Mechanical Engineering Commons^™

Indentation Fracture Of Bovine Cortical Bone: Acoustic Emission Technique, Ashkan Safari, Ger Reilly, Brendan Mccormack

Conference Papers

Indentation cutting may result in microcracking and main crack growth which was previously reported. In this study, we recorded the AE signals produced by cracking processes during cutting on cortical bone, measuring the cutting force and correlating between load-displacement curves and AE activities.

Remote Terrain Navigation For Unmanned Air Vehicles, Stephen R. Griffiths

Theses and Dissertations

There are many applications for which small unmanned aerial vehicles (SUAVs) are well suited, including surveillance, reconnaissance, search and rescue, convoy support, and short-range low-altitude perimeter patrol missions. As technologies for microcontrollers and small sensors have improved, so have the capabilities of SUAVs. These improvements in SUAV performance increase the possibility for hazardous missions through mountainous and urban terrain in the successful completion of many of these missions. The focus of this research was on remote terrain navigation and the issues faced when dealing with limited onboard processing and limited payload and power capabilities. Additional challenges associated with canyon and …

On The Determination Of Residual Stress And Mechanical Properties By Indentation, Xi Chen, Jin Yan Yan, Anette M. Karlsson

Mechanical Engineering Faculty Publications

Residual stresses are of practical importance in bulk materials and coatings, which critically affects their mechanical integrity and reliability. Comparing with traditional techniques, the depth-sensing indentation technique provides a quick and effective method of measuring the residual stress field. In this study, we have used the finite element method to investigate the effect of in-plane residual stress on hardness and stiffness measurements of a bulk material/thick coating. It is found that the contact hardness, stiffness, and indentation work are sensitive to the residual stress, in particular for materials with a relatively high yield strain. Based on the reverse analysis, a …

Elastic Modulus Of Amorphous Sio2 Nanowires, Hai Ni, Xiaodong Li, Hongsheng Gao

Faculty Publications

Amorphous SiO₂ nanowires with diameter ranging from 50 to 100 nm were synthesized using chemical vapor deposition(CVD) under an argon atmosphere at atmospheric pressure. Nanoscale three-point bending tests were performed directly on individual amorphous SiO₂ nanowires using an atomic force microscope (AFM).Elastic modulus of the amorphous SiO₂ nanowires was measured to be 76.6±7.2GPa, which is close to the reported value of the bulk SiO₂ and thermally grown SiO₂ thin films, but lower than that of plasma-enhanced CVD SiO₂ thin films. The amorphous SiO₂ nanowires exhibit brittle fracture failure in bending.

High Temperature Heat Exchanger Project: Quarterly Progress Report October 1, 2005 Through December 31, 2005, Anthony Hechanova

Publications (NSTD)

• Liquid Salt Technical Working Group Meeting. The first meeting of the Liquid Salt Technical Working Group was held on October 28, 2005 at the Pratt Whitney Rocketdyne facility in Canoga Park, CA. 20 experts from academia, industry, and national laboratories participated to discuss current state of knowledge and research needs for high temperature liquid salt applications.
• Nuclear Hydrogen Initiative Semi-annual Review. Several participants from the UNLVRF University Consortium gave technical presentations at the NHI Semi-annual Review meeting in Rockville, MD, November 9-10, 2005.
• Quarterly Collaboration Meeting. The University of Nevada, Las Vegas hosted a UNLVRF HTHX Project quarterly meeting December …

Ultrasonic Method For Aircraft Wake Vortex Detection, Rebecca J. Rodenhiser, William W. Durgin, Hamid Johari

Office of the Provost Scholarship

This paper describes the experimental proof of concept study for an ultrasonic method of wake vortex detection for airport use. This new acoustic method utilizes travel time of acoustic pulses around a closed path to measure the net circulation within the acoustic path. In this application the closed path encloses the vorticity shed from one side of a Piper PA28 aircraft wing. Magnitude and sign of circulation detected is comparable to the expected circulation generated by the Piper PA28 test aircraft. This study demonstrates the validity of the acoustic method in detecting aircraft wake vortices. Further investigations and applications utilizing …

High-Pressure Torsion-Induced Grain Growth In Electrodeposited Nanocrystalline Ni, X. Z. Liao, A. R. Kilmametov, R. Z. Valiev, Hongsheng Gao, Xiaodong Li, A. K. Mukherjee, J. F. Blingert, Y. T. Zhu

Faculty Publications

Deformation-induced grain growth has been reported in nanocrystalline (nc) materials under indentation and severe cyclic loading, but not under any other deformation mode. This raises an issue on critical conditions for grain growth in nc materials. This study investigates deformation-induced grain growth in electrodeposited nc Ni during high-pressure torsion (HPT). Our results indicate that high stress and severe plastic deformation are required for inducing grain growth, and the upper limit of grain size is determined by the deformation mode and parameters. Also, texture evolution suggests that grain-boundary-mediated mechanisms played a significant role in accommodating HPT strain.

