En
  • دکتری (1367)

    مهندسی مکانیک

    بیرمنگام، انگلستان

  • کارشناسی‌ارشد (1358)

    مهندسی مکانیک

    دانشگاه صنعتی شریف،

  • کارشناسی (1355)

    مهندسی مکانیک

    دانشگاه صنعتی شریف،

  • ماشین های ابزار و ماشین کاری
  • شکل دهی فلزات

    داده ای یافت نشد

    ارتباط

    رزومه

    Reducing search space of optimization algorithms for determination of machining sequences by consolidating decisive agents

    Davood Manafi, Mohammad Javad Nategh
    Journal PapersProceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture , Volume 234 , Issue 07-Jun, 2020 May , {Pages 1057-1068 }

    Abstract

    One of the main objectives of computer-aided process planning is to determine the optimum machining sequences and setups. Among the different methods to implement this task, it can be named the constrained optimization algorithms. The immediate drawback of these algorithms is usually a large space needed to be searched for the solution. This can easily hinder the convergence of the solution and increase the possibility of getting trapped in the local minima. A novel approach has been developed in this work with the objective of reducing the search space. It is based on consolidating the decisive factors influencing the consecutive features. This helps prevent creation of sequences which need the change of setup, machine tool, and cutting to

    Integrating the setup planning with fixture design practice by concurrent consideration of machining and fixture design principles

    D Manafi, MJ Nategh
    Journal PapersInternational Journal of Production Research , 2020 March 6, {Pages 20-Jan }

    Abstract

    In the conventional setup planning methods, the required fixtures are planned in a sequential order relative to other activities of the setup planning. In the present study, a new approach has been developed and a concurrent method has been proposed for integrating the setup planning and fixture design practice, which paves the way for considering the fixture design principles in parallel to setup planning activities. This eliminates the need to revise the setup plans to remedy the possible conflicts which are common to conventional procedures. The fixture principles have been cast into mathematical relations as a means to developing the proposed method. In the present study, the locating surfaces are determined as the most important step o

    Development of computer aided clamping system design for workpieces with freeform surfaces

    Mohammad Javad Nategh, Hadi Parvaz
    Journal PapersComputer-Aided Design , Volume 95 , 2018 February 1, {Pages 52-61 }

    Abstract

    The development of computer aided fixture design has already encountered numerous mathematical and technical challenges having hampered realization of automated design of fixturing system consisting of locating and clamping systems. This is more critical for workpieces of freeform surfaces compared with those of polyhedral geometry. In the present study, the mathematical foundation of clamping system design has been developed by using the concept of screw theory and the minimum norm principle. An algorithm has been proposed to realize the developed theory. In this algorithm, three criteria have been taken into consideration to be respected when designing the clamping system. These are minimum number of clamps, maximum contrariety of clampin

    The analysis of the Timoshenko transverse vibrations of workpiece in the ultrasonic vibration-assisted turning process and investigation of the machining error cause...

    H Soleimanimehr, MJ Nategh, A Forouzan Najafabadi, A Zarnani
    Journal PapersPrecision Engineering , 2018 May 22, {Pages }

    Abstract

    Deformation of workpiece causes diametrical error in the turning process. In order to analyze the diametrical error, a model of elastic deformation of workpiece is required. In this article, an efficient elastic deformation model is developed by using of transverse vibration analysis of Timoshenko workpiece method. It is assumed that the workpiece is only held in one side with the chuck in lathe machine. The obtained results illustrated that in the ultrasonic vibration assisted turning process, diametrical error in workpiece after machining was about 35% less than the conventional machining method. Furthermore, by comparing different vibration analysis methods, it was observed that in the same experimental condition, there is a small differ

    An investigation on the motion error of machine tools’ hexapod table

    Mohammad Reza Chalak Qazani, Siamak Pedrammehr, Mohammad Javad Nategh
    Journal PapersInternational Journal of Precision Engineering and Manufacturing , Volume 19 , Issue 4, 2018 April 1, {Pages 463-471 }

    Abstract

    Accuracy is greatly affected by the nonlinear motion of hexapods. This need is more apparent when these mechanisms are employed in machining industry where precision and surface qualities are of critical importance. In this paper, a comprehensive algorithm for tool path programming of the hexapod table is developed. This algorithm is developed based on a circular motion in C#. Net and has the capability of investigating nonlinear motion error to keep it in a controlled range as well. Improved Tustin algorithm is used for interpolating circular path. The effects of different parameters on the nonlinear error of machine tools’ hexapod table during circular interpolation are also investigated in this study. In the circular motion, the optima

