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Full-Text Articles in Engineering Science and Materials

Investigation Of A Numerical Algorithm For A Discretized Rubber-Belt Continuously Variable Transmission Dynamic Model And Techniques For The Measurement Of Belt Material Properties., Brian Gene Ballew Dec 2015

Investigation Of A Numerical Algorithm For A Discretized Rubber-Belt Continuously Variable Transmission Dynamic Model And Techniques For The Measurement Of Belt Material Properties., Brian Gene Ballew

Theses and Dissertations

A numerical algorithm for modeling the dynamic response of a rubber-belt Continuously Variable Transmission (CVT) belt is recreated. The numerical attributes applied to the algorithm and difficulties with numerical stability are discussed in detail. The degrees of freedom of the system have been expanded to include the dynamics of the engine torque output and vehicle loads such as rolling resistance and aerodynamic drag. This was done to emphasize the use of the model as an analysis tool for simulating CVT/engine/vehicle response. The increased degrees of freedom require the addition of a linear dampening element between belt nodes to ...


Development Of A Two-Fluid Drag Law For Clustered Particles Using Direct Numerical Simulation And Validation Through Experiments, Ahmadreza Abbasi Baharanchi Nov 2015

Development Of A Two-Fluid Drag Law For Clustered Particles Using Direct Numerical Simulation And Validation Through Experiments, Ahmadreza Abbasi Baharanchi

FIU Electronic Theses and Dissertations

This dissertation focused on development and utilization of numerical and experimental approaches to improve the CFD modeling of fluidization flow of cohesive micron size particles. The specific objectives of this research were: (1) Developing a cluster prediction mechanism applicable to Two-Fluid Modeling (TFM) of gas-solid systems (2) Developing more accurate drag models for Two-Fluid Modeling (TFM) of gas-solid fluidization flow with the presence of cohesive interparticle forces (3) using the developed model to explore the improvement of accuracy of TFM in simulation of fluidization flow of cohesive powders (4) Understanding the causes and influential factor which led to improvements and ...


Electromechanical Coupling Behavior Of Dielectric Elastomer Transducers, Jianyou Zhou Sep 2015

Electromechanical Coupling Behavior Of Dielectric Elastomer Transducers, Jianyou Zhou

Electronic Thesis and Dissertation Repository

Dielectric elastomer transducers with large deformation, high energy output, light weight and low cost have been drawing great interest from both the research and industry communities, and shown potential for versatile applications in biomimetics, dynamics, robotics and energy harvesting. However, in addition to multiple failure modes such as electrical breakdown, electromechanical instability, loss-of-tension and fatigue, the performance of dielectric elastomer transducers are also strongly influenced by the hyperelastic and viscoelastic properties of the material. Also, the interplay among these material properties and the failure modes is rather difficult to predict. Therefore, in order to provide guidelines for the optimal design ...


Analytical And Numerical Analysis Of Low Velocity Impact On Metallic Sandwich Panel With Polyurethane Foam Core, Mohsen Mahdian, Hossein Ebrahimi Aug 2015

Analytical And Numerical Analysis Of Low Velocity Impact On Metallic Sandwich Panel With Polyurethane Foam Core, Mohsen Mahdian, Hossein Ebrahimi

Hossein Ebrahimi

No abstract provided.


Traction-Separation Relationships For Hydrogen-Induced Grain Boundary Embrittlement In Nickel Via Molecular Dynamics Simulations, Wesley Allen Barrows Jul 2015

Traction-Separation Relationships For Hydrogen-Induced Grain Boundary Embrittlement In Nickel Via Molecular Dynamics Simulations, Wesley Allen Barrows

Theses and Dissertations

The deleterious effects of atomic and molecular hydrogen on the mechanical properties of metals have long been observed. Although several theories exist describing the mechanisms by which hydrogen negatively influences the failure of materials, a consensus has yet to be reached regarding the exact mechanism or combination of mechanisms. Two mechanisms have gained support in explaining hydrogen’s degradative role in non-hydride forming metals: hydrogen-enhanced localized plasticity and hydrogen-enhanced decohesion. Yet, the interplay between these mechanisms and microstructure in metallic materials has not been explained. Accordingly, for this thesis, the three main objectives are: (i) to develop a numerical methodology ...