Application Of An Hp-Adaptive Finite Element Method For Thermal Flow Problems, Xiuling Wang, Darrell Pepper

Mechanical Engineering Faculty Research

Numerical results are presented for a set of convective thermal flow problems using an hp-adaptive finite element technique. The hp-adaptive model is based on mesh refinement and spectral order incensement to produce enhanced accuracy while attempting to minimize computational requirements. An a-posteriori error estimator based on the L₂ norm is employed to guide the adaptation procedure. Example test cases consisting of natural convection in a differentially heated enclosure, flow with forced convection heat transfer over a backward facing step and natural convection within an enclosed partition are presented. Numerical results are compared with published data in the …

Design Of 'Iris', A Small Autonomous Surveillance Uav, Jennifer Boyce, Ryan Carr, Donovan Chipman, Greg Larson, Nathan Hopkins, Doug F. Hunsaker, W. Jerry Bowman

Mechanical and Aerospace Engineering Faculty Publications

This paper documents the design process used for a small autonomous surveillance UAV. The most significant requirements for the plane were size (man-packable), endurance (about 1 hour) and cost (essentially disposable). The plane that resulted, named "Iris", is a tailless plane with a 45 cm wing span and a total mass of less than 200g. During flight tests, it achieved an endurance of 52 minutes. The estimated cost to manufacture the planes was $343, excluding the autopilot.

Lattice-Based Structures For Studying Percolation In Two-Dimensional Grain Networks, Brent L. Adams, John A. Basinger, David T. Fullwood

Faculty Publications

This work was supported primarily by the MRSEC program of the National Science Foundation under DMR-0079996. The applicability of standard lattice percolation models to a random 2-D grain structure is explored. A random network based on the triangle lattice is proposed as a more appropriate model, and results in a higher percolation threshold (0.711 compared with 0.653 for the standard hexagonal lattice). The triple junction constraint inherent in grain boundary structures is subsequently applied to the new network. This results in a lowering of the percolation threshold to 0.686; this is opposite to its effect on the standard hexagonal lattice. …

Aerothermodynamic Cycle Analysis Of A Dual-Spool, Separate-Exhaust Turbofan Engine With An Interstage Turbine Burner, Ka Heng Liew

Dissertations, Master's Theses and Master's Reports - Open

This study focuses on a specific engine, i.e., a dual-spool, separate-flow turbofan engine with an Interstage Turbine Burner (ITB). This conventional turbofan engine has been modified to include a secondary isobaric burner, i.e., ITB, in a transition duct between the high-pressure turbine and the low-pressure turbine. The preliminary design phase for this modified engine starts with the aerothermodynamics cycle analysis is consisting of parametric (i.e., on-design) and performance (i.e., off-design) cycle analyses.

In parametric analysis, the modified engine performance parameters are evaluated and compared with baseline engine in terms of design limitation (maximum turbine inlet temperature), flight conditions (such as …

Hybrid Solar Cells From Water-Soluble Polymers, James T. Mcleskey Jr., Qiquan Qiao

Mechanical and Nuclear Engineering Publications

We report on the use of a water-soluble, light-absorbing polythiophene polymer to fabricate novel photovoltaic devices. The polymer is a water-soluble thiophene known as sodium poly[2-(3-thienyl)-ethoxy-4-butylsulfonate] or PTEBS. The intention is to take advantage of the properties of conjugated polymers (flexible, tunable, and easy to process) and incorporate the additional benefits of water solubility (easily controlled evaporation rates and environmentally friendly). The PTEBS polythiophene has shown significant photovoltaic response and has been found to be effective for making solar cells. To date, solar cells in three different configurations have been produced: titanium dioxide (TiO2) bilayer cells, TiO2 bulk heterojunction solar …

