Engineering Science and Materials Commons^™

College Of Engineering Senior Design Competition Spring 2006, University Of Nevada, Las Vegas

Fred and Harriet Cox Senior Design Competition Projects

Part of every UNLV engineering student’s academic experience, the senior design project stimulates engineering innovation and entrepreneurship. Each student in their senior year chooses, plans, designs and prototypes a product in this required element of the curriculum. A capstone to the student’s educational career, the senior design project encourages the student to use everything learned in the engineering program to create a practical, real world solution to an engineering challenge.

The senior design competition helps to focus the senior students in increasing the quality and potential for commercial application for their design projects. Judges from local industry evaluate the projects …

Modeling And Representation Of Geometric Tolerances Information In Integrated Measurement Processes, Xiaoping Zhao, T. M. Kethara Pasupathy, Robert G. Wilhelm

Department of Mechanical and Materials Engineering: Faculty Publications

Modeling and representation of geometric tolerances information across an enterprise is viable due to the advances in Internet technologies and increasing integration requirements from industry. In Integrated Measurement Processes (IMP), geometric tolerances data model must support different models from several well-defined standards: including ASME Y14.5M-1994, STEP, DMIS, and others. In this paper, we propose a layered conformance level geometric tolerances representation model. This model uses the widely applied ASME Y14.5M-1994 as its foundation layer by abstracting most information from this standard. The additional geometric tolerances information defined by DMIS and STEP is incorporated into this model to form corresponding conformance …

Experimental And Finite Element Analysis Of Preloaded Bolted Joints Under Impact Loading, Brendan O'Toole, Kumarswamy Karpanan, Masoud Feghhi

Mechanical Engineering Faculty Research

One of the primary parameters in analyzing bolted joints is preload in the bolt. We have considered several possible preload modeling techniques to analyze the effect of preload on the dynamic response of the bolted joints. Five different methods of applying preload in the nonlinear finite element analysis are evaluated. These methods are “force on bolt and nut”, “force on bolt shank”, “interference fit”, “thermal gradient” and “initial stress method”. Explicit and implicit analyses are used for transient response and preload generation in bolt respectively. Time history and shock response spectrum are used to compare experimental and simulation results. Simulation …

Energy Efficient Process Heating: Managing Air Flow, Kevin Carpenter, J. Kelly Kissock

Mechanical and Aerospace Engineering Faculty Publications

Much energy is lost through excess air flow in and out of process heating equipment. Energy saving opportunities from managing air flow include minimizing combustion air, preheating combustion air, minimizing ventilation air, and reconfiguring openings to reduce leakage.

This paper identifies these opportunities and presents methods to quantify potential energy savings from implementing these energy-savings measures. Case study examples are used to demonstrate the methods and the potential energy savings.The method for calculating savings from minimizing combustion air accounts for improvement in efficiency from increased combustion temperature and decreased combustion gas mass flow rate.

The method for calculating savings from …

Flexible Tools For Specifying Design Variation, Trichy Pasupathy, Xiaoping Zhao, Robert Wilhelm

Department of Mechanical and Materials Engineering: Faculty Publications

This paper describes flexible tools for specifying design variations that are based on nonuniform profile tolerance definitions. These tools specify bounds of design performance that can be used for negotiation among engineers in a collaborative design process. These specification methods allow for the capture of many different design functions that are not easily described with current tool designs. In addition, these specification methods lend themselves to efficient verification methods. Profile tolerance definitions provide the most general variation controls for complex mechanical surfaces. Common design practices and engineering standards for profile tolerances exhibit many weaknesses and limitations. We present a rationale …

Analysis And Simulation Of Hypervelocity Gouging Impacts, John D. Cinnamon

Theses and Dissertations

In this work, a summary of past and present research efforts, as well as the theoretical foundation, of hypervelocity gouging is presented. As the Holloman AFB High Speed Test Track (HHSTT) sled's speed has increased to Mach 8.5, material interactions develops which causes "gouging" - this can result in catastrophic failure. A characterization of gouging, including a thermodynamic history, is developed from an examination of a gouged rail. An extensive study is performed that determines the specific material flow models for VascoMax 300 and 1080 steel. The models are validated utilizing several experimental tests which are successfully simulated using CTH …

Application Of Spline Variational Analysis Method In The Modeling Of Composite Repairs, Brian M. Fredrickson

