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Articles 1 - 13 of 13
Full-Text Articles in Engineering
Investigation Of Through Thickness Microstructure And Mechanical Properties In Friction Stir Welded 7n01 Aluminum Alloy Plate, Xingxin Zhao, Zhiyong Yang, Joseph P. Domblesky, Jianmin Han, Zhiqiang Li, Xiaolong Liu
Investigation Of Through Thickness Microstructure And Mechanical Properties In Friction Stir Welded 7n01 Aluminum Alloy Plate, Xingxin Zhao, Zhiyong Yang, Joseph P. Domblesky, Jianmin Han, Zhiqiang Li, Xiaolong Liu
Mechanical Engineering Faculty Research and Publications
An on-going problem in friction stir welded (FSW) joints used in the high-speed train sector is that the microstructure and mechanical properties can significantly vary in thick sections. Because inhomogeneous properties can reduce weld efficiency and degrade service performance, it is of some interest to understand how inhomogeneous properties can develop in FSW welds made from precipitation hardening alloys such as 7N01. In the current study, butt welds were made using 12 mm thick plates and then sectioned perpendicular to the weld line. Five 2.2 mm thick slices were cut from a section and used to measure tensile properties access …
Crack Propagation And Microstructural Transformation On The Friction Surface Of A High-Speed Railway Brake Disc, Zhizhong Wang, Jianmin Han, Joseph P. Domblesky, Zhiqiang Li, Xinguang Fan, Xiaolong Liu
Crack Propagation And Microstructural Transformation On The Friction Surface Of A High-Speed Railway Brake Disc, Zhizhong Wang, Jianmin Han, Joseph P. Domblesky, Zhiqiang Li, Xinguang Fan, Xiaolong Liu
Mechanical Engineering Faculty Research and Publications
While brake disc wear represents a significant problem in high-speed rail systems, the progressive development of fatigue cracks during successive braking cycles also plays a great role in braking integrity. The modified microstructure consisting of a white etching layer (WEL) containing nanosized ferrite was observed on the friction surface of worn brake discs. In order to analyze how sequential thermal and mechanical stress affected crack propagation and microstructure evolution in brake discs, successive braking cycles were simulated on a full-scale braking bench test rig. Crack initiation and propagation mechanisms were proposed based on the experimental results, i.e., (i) occurrence of …
Micro-Ct-Based Approaches For Quantifying The Morphology Of Pulverized Char Particles, Scott Jorgensen, Simcha L. Singer
Micro-Ct-Based Approaches For Quantifying The Morphology Of Pulverized Char Particles, Scott Jorgensen, Simcha L. Singer
Mechanical Engineering Faculty Research and Publications
Morphological analysis of pulverized coal char particles using two-dimensional (2-D) cross-sectional imaging has been widely employed, but its accuracy has not been adequately assessed. In this study, pulverized coal char particles are imaged in three dimensions (3-D) using high-resolution X-ray microcomputed tomography (micro-CT). Particle volume, macropore volume, and macroporosity are measured in three dimensions and analyzed as a function of distance from the particle center using averaging at each radial location. A technique for extracting each particle’s average wall thickness, another morphological parameter used for classification, is also presented based on micro-CT imaging. When applied to pulverized bituminous coal char …
Geometry Based Synthesis Of Planar Compliances With Redundant Mechanisms Having Five Compliant Components, Shuguang Huang, Joseph M. Schimmels
Geometry Based Synthesis Of Planar Compliances With Redundant Mechanisms Having Five Compliant Components, Shuguang Huang, Joseph M. Schimmels
Mechanical Engineering Faculty Research and Publications
In this paper, a geometric approach to the passive realization of any planar compliance with a redundant compliant mechanism is presented. The mechanisms considered are either simple serial mechanisms consisting of five elastic joints or simple parallel mechanisms consisting of five springs. For each type of mechanism, realization conditions to achieve a given compliance are derived. The physical significance of each condition is identified and graphically interpreted. Geometry based synthesis procedures to achieve any given compliance are developed for both types of mechanisms. Since each realization condition imposes restrictions solely on the mechanism geometry, the procedures allow one to choose …
Partial Pressures And High-Temperature Thermodynamic Properties For The Germanium-Tellurium System, Robert F. Brebrick
Partial Pressures And High-Temperature Thermodynamic Properties For The Germanium-Tellurium System, Robert F. Brebrick
