Ghader Faraji
Department of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran
[ 1 ] - Upper bound and numerical analysis of cyclic expansion extrusion (CEE) process
Deformation of the material during cyclic expansion extrusion (CEE) is investigated using upper-bound theorem. The analytical approximation of forming loads agrees very well with the FEM results for different amounts of chamber diameter, friction factor and also for lower die angles. However, the difference between analytical and numerical solution increases at higher die angles which are expla...
[ 2 ] - Punch plastic deformation pipe cladding (PPDPC) as a novel tube cladding method
This study presents a new mechanical tube cladding process named punch plastic deformation pipe cladding (PPDPC) based on local deformation by pressing a punch into the inner layer of the bimetal tube. To investigate the capability of the process, stainless steel tube (as the inner layer) is bonded to a carbon steel pipe (as the outer layer) to fabricate a bimetal pipe. Shear punch tests were u...
[ 3 ] - Numerical Analysis of Severe Plastic Deformation by High Pressure Torsion
High-pressure torsion (HPT) is a metal processing method in which the sample is subjected to a very high plastic shear deformation. This process can produce exceptional levels of grain refinement, and provides a corresponding improvement in mechanical properties. To investigate the stress and strain distribution due to HPT process finite element simulation were conducted to investigate effectiv...
[ 4 ] - Size effect in equal channel angular pressing (ECAP) process
The influence of the sample size (diameter while keeping the length constant) in equal channel angular pressing (ECAP) of pure aluminum is examined using finite element method (FEM) and experiment. Different sized aluminum rods were processed via ECAP and the effect of sample size on the strain homogeneity, process load, and the ratio of the friction to the total force were evaluated. The resul...
[ 5 ] - Numerical investigation of strain distribution during cyclic expansion extrusion (CEE)
Strain distribution of Al 1100 was numerically investigated during cyclic expansion extrusion (CEE) process using finite element method (FEM). Die angle, corner fillet radius and die chamber diameter were considered as die parameters and friction factor and number of passes as process parameters. The effects of these parameters were investigated on the effective strain and strain homogeneity in...
[ 6 ] - A new approach for achieving excellent strain homogeneity in tubular channel angular pressing (TCAP) process
Tubular channel angular pressing (TCAP) is a recently invented novel severe plastic deformation technique for producing UFG tubes. Plastic deformation analysis using the finite element method (FEM) was carried out to investigate the effects of trapezoidal channel geometry on strain inhomogeneity index (SII), strain level and required load compared to previously used channel geometries. The resu...
[ 7 ] - Plastic deformation analysis in parallel tubular channel angular pressing (PTCAP)
Parallel tubular channel angular pressing (PTCAP) process is a novel recently developed severe plastic deformation technique for fabrication of ultrafine grained (UFG) metallic tubes. This new process consists of two half cycles and is affected by several parameters such as channel angles, deformation ratio and curvature angles. In this paper, the effects of these parameters on the plastic defo...
[ 8 ] - Numerical and analytical investigation of an ultrasonic assisted ECAP process
One of the great challenges in the processing of materials using Equal Channel Angular Pressing (ECAP) is the high forming forces required to produce large shear deformation in the material. Researchers show that the friction forces between the die and the sample constitute a great part of the total forming forces. Recently, ultrasonic vibrations are successfully implemented into the ECAP proce...
[ 9 ] - Microstructure and mechanical properties of AZ91 tubes fabricated by Multi-pass Parallel Tubular Channel Angular Pressing
Parallel Tubular Channel Angular Pressing (PTCAP) process is a novel recently developed severe plastic deformation (SPD) method for producing ultrafine grained (UFG) and nanograined (NG) tubular specimens with excellent mechanical and physical properties. This process has several advantageous compared to its TCAP counterparts. In this paper, a fine grained AZ91 tube was fabricated via multi pas...
[ 10 ] - MICROSTRUCTURE AND MECHANICAL PROPERTIES OF THE ULTRAFINE-GRAINED COPPER TUBE PRODUCED BY SEVERE PLASTIC DEFORMATION
In this paper, cyclic flaring and sinking (CFS) as a new severe plastic deformation (SPD) method was employed to produce the ultrafine grain (UFG) copper tubes. The extra friction has eliminated in the CFS method that provided the possibility for production of longer UFG tubes compared to the other SPD methods. This process was done periodically to apply more strain and consequently finer grain...
[ 11 ] - شبیه‌سازی و بررسی نانو کامپوزیت پلیمری تقویت‌شده با نانولوله‌های کربنی و نانو هلیکال‌های کربنی
نانولوله‌های کربنی (CNT) و نانوهلیکال‌های کربنی (CCNT) خواص استثنایی دارند و باعث بهبود خواص مکانیکی، حرارتی و الکتریکی نانوکامپوزیت‌ها می‌شوند و از همین رو، اخیراً مطالعات زیادی روی آن‌ها صورت می‌گیرد. در این مقاله با استفاده از کدنویسی پایتون و مدل‌سازی چند مقیاس در نرم‌افزار آباکوس نمودار تنش ـ کرنش نانوکامپوزیت‌های شبیه‌سازی شده، به دست آمده است. تأثیر هندسه‌ی تقویت‌کننده‌ها که به دو ص...
[ 12 ] - Experimental and Finite Element Analyses of the Hydrostatic Cyclic Expansion Extrusion (HCEE) Process with Back-Pressure
It is generally known that severe plastic deformation processes with back pressure not only apply higher hydrostatic stress and more deformation compared to what a regular process can apply to a workpiece but also prevent surface defects in the workpiece during the process. Hydrostatic cyclic expansion extrusion (HCEE) was developed recently for processing long ultrafine-grained metals and allo...
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