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 Science – Methodology – Study and teaching (Higher) (1)
 Multilayers; Oxidation; Plastic; Thermal cycling; Thermal barrier coating (1)
 Thermomechanical process; Elastic– plastic material; Thermal stresses; Analytical function; Finite elements (1)
 College students (1)
 Distributed parameter systems (1)

 Problem solving – Study and teaching (Higher) (1)
 Fatigue crack initiation (1)
 Fault detection (1)
 Microstructure (1)
 Fatigue of Ti6Al4V (1)
 Engineering – Study and teaching (Higher) (1)
 Journal bearing; Cavitation; Mobility method; Mass conservation algorithm (1)
 Multilayers; Oxidation; Thermal cycling (1)
 Mean stress effects (1)
 Falling; Prevention; Simulation; Aging; Locomotion (1)
Articles 1  14 of 14
FullText Articles in Mechanical Engineering
Comment On "Quadriceps Protects The Anterior Cruciate Ligament", Antonie J. Van Den Bogert
Comment On "Quadriceps Protects The Anterior Cruciate Ligament", Antonie J. Van Den Bogert
Mechanical Engineering Faculty Publications
No abstract provided.
A Fundamental Model Of Cyclic Instabilities In Thermal Barrier Systems, Anette M. Karlsson, J. W. Hutchinson, A. G. Evans
A Fundamental Model Of Cyclic Instabilities In Thermal Barrier Systems, Anette M. Karlsson, J. W. Hutchinson, A. G. Evans
Mechanical Engineering Faculty Publications
Cyclic morphological instabilities in the thermally grown oxide (TGO) represent a source of failure in some thermal barrier systems. Observations and simulations have indicated that several factors interact to cause these instabilities to propagate: (i) thermal cycling; (ii) thermal expansion misfit; (iii) oxidation strain; (iv) yielding in the TGO and the bond coat; and (v) initial geometric imperfections. This study explores a fundamental understanding of the propagation phenomenon by devising a spherically symmetric model that can be solved analytically. The applicability of this model is addressed through comparison with simulations conducted for representative geometric imperfections and by analogy with the ...
Die Soldering: Mechanism Of The Interface Reaction Between Molten Aluminum Alloy And Tool Steel, Sumanth Shankar, Diran Apelian
Die Soldering: Mechanism Of The Interface Reaction Between Molten Aluminum Alloy And Tool Steel, Sumanth Shankar, Diran Apelian
Mechanical Engineering Faculty Publications
Die soldering is the result when molten aluminum sticks to the surface of the die material and remains there after the ejection of the part; it results in considerable economic and production losses in the casting industry, and is a major quality detractor. In order to alleviate or mitigate die soldering, one must have a thorough understanding of the mechanism by which the aluminum sticks to the die material. A key question is whether the die soldering reaction is diffusion controlled or interface controlled. A set of diffusion couple experiments between molten aluminum alloy and the ferrous die was carried ...
Alternative Ways To Teaching Hvac And Related Subjects Through Actual Project InvolvementThree Case Studies, Samir F. Moujaes
Alternative Ways To Teaching Hvac And Related Subjects Through Actual Project InvolvementThree Case Studies, Samir F. Moujaes
Mechanical Engineering Faculty Publications
No abstract provided.
An Interactive Visual Environment For Scientific Problem Solving, Georg F. Mauer
An Interactive Visual Environment For Scientific Problem Solving, Georg F. Mauer
Mechanical Engineering Faculty Publications
Science and engineering students do not typically receive explicit training in scientific problem solving, i.e. applying science principles to specific situations. Students’ problem solving skills often show little improvement throughout their course of studies. This paper describes a structured, graphical, interactive (GUI) learning environment, which presents problems and tools for analysis in systematic and logical order, and encourages the student to develop the solution path in the manner of an experienced expert. The learning environment’s subject area is Engineering Dynamics, which was selected for its systematic structure and its early (usually sophomore) place in the undergraduate curriculum. The ...
