforementioned algorithms are used for the prediction of surface roughness in milling, trained with the same input parameters and output data so that they can be compared. The advantages and disadvantages, in terms of the quality of the results, computational cost and time are identified. An algorithm for the selection of the spread constant is applied and tests are performed for the determination of the neural network with the best performance. The finally selected neural networks can satisfactorily predict the quality of the manufacturing process performed, through simulation and input–output surfaces for combinations of the input data, which correspond to milling cutting conditions. پرونده مقاله -
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44 - Assessment of manning’s resistance coefficient in compound channels
H Hajikandi M HatamiIn this paper twelve different empirical resistance coefficients expressed in terms of Manning's roughness are used apiece in seventeen known compositing methods. The data obtained from ten different cross-sections of the Sefidrood River, Iran, are used for the evaluati چکیده کاملIn this paper twelve different empirical resistance coefficients expressed in terms of Manning's roughness are used apiece in seventeen known compositing methods. The data obtained from ten different cross-sections of the Sefidrood River, Iran, are used for the evaluation of the empiricalformulas. The present case-study is selected from a reach with gravel bed topology. Then no remarkable bed form exists. Comparison of the calculated discharges and resistance coefficients with measurements shows that the Keulegan formula used simultaneously with the Brownlieformula in different compositing methods results in highly over estimated discharges, while the Meyer-Peter & Muller, Marion, Chien-Mai formulas in conjunction with the total force approach match best with the measurements. Also comparison of the calculated discharges from empirical formulas in individual sections reveals that Chien-Mai and Subramanya formulas have the least discrepancies from measurements. پرونده مقاله -
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45 - Effect of surface roughness on steel-steel dry friction coefficient
ح. چارستاد س.م خورسندی جوThe influence of surface roughness magnitude and direction on dry static friction coefficient between two similar steel samples has been studied through an experiment. A testing apparatus has been designed and fabricated to measure the friction coefficient for a few for چکیده کاملThe influence of surface roughness magnitude and direction on dry static friction coefficient between two similar steel samples has been studied through an experiment. A testing apparatus has been designed and fabricated to measure the friction coefficient for a few forms of surface asperity. According to the results of the experiments, dry friction coefficient is affected by both magnitude and direction of surface roughness. پرونده مقاله -
دسترسی آزاد مقاله
46 - بررسی عوامل موثر بر مورفولوژی و ساختار نانویی پوشش‌های آلیاژی نیکل-آهن تهیه شده به روش آبکاری الکتریکی
سارا فضلی محمد ابراهیم بحرالعلومآبکاری پوشش های آلیاژی نیکل –آهن در ترکیب جدیدی از الکترولیت صورت گرفت. دما، میزان ساخارین و نحوه همزدن حمام به عنوان عوامل موثر بر ساختار، مورفولوژی و درصد پوشش های آلیاژی، مورد بررسی قرار گرفتند. پوشش‌های آلیاژی نیکل-آهن با ضخامت µm 100 پس از 3 ساعت آبکاری چکیده کاملآبکاری پوشش های آلیاژی نیکل –آهن در ترکیب جدیدی از الکترولیت صورت گرفت. دما، میزان ساخارین و نحوه همزدن حمام به عنوان عوامل موثر بر ساختار، مورفولوژی و درصد پوشش های آلیاژی، مورد بررسی قرار گرفتند. پوشش‌های آلیاژی نیکل-آهن با ضخامت µm 100 پس از 3 ساعت آبکاری در دماهای 25، 45 و °C75 ، در حضور مقادیر مختلف ساخارین (1، 3، 5 و g/L10) در 8/3pH= و دانسیته جریان mA/cm2 100 حاصل شدند. تصاویر میکروسکوپ الکترونی روبشی و الگو پراش اشعه ایکس سطح پوشش‌ها، حاکی از وجود ساختار گل کلم شکل و دانه‌بندی نانومتری ( nm65/26) می باشد. افزایش دما به علت افزایش حلالیت نیکل در حمام، افزایش رسانایی، افزایش بازده و کاهش پلاریزاسیون کاتد و آند، سبب افزایش میزان نیکل و کاهش آهن در پوشش شد. به علاوه کاهش اندازه دانه و کاهش زبری سطح نیز با افزایش دمای آبکاری حاصل شد. مقدار بهینه ساخارین در حمام g/L1 تعیین شد که به علت افزایش پتانسیل کاتدی اضافی و جلوگیری از رشد دانه ها، سبب افزایش نرخ جوانه زنی و در نتیجه کاهش اندازه دانه در پوشش شد. مقادیر بیشتر ساخارین با وجود تاثیر ساخارین در ریز کردن اندازه دانه، به علت وجود ذرات زیاد ساخارین در پوشش باعث افزایش زبری سطح شد. همزدن مغناطیسی به علت مغناطیسی بودن پوشش آلیاژی، سبب تغییر مورفولوژی پوشش ها شد. به منظور دستیابی به پوشش آلیاژی بهینه با چسبندگی مناسب و حداقل کرنش داخلی، حفره و ناخالصی، آبکاری الکتریکی در حضور g/L1 ساخارین در دمای °C25 و با همزن مکانیکی صورت گرفت. پرونده مقاله -