Comparison Of The Pull-Out Strengths Of Three Different Screws In Pedicular Screw Revisions: A Biomechanical Study, Irfan Esenkaya, Yurdaer Denizhan, Mehmet Akif Kaygusuz, Mehmet Yetmez, Mehmet Halidun Keleştemur

Faculty Publications - Mechanical Engineering

OBJECTIVES: We investigated the possible effects of three pedicular screws on axial pull-out strength in pedicular revision surgery. METHODS: Two study groups were formed from calf lumbar vertebrae. Initially, Alici pedicular screws with an outer diameter of 6.5 mm were applied (with or without tapping) to all the pedicles. All the pedicles were subjected to axial pull-out testing to induce pedicular insufficiency. Then, Alici pedicular screws with an outer diameter of 7 mm were applied to the left pedicles. The right pedicles in the two study groups were assigned to receive two different types of pedicular screws with an expandable …

Cool Flames At Terrestrial, Partial, And Near-Zero Gravity, Michael R. Foster, Howard Pearlman

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

Natural convection plays an important role in all terrestrial, Lunar, and Martian-based, unstirred, static reactor cool flame and low-temperature autoignitions, since the Rayleigh number (Ra) associated with the self-heating of the reaction exceeds the critical Ra (approximately 600) for onset of convection. At near-zero gravity, Ra < 600 can be achieved and the effects of convection suppressed. To systematically vary the Ra without varying the mixture stoichiometry, reactor pressure, or vessel size, cool flames are studied experimentally in a closed, unstirred, static reactor subject to different gravitational accelerations (terrestrial, 1g; Martian, 0.38g; Lunar, 0.16g; a n dr e - duced gravity, ∼10−2g). Representative results show the evolution of the visible light emission using an equimolar n-butane:oxygen premixture at temperatures ranging from 320 to 350 ◦C (593–623 K) at subatmospheric pressures. For representative reduced-gravity, spherically propagating cool flames, the flame radius based on the peak light intensity is plotted as a function of time and the flame radius (and speed) is calculated from a polynomial fit to data. A skeletal chemical kinetic Gray-Yang model developed previously for a one-dimensional, reactive– diffusive system by Fairlie and co-workers is extended to a two-dimensional axisymmetric, spherical geometry. The coupled species, energy, and momentum equations are solved numerically and the spatio-temporal variations in the temperature profiles are presented. A qualitative comparison is made with the experimental results.

Transient Heat Partition Factor For A Sliding Railcar Wheel, T C. Kennedy, C Plengsaard, Robert F. Harder

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

During a wheel slide the frictional heat generated at the contact interface causes intense heating of the adjacent wheel material. If this material exceeds the austenitising temperature and then cools quickly enough, it can transform into martensite, which may ultimately crack and cause wheel failure. A knowledge of the distribution of the heat partitioned into the wheel and the rail and the resulting temperature fields is critical to developing designs to minimize these deleterious effects. A number of theoretical solutions have appeared in the literature to model the thermal aspects of this phenomenon. The objective of this investigation was to …

Unbalanced Return Air In Residences: Causes, Consequences, And Solutions, Florida Solar Energy Center, James Cummings

FSEC Energy Research Center®

Field research performed in 70 central Florida homes found that return grills are almost always located in the central zone of the house, and that individual rooms rarely have ducted return air or return transfer pathways. When interior doors were closed, the closed rooms went to +0.0249 inches of water gauge (in w.g.) (+6.2 pascals (Pa)) wrt outdoors (wrt = with respect to), and the central zone went to -0.0116 in w.g. (-2.9 Pa) wrt outdoors. Room pressures as high as +0.150 in w.g. (+37.3 Pa) and central zone pressure as low as -0.059 in w.g. (-14.7 Pa) wrt outdoors …

A Numerical Acoustic Fluid-Structure Simulation Of Therapeutic Ultrasound Angioplasty, Graham Gavin, Finbar Dolan, M.S J. Hashmi, Garrett Mcguinness

Conference Papers

INTRODUCTION Therapeutic ultrasound angioplasty is the delivery of high amplitude ultrasonic displacements to the distal-tip of small diameter wire waveguides with the goal of disrupting atherosclerotic plaques. This is a minimally invasive procedure that may have potential' in the treatment of complicated chronic total occlusions. The disruption of plaque is due to direct contact ablation and also cavitation, pressure waves and acoustic streaming in the fluid surrounding the vibrating waveguide distal-tip [1]. Cavitation appears to play a major role and some authors have suggested that plaque ablation is only evident above the cavitation threshold [2]. Makin and Everbach [3] performed …