    Development of locating system design module for freeform workpieces in computer-aided fixture design platform

    Hadi Parvaz, Mohammad Javad Nategh
    Journal PapersComputer-Aided Design , Volume 104 , 2018 November 1, {Pages 14-Jan }

    Abstract

    Abstract Development of an efficient computer-aided platform for fixture design requires intelligent algorithms to be developed as decision making tools for different designing functions. Locating system design is among the representative fixture design functions which are in need of such intelligent algorithms to implement their complicated roles. This rather unmet need has already hampered the development of automated computer-aided fixture design systems. The authors have proposed an analytical and algorithmic locating system design procedure as a part of their continuous effort to establish a PythonOCC-based platform, which is the subject of the present paper. In order to surmount the geometrical restrictions, workpieces with freeform g

    An Investigation on the Qusta ibn Luqa's Translation of Heron's Treatise on Crane

    MOHAMMAD JAVAD NATEGH, MOSTAFA KARIMI
    Journal Papers , Volume 51 , Issue 100681, 2018 January 1, {Pages 117-140 }

    Abstract

    The Arabic translation of Heron's treatise on crane by Qusta ibn Luqa, in the absence of its Greek original, is among the most important texts on mechanics remained from the Islamic civilization. It was thought hitherto the extant manuscripts of this translation were limited to those available in Leiden, Britania and Manchester libraries. The authors of the present paper have found some manuscripts of the Arabic translation of Heron's treatise in Iran's libraries, in addition to several Persian treatises. These Arabic manuscripts are important for completing the works already undertaken by some orientalists such as Carra de Vaux, Nix and Schmidt. The Persian manuscripts were inspired by Qusta's translation. It is tried in the present paper

    The analysis of the Timoshenko transverse vibrations of workpiece in the ultrasonic vibration-assisted turning process and investigation of the machining error caused by this …

    H Soleimanimehr, MJ Nategh, AF Najafabadi, A Zarnani
    Journal Papers , , {Pages }

    Abstract

    Extracting the manufacturing information of machining features for computer-aided process planning systems

    D Manafi, MJ Nategh, H Parvaz
    Journal PapersProceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture , Volume 231 , Issue 12, 2017 October , {Pages 2072-2083 }

    Abstract

    An integrated manufacturing system needs automated conversion of design information into its manufacturing counterpart. This is partly dealt with in the present study for extracting the manufacturing information for computer-aided process planning systems, including the identification of tool approach direction, attributing the dimensional and geometric tolerances to the machining features, and identification of the reference faces. In spite of extensive study conducted on computer-aided process planning systems, further investigation is still needed to develop automation in attributing tolerances to machining features and identifying the reference faces. The authors have proposed new methods to implement these tasks. A detailed case study

    The effects of joint clearance on the kinematic error of the hexapod tables

    Mohammad Javad Tajaril, Siamak Pedrammehr, Mohammad Reza Chalak Qazani, Mohammad Javad Nategh
    Conference Papers2017 5th RSI International Conference on Robotics and Mechatronics (ICRoM) , 2017 October 25, {Pages 39-44 }

    Abstract

    Clearance in spherical joints of a hexapod table is useful for decreasing the sensitivity of the table to manufacturing inaccuracies. However, such clearance affects the kinematic accuracy of the table and other adverse effects such as noise and vibration. The present paper investigates the influence of clearance in the spherical joints on the kinematics error in positioning and orientating of the table. A mathematical model for the relationship between the clearance in the spherical joints on the motion error of the table is derived. Numerical analysis of the error model is performed and experimental tests validate the proposed model.