دسترسی آزاد مقاله
47 - مطالعه اثر میدان مغناطیسی بر زبری سطح قطعه‌کار در ماشینکاری تخلیه الکتریکی ماده مرکب آلومینیوم 413 تقویت شده با آلومینا
احمدرضا میزبانی سیداحسان میرمحمدصادقی علی مختاریاندر این پژوهش، تأثیر پارامترهای ورودی ماشینکاری تخلیه الکتریکی بر روی زبری سطح قطعه‌کار از جنس ماده مرکب A413 تقویت شده با %5/2 Al2O3، در دو حالت با حضور میدان مغناطیسی و بدون وجود میدان مغناطیسی مورد بررسی و مقایسه قرار گرفته است. تحقیق ارائه شده با رویکرد طراحی آزمای چکیده کاملدر این پژوهش، تأثیر پارامترهای ورودی ماشینکاری تخلیه الکتریکی بر روی زبری سطح قطعه‌کار از جنس ماده مرکب A413 تقویت شده با %5/2 Al2O3، در دو حالت با حضور میدان مغناطیسی و بدون وجود میدان مغناطیسی مورد بررسی و مقایسه قرار گرفته است. تحقیق ارائه شده با رویکرد طراحی آزمایشات به روش تاگوچی بر مبنای آرایه متعامد L9 و تکنیک سطوح تکراری به انجام رسیده است. پارامترهای ورودی این آزمایشات شامل ولتاژ (دو سطحی)، شدت‌جریان (سه سطحی)، زمان روشنی پالس (سه سطحی) و زمان خاموشی پالس (سه سطحی) در نظر گرفته شده است. نتایج آزمایشات نشان دهنده کاهش زبری سطح ماشینکاری شده تا 32 درصد در حضور میدان مغناطیسی می باشد. تحلیل نتایج شامل تعیین نمودار‌های نسبت سیگنال به نویز متناظر با هر یک از پارامترهای ورودی و آنالیز واریانس توسط نرم‌افزار Minitab صورت گرفته است. نتایج بدست آمده گویای بهبود کیفیت سطح قطعه‌کار در حضور میدان مغناطیسی در مقایسه با شرایط ماشینکاری بدون وجود میدان مغناطیسی است. همچنین برمبنای نتایج حاصل از آنالیز واریانس در هر دو حالت مذکور، شدت جریان مؤثرترین پارامتر ورودی بر روی زبری سطح قطعه‌کار از جنس ماده مرکب A413 تقویت شده با %5/2 Al2O3، تعیین شده است. پرونده مقاله -
دسترسی آزاد مقاله
48 - Micromachining the Aluminium Tubes Using Abrasive Finishing in Alternating Magnetic Field
Reza Abedinzadeh Rasoul GorjiThis study introduced a method based on magnetic field assisted finishing mechanism for micromachining the inner surfaces of Aluminum tubes. In this approach, using the alternating magnetic field of an AC electromotor, abrasive particles were formed as Magnetic Rods (Ma چکیده کاملThis study introduced a method based on magnetic field assisted finishing mechanism for micromachining the inner surfaces of Aluminum tubes. In this approach, using the alternating magnetic field of an AC electromotor, abrasive particles were formed as Magnetic Rods (Magnetic Clusters) and surface micromachining was carried out by the dynamic particular pattern made by an alternating magnetic field. The aim of this process was to improve machining efficiency of Aluminum tubes based on surface roughness and dimensional tolerance. Continuously, the effects of parameters such as tube inner diameter, abrasive particles weight, current frequency and machining time on changes of surface roughness were assessed by DOE technique. Taguchi standard orthogonal method (L9 (34)) was used to analyze the process factors. Moreover, the output results derived from experiments were analyzed by two most widely used analytical techniques including Signal to Noise ratio (S/N) and Analysis of Variance (ANOVA). Finally, by considering the results of analysis and plotted graphs, abrasive particles weight and current frequency were identified as significant factors and the optimum conditions of process including tube inner diameter of 55 mm, abrasive particles weight of 1 g, frequency of 40 Hz and machining time of 60 s were obtained. پرونده مقاله -
دسترسی آزاد مقاله
49 - Improving surface roughness in barrel finishing process using supervised machine learning
Mohammad Sajjad Mahdieh Mehdi Bakhshi Zadeh Amirhossein Zare ReisabadiThe Barrel finishing process is a finishing method applied for cleaning, polishing, improving surface quality, Deburring, and rounding corners of both metallic and non-metallic parts. There are Several factors affect the final surface integrity of the barrel finished sa چکیده کاملThe Barrel finishing process is a finishing method applied for cleaning, polishing, improving surface quality, Deburring, and rounding corners of both metallic and non-metallic parts. There are Several factors affect the final surface integrity of the barrel finished samples such as initial surface roughness, piece length, operation time, and different abrasive materials (i.e. aluminum oxide, steel balls, and ceramic). On the other hand, each factor has different levels, and handling this amount of data to reach desired results is approximately impossible due to the “curse