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Full-Text Articles in Mechanical Engineering

Influence Of Scandium Addition On The High-Temperature Grain Size Stabilization Of Oxide-Dispersion-Strengthened (Ods) Ferritic Alloy, Lulu Li, Weizong Xu, Mostafa Saber, Yuntian Zhu, Carl C. Koch, Ronald O. Scattergood Feb 2016

Influence Of Scandium Addition On The High-Temperature Grain Size Stabilization Of Oxide-Dispersion-Strengthened (Ods) Ferritic Alloy, Lulu Li, Weizong Xu, Mostafa Saber, Yuntian Zhu, Carl C. Koch, Ronald O. Scattergood

Mostafa Saber

The influence of 1–4 at% Sc addition on the thermal stability of mechanically alloyed ODS ferritic alloy was studied in this work. Sc addition was found to significantly stabilize grain size and microhardness at high temperatures. Grain sizes of samples with 1 and 4 at% Sc was found maintained in the nanoscale range at temperatures up to 1000 °C with hardness maintained at 5.6 and 6.7 GPa, respectively. The detailed microstructure was also investigated from EDS elemental mapping, where nanofeatures [ScTiO] were observed, while nanosized [YTiO] particles were rarely seen. This is probably due to the concentration ...


Microstructures And Stabilization Mechanisms Of Nanocrystalline Iron-Chromium Alloys With Hafnium Addition, Weizong Xu, Lulu Li, Mostafa Saber, Carl C. Koch, Yuntian Zhu, Ronald O. Scattergood Feb 2016

Microstructures And Stabilization Mechanisms Of Nanocrystalline Iron-Chromium Alloys With Hafnium Addition, Weizong Xu, Lulu Li, Mostafa Saber, Carl C. Koch, Yuntian Zhu, Ronald O. Scattergood

Mostafa Saber

The low thermal stability of nanocrystalline metals severely limits their applications at high temperatures. In this study, we investigate the nanocrystalline stabilization mechanisms for Fe-14Cr alloys with 1, 2, and 4 at. pct Hf addition at 1173 K (900 °C). Microstructural characterizations using aberration-corrected scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy reveal high density of HfO2 nanoparticles with sizes of ~4 nm dispersed throughout the ferritic matrix. This indicates that kinetic stabilization by HfO2 nanoparticle pinning is primarily responsible for the observed high thermal stability. In addition, some Hf and Cr segregation on grain boundaries is observed in the ...


Engineering Design: Representation And Reasoning, Clive Dym, David Brown Dec 2015

Engineering Design: Representation And Reasoning, Clive Dym, David Brown

David C. Brown

This text demonstrates that symbolic representation, and related problem-solving methods, offer significant opportunities to clarify and articulate concepts of design to give a better framework for design research and education. This edition includes recent work on design reasoning, computational design, AI in design, and design cognition, with pointers to the current literature.


Material Properties And Microstructural Characterization Of Specimens, T.J. Silverman, Allison Kinney, B. South, W. Yong, J.H. Koo Dec 2015

Material Properties And Microstructural Characterization Of Specimens, T.J. Silverman, Allison Kinney, B. South, W. Yong, J.H. Koo

Allison Kinney

The HiQ upgrade to the 3D Systems Vanguard selective laser sintering (SLS) machine incorporates a revised thermal calibration system and new software. This paper quantifies differences in mechanical and morphological properties of specimens built first using a Vanguard HS (high-speed) system and again using the same system with the HiQ upgrade applied. Standard specimens are built from DuraForm PA material and tested for tensile modulus, tensile strength, elongation at break, flexural modulus and Izod impact strength. The design of the specimen battery, the conduction of the tests and the significance of the results are discussed. The upgrade is found to ...


Study Of An Axial Fan Combined With A Microperforated Duct, Seungkyu Lee Aug 2015

Study Of An Axial Fan Combined With A Microperforated Duct, Seungkyu Lee

Seungkyu Lee

The fans used in the ventilation duct systems usually fall into two categories: (i) axial, and (ii) centrifugal. These types of fans are distinguished by having different performance characteristics. For instance, centrifugal fans are capable of generating high static pressures compare to axial fans. However, an axial fan can deal with higher air volume flow rates than a centrifugal fan, and, more importantly, an axial fan produces relatively low fan noise compared to a centrifugal fan. Thus, even though axial fans may be advantageous from a noise point-of-view, they are generally avoided in duct systems when relatively high static pressures ...