Theses and Dissertations

The purpose of this thesis is to apply a non-commercialized spline-based (BSpline Analysis Method or BSAM) computer program to model and predict strain fields in two composite repairs, a scarf joint and a stepped-lap joint, subjected to static tensile loading. Test specimens with scarf and stepped-lap joints are fabricated using quasiisotropic sixteen ply panels made from IM6/3501-6 prepreg with a [+45₂/0₂/-45₂/90₂]_s lay-up. The panels were bonded together with FM-300M (0.05psf), a 176°C cure film adhesive, under positive pressure. A total of five coupons of each joint type are made. Two of …

Characterization Of Compressive Creep Behavior Of Oxide/Oxide Composite With Monazite Coating At Elevated Temperature, Patrick R. Jackson

Theses and Dissertations

The compressive creep behavior of a N610/monazite/alumina composite was investigated in this work. The composite consists of a porous alumina matrix reinforced with NextelTM610 fibers coated with monazite in a symmetric cross-ply (0°/90°/0°/90°)s orientation. Compressive stress-strain behavior was investigated as well. The addition of monazite coating resulted in ~ 35% loss in compressive strength at 900°C and in ~45% loss in compressive strength at 1100°C. Compressive creep behavior was examined at 900 and 1100°C for creep stresses ranging from 50 to 95 MPa. Primary and secondary creep regimes were observed at both temperatures. Minimum creep rate was reached in all …

Fretting Fatigue Behavior Of Nickel Alloy In-100, Elhoucine Madhi

Theses and Dissertations

In this study, a systematic investigation of the fretting fatigue behavior of nickel alloy, IN-100 was carried out. The study includes both experimental work and the corresponding analysis of the contact conditions, and the latter is accomplished using the finite element method. Fretting fatigue tests were performed over a wide range of axial stresses to examine both low and high cycle fretting fatigue under constant contact load and the influence of different pad geometries was also explored. It was observed that fretting reduced the fatigue strength of IN- 100, and that increasing cylindrical pad radii does not have the same …

Effect Of Hold Times On Fatigue Behavior Of Nextel 720™/Alumina Ceramic Matrix Composite At 1200°C In Air And In Steam Environment, John M. Mehrman

Theses and Dissertations

The aerospace field requires structural materials that can maintain superior mechanical properties while subjected to high temperatures and oxidizing environments. This research investigated the effect of hold times at maximum load on fatigue performance of a Nextel 720/Alumina ceramic matrix composite at 1200 C, explored the influence of environment on material response to cyclic loading with hold times at maximum load, and assessed the effects of loading history on material behavior and environmental durability. The N720/A composite relies on an oxide/oxide composition for inherent oxidation resistance and a porous matrix with no interphase between the fiber and matrix for damage …

Structural Health Monitoring Considering Internal Beam Damage, Jessica B. Chronister

Theses and Dissertations

The present study establishes a nondestructive method of damage detection and assessment in cantilever beams. The specimens used are twelve-inch aluminum 2024-T3 beams with machined notches of varying lengths and locations. Laser Doppler vibrometry is used to obtain the frequency response of vibrating beams. Experimental methods are developed to detect the presence, location and extent of damage by direct observation of the eigenvector in the third through eighth modes. Models in MATLAB and ABAQUS are used to predict and validate the observed data. With this experimental method developed, the validity of the method is tested for specimens that have been …

Evaluation Of Factors Contributing To Damping Of Coated And Uncoated Titanium Plates, Dustin W. Lee

Theses and Dissertations

High Cycle Fatigue (HCF) is the leading cause of component failure in gas turbine engines today, which poses great risk to aircraft, engines, and their crews. Mitigation of HCF effects has become a priority topic, and the damping benefits of hard coatings are being reevaluated for this purpose. Research was conducted to further understanding of damping measurements on these coatings. This study continues work to characterize the damping effects of a magnesium aluminate spinel (mag spinel) coating applied to a titanium plate via vibration testing. Two different plate sizes were evaluated in a clamped-free-free-free condition and a free-free-free-free condition, respectively. …

Validation Of A Scaled Plane Strain Hypervelocity Gouging Model, Ronald J. Pendleton

Theses and Dissertations

The phenomenon of high speed impact is of great interest to the Air Force of Scientific Research and the Air Force Research Laboratory's Holloman High Speed test track. Rocket sled tests at the facility frequently are limited to velocities lower than actually attainable due to damage to the rail in the form of gouges. Direct observation of the gouging phenomenon is not currently possible. This leaves computational modeling as the only means to study the phenomenon. A computer model has previously been used to model the development of gouging at the Holloman High Speed Test Track. However, this model has …

Development Of In-Plane Surface Deformation Sensing For Thin Film Pvdf Actuated Membrane Mirrors, John J. Cornelius