Mechanical Engineering Faculty Research and Publications
Our earlier optical density measurements over Ge-Te compositions are reanalyzed. Spectral characteristics of the GeTe(g) spectrum are determined from measurements with a 1 at.% Te sample near 1200 K. Beers law constants for GeTe(g) are established by requiring consistency between spectroscopic results for the dissociation of GeTe(g) into Ge(g) and Te2(g) and our description in terms of the partial pressure of Te2 and the partial optical density of GeTe over Ge saturated GeTe(c). Between 870 and 997 K the partial pressures over Ge saturated GeTe(c) are ln P(Te2,atm) = − 24,800/T + 17.600 and ln …
Shattered Rim And Shelling Of High-Speed Railway Wheels In The Very-High-Cycle Fatigue Regime Under Rolling Contact Loading, Tao Cong, Jianmin Han, Jianmin Han, Joseph P. Domblesky, Xiaolong Liu
Shattered Rim And Shelling Of High-Speed Railway Wheels In The Very-High-Cycle Fatigue Regime Under Rolling Contact Loading, Tao Cong, Jianmin Han, Jianmin Han, Joseph P. Domblesky, Xiaolong Liu
Mechanical Engineering Faculty Research and Publications
Due to the improvement of the wear property, rolling contact fatigue including shattered rim and shelling are the main failure causes of the high-speed railway wheels. In this paper, shattered rim and shelling occurred on the service wheels of the China Railway High-speed (CRH) trains were systematically investigated. The recorded data of the last ten years CRH operation indicated that all shattered rims and shelling were detected with serving >106 km (corresponding to the fatigue life 107–109 cycles) which is very-high-cycle fatigue (VHCF). The crack initiationregion of shattered rim located at the depth of 10–25 mm …
Analysis Of The Forming Characteristics For Cu/Al Bimetal Tubes Produced By The Spinning Process, Kai Jin, Qiwei Yuan, Jie Tao, Joseph P. Domblesky, Xunzhong Guo
Analysis Of The Forming Characteristics For Cu/Al Bimetal Tubes Produced By The Spinning Process, Kai Jin, Qiwei Yuan, Jie Tao, Joseph P. Domblesky, Xunzhong Guo
Mechanical Engineering Faculty Research and Publications
Tube spinning technology represents a process with high forming precision and good flexibility and is increasingly being used in the manufacture of bimetal composite tubular structures. In the present study, a forming analysis of clad tube and base tube in spinning process was conducted through numerical simulations and experiments. There was an equivalent stress transition on the interface since the stress transmission was retarded from clad tube to base tube. The yield strength became a main consideration during a design bimetal composite tube. Meanwhile, the strain distributions in axial direction, tangential direction, and radial direction were also investigated to determine …
A Detailed Modeling Study Of Radiative Heat Transfer In A Heavy-Duty Diesel Engine, Chandan Paul, Sebastian Ferreyro Fernandez, Daniel C. Haworth, Somesh Roy, Michael F. Modest
A Detailed Modeling Study Of Radiative Heat Transfer In A Heavy-Duty Diesel Engine, Chandan Paul, Sebastian Ferreyro Fernandez, Daniel C. Haworth, Somesh Roy, Michael F. Modest
Mechanical Engineering Faculty Research and Publications
In recent years, the importance of radiative heat transfer in combustion has been increasingly recognized. Detailed models have become available that accurately represent the complex spectral radiative properties of reacting gas mixtures and soot particles, and new methods have been developed to solve the radiative transfer equation (RTE). At the same time, the trends toward higher operating pressures and higher levels of exhaust-gas recirculation in compression-ignition engines, together with the demand for higher quantitative accuracy from in-cylinder CFD models, has led to renewed interest in radiative transfer in engines. Here an in-depth investigation of radiative heat transfer is performed for …
An Efficient Monte Carlo-Based Solver For Thermal Radiation In Participating Media, Joseph Farmer, Somesh Roy
An Efficient Monte Carlo-Based Solver For Thermal Radiation In Participating Media, Joseph Farmer, Somesh Roy
Mechanical Engineering Faculty Research and Publications
Monte Carlo-based solvers, while well-suited for accurate calculation of complex thermal radiation transport problems in participating media, are often deemed computationally unattractive for use in the solution of real-world problems. The main disadvantage of Monte Carlo (MC) solvers is their slow convergence rate and relatively high computational cost. This work presents a novel approach based on a low-discrepancy sequence (LDS) and is proposed for reducing the error bound of a Monte Carlo-based radiation solver. Sobols sequence – an LDS generated with a bit-by-bit exclusive-or operator – is used to develop a quasi-Monte Carlo (QMC) solver for thermal radiation in this …