A Model Study Of Displacement Instabilities During Cyclic Oxidation, Anette M. Karlsson, C. G. Levi, A. G. Evans
A Model Study Of Displacement Instabilities During Cyclic Oxidation, Anette M. Karlsson, C. G. Levi, A. G. Evans
Mechanical Engineering Faculty Publications
The shape changes that occur at imperfections on the surface of an aluminaforming alloy, subject to thermal cycling, have been simulated and measured. Observations have been made by emplacing a surface groove into a FeCrAlY material. Upon thermal cycling, large shape distortions have been observed: whereas, for comparable isothermal oxidation, the shape changes are minimal. The simulations predict similar responses. Upon cycling, upward displacements (pileup) occur around the perimeter, accompanied by downward displacements at the center. Yet, minimal displacements arise upon isothermal oxidation. To realize cyclic displacements comparable in magnitude to those found experimentally, large values of the inplane growth ...
Mathematical Modeling And Computer Simulation Of The Rotating Impeller Particle Flotation Process: Part I. Fluid Flow, Mohammed D. Maniruzzaman, Makhlouf M. Makhlouf
Mathematical Modeling And Computer Simulation Of The Rotating Impeller Particle Flotation Process: Part I. Fluid Flow, Mohammed D. Maniruzzaman, Makhlouf M. Makhlouf
Mechanical Engineering Faculty Publications
Removal of unwanted particles from molten metal by flotation is one of the most useful melt cleansing techniques used by the foundry industry. An effective way of flotation of particles in a melt relies on purging a gas into the molten metal through holes in a rotating impeller. Impeller rotation creates turbulence inside the melt, which helps agglomerate the impurity particles and. thereby, enhances their removal from the melt. In addition, turbulence increases the probability of particles attaching to the rising gas bubbles and, therefore, enhances the chance of their removal from the molten metal. A mathematical model has been ...
Mathematical Modeling And Computer Simulation Of The Rotating Impeller Particle Flotation Process: Part Ii. Particle Agglomeration And Flotation, Mohammed D. Maniruzzaman, Makhlouf M. Makhlouf
Mathematical Modeling And Computer Simulation Of The Rotating Impeller Particle Flotation Process: Part Ii. Particle Agglomeration And Flotation, Mohammed D. Maniruzzaman, Makhlouf M. Makhlouf
Mechanical Engineering Faculty Publications
Effective removal of unwanted particles from a molten metal alloy by flotation relies on purging a gas into the melt through a rotating impeller. This device is commonly known as a rotary degasser. Unwanted particles in the melt attach to the rising gas bubbles and rise to the slag layer where they are removed from the metal bulk. In addition, the turbulence created by the rotating impeller causes the randomly distributed solid particles to agglomerate into relatively large clusters. These clusters float up or settle down due to the difference between their density and that of the melt. A mathematical ...
Investigation Of Fatigue Crack Initiation In Ti6al4v During TensileTensile Fatigue, Svetlana G. Ivanova, Ronald R. Biederman, Richard D. Sisson Jr.
Investigation Of Fatigue Crack Initiation In Ti6al4v During TensileTensile Fatigue, Svetlana G. Ivanova, Ronald R. Biederman, Richard D. Sisson Jr.
Mechanical Engineering Faculty Publications
Fatigue crack initiation in Ti6Al4V has been investigated in high cycle fatigue (HCF) and low cycle fatigue (LCF) regimes at stress ratio R = 0.1 using the replication technique. In all four tested α/β microstructures, the crack was initiated by fracture of equiaxed alpha grain. Fractured alpha grains are seen on the fracture surface as flat facets with features characteristic of cleavage fracture. In the regime of low stress amplitudes and in the absence of reverse loading, cleavage fracture contributes to crack initiation and early stages of crack growth in Ti6Al4V. This mechanism is discussed in relation to the ...