Me-Em 2006 Annual Report, Department Of Mechanical Engineering-Engineering Mechanics, Michigan Technological University

Department of Mechanical and Aerospace Engineering Annual Reports

Table of Contents

• Overview, Mission, and Vision
• Comments on the Strategic Plan
• Enrollment, Degrees, and Expenditure Data
• External Advisory Board
• Faculty and Staff
• Students
• Alumni
• Resources
• Graduates
• Publications

Unbalanced Return Air In Commercial Buildings, Florida Solar Energy Center, Charles Withers, Jr.

FSEC Energy Research Center®

Research in 88 central Florida commercial buildings during the last decade has found that 26% of the air distribution systems had substantially unbalanced return air. Unbalanced return air occurs when there is a restriction to air flow between the supply discharge and the return air, creating positive and negative pressure fields throughout the building. Severe consequences in commercial buildings can occur as a result of unbalanced air flows. This paper examines unbalanced return air and its consequences in three commercial buildings, and explains why balancing air flow in buildings is a critical part of maintaining a healthy and energy efficient …

Understanding The Dehumidification Performance Of Air-Conditioning Equipment At Part-Load Conditions, Florida Solar Energy Center, Don B. Shirey Iii

FSEC Energy Research Center®

Air conditioner cooling coils typically provide both sensible cooling and moisture removal. Data from a limited number of field studies (Khattar et al. 1985; Henderson and Rengarajan 1996; Henderson 1998) have demonstrated that the moisture removal capacity of a cooling coil degrades at part-load conditions - especially when the supply fan operates continuously while the cooling coil cycles on and off. Degradation occurs because moisture that condenses on the coil surfaces during the cooling cycle evaporates back into air stream when the coil is off. This degradation affects the ability of cooling equipment to maintain proper indoor humidity levels and …

Abstract/Conclusion: Understanding The Dehumidification Performance Of Air-Conditioning Equipment At Part-Load Conditions, Florida Solar Energy Center, Don B. Shirey Iii

FSEC Energy Research Center®

Air conditioner cooling coils typically provide both sensible cooling and moisture removal. Data from a limited number of field studies (Khattar et al. 1985; Henderson and Rengarajan 1996; Henderson 1998) have demonstrated that the moisture removal capacity of a cooling coil degrades at part-load conditions, especially when the supply fan operates continuously while the cooling coil cycles on and off. Degradation occurs because moisture that condenses on the coil surfaces during the cooling cycle evaporates back into air stream when the coil is off. This degradation affects the ability of cooling equipment to maintain proper indoor humidity levels and may …

Geographic Variation Of Solar Water Heater Performance In Europe, Y. Yohanis, O. Popel, S. Frid, Brian Norton

Articles

Solar water heater (SWH) performance has been analysed using the ‘number of days’ method for 147 different sites in all European countries. The total number of days that the temperature of delivered solar heated water reaches or exceeds specified demand temperatures is correlated with solar radiation on a horizontal surface for summer, warm half-year, and whole year periods. Maps are presented and discussed showing the contours for the number of days that an illustrative SWH met different hot water demand temperatures. Correlations between number of days water is provided at a specified temperature and solar fractions for the same periods …

Test 1880: Mccormick Xtx 185/Mccormick Mtx 165 Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Better Understanding Of Resonance Through Modeling And Visualization, Daniel O. Ludwigsen, Cayla Jewett, Matthew Jusczcyk

Physics Presentations And Conference Materials

Students encounter cavity resonance and waveguide phenomena in acoustics courses and texts, where the study is usually limited to cases with simple geometries: parallelepipeds, cylinders, and spheres. Long-wavelength approximations help with situations of more complexity, as in the classic Helmholtz resonator. At Kettering University, we are beginning to employ finite element modeling in our acoustics classes to help undergraduates better understand the acoustic modes of actual structures. This approach to the time-independent wave equation (the Helmholtz equation) was first used in a research and measurements class to investigate two classic resonance problems. The first problem was a study of resonance …

Experimental And Modeling Study Of The Filtration And Oxidation Characteristics Of A Diesel Oxidation Catalyst And A Catalyzed Particulate Filter, Kiran C. Premchand

