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Articles 1 - 19 of 19
Full-Text Articles in Mechanical Engineering
Driving Force For Binary Alloy Solidification Under Far From Local Equilibrium Conditions, Sergey Sobolev
Driving Force For Binary Alloy Solidification Under Far From Local Equilibrium Conditions, Sergey Sobolev
Sergey Sobolev
No abstract provided.
Single-Layer Graphene Oxide Reinforced Metal Matrix Composites By Laser Sintering: Microstructure And Mechanical Property Enhancement, Dong Lin
dong lin
No abstract provided.
A Case Study Of Heat Treatment On Aisi 1020 Steel, Sayed Shafayat Hossain, Md. Maksudul Islam, Md. Sajibul Alam Bhuyan
A Case Study Of Heat Treatment On Aisi 1020 Steel, Sayed Shafayat Hossain, Md. Maksudul Islam, Md. Sajibul Alam Bhuyan
Md. Maksudul Islam
Proper heat treatment of steels is one of the most important factors in determining how they will perform in service. Engineering materials, mostly steel, are heat treated under controlled sequence of heating and cooling to alter their physical and mechanical properties to meet desired engineering applications. In this study we have chosen AISI 1020 steel as for our research work and we have tried to find out the mechanical properties (hardness) and micro structural properties (martensite formation, carbon self-locking region) by means of appropriate heat treatment process (annealing, normalizing & hardening). Here the steel specimens were heat treated in a …
Modelling Three-Phase Flow In Metallurgical Processes, Christoph Goniva, Gijsbert Wierink, Kari Heiskanen, Stefan Pirker, Christoph Kloss
Modelling Three-Phase Flow In Metallurgical Processes, Christoph Goniva, Gijsbert Wierink, Kari Heiskanen, Stefan Pirker, Christoph Kloss
Gijsbert Wierink
The interaction between gasses, liquids, and solids plays a critical role in many processes, such as coating, granulation and the blast furnace process. In this paper we present a comprehensive numerical model for three phase flow including droplets, particles and gas. By means of a coupled Computational Fluid Dynamics (CFD) - Discrete Element Method (DEM) approach the physical core phenomena are pictured at a detailed level. Sub-models for droplet deformation, breakup and coalescence as well as droplet-particle and wet particle-particle interaction are applied. The feasibility of this model approach is demonstrated by its application to a rotating drum coater. The …
A Large Deformation, Rotation-Free, Isogeometric Shell, D. J. Benson, Y. Bazilevs, Ming-Chen Hsu, T. J. R. Hughes
A Large Deformation, Rotation-Free, Isogeometric Shell, D. J. Benson, Y. Bazilevs, Ming-Chen Hsu, T. J. R. Hughes
Ming-Chen Hsu
Conventional finite shell element formulations use rotational degrees of freedom to describe the motion of the fiber in the Reissner–Mindlin shear deformable shell theory, resulting in an element with five or six degrees of freedom per node. These additional degrees of freedom are frequently the source of convergence difficulties in implicit structural analyses, and, unless the rotational inertias are scaled, control the time step size in explicit analyses. Structural formulations that are based on only the translational degrees of freedom are therefore attractive. Although rotation-free formulations using C0 basis functions are possible, they are complicated in comparison to their C1 …
Isogeometric Shell Analysis: The Reissner–Mindlin Shell, D. J. Benson, Y. Bazilevs, Ming-Chen Hsu, T.J.R. Hughes
Isogeometric Shell Analysis: The Reissner–Mindlin Shell, D. J. Benson, Y. Bazilevs, Ming-Chen Hsu, T.J.R. Hughes
Ming-Chen Hsu
A Reissner–Mindlin shell formulation based on a degenerated solid is implemented for NURBS-based isogeometric analysis. The performance of the approach is examined on a set of linear elastic and nonlinear elasto-plastic benchmark examples. The analyses were performed with LS-DYNA, an industrial, general-purpose finite element code, for which a user-defined shell element capability was implemented. This new feature, to be reported on in subsequent work, allows for the use of NURBS and other non-standard discretizations in a sophisticated nonlinear analysis framework.