The Effect Of The Thermal Barrier Coating On The Displacement Instability In Thermal Barrier Systems, Anette M. Karlsson, T. Xu, A. G. Evans
The Effect Of The Thermal Barrier Coating On The Displacement Instability In Thermal Barrier Systems, Anette M. Karlsson, T. Xu, A. G. Evans
Mechanical Engineering Faculty Publications
Thermal barrier systems are susceptible to instability of the thermally grown oxide (TGO) at the interface between the bond coat and the thermal barrier coating (TBC). The instabilities have been linked to thermal cycling and initial geometrical imperfections, as well as to misfit strains due to both oxide growth and thermal expansion misfit. Numerical simulations are used to investigate the role of the thermomechanical properties of the TBC in this instability. It is found that the TBC constrains the deformation, whereupon instabilities develop preferentially in regions where cracklike imperfections either preexist in the TBC or are created because of the ...
LotkaVolterra System In A Random Environment, Mikhail F. Dimentberg
LotkaVolterra System In A Random Environment, Mikhail F. Dimentberg
Mechanical Engineering Faculty Publications
Classical LotkaVolterra (LV) model for oscillatory behavior of population sizes of two interacting species (predatorprey or parasitehost pairs) is conservative. This may imply unrealistically high sensitivity of the system's behavior to environmental variations. Thus, a generalized LV model is considered with the equation for preys' reproduction containing the following additional terms: quadratic "damping'' term that accounts for interspecies competition, and term with whitenoise random variations of the preys' reproduction factor that simulates the environmental variations. An exact solution is obtained for the corresponding FokkerPlanckKolmogorov equation for stationary probability densities (PDF's) of the population sizes. It shows that both ...
Response Time Is More Important Than Walking Speed For The Ability Of Older Adults To Avoid A Fall After A Trip, Antonie J. Van Den Bogert, M. J. Pavol, M. D. Grabiner
Response Time Is More Important Than Walking Speed For The Ability Of Older Adults To Avoid A Fall After A Trip, Antonie J. Van Den Bogert, M. J. Pavol, M. D. Grabiner
Mechanical Engineering Faculty Publications
We previously reported that the probability of an older adult recovering from a forward trip and using a “lowering” strategy increases with decreased walking velocity and faster response time. To determine the withinsubject interaction of these variables we asked three questions: (1) Is the body orientation at the time that the recovery foot is lowered to the ground (“tilt angle”) critical for successful recovery? (2) Can a simple inverted pendulum model, using subjectspecific walking velocity and response time as input variables, predict this body orientation, and thus success of recovery? (3) Is slower walking velocity or faster response time more ...
A ModelBased Fault Detection And Diagnosis Scheme For Distributed Parameter Systems: A Learning Systems Approach, Michael A. Demetriou
A ModelBased Fault Detection And Diagnosis Scheme For Distributed Parameter Systems: A Learning Systems Approach, Michael A. Demetriou
Mechanical Engineering Faculty Publications
In this note, fault detection techniques based on finite dimensional results are extended and applied to a class of infinite dimensional dynamical systems. This special class of systems assumes linear plant dynamics having an abrupt additive perturbation as the fault. This fault is assumed to be linear in the (unknown) constant (and possibly functional) parameters. An observerbased model estimate is proposed which serves to monitor the system's dynamics for unanticipated failures, and its well posedness is summarized. Using a Lyapunov synthesis approach extended and applied to infinite dimensional systems, a stable adaptive fault diagnosis (fault parameter learning) scheme is ...
Comparison Of Mobility Method And Mass Conservation Method In A Study Of Dynamically Loaded Journal Bearings, Biao Yu, Jerzy T. Sawicki
Comparison Of Mobility Method And Mass Conservation Method In A Study Of Dynamically Loaded Journal Bearings, Biao Yu, Jerzy T. Sawicki
Mechanical Engineering Faculty Publications
The inverse problem of dynamically loaded journal bearings was solved using generalized Reynolds equation coupled with a complete mass conservative cavitation boundary conditions, as outlined by the JacobssonFloberg and Olsson (JFO) cavitation theory. In the course of solution, the modified Thomas algorithms was employed, instead of standard Gauss±Jordan reduction method, which fully utilizes the sparse character of the system matrix, and thus greatly reduces computational time. The developed model was tested against the wellknown mobility method for the case of journal bearings in a commercial reciprocating air compressor. It was found that the mobility method overestimates minimum film thickness ...