Dissertations, Master's Theses and Master's Reports - Open

A diesel oxidation catalyst (DOC) with a catalyzed diesel particulate filter (CPF) is an effective exhaust aftertreatment device that reduces particulate emissions from diesel engines, and properly designed DOC-CPF systems provide passive regeneration of the filter by the oxidation of PM via thermal and NO₂/temperature-assisted means under various vehicle duty cycles. However, controlling the backpressure on engines caused by the addition of the CPF to the exhaust system requires a good understanding of the filtration and oxidation processes taking place inside the filter as the deposition and oxidation of solid particulate matter (PM) change as functions of loading …

The Effect Of Reflow Profile On Snpb And Snagcu Solder Joint Shear Strength, Jianbiao Pan, Brian J. Toleno, Tzu-Chien Chou, Wesley J. Dee

Industrial and Manufacturing Engineering

Purpose –The purpose of this work is to study the effect of the reflow peak temperature and time above liquidus on both SnPb and SnAgCu solder joint shear strength.

Design/methodology/approach –Nine reflow profiles for Sn3.0Ag0.5Cu and nine reflow profiles for Sn37Pb have been developed with three levels of peak temperature (230°C, 240°C, and 250°C for Sn3.0Ag0.5Cu; and 195°C, 205°C, and 215°C for Sn37Pb) and three levels of time above solder liquidus temperature (30, 60, and 90 s). The shear force data of four different sizes of chip resistors (1206, 0805, 0603, and 0402) are compared across the different …

A Simplified Model For Ploughing Forces In Turning, Daniel Waldorf

Industrial and Manufacturing Engineering

This paper aims to provide experimental data in support of a modified theoretical model for quantifying the effect of cutting tool edge geometry on machining forces. A previously published slip-line model is simplified and extended to the case of turning. Several sets of machining experiments were run with custom-fabricated cutting inserts of varying edge hone radius and chamfer geometry. Cutting forces were measured using a dynamometer during cutting. Results show that varying edge geometry can have a major effect on cutting forces. The developed model effectively captures the edge phenomenon and its effect on cutting forces and also offers a …

Nanoparticle-Induced Negative Differential Resistance And Memory Effect In Polymer Bistable Light-Emitting Device, Ricky J. Tseng, Jianyong Ouyang, Chih-Wei Chu, Jinsong Huang, Yang Yang

Department of Mechanical and Materials Engineering: Faculty Publications

Recently, electrical bistability was demonstrated in polymer thin films incorporated with metal nanoparticles [J. Ouyang, C. W. Chu, C. R. Szmanda, L. P. Ma, and Y. Yang, Nat. Mater. 3, 918 (2004)]. In this letter, we show the evidence that electrons are the dominant charge carriers in these bistable devices. Direct integration of bistable polymer layer with a light-emitting polymer layer shows a unique light-emitting property modulated by the electrical bistability. A unique negative differential resistance induced by the charged gold nanoparticles is observed due to the charge trapping effect from the nanoparticles when interfaced with the light-emitting layer.

In Vivo Laparoscopic Robotics, Mark E. Rentschler, Stephen R. Platt, Jason Dumpert, Shane M. Farritor, Dmitry Oleynikov

Department of Mechanical and Materials Engineering: Faculty Publications

Robotic laparoscopic surgery is evolving to include in vivo robotic assistants. The impetus for the development of this technology is to provide surgeons with additional viewpoints and unconstrained manipulators that improve safety and reduce patient trauma. A family of these robots have been developed to provide vision and task assistance. Fixed-base and mobile robots have been designed and tested in animal models with much success. A cholecystectomy, prostatectomy, and nephrectomy have all been performed with the assistance of these robots. These early successful tests show how in vivo laparoscopic robotics may be part of the next advancement in surgical technology.

A Minimum-Impact Method For Measuring Corrosion Rate Of Steel-Hulled Shipwrecks In Seawater, Matthew A. Russell, David Conlin, Larry E. Murphy, Donald L. Johnson, Brent Wilson, James Carr

Department of Mechanical and Materials Engineering: Faculty Publications

Current research on USS Arizona is focused on a minimum-impact technique for calculating corrosion rate of the battleship’s steel hull by analyzing physical and chemical properties of marine encrustation covering the exposed hull. An equation is derived that allows concretion thickness, density, and total iron content to be used to calculate corrosion rate of steel hull plate.