Ranges And Limitations Of Optimum Design For Convecting-Radiating Annular Fins Of Trapezoidal Profile, Benjamin T.F. Chung, Y. Zhou, Y. Wang, L. T. Yeh Apr 2015

Ranges And Limitations Of Optimum Design For Convecting-Radiating Annular Fins Of Trapezoidal Profile, Benjamin T.F. Chung, Y. Zhou, Y. Wang, L. T. Yeh

Dr. Benjamin T.F. Chung

This paper deals with a controversial problem in answering the question “Does the optimum fin design always exist? If not, what are the optimization ranges and limitations?” These authors employ a general example of convecting-radiating trapezoidal annular fin with heat transfer at the tip and wall resistance at the interface. The present results indicate that the answer to the above first question is negative. The ranges of fin optimum design under different thermal and physical conditions are proposed. The effects of Biot number, radiation number, the heat loss at the tip, fin profile and overall wall resistance on fin optimization ...


Bimodal Nanocrystallization Of Niti Shape Memory Alloy By Laser Shock Peening And Post-Deformation Annealing, Chang Ye, Sergey Suslov, Xueling Fei, Gary J. Cheng Apr 2015

Bimodal Nanocrystallization Of Niti Shape Memory Alloy By Laser Shock Peening And Post-Deformation Annealing, Chang Ye, Sergey Suslov, Xueling Fei, Gary J. Cheng

Dr. Chang Ye

In this paper, surface nanocrystallization of NiTi intermetallic alloy by a novel method is reported. The NiTi alloy is processed by laser shock peening (LSP) and controlled annealing. The microstructure of the NiTi alloy after processing is characterized by transmission electron microscopy. At the top surface of the material, a nanostructure with bimodal grains is obtained. The mechanism of the formation of the bimodal microstructure is discussed. At the material subsurface, deformation twins are generated by LSP and retained after controlled annealing. Tensile test results showed that both strength and ductility are significantly improved through LSP and controlled annealing.


An Extended Finite Element Method (Xfem) Study On The Effect Of Reinforcing Particles On The Crack Propagation Behavior In A Metal–Matrix Composite, Chang Ye, Jay Shi, Gary J. Cheng Apr 2015

An Extended Finite Element Method (Xfem) Study On The Effect Of Reinforcing Particles On The Crack Propagation Behavior In A Metal–Matrix Composite, Chang Ye, Jay Shi, Gary J. Cheng

Dr. Chang Ye

In this paper, the eXtended Finite Element Method (XFEM) was integrated in ABAQUS to simulate crack propagation and to predict the effect of reinforcing particles to the crack propagation behavior of Al2O3/Al6061 composite materials. It has been demonstrated that, higher reinforcing particle volume fraction leads to improved fatigue resistance and smaller particles size is more effective than larger particles at the same particle volume fraction. The underlying mechanisms of these effects are systematically investigated. The stress fields captured by XFEM during the crack propagation help in understanding the crack propagation behavior during cyclic loading.


The Third-Type Of Strain Aging And The Constitutive Modeling Of A Q235b Steel Over A Wide Range Of Temperatures And Strain Rates, Jianjun Wan, Wei-Guo Guo, Xiaosheng Gao, Jing Su Apr 2015

The Third-Type Of Strain Aging And The Constitutive Modeling Of A Q235b Steel Over A Wide Range Of Temperatures And Strain Rates, Jianjun Wan, Wei-Guo Guo, Xiaosheng Gao, Jing Su

Dr. Xiaosheng Gao

In this study, uniaxial compression experiments of a Q235B steel are conducted over the temperature range of 93–1173 K and the strain rate range of 0.001–7000 s−1. Through the mechanism analysis, an argument is made that the third-type of strain aging (the 3rd SA) effect, the Portevin–Le Chatelier (PLC) effect and the blue brittleness are different manifestations of the dynamic strain aging. Based on the experiment results, the characteristics of the 3rd SA effect are analyzed and a constitutive model is developed to describe the plastic behavior of the Q235B steel. The model accounts for ...


Burning Characteristics Of Pulverized Coal Within Blast Furnace Raceway At Various Injection Operations And Ways Of Enriched Oxygen., Wei-Hsin Chen Feb 2015

Burning Characteristics Of Pulverized Coal Within Blast Furnace Raceway At Various Injection Operations And Ways Of Enriched Oxygen., Wei-Hsin Chen

Wei-Hsin Chen

No abstract provided.