of dimensionality”. Machine learning is a promising method to pave this avenue for computing huge amounts of data and predicting the future state of the system. Accordingly, in this study, it is attempted to apply a supervised machine learning algorithm, an artificial neural network- to improve surface quality in the barrel finishing process. Python is used to code the program and extract several simulations and related graphs. Results show that time has the greatest effect on surface roughness, moreover, among the different abrasive media, steel balls have the best performance to improve surface roughness and the combination of 75% steel balls and 25% aluminum oxide has the effective effect. The simulation results have an acceptable compatibility with experimental ones. پرونده مقاله -
دسترسی آزاد مقاله
50 - Investigating on surface roughness of nanohybrid and micro-hybrid composite resins following the use of a simplified polishing system
Seyedeh Parvin Hosseini Fadabobeh Mehrdad Kazemian M. R Malekipour EsfahaniThis in vitro experimental study compared the average surface roughness (Ra value) of Z250 microhybrid and Z350 nanohybrid composite resins following polishing with the EVE simplified polishing system versus the multi-step Sof-Lex discs. Ninety-six composite discs (8 x چکیده کاملThis in vitro experimental study compared the average surface roughness (Ra value) of Z250 microhybrid and Z350 nanohybrid composite resins following polishing with the EVE simplified polishing system versus the multi-step Sof-Lex discs. Ninety-six composite discs (8 x 2 mm) were randomly divided into four subgroups: control (surface under the Mylar strip, no finishing/polishing), polishing with Sof-Lex discs, polishing with EVE discs, and polishing with EVE discs + EVE polishing paste. Prior to polishing, the specimens were ground with 1200-grit silicon carbide abrasive paper. The average surface roughness of each specimen was measured before (baseline) and after polishing using a profilometer. The results were analyzed using ANOVA and Bonferroni tests. The control subgroups showed the smoothest surfaces. A significant difference in surface roughness was found in the Z350 subgroups, with the Sof-Lex system yielding the roughest surface (P<0.05). The EVE discs + EVE paste system yielded the smoothest surface after the control subgroup. The difference in surface roughness was also significant among the Z250 subgroups, with the Sof-Lex system creating significantly rougher surfaces than the EVE discs + paste system. A significant difference in surface roughness was observed in all eight subgroups, with Z350 specimens polished with Sof-Lex discs and Z350 control specimens showing the maximum and minimum roughness, respectively. The study concludes that the two-step EVE polishing system may be preferred over the multi-step Sof-Lex discs for polishing Z250 and Z350 composites, as it provided significantly smoother surfaces. پرونده مقاله -
دسترسی آزاد مقاله
51 - Influence of EDM Characteristic Parameters on the Surface Microstructure in CK45 Alloy Steel
سینا عابدپور اسماعیل جعفری احمد افسری سعید حدیدی مودElectro Discharge Machining (EDM) is a very efficient machining process widely used in manufacturing components of complicated geometry. Based on its nature, i.e. material removal by electric discharge, the process induces thermal stresses that in turn result in generat چکیده کاملElectro Discharge Machining (EDM) is a very efficient machining process widely used in manufacturing components of complicated geometry. Based on its nature, i.e. material removal by electric discharge, the process induces thermal stresses that in turn result in generation of wide spread micro-cracks on the surface of the machined part. In this paper the influence of EDM characteristic parameters on the surface microstructure in CK45 alloy steel which is suitable for manufacturing of forging dies has been extensively investigated. An extensive experimental programme has been carried out to explore the role of various EDM parameters on the quality of the machined surface. The relation of EDM parameters has been evaluated quantitatively using the test results and regression analysis. Predicting the impact of EDM parameters on the surface quality as the outcome of this study provides means to appropriately decide on the adjustment of parameters to their optimum values and achieve the desired die surface quality at reasonable manufacturing time and cost. پرونده مقاله
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