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    Bifurcation analysis of nonlinear milling process with tool wear and process damping: Sub-harmonic resonance under regenerative chatter

    , Article International Journal of Mechanical Sciences ; Vol. 85, issue , August , 2014 , p. 1-19 Moradi, H ; Vossoughi, G ; Movahhedy, M. R ; Sharif University of Technology
    Abstract
    In this paper, bifurcation analysis is performed for the nonlinear milling process under sub-harmonic resonance and regenerative chatter, with tool wear and process damping effects. Multiple-scales approach is used to construct analytical approximate solutions for non-autonomous parametrically excited equations of the system with time delay terms. The new bifurcation parameters are the detuning parameter (deviation of the tooth passing frequency from three times of the chatter frequency), damping ratio (affected by process damping) and tool wear width. Jump phenomenon and multi-values responses are observed in the first order solution under sub-harmonic resonance condition. Periodic,... 

    Tunable vibration absorber for improving milling stability with tool wear and process damping effects

    , Article Mechanism and Machine Theory ; Volume 52 , June , 2012 , Pages 59-77 ; 0094114X (ISSN) Moradi, H ; Movahhedy, M. R ; Vossoughi, G ; Sharif University of Technology
    2012
    Abstract
    This paper deals with the problem of chatter suppression in milling process in order to achieve higher precision, better surface quality and larger material removal rate (MRR). The peripheral milling process is modeled as a two degrees of freedom system and the effects of tool wear and process damping are considered. It is shown that when regenerative chatter develops, both tool wear and process damping act as stabilizing factors. For larger values of depth of cut and consequently higher MRR, tunable vibration absorbers (TVA) (in x-y directions) are designed to improve stability. An optimal algorithm is developed which determines the optimum values for absorbers' parameters. The effects of... 

    Nonlinear behaviour of the regenerative chatter in turning process with a worn tool: Forced oscillation and stability analysis

    , Article Mechanism and Machine Theory ; Volume 45, Issue 8 , 2010 , Pages 1050-1066 ; 0094114X (ISSN) Moradi, H ; Bakhtiari Nejad, F ; Movahhedy, M. R ; Ahmadian, M. T ; Sharif University of Technology
    2010
    Abstract
    Self-excited and forced vibrations are important topics in machining processes because their occurrence results in poor surface finish, increase in tool wear and reduction of material removal rate. In this paper, turning process is modeled as a single degree of freedom (SDOF) dynamic system including quadratic and cubic structural nonlinearities. The effect of tool flank wear, as a contact force between the workpiece and tool, is addressed vigorously. Multiple scale method is used to find the solution of the nonlinear delay-differential equation including regenerative chatter, forced excitation and tool wear. During the stability analysis, it is shown that width of cut can be considered as... 

    Nonlinear oscillation and stability analysis of the turning process with a worn tool

    , Article Proceedings of the ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference 2009, DETC2009, 30 August 2009 through 2 September 2009 ; Volume 1, Issue PART B , August–September , 2010 , Pages 927-934 ; 9780791848982 (ISBN) Moradi, H ; Ahmadian, M. T ; Bakhtiari Nejad, F ; The Design Engineering Division, ASME; The Computers and Information in Engineering Division, ASME ; Sharif University of Technology
    2010
    Abstract
    Self-excited and forced vibrations are important topics in machining processes because their occurrence results in poor surface finish, increase in tool wear and hampers productivity. In this paper, turning process is modeled as a SDOF dynamic system including quadratic and cubic structural nonlinearities. The effect of tool flank wear, as a contact force between the work-piece and tool, is addressed vigorously. Multiple scale method is used to find the solution of the nonlinear dynamic equation including regenerative chatter, forced excitation and tool wear. It is shown that, width of cut can be considered as the bifurcation parameter of the system. Primary, super-harmonic and sub-harmonic... 

    Nonlinear oscillation and stability analysis of the turning process with a worn tool

    , Article Proceedings of the ASME Design Engineering Technical Conference, 30 August 2009 through 2 September 2009 ; Volume 1, Issue PARTS A AND B , 2009 , Pages 927-934 ; 9780791848982 (ISBN) Moradi, H ; Ahmadian, M. T ; Bakhtiari Nejad, F ; Sharif University of Technology
    Abstract
    Self-excited and forced vibrations are important topics in machining processes because their occurrence results in poor surface finish, increase in tool wear and hampers productivity. In this paper, turning process is modeled as a SDOF dynamic system including quadratic and cubic structural nonlinearities. The effect of tool flank wear, as a contact force between the work-piece and tool, is addressed vigorously. Multiple scale method is used to find the solution of the nonlinear dynamic equation including regenerative chatter, forced excitation and tool wear. It is shown that, width of cut can be considered as the bifurcation parameter of the system. Primary, super-harmonic and sub-harmonic... 

    Microstructure and cutting performance investigation of Ti(C, N)-based cermets containing various types of secondary carbides

    , Article International Journal of Machine Tools and Manufacture ; Volume 47, Issue 5 SPEC. ISS , 2007 , Pages 768-772 ; 08906955 (ISSN) Rahimi Dizaji, V ; Rahmani, M ; Faghihi Sani, M ; Nemati, Z ; Akbari, J ; Sharif University of Technology
    Elsevier Ltd  2007
    Abstract
    In this paper, the effects of type and amount of various secondary carbides on the microstructure and cutting performance of Ti(C0.7N0.3)-12Co system have been investigated. Nine alloys with different amounts of WC, Mo2C and Ta0.7Nb0.3C additives were studied, using scanning electron microscopy (SEM), Vickers hardness (HV), transverse rupture strength (TRS) and continuous turning tests. Alloys including Mo2C and WC presented finer carbonitride grain structure, as well as higher wear resistance resulting from their higher hardness and highly solution hardened binder phase. © 2006 Elsevier Ltd. All rights reserved  

    Processing of squeeze cast Al6061-30vol% SiC composites and their characterization

    , Article Materials and Design ; Volume 27, Issue 3 , 2006 , Pages 216-222 ; 02613069 (ISSN) Reihani, S. M. S ; Sharif University of Technology
    Elsevier Ltd  2006
    Abstract
    6061 aluminum matrix composites containing 30vol% SiC with mean mass particle size of 16 and 22 μm as the reinforcing phase were synthesized by squeeze casting route. The process consisted of fabricating of SiC preform followed by squeeze casting of 6061 aluminum alloy. The SiC preform was made by blending SiC particles with silica as a coal and sintering. The microstructural features, aging behavior, mechanical properties and wear characteristics of the composites were investigated. The results indicated that a homogenous distribution of SiC particles in the aluminum matrix, which is almost free of pores, can be obtained by squeeze casting method. Higher strength and lower wear rates were... 

    Test methodology and wear characteristics of austenitic stainless steel aisi type 316 at cryogenic environment

    , Article Lecture Notes in Engineering and Computer Science ; Vol. 2 , 2-4 July , 2014 , pp. 1214-1217 ; ISSN: 20780958 ; ISBN: 9789881925350 Farrahi, G. H ; Kazerani, V ; Ghorashi, M. S ; Sharif University of Technology
    Abstract
    Components in cryogenic milieu with relative motion, like seals and pumps cannot be lubricated by using oils or other lubricants. Therefore materials wear in cryogenic condition is a great concern. To earn valid data about the wear properties of common and super useful material in cryogenic tribosystems, reconstruction wear test apparatus at cryogenic temperature is needed. Investigations on metal-metal couple show that austenitic stainless steels have favorable and auspicious sliding properties at cryogenic temperature. This research provides the wear parameters of austenitic stainless steel AISI type 316 in cryogenic environment. For this purpose two sets of test environment are prepared,... 

    Manufacturing error compensation based on cutting tool location correction in machining processes

    , Article International Journal of Computer Integrated Manufacturing ; Vol. 27, Issue. 11 , 29 Oct , 2014 , pp. 969-978 ; ISSN: 0951192X Khodaygan, S ; Sharif University of Technology
    Abstract
    Inaccuracies in workpiece location lead to errors in position and orientation of machined features on the workpiece, and strongly affect the assemblability and the quality of the product. The accurate positioning of workpiece on a fixture is influenced by rigid body displacements and rotations of the workpiece due to several errors (e.g. geometric radial and position errors in locators and manufacturing tolerances of the workpiece). In this paper, an efficient approach is introduced for analysis and compensation errors in the workpiece-fixture-cutting tool system. A new mathematical formulation of workpiece-fixture modelling is proposed to establish the relationship between the locating... 

    Effect of alumina nanoparticle on the tribological performance of automotive brake friction materials

    , Article Journal of Reinforced Plastics and Composites ; Vol. 33, issue. 2 , October , 2014 , pp. 166-178 ; ISSN: 07316844 Etemadi, H ; Shojaei, A ; Jahanmard, P ; Sharif University of Technology
    Abstract
    Brake friction materials filled with nanoalumina were produced by both conventional and solvent-assisted mixing methods. It was shown that nanoalumina loading led to the reduction of friction coefficient and improvement in mechanical, wear and thermal behaviors. Such behavior was attributed to the role of nanoalumina in producing stable friction layer and easy conduction path in matrix. It was postulated that nanoalumina is able to attach on the surface of microalumina facilitating the rolling of microalumina at interface. Solution-processed samples exhibited lower improvement in tribological and mechanical properties compared to the conventional mixing due to the limited interaction between... 

    Friction and wear performance of copper-graphite surface composites fabricated by friction stir processing (FSP)

    , Article Wear ; Volume 304, Issue 1-2 , 2013 , Pages 1-12 ; 00431648 (ISSN) Sarmadi, H ; Kokabi, A. H ; Seyed Reihani, S. M ; Sharif University of Technology
    2013
    Abstract
    Copper-graphite composites which have low friction coefficient can be used as bearing materials in lieu of materials containing lead which cause environmental problems. So far, some methods such as powder metallurgy and centrifugal casting have been employed to produce these composites. In this study, friction stir processing (FSP) was used to produce copper-graphite surface composites. Five tools with different pin profile were employed in order to achieve a comprehensive dispersion. Results show that the tool with triangular pin gives rise to a better dispersion of graphite particles. Furthermore, four copper-graphite composites containing different graphite content were prepared using... 

    Forced vibration analysis of the milling process with structural nonlinearity, internal resonance, tool wear and process damping effects

    , Article International Journal of Non-Linear Mechanics ; Volume 54 , 2013 , Pages 22-34 ; 00207462 (ISSN) Moradi, H ; Vossoughi, G ; Movahhedy, M. R ; Ahmadian, M. T ; Sharif University of Technology
    2013
    Abstract
    In this paper, forced vibration analysis of an extended dynamic model of the milling process is investigated, in the presence of internal resonance. Regenerative chatter, structural nonlinearity, tool wear and process damping effects are included in the proposed model. Taking into account the average and first order expansion of Fourier series for cutting force components; their closed form expressions are derived. Moreover, in the presence of large vibration amplitudes, the loss of contact effect is included in this model. Analytical approximate response of the nonlinear system is constructed through the multiple-scales approach. Dynamics of the system is studied for two cases of primary... 

    Effect of nano Al2O3 addition on mechanical properties and wear behavior of NiTi intermetallic

    , Article Materials and Design ; Volume 51 , October , 2013 , Pages 375-382 ; 02613069 (ISSN) Farvizi, M ; Ebadzadeh, T ; Vaezi, M. R ; Kim, H. S ; Simchi, A ; Sharif University of Technology
    Elsevier Ltd  2013
    Abstract
    It has been found that the high wear resistance of NiTi alloy is mainly attributed to its pseudoelasticity which is only effective within a small temperature range. It is believed that pseudoelasticity becomes ineffective by applying high-load wear condition which yields plastic deformation and temperature increment during wear test. Therefore, the enhanced wear resistance can be obtained from the improvement of mechanical property of the alloy without much reduction of pseudoelasticity. In this study, a low weight percentage of hard Al2O3 nanoparticles were added to NiTi atomized powders. The resultant powder mixture was homogenized by ball milling and sintered in a vacuum furnace in order... 

    Aseptic loosening of femoral components - A review of current and future trends in materials used

    , Article Materials and Design ; Volume 42 , 2012 , Pages 459-470 ; 02641275 (ISSN) Bahraminasab, M ; Sahari, B. B ; Edwards, K. L ; Farahmand, F ; Arumugam, M ; Hong, T. S ; Sharif University of Technology
    2012
    Abstract
    The variety of new biomaterials and different surface treatments being applied to existing materials all intended for total knee replacement (TKR) are self-evident of the demand for longer lasting knee prostheses. Aseptic loosening is one of the main reasons for the revision of TKR components including the femoral component, which has more challenging problems because of the different causes of failure. This paper therefore, focuses on aseptic loosening of femoral components and materials options available. Several current and promising new metallic, ceramic and polymeric biomaterials are discussed to highlight their advantages and their shortcomings. It is concluded that current materials... 

    Taguchi's optimization in ultrasonic drilling of alumina ceramic

    , Article Proceedings of the 6th International Conference on Leading Edge Manufacturing in 21st Century, LEM 2011, 8 November 2011 through 10 November 2011 ; November , 2011 Hoseini, S. M ; Akbari, J ; Japan Society of Mechanical Engineers (JSME),; Manufacturing and Machine Tool Division ; Sharif University of Technology
    2011
    Abstract
    This paper outlines the effectiveness of the ultrasonic machining of alumina in terms of tool wear rate of the tool used and the material removal rate of work piece produced. The optimum combination of various input factors as type of abrasive slurry, their size and concentration, power and feed rate, in the machining of alumina has been determined by applying the Taguchi technique, also analysis is used to choose the best shape for horn. The study shows that among input parameters, power has the highest effect on MRR (material removal rate). Effects of grit size and feed rate on TWR (tool wear rate) also investigated  