Investigation Of Void Formation In Friction Stir Welding Of 7n01 Aluminum Alloy, Xingxin Zhao, Jianmin Han, Joseph P. Domblesky, Zhiyong Yang, Zhiqiang Li, Xiaolong Liu
Investigation Of Void Formation In Friction Stir Welding Of 7n01 Aluminum Alloy, Xingxin Zhao, Jianmin Han, Joseph P. Domblesky, Zhiyong Yang, Zhiqiang Li, Xiaolong Liu
Mechanical Engineering Faculty Research and Publications
Friction Stir Welding (FSW) is a solid state joining process that is widely used to produce high integrity aluminum weldments for a variety of industries. While extensive work has been conducted to understand flow behavior, much less research has been performed to identify how void defects form and how to predict them. In the present study, the relationship between rotation speed, plasticized region, and defect formation was investigated. To analyze how tunneling and cavity type void defects form during FSW, a 3-D Computational fluid dynamics(CFD) model based on the Fluent software code was used to simulate butt welding. The CFD …
A Hybrid Droplet Vaporization-Chemical Surrogate Approach For Emulating Vaporization, Physical Properties, And Chemical Combustion Behavior Of Multicomponent Fuels, Alanna Y. Cooney, Simcha L. Singer
A Hybrid Droplet Vaporization-Chemical Surrogate Approach For Emulating Vaporization, Physical Properties, And Chemical Combustion Behavior Of Multicomponent Fuels, Alanna Y. Cooney, Simcha L. Singer
Mechanical Engineering Faculty Research and Publications
The complex nature of multicomponent aviation fuels presents a daunting task for accurately simulating combustion behavior without incurring impractical computational costs. To reduce computation time, chemical fuel surrogates comprised of only a few species are used to emulate the combustion of complex pre-vaporized fuels. These surrogates are often unable to match the vaporization behavior and physical properties of the real fuel and fail to capture the effect of preferential vaporization on combustion behavior. Therefore, a computationally efficient, hybrid droplet vaporization-chemical surrogate approach has been developed which emulates both the physical and chemical properties of a multicomponent kerosene fuel. The droplet …
Effect Of Diffusion Distance On Evolution Of Kirkendall Pores In Titanium-Coated Nickel Wires, Aaron R. Yosta, Dinc Erdeniz, Ashley E. Paz Y Puente, David C. Dunanda
Effect Of Diffusion Distance On Evolution Of Kirkendall Pores In Titanium-Coated Nickel Wires, Aaron R. Yosta, Dinc Erdeniz, Ashley E. Paz Y Puente, David C. Dunanda
Mechanical Engineering Faculty Research and Publications
Microtubes of near-equiatomic nickel-titanium (NiTi) alloys can be created via the Kirkendall effect during NiTi interdiffusion, when nickel wires are surface-coated with titanium via pack cementation and subsequently homogenized. This study explores the effect of diffusion distance upon Kirkendall microtube formation in NiTi by considering a range of Ni wire diameters. For Ni wire diameters of 25, 50 and 100 μm, titanized at 925 °C for 0.5, 2, and 8 h to achieve average NiTi composition, partial interdiffusion occurs concurrently with Ti surface deposition, resulting in concentric shells of NiTi2, NiTi and Ni3Ti around a Ni …
Structure And Growth Of Core–Shell Nanoprecipitates In Al–Er–Sc–Zr–V–Si High-Temperature Alloys, Wahaz Nasim, Saegh Yazdi, Ruben Santamarta, Jahanzaib Malik, Dinc Erdeniz, Bilal Mansoor, David N. Seidman, David C. Dunand, Ibrahim Karaman
Structure And Growth Of Core–Shell Nanoprecipitates In Al–Er–Sc–Zr–V–Si High-Temperature Alloys, Wahaz Nasim, Saegh Yazdi, Ruben Santamarta, Jahanzaib Malik, Dinc Erdeniz, Bilal Mansoor, David N. Seidman, David C. Dunand, Ibrahim Karaman
Mechanical Engineering Faculty Research and Publications
Lightweight Sc-containing aluminum alloys exhibit superior mechanical performance at high temperatures due to core–shell, L12-ordered trialuminide nanoprecipitates. In this study, the structure of these nanoprecipitates was studied, using different transmission electron microscopy (TEM) techniques, for an Al–Er– Sc–Zr–V–Si alloy that was subjected to a two-stage overaging heat treatment. Energy-dispersive X-ray spectroscopy of the spherical Al3(Sc, Zr, Er ,V) nanoprecipitates revealed a core–shell structure with an Sc- and Er-enriched core and a Zr-enriched shell, without a clear V outer shell. This structure is stable up to 72% of the absolute melting temperature of Al for extended periods …