Development Of An Optoelectronic Holographic Platform For Otolaryngology Applications, Ellery Harrington, Ivo Dobrev, Nikhil Bapat, Jorge Flores, Cosme Furlong, John Rosowski, Jeffery Cheng, Christopher Scarpino, Michael Ravicz Jan 2015

Development Of An Optoelectronic Holographic Platform For Otolaryngology Applications, Ellery Harrington, Ivo Dobrev, Nikhil Bapat, Jorge Flores, Cosme Furlong, John Rosowski, Jeffery Cheng, Christopher Scarpino, Michael Ravicz

Ivo Dobrev

No abstract provided.


Quantitative Measurement Of Binary Liquid Distributions Using Multiple-Tracer X-Ray Fluorescence And Radiography, Terrence R. Meyer Dec 2014

Quantitative Measurement Of Binary Liquid Distributions Using Multiple-Tracer X-Ray Fluorescence And Radiography, Terrence R. Meyer

Terrence R Meyer

No abstract provided.


Flow-Field Design For Improving Hydrogen Recovery In A Palladium Membrane Tube., Wei-Hsin Chen Nov 2014

Flow-Field Design For Improving Hydrogen Recovery In A Palladium Membrane Tube., Wei-Hsin Chen

Wei-Hsin Chen

No abstract provided.


Geometric Effect On Cooling Power And Performance Of An Integrated Thermoelectric Generation-Cooling System., Wei-Hsin Chen Oct 2014

Geometric Effect On Cooling Power And Performance Of An Integrated Thermoelectric Generation-Cooling System., Wei-Hsin Chen

Wei-Hsin Chen

No abstract provided.


Single-Layer Graphene Oxide Reinforced Metal Matrix Composites By Laser Sintering: Microstructure And Mechanical Property Enhancement, Dong Lin Oct 2014

Single-Layer Graphene Oxide Reinforced Metal Matrix Composites By Laser Sintering: Microstructure And Mechanical Property Enhancement, Dong Lin

dong lin

No abstract provided.


Thermal Decomposition Dynamics And Severity Of Microalgae Residues In Torrefaction., Wei-Hsin Chen Sep 2014

Thermal Decomposition Dynamics And Severity Of Microalgae Residues In Torrefaction., Wei-Hsin Chen

Wei-Hsin Chen

No abstract provided.


Planning Of Methane Emission Control From Hoggery Using An Inexact Two-Stage Optimization Model., Wei-Hsin Chen Sep 2014

Planning Of Methane Emission Control From Hoggery Using An Inexact Two-Stage Optimization Model., Wei-Hsin Chen

Wei-Hsin Chen

No abstract provided.


Thermal Characterization Of Oil Palm Fiber And Eucalyptus In Torrefaction., Wei-Hsin Chen Jun 2014

Thermal Characterization Of Oil Palm Fiber And Eucalyptus In Torrefaction., Wei-Hsin Chen

Wei-Hsin Chen

No abstract provided.


Pretreatment Of Biomass By Torrefaction And Carbonization For Coal Blend Used In Pulverized Coal Injection., Wei-Hsin Chen May 2014

Pretreatment Of Biomass By Torrefaction And Carbonization For Coal Blend Used In Pulverized Coal Injection., Wei-Hsin Chen

Wei-Hsin Chen

No abstract provided.


Molecular Modeling Approach To Prediction Of Thermo-Mechanical Behavior Of Thermoset Polymer Networks, Natalia Shenogina, Mesfin Tsige, Soumya Patnaik, Sharmila Mukhopadhyay May 2014

Molecular Modeling Approach To Prediction Of Thermo-Mechanical Behavior Of Thermoset Polymer Networks, Natalia Shenogina, Mesfin Tsige, Soumya Patnaik, Sharmila Mukhopadhyay

Mesfin Tsige

Molecular dynamics and molecular mechanics simulations have been used to study thermo-mechanical response of highly cross-linked polymers composed of epoxy resin DGEBA and hardener DETDA. The effective cross-linking approach used in this work allowed construction of a set of stress-free molecular models with high conversion degree containing up to 35000 atoms. The generated structures were used to investigate the influence of model size, length of epoxy strands, and degree of cure on thermo-mechanical properties. The calculated densities, coefficients of thermal expansion, and glass transition temperatures of the systems are found to be in good agreement with experimental data. The computationally ...


Isothermal And Non-Isothermal Torrefaction Characteristics And Kinetics Of Microalga Scenedesmus Obliquus Cnw-N., Wei-Hsin Chen Feb 2014

Isothermal And Non-Isothermal Torrefaction Characteristics And Kinetics Of Microalga Scenedesmus Obliquus Cnw-N., Wei-Hsin Chen

Wei-Hsin Chen

No abstract provided.