Energy Selective Neutron Imaging For The Characterization Of Polycrystalline Materials, Robin Woracek May 2015

Energy Selective Neutron Imaging For The Characterization Of Polycrystalline Materials, Robin Woracek

Doctoral Dissertations

This multipart dissertation focuses on the development and evaluation of advanced methods for material testing and characterization using neutron diffraction and imaging techniques. A major focus is on exploiting diffraction contrast in energy selective neutron imaging (often referred to as Bragg edge imaging) for strain and phase mapping of crystalline materials. The dissertation also evaluates the use of neutron diffraction to study the effect of multi-axial loading, in particular the role of applying directly shear strains from the application of torsion. A portable tension-torsion-tomography loading system has been developed for in-situ measurements and integrated at major user facilities around the ...


Effects Of Temperature Change On Interfacial Delamination In Thermal Barrier Coatings, Hossein Ebrahimi, Soheil Nakhodchi Apr 2015

Effects Of Temperature Change On Interfacial Delamination In Thermal Barrier Coatings, Hossein Ebrahimi, Soheil Nakhodchi

Hossein Ebrahimi

No abstract provided.


High Temperature Flow Solver For Aerothermodynamics Problems, Huaibao Zhang Jan 2015

High Temperature Flow Solver For Aerothermodynamics Problems, Huaibao Zhang

Theses and Dissertations--Mechanical Engineering

A weakly ionized hypersonic flow solver for the simulation of reentry flow is firstly developed at the University of Kentucky. This code is the fluid dynamics module of known as Kentucky Aerothermodynamics and Thermal Response System (KATS). The solver uses a second-order finite volume approach to solve the laminar Navier– Stokes equations, species mass conservation and energy balance equations for flow in chemical and thermal non-equilibrium state, and a fully implicit first-order backward Euler method for the time integration. The hypersonic flow solver is then extended to account for very low Mach number flow using the preconditioning and switch of ...


Influence Of Spatial Variations Of Railroad Track Stiffness And Material Inclusions On Fatigue Life, Celestin Nkundineza Jan 2015

Influence Of Spatial Variations Of Railroad Track Stiffness And Material Inclusions On Fatigue Life, Celestin Nkundineza

Mechanical (and Materials) Engineering -- Dissertations, Theses, and Student Research

Railroad transportation is very important for economic growth and effective maintenance is one critical factor for its economic sustainability. The high repetitive forces from a moving railcar induce cyclic stresses that lead to rail bending and potential deterioration due to fatigue crack initiation and propagation. Previous research for prediction of fatigue life has been done under the assumptions of a uniform track bed and a homogeneous rail. However the spatial variation of the track stiffness is expected to increase the maximum stresses in the rail and, therefore, accelerate the fatigue process. The research described in this dissertation is focused on ...


Authoring Effective Embedded Tutors: An Overview Of The Extensible Problem Specific Tutor (Xpst) System, Stephen B. Gilbert, Stephen B. Blessing, Enruo Guo Jan 2015

Authoring Effective Embedded Tutors: An Overview Of The Extensible Problem Specific Tutor (Xpst) System, Stephen B. Gilbert, Stephen B. Blessing, Enruo Guo

Industrial and Manufacturing Systems Engineering Publications

The Extensible Problem Specific Tutor (xPST) allows authors who are not cognitive scientists and not programmers to quickly create an intelligent tutoring system that provides instruction akin to a model-tracing tutor. Furthermore, this instruction is overlaid on existing software, so that the learner’s interface does not have to be made from scratch. The xPST architecture allows for extending its capabilities by the addition of plug-ins that communicate with additional third-party software. After reviewing this general architecture, we describe three major implementations that we have created using the xPST system, each using different third-party software as the learner’s interface ...


Using Conceptgrid As An Easy Authoring Technique To Check Natural Language Responses, Stephen B. Blessing, Shrenik Devasani, Stephen B. Gilbert, Jivko Sinapov Jan 2015

Using Conceptgrid As An Easy Authoring Technique To Check Natural Language Responses, Stephen B. Blessing, Shrenik Devasani, Stephen B. Gilbert, Jivko Sinapov

Industrial and Manufacturing Systems Engineering Publications

ConceptGrid provides a template-style approach to check natural language responses by students using a model-tracing style intelligent tutoring system. The tutor-author creates, using a web-based authoring system, a latticestyle structure that contains the set of required concepts that need to be in a student response. The author can also create just-in-time feedback based on the concepts present or absent in the student's response. ConceptGrid is integrated within the xPST authoring tool and was tested in two experiments, both of which show the efficacy of the technique to check student answers. The first study tested the tutor's effectiveness overall ...