Gtaw ايجادشده با روش جوشکاری Tini-Tic و Tini بررسی ريزساختاری پوشش, Masoud Harooni, Morteza Shamanian, Alireza Fadaei Tehrani
Gtaw ايجادشده با روش جوشکاری Tini-Tic و Tini بررسی ريزساختاری پوشش, Masoud Harooni, Morteza Shamanian, Alireza Fadaei Tehrani
Masoud Harooni
هدف از انجام اين پژوهش بهبود سختي سطحي و ريزساختار فولاد ساده کربنی از نوع 52 و مقايسه ريز ساختار اين دو با هم GTAW ايجاد شده به روش جوشکاری TiNi-TiC و TiNi پوششی از بترتيب با نسبت استوکيومتری مساوي و نسبت ۲۰ Ti-Ni-C و Ti-Ni است. بدين منظور مخلوط پودری به طور جداگانه توسط روش فعال سازی مکانيکی فعال شد و سپس بر سطح TiC درصد تقويت کننده به ضخامت ۱ ميليمتر پيش نشانده شده با استفاده از روش جوشکاری قوسی St نمونه های فولادی 52 تنگستن- گاز ذوب و با فلز پايه امتزاج يافته است. جهت بررسي نوع …
Modeling Of The Size Effects On The Behavior Of Metals In Microscale Deformation Processes, Gap-Yong Kim, Jun Ni, Muammer Koc
Modeling Of The Size Effects On The Behavior Of Metals In Microscale Deformation Processes, Gap-Yong Kim, Jun Ni, Muammer Koc
Gap-Yong Kim
For the accurate analysis and design of microforming process, proper modeling of material behavior at the micro/mesoscale is necessary by considering the size effects. Two size effects are known to exist in metallic materials. One is the “grain size” effect, and the other is the “feature/specimen size” effect. This study investigated the feature/specimen size effect and introduced a scaling model which combined both feature/specimen and grain size effects. Predicted size effects were compared with three separate experiments obtained from previous research: a simple compression with a round specimen, a simple tension with a round specimen, and a simple tension in …
An Experimental Investigation On Semi-Solid Forming Of Micro/Meso-Scale Features, Gap-Yong Kim, Jun Ni, Rhett Mayor, Heesool Kim
An Experimental Investigation On Semi-Solid Forming Of Micro/Meso-Scale Features, Gap-Yong Kim, Jun Ni, Rhett Mayor, Heesool Kim
Gap-Yong Kim
The potentials of semi-solid forming technology have generated much interest regarding its application in micromanufacturing. This study investigates the feasibility of using semi-solid forming technology to produce parts with micro/meso features. An experimental setup has been developed to study the effects of die/punch temperature, initial solid fraction, punch speed, and workpiece shape on the semi-solid forming process. A part has been produced for a microreactor application and has been analyzed with an optical measurement system for feature formation. The results indicated complex interaction among the process parameters and the material flow, which affected the final pin formation. The punch temperature …
Modeling Of The Semi-Solid Material Behavior And Analysis Of Micro-/Mesoscale Feature Forming, Gap-Yong Kim, Muammer Koc, Rhet Mayor, Jun Ni
Modeling Of The Semi-Solid Material Behavior And Analysis Of Micro-/Mesoscale Feature Forming, Gap-Yong Kim, Muammer Koc, Rhet Mayor, Jun Ni
Gap-Yong Kim
One of the major challenges in simulation of semi-solid forming is characterizing the complex behavior of a material that consists of both solid and liquid phases. In this study, a material model for an A356 alloy in a semi-solid state has been developed for high solid fractions (>0.6) and implemented into a finite element simulation tool to investigate the micro-/mesoscale feature formation during the forming process. Compared to previous stress models, which are limited to expressing the stress dependency on only the strain rate and the temperature (or the solid fraction), the proposed stress model adds the capability of …
Modeling Of The Size Effects On The Behavior Of Metals In Microscale Deformation Processes, Gap-Yong Kim, Jun Ni, Muammer Koc
Modeling Of The Size Effects On The Behavior Of Metals In Microscale Deformation Processes, Gap-Yong Kim, Jun Ni, Muammer Koc
Gap-Yong Kim
For the accurate analysis and design of microforming process, proper modeling of material behavior at the micro/mesoscale is necessary by considering the size effects. Two size effects are known to exist in metallic materials. One is the “grain size” effect, and the other is the “feature/specimen size” effect. This study investigated the feature/specimen size effect and introduced a scaling model which combined both feature/specimen and grain size effects. Predicted size effects were compared with three separate experiments obtained from previous research: a simple compression with a round specimen, a simple tension with a round specimen, and a simple tension in …
Modeling Of The Semi-Solid Material Behavior And Analysis Of Micro-/Mesoscale Feature Forming, Gap-Yong Kim, Muammer Koc, Rhet Mayor, Jun Ni
Modeling Of The Semi-Solid Material Behavior And Analysis Of Micro-/Mesoscale Feature Forming, Gap-Yong Kim, Muammer Koc, Rhet Mayor, Jun Ni
Gap-Yong Kim
One of the major challenges in simulation of semi-solid forming is characterizing the complex behavior of a material that consists of both solid and liquid phases. In this study, a material model for an A356 alloy in a semi-solid state has been developed for high solid fractions (>0.6) and implemented into a finite element simulation tool to investigate the micro-/mesoscale feature formation during the forming process. Compared to previous stress models, which are limited to expressing the stress dependency on only the strain rate and the temperature (or the solid fraction), the proposed stress model adds the capability of …
An Experimental Investigation On Semi-Solid Forming Of Micro/Meso-Scale Features, Gap-Yong Kim, Jun Ni, Rhett Mayor, Heesool Kim
An Experimental Investigation On Semi-Solid Forming Of Micro/Meso-Scale Features, Gap-Yong Kim, Jun Ni, Rhett Mayor, Heesool Kim
Gap-Yong Kim
The potentials of semi-solid forming technology have generated much interest regarding its application in micromanufacturing. This study investigates the feasibility of using semi-solid forming technology to produce parts with micro/meso features. An experimental setup has been developed to study the effects of die/punch temperature, initial solid fraction, punch speed, and workpiece shape on the semi-solid forming process. A part has been produced for a microreactor application and has been analyzed with an optical measurement system for feature formation. The results indicated complex interaction among the process parameters and the material flow, which affected the final pin formation. The punch temperature …
Piezoelectric In Situ Transmission Electron Microscopy Technique For Direct Observations Of Fatigue Damage Accumulation In Constrained Metallic Thin Films, Xiaoli Tan, T. Du, J.K. Shang
Piezoelectric In Situ Transmission Electron Microscopy Technique For Direct Observations Of Fatigue Damage Accumulation In Constrained Metallic Thin Films, Xiaoli Tan, T. Du, J.K. Shang
Xiaoli Tan
A piezoelectricin situtransmission electron microscopy(TEM) technique has been developed to observe the damage mechanism in constrained metallic thin films under cyclic loading. The technique was based on the piezoelectric actuation of a multilayered structure in which a metallic thin film was sandwiched between a piezoelectric actuator and a silicon substrate. An alternating electric field with a static offset was applied on the piezoelectric actuator to drive the crack growth in the thin metallic layer while the sample was imaged in TEM. The technique was demonstrated on solder thin films where cavitation was found to be the dominant fatigue damage mechanism.