Co2 Conversion For Syngas Production In Methane Catalytic Partial Oxidation., Wei-Hsin Chen Feb 2014

Co2 Conversion For Syngas Production In Methane Catalytic Partial Oxidation., Wei-Hsin Chen

Wei-Hsin Chen

No abstract provided.


Characterization Of Transient Co2 Transport In Two Convecting Aerosol Droplets In Tandem, Wei-Hsin Chen Jan 2014

Characterization Of Transient Co2 Transport In Two Convecting Aerosol Droplets In Tandem, Wei-Hsin Chen

Wei-Hsin Chen

No abstract provided.


Non-Oxidative And Oxidative Torrefaction Characterization And, Wei-Hsin Chen Jan 2014

Non-Oxidative And Oxidative Torrefaction Characterization And, Wei-Hsin Chen

Wei-Hsin Chen

No abstract provided.


Full-Field Vibrometry By High-Speed Digital Holography For Middle-Ear Mechanics, Ivo Dobrev Dec 2013

Full-Field Vibrometry By High-Speed Digital Holography For Middle-Ear Mechanics, Ivo Dobrev

Ivo Dobrev

Hearing loss affects approximately 1 in 10 people in the world and this percentage is increasing every year. Some of the most common courses for hearing loss are disorders of the human tympanic membrane (TM or eardrum) and middle-ear. Early detection and diagnosis of hearing loss as well as research and understanding of the hearing process depend on medical and research tools for quantification of the hearing capabilities, including the function of the human TM in the complex acoustic-mechanical transformation of environmental sounds into vibrations of the middle- and the inner-ear.

Current ear exams are assessing the state of the ...


Modeling And Simulation For The Design Of Thermal-Concentrated Solar Thermoelectric Generator., Wei-Hsin Chen Dec 2013

Modeling And Simulation For The Design Of Thermal-Concentrated Solar Thermoelectric Generator., Wei-Hsin Chen

Wei-Hsin Chen

No abstract provided.


Product Yields And Characteristics Of Corncob Waste Under Various Torrefaction Atmospheres, Wei-Hsin Chen Dec 2013

Product Yields And Characteristics Of Corncob Waste Under Various Torrefaction Atmospheres, Wei-Hsin Chen

Wei-Hsin Chen

No abstract provided.


Polarization Phenomena Of Hydrogen-Rich Gas In High-Permeance Pd And Pd–Cu Membrane Tubes, Wei-Hsin Chen Dec 2013

Polarization Phenomena Of Hydrogen-Rich Gas In High-Permeance Pd And Pd–Cu Membrane Tubes, Wei-Hsin Chen

Wei-Hsin Chen

No abstract provided.


Impact Damage On A Thin Glass Plate With A Thin Polycarbonate Backing, Wenke Hu, Yenan Wang, Jian Yu, Chian-Fong Yen, Florin Bobaru Nov 2013

Impact Damage On A Thin Glass Plate With A Thin Polycarbonate Backing, Wenke Hu, Yenan Wang, Jian Yu, Chian-Fong Yen, Florin Bobaru

Florin Bobaru Ph.D.

We present experimental and computational results for the impact of a spherical projectile on a thin glass plate with a thin polycarbonate backing plate, restrained in a metal frame, or in the absence of the frame. We analyze the dependence of the damage patterns in the glass plate on the increasing impact velocities, from 61 m/s to 200 m/s. Experimental results are compared with those from peridynamic simulations of a simplified model. The main fracture patterns observed experimentally are captured by the peridynamic model for each of the three projectile velocities tested. More accurate implementation of the actual ...


A Comparison Of Gasification Phenomena Among Raw Biomass, Torrefied Biomass And Coal In An Entrained-Flow Reactor, Wei-Hsin Chen Nov 2013

A Comparison Of Gasification Phenomena Among Raw Biomass, Torrefied Biomass And Coal In An Entrained-Flow Reactor, Wei-Hsin Chen

Wei-Hsin Chen

Gasification of torrefied biomass is a promising technique for producing synthesis gas (syngas) of higher quality than has previously been available. In this study, in order to evaluate the potential of the technique, gasification processes for three different materials, which include raw bamboo, torrefied bamboo (at 280 C for 1 h), and high-volatile bituminous coal in an entrained-flow gasifier using O2 as the gasifi- cation agent, are studied numerically and compared to each other. The obtained results suggest that in all cases, the carbon conversions of the three fuels are higher than 90%. However, the cold gasification effi- ciency for ...