    تبیین رابطة قابلیت‎ های بازاریابی و عملکرد مالی سازمان‎

    دهدشتی شاهرخ, ناطق, احسانی‎
    Journal Papers , , {Pages }

    Abstract

    Analytical and experimental analysis of response of the cutting tool and the workpiece by the chatter phenomenon in turning

    Morteza Shankayi, Mohammad Javad Nategh
    Journal PapersModares Mechanical Engineering , Volume 15 , Issue 20, 2016 February 15, {Pages 218-222 }

    Abstract

    Chatter phenomenon is self-exited vibrations in machining processes that reduces the surface finish, causes damages to the tool and workpiece and in severe cases can be detrimental to the machine and operator. Understanding this phenomenon leads to the right choice of machining parameters and helps avoiding it. ne way to understand a physical phenomenon is through its modeling. In this paper, a strong base was built to simulate the chatter phenomenon. A number of tests were carried out where chatter phenomenon occurred. In the tests, cutting forces and displacements of tool and the workpiece were recorded. The forces that cause displacement in the tool and the workpiece were obtained by continuum system analysis and verified by the dynamome

    An elastokinematic solution to the inverse kinematics of microhexapod manipulator with flexure joints of varying rotation center

    E Rouhani, MJ Nategh
    Journal PapersMechanism and Machine Theory , Volume 97 , 2016 March 1, {Pages 127-140 }

    Abstract

    In parallel manipulators with flexural joints, the position of the joint's rotation center continuously changes with the variation of the end effector's pose. The change occurring in the joints' rotation center is commonly ignored in the available solutions, which can lead to considerable error. In order to overcome this shortcoming, a new method has been developed by the present authors on the basis of elastokinematic analysis in which the elastic deformation of the flexure joints is taken into account for the kinematic analysis. The results have been verified by several cases of the moving platform's displacement and by finite element method.

    Stability analysis of free-form workpieces in fixtures

    Hadi Parvaz, Mohammad Javad Nategh
    Journal PapersModares Mechanical Engineering , Volume 16 , Issue 2, 2016 April 15, {Pages 245-252 }

    Abstract

    The stability analysis of workpiece in fixtures is considered as one of the stages of the fixture verification system. The stability of free-form workpieces in fixtures is affected by different agents including weight, locators, clamps and machining wrenches. In this study, a mathematical model has been presented for part stability analysis based on the minimum norm principle that led to a non-linear quadratic optimization problem. The solution to this problem is the reaction forces at the contact points between workpiece and locators. The study includes the workpiece stability analysis at the loading stages, determination of stability span for workpiece and the investigating the effect of the base locators distances on the workpiece stabil

    Analytical model of locating system design for parts with free form surfaces

    Hadi Parvaz, Mohammad Javad Nategh
    Journal PapersModares Mechanical Engineering , Volume 15 , Issue 20, 2016 February 15, {Pages 129-133 }

    Abstract

    In this study, an analytical model for designing the locating system for non-polyhedral parts is presented. The model is based on constraining maximum (possible) workpiece D Fs using accurately posed locators. The model consists of three main rules: parallelism between locators, maximum (available) distance between locators and maximum reciprocity (in screw theory) between base, side and stop locators. The model states that the simultaneous consideration of the mentioned three rules is necessary for obtaining a robust locating system. The modeling of the rules is implemented using the innovative base, side and stop locating matrices. The scoring method is employed for selecting the base, side and stop surfaces between locating candidates. A

    Mathematical modeling for effect of machine tools in setup planning method based on permutation for prismatic parts

    Davood Manafi, Mohammad Javad Nategh
    Journal PapersModares Mechanical Engineering , Volume 15 , Issue 20, 2016 February 15, {Pages 139-143 }

    Abstract

    Setup planning is an important function in CAPP systems which is a bridge for integration of CAD and CAPP systems. All features in a specific setup must have the same TAD and satisfy the technical and geometrical rules. Also, these features must be machined in one machine tool. Setup planning must be regenerated if features in a specific setup need different equipment and machine tools. So, it is important for machine tools to be considered during the setup planning to avoid the setup replanning. In this paper, the effect of machine tools on the setup planning was studied and the mathematical formulas were introduced for this purpose. Finally, setup planning method was developed based on these mathematical formulas. The algorithm was progra

    Machining Free Form Surfaces with Hexapod Machine Tool

    ALi Rabbani, Mohammad Javad Nategh, Davood Karimi
    Journal PapersModares Mechanical Engineering , Volume 16 , Issue 8, 2016 October 15, {Pages 395-400 }

    Abstract

    A hexapod machine tool with a parallel structure has six degrees of freedom. This machine has a high dexterity unlike traditional machine tools. The hexapod can be used in machining free form surfaces. Free form surfaces are widely used in today industries. These surfaces are much encountered in auto, aerospace and mold design industries. Therefore machining of these surfaces has attracted the attention of researchers. In this field much research has been done in five axis machine tools. In this paper machining free form surfaces with hexapod machine tool has been investigated. The main topic of this paper is the feasibility of using hexapod as a machine tool table and machining with it. First, the interpolation of free form surfaces for pa