Theses and Dissertations

This study investigated the feasibility of surface deformation sensing of a membrane mirror using only embedded PVDF sensors. Results were compared to measured deformations using a scanning laser vibrometer. The frequency response function (FRF) was measured based on recorded voltages of a single-layer 7-sensor mirror actuated externally from the embedded PVDF actuators. Additionally, a two-layer, 7-sensor, 7-actuator membrane mirror was constructed for use, with one layer acting as the sensing layer and the other acting as the actuation layer. The measured FRF for this mirror was compared to previous results. Finally a single-layer 61-sensor PVDF mirror was constructed to experimentally …

Creep-Rupture And Fatigue Behaviors Of Notched Oxide/Oxide Ceramic Matrix Composite At Elevated Temperature, Mark A. Sullivan

Theses and Dissertations

Oxide/oxide composites are being considered for use in high temperature aerospace applications where their inherent resistance to oxidation provides for better long life properties at high temperature than most other ceramic matrix composites (CMCs). One promising oxide/oxide CMC is Nextel 720/A (N720/A) which uses an 8-harness satin weave (8HSW) of Nextel 720 fibers embedded in a porous alumina matrix. Possible aerospace applications for N720/A will likely require inserting holes into the material for mounting and cooling purposes. The notch characteristics must be understood to ensure designs using the material are sufficient for the desired application. This research effort examined the …

Electroless Nickel Plating On Carbon Nanotube With Non-Palladium Activation Procedure, Guang-Hui Hu, Hui-Huang Wu, Fang-Zu Yang

Journal of Electrochemistry

A new procedure of surface activation without using palladium salt was proposed for electroless nickel plating on carbon nanotubes.In the procedure,carbon nanotubes were oxidized by nitric acid and then neutralized with NaOH to create carboxyl surface groups which were used to adsorb Ni²⁺ ions,thereafter the adsorbed Ni²⁺ ions were chemically reduced into Ni nano-particles as a catalytic center for electroless nickel deposition,all these were further confirmed by infrared absorption spectra and electron microscopic observations.The results indicate that the procedure is feasible to electroless nickel plating on carbon nanotubes.The different morphology of deposits obtained from electroless plating was also …

Anodic Behaviors Of Pb-Ca-Sn-Re Alloy And Tradditional Pb-Ca-Sn Alloy In Sulfuric Acid Solutions, Dang-Guo Li, Gen-Shu Zhou, Liang Yao, Guan-Fa Lin, Mao-Sheng Zheng

Journal of Electrochemistry

The anodic behaviors of Pb-Ca-Sn-Re and Pb-Ca-Sn alloys were investigated at 1.28 V(vsHg/(H₂SO₄)) in 4.5 mol/L sulfuric acid solution by means of ac voltammetry,ac impedance and cyclic voltammetry.The results showed that the corrosion-resistance property of Pb-Ca-Sn-Re alloy is better than that of tradditional Pb-Ca-Sn alloy,the growth of Pb(Ⅱ) compounds was inhibited in the film of Pb-Ca-Sn-Re alloy,and the film impedance of Pb-Ca-Sn-Re alloy was decreased,indicating that the conductivity of the film was(increased),which is helpful to enhance the deep recycling property for lead acid battery.

Mechanism Of Self Discharge Performance Improvement In The Ni-Mh Batteries With Naoh Electrolyte, Xiao-Feng Li, Tong-Chi Xia, Hui-Chao Dong, Yan-Wei Wei

Journal of Electrochemistry

The self-discharge performance and charge efficiency at 60 ℃ for Ni-MH battery can be markedly enhanced by using NaOH electrolyte instead of KOH electrolyte.Both the results of electrochemical impedance spectroscopy and cyclic voltammetry tests indicate that the separation of H₂ from the negative electrode may be partly blocked in the former because of the change of the adsorption/desorption behavior of H on the surface of the negative electrode,thus results in an improvement of self-discharge performance of the battery.

2006 National Conference On Corrosion Electrochemistry And Measuring Methods, Editorial Office Of J.Electrochem.

Journal of Electrochemistry

No abstract provided.

Electrocatalytic Oxidation Of Glucose On Nano Pt/C Electrode, Cui-Lian Chen, Xiao-Lan Wei, Pei Kang Shen

Journal of Electrochemistry

Nano Pt/C electrocatalysts were prepared by intermittent microwave heating method.The electrooxidation of glucose on smooth Pt and～Pt/C electrodes has been studied and compared.The results showed that the electrochemical properties on nano Pt/C were improved due to the reduction of the overpotential and the increase in the kinetic rate.The surface area would be significantly increased when the particle size of the catalyst was reduced to nano-scale,resulting in the increase in the activity.The enhancement in the resistance to poisoning could be explained that the oxygen-containing species are easier to react with poisoning species on nano Pt/C and re-active the electrode.

Effects Of Sulfide Ions On The Inhibiting Efficiency Of Eda As A Copper Corrosion Inhibitor In Dilute Hcl Solution, Wen-Juan Qu, Rong-Gui Du, Chang-Jian Lin

Journal of Electrochemistry

The anticorrosion action of EDA on copper in dilute HCl solution and the effect of sulfide ions on the inhibiting efficiency were studied by the Tafel plot method.The corrosion potential of Cu shifted to more positive value and the corrosion current density decreased after the addition of Na₂S to the solution.The results indicated that sulphide ions could increase the inhibiting efficiency of EDA because of the synergistic inhibition effect between EDA and Na₂S,resulting from the adsorption of HS^- on the surface of Cu,facilitated the adsorption of EDA to form a highly protective adsorbed layer which …

The Complex Of Pasp And Tungstate As Inhibitors Of Cupronickel B10′S Corrosion In 3% Nacl Solution, Qun-Jie Xu, Guo-Ding Zhou, Hui-Feng Wang, Wen-Bin Cai

Journal of Electrochemistry

AC impedance and polarization curve measurements were conducted to study the effects of environ-ment-friendly inhibitors PASP,Na₂WO₄ and their complexes on the corrosion of cupronickel B10 in 3%NaCl solution.The results indicate that PASP or Na₂WO₄ alone does inhibit the corrosion of B10,and most effectiveconcentrations are 40 mg/L and 60 mg/L for PASP and Na₂WO₄,respectively.With the total concentration of 40mg/L for the complex inhibitors,the optimum complex ratio of PASP to Na₂WO₄ was 3:1.The complex of such a combination showed a significantly synergetic inhibition effect on the corrosion of B10.

The Effect Of Solution Concentration On Properties Of Ru-Ti-Ir Oxide Anode Coatings, Ke Wang, Yan Han, Jun-Tao Wang, Xiao-Ling Zhang, Yu-Pu Sun

Journal of Electrochemistry

The anode coatings of Ru-Ti-Ir oxide with various solution concentrations were prepared by thermal decomposition.The scanning electron microscope(SEM),energy dispersive X-ray detector(EDX),X-ray diffraction(XRD),accelerated life,polarization curve,cyclic voltammetry and electrochemical impedance.spectroscopy(EIS)tests were carried out.The results showed that there was an obvious effect of solution concentrations on the morphology of the coatings,but little effect on polarization of chlorine evolution.Voltammetric charges and double layer capacitances of anode coatings had a tendency to fall down firstly then increase afterwards as the solution concentration increased.

Electrochemical Reduction Behavior Of Benzaldehyde In The Ionic Liquids, Ning Zhao, Wen-Ju Dong, Qi-Zeng Shi

Journal of Electrochemistry

In this paper, the electrochemical reduction of benzaldehyde was investigated in C₄MIMBF₄, C₆MIMBF₄  and C₈MIMBF₄ ionic liquids by cyclic linear sweep voltammetry,cyclic square-wave voltammetry and chronocoulometry.Benzaldehyde exhibits two successive one-electron irreversible reduction(E_P1=-1.39 V, E_P2=1.69 V) with GC electrode in C₄MIMBF₄, the voltammetric data for benzaldehyde give diffusion coefficients of 1.5*10^-8cm²/s and 1.3*10⁸cm²/s. There is one current peak in C₆MIMBF₄  and C₈MIMBF₄ ionic liquids due to their stronger alkalinity …

Oxygen Enrichment Effect Of Ceo2 To The Cathode Performance Of Proton Exchange Membrane Fuel Cell, Xiang-Li Hou, Hong-Feng Xu, Jian-Hua Dong, Xin Sun

Journal of Electrochemistry

CeO₂ was added to Pt/C catalyst in the cathode of PEMFC by both sol and impregnation methods.The samples were evaluated by TEM,cyclic voltammogram techniques and proton exchange membrane fuel cell performance test.The addition of CeO₂ obviously improved the performance of PEMFC and represented a notable function of oxygen enrichment in the cathode side.But with the addition of CeO₂,part of the catalyst surface was covered and led to the performance drop of the PEMFC.The best content of CeO₂ is 1% when it is added by impregnation method and 3% when it is added by sol method.

Effects Of Srb Biofilm And Corrosion Product Films On Corrosion Behavior Of Carbon Steel, Jing Lin, Yong-Gui Yan, Guang-Zhang Chen, Guang-Zhou Liu, Qing-Fen Li

Journal of Electrochemistry

Electrochemical techniques and surface analysis techniques were applied to study corrosion characteristic of A₃ steel.The effects on