    Effect of starting materials on the wear performance of NiTi-based composites

    , Article Wear ; Volume 334-335 , July , 2015 , Pages 35-43 ; 00431648 (ISSN) Farvizi, M ; Ebadzadeh, T ; Vaezi, M. R ; Yoon, E. Y ; Kim, Y. J ; Kang, J. Y ; Kim, H. S ; Simchi, A ; Sharif University of Technology
    Elsevier Ltd  2015
    Abstract
    NiTi alloys have exhibited significant potential as a matrix of wear resistant composites. In this study, in order to examine the effect of starting materials on the wear performance of NiTi-based composites, both elemental Ni/Ti and prealloyed NiTi powders were used to fabricate NiTi-6wt% nano-Al2O3 composites using hot isostatic pressing (HIP). Nanoindentation and microhardness test results indicate that the composite samples produced from the elemental Ni/Ti powders exhibited higher hardness and lower pseudoelasticity properties than those of the samples fabricated from the prealloyed NiTi powders; this is attributed to the higher amount of... 

    Wear wear properties of rheo-squeeze cast aluminum matrix reinforced with nano particulates

    , Article Protection of Metals and Physical Chemistry of Surfaces ; Volume 52, Issue 3 , 2016 , Pages 486-491 ; 20702051 (ISSN) Ostad Shabani, M ; Heydari, F ; Tofigh, A. A ; Rahimipour, M. R ; Razavi, M ; Mazahery, A ; Davami, P ; Sharif University of Technology
    Maik Nauka Publishing / Springer SBM 
    Abstract
    There are many approaches to fabricate nanoparticles reinforced aluminum matrix composites. However, uniform distribution of nanoparticle within aluminum matrix remains a difficult challenge. In this study, a novel method is used by taking the advantages from squeeze casting of semi-solid aluminum slurry combined with electromagnetic field to refine the microstructure of the primary Al and eutectic Si phase, plus to obtain uniform distribution nano alumina particles in the aluminum matrix. It is noted that electromagnetic field plays an important role in the formation of non-dendritic primary α-Al particles and a great microstructure refinement occurs as a consequence of the pressure... 

    Mechanical properties of Al–30Si–5Fe alloy using combination of rapid solidification and thixoforming processes

    , Article Metallography, Microstructure, and Analysis ; Volume 6, Issue 6 , 2017 , Pages 502-511 ; 21929262 (ISSN) Shafizadeh, M ; Aashuri, H ; Nikzad, S ; Ferasat, K ; Sharif University of Technology
    Abstract
    In this study, a combination of rapid solidification (melt-spinning) and semisolid forming (thixoforming) processes was used to refine the coarse microstructure of “as-cast” Al–30Si–5Fe alloy and improve its mechanical properties. Al–30Si–5Fe ribbons produced by the melt-spinning process were pulverized and subsequently consolidated at 300 °C in an argon atmosphere. Prepared specimens were thixoformed at temperatures ranging from 580 to 700 °C for various holding times. Some cast samples were also directly thixoformed as reference. In all thixoformed samples, microstructures were modified and needle-like intermetallic compounds as well as silicon particles in the as-cast part were changed... 

    Improvement of dry sliding tribological properties of polyamide 6 using diamond nanoparticles

    , Article Tribology International ; Volume 115 , 2017 , Pages 370-377 ; 0301679X (ISSN) Karami, P ; Shojaei, A ; Sharif University of Technology
    Elsevier Ltd  2017
    Abstract
    In the present study, it was revealed that incorporation of nanodiamond containing carboxylic group (ND-COOH) decreased considerably specific wear rate (∼30%) and COF (∼60%) of polyamide 6 (PA6) at 1 wt% loading. Compared with ND-COOH, amino functionalized ND enhanced further wear performance of PA6 which was associated with its finer dispersion as well as greater influence on the improvement of mechanical properties, toughness and crystallinity of PA6. Surface temperature increment caused by frictional heat was in close agreement with COF and wear characteristics of the samples. Optical microscopy images revealed that NDs promote the abrasive wear mechanism in PA6/ND composites. © 2017... 

    Correlating the microstructure to mechanical properties and wear behavior of an accumulative back extruded Al-Mg2Si in-situ composite

    , Article Tribology International ; Volume 115 , 2017 , Pages 199-211 ; 0301679X (ISSN) Ebrahimi, M ; Zarei Hanzaki, A ; Abedi, H. R ; Azimi, M ; Mirjavadi, S. S ; Sharif University of Technology
    Elsevier Ltd  2017
    Abstract
    The present work was conducted to study the effects of microstructural evolutions on the mechanical and wear behavior of an accumulative back extruded aluminum-based in-situ composite. The mechanical fragmentation and thermal disintegration of the primary and secondary Mg2Si particles were found as the main microstructural changes. For that reason, the particle interspacing was decreased, the sharp ends were modified, and the reinforcements were more uniformly distributed. Surprisingly, the wear loss was dramatically decreased in processed materials in comparison to the as-received one. Oxidation and delamination were identified as the dominant wear mechanisms. These were addressed...