    Design of clamping system for workpiece with freeform geometry

    Hadi Parvaz, Mohammad Javad Nategh
    Journal PapersModares Mechanical Engineering , Volume 16 , Issue 9, 2016 November 15, {Pages 195-206 }

    Abstract

    Jig and fixture design for workpieces with freeform geometry has more complexity in comparison with the polyhedral parts. The locating and clamping system design construct the basis of the jig and fixture design activities. In this study, a theoretical analysis is suggested for automatic design of clamping points for freeform workpieces. The clamping design is performed in three main stages which the clamping application points are determined through the first two principles and being verified through the last stage. The mentioned principles consist of:(1) the minimum quantity of clamps,(2) the maximum clamping force components on the locating directions and (3) the workpiece static stability under the external wrenches. After mathematical

    Machining NURBS curves with hexapod machine tool

    Ali Rabbani, Reza Ahadi, Mohammad Javad Nategh
    Journal PapersModares Mechanical Engineering , Volume 15 , Issue 20, 2016 February 15, {Pages 490-494 }

    Abstract

    For increasing the production speed along with decreasing the costs in competitive industry, machines with high dynamic performance and stiffness are needed with low driven mass. Since serial mechanism of the traditional machine tools is not appropriate for above requirement, robots with parallel mechanism have been given attention. Hexapod machine tool is a parallel robot which is based on Stewart platform. The latter consists of two platforms. The lower platform is fixed in its place and the upper platform’s position changes by changing the lengths of pods. This platform has six degrees of freedom and acts as a table of machine tool. This machine is able to convert an ordinary machine tool into a new CNC machine tool. In this research,

    Automatic selection of locating and clamping surfaces in polyhedral parts milling based on normal vector graph and linear algebra

    Vahid Sanjabi, Mohammad Javad Nategh
    Journal PapersModares Mechanical Engineering , Volume 15 , Issue 20, 2016 February 15, {Pages 134-138 }

    Abstract

    Appropriate fixture design for manufacturing a product with quality and in accordance with the requirements is important task and depends on the designer’s experience and skills. In fixture design, the appropriate locating and clamping surfaces automatic selection is the most important of design step. Computer aided fixture design softwares ease the fixture design. In this paper, a new method is presented for automatic selection of appropriate clamping and locating surfaces based on the normal vector graph and linear algebra. At first, locating and clamping surfaces are classified with normal vector graph. Then, the best surfaces among the classified locating and clamping surfaces has been selected with the use of linear algebra method. T

    /pro/academic_staff/nategh/publication

    دروس نیمسال جاری

    • كارشناسي ارشد
      تاريخ و فلسفه علم و فناوري ( واحد)
      دانشکده مهندسی مکانیک، گروه مهندسي ساخت و توليد

    دروس نیمسال قبل

    • كارشناسي ارشد
      طراحي اجزاء و سازه ماشين ابزار ( واحد)
      دانشکده مهندسی مکانیک، گروه مهندسي ساخت و توليد
    • 1397
      قرباني, بهمن
      مدل‌سازي نيرويي و بررسي مهندسي سطح در تراشكاري فولاد زنگ نزن متخلخل 316 كم كربن به كمك ارتعاش التراسونيك
    • عضو کارگروه بررسی صلاحیت علمی دانشکده فنی و مهندسی- بخش مهندسی مکانیک
    • عضو کمیسیون تخصصی گروه مهندسی مکانیک، عمران و رشته های مرتبط
    • عضو هیئت تحریریة نشریة علمی-پژوهشی تاریخ علم
    • عضو هیئت تحریریة نشریة علمی-پژوهشی تاریخ علم
    • رئیس بخش مهندسی مکانیک دانشکده فنی و مهندسی
    • عضو شورای پژوهشی پژوهشکده تاریخ علم دانشگاه تهران
    • نماینده بخش در شورای آموزشی دانشکده
    • عضویت در کمیسیون ارزشیابی مدارک تحصیلی کشورهای انگلیسی زبان
    • عضو هیئت امنای دانشگاه علوم و فنون مازندران
      داده ای یافت نشد

    مهم

    جدید

      اطلاعیه ای درج نشده است