Melting And Resolidification Of A Substrate Caused By Molten Microdroplet Impact, Daniel Attinger, D. Poulikakos
Melting And Resolidification Of A Substrate Caused By Molten Microdroplet Impact, Daniel Attinger, D. Poulikakos
Daniel Attinger
This paper describes the main features and results of a numerical investigation of molten microdroplet impact and solidification on a colder flat substrate of the same material that melts due to the energy input from the impacting molten material. The numerical model is based on the axisymmetric Lagrangian Finite-Element formulation of the Navier–Stokes, energy and material transport equations. The model accounts for a host of complex thermofluidic phenomena, exemplified by surface tension effects and heat transfer with solidification in a severely deforming domain. The dependence of the molten volume on time is determined and discussed. The influence of the thermal …
An Experimental Study Of Molten Microdroplet Surface Deposition And Solidification: Transient Behavior And Wetting Angle Dynamics, Daniel Attinger, Z. Zhao, D. Poulikakos
An Experimental Study Of Molten Microdroplet Surface Deposition And Solidification: Transient Behavior And Wetting Angle Dynamics, Daniel Attinger, Z. Zhao, D. Poulikakos
Daniel Attinger
The basic problem of the impact and solidification of molten droplets on a substrate is of central importance to a host of processes. An important and novel such process in the area of micromanufacturing is solder jetting where microscopic solder droplets are dispensed for the attachment of microelectronic components. Despite the recent appearance of a few numerical studies focusing on the complex transient aspects of this process, no analogous experimental results have been reported to date to the best of our knowledge. Such a study is reported in this paper. Eutectic solder (63Sn37Pb) was melted to a preset superheat and …
Rapid Solidification: Fundamentals And Modeling, Guo-Xiang Wang, Vish Prasad
Rapid Solidification: Fundamentals And Modeling, Guo-Xiang Wang, Vish Prasad
Dr. Guo-Xiang Wang
No abstract provided.
Brittle Composites Modeling: Compazisons With Mosi2/Zro2, S.P. Chen, Richard Alan Lesar, A. D. Rollett
Brittle Composites Modeling: Compazisons With Mosi2/Zro2, S.P. Chen, Richard Alan Lesar, A. D. Rollett
Richard Alan Lesar
We have calculated the mechanical properties of brittle composites with spring-network (SN) model. The composites that we studied involve the transformation toughening effects and the accompanying micro-cracking. Our simulation results are consistent with experiments of MoSi2 toughened with ZrO2. By monitoring the stress changes due to the transformation and micro-cracking we are able to separate, for the first time, the contributions from these two competing effects. We also found that the fracture toughness of the composite increases as the modulus, interfacial cohesion of particle increases.
Free Energy Simulation Of Grain Boundary Segregation And Thermodynamics In Ni3−Xal1+X, R. Najafabadi, H.Y. Wang, D. J. Srolovitz, Richard Alan Lesar
Free Energy Simulation Of Grain Boundary Segregation And Thermodynamics In Ni3−Xal1+X, R. Najafabadi, H.Y. Wang, D. J. Srolovitz, Richard Alan Lesar
Richard Alan Lesar
The free energy simulation method is employed to study segregation to Σ5 and Σ13 (001) twist grain boundaries and their free energies in ordered Ni3−xAl1+x. In the temperature range studied (300–900K), it is shown that there is almost no segregation, strong Al segregation, and weak Ni segregation to the grain boundary for the stoichiometric, Al-rich, and Ni-rich bulk compositions respectively. It is also shown that the segregation is limited to a few (002) planes around the grain boundary and its magnitude decreases with increasing temperature. For Al-rich bulk composition, it is demonstrated that segregation at low temperature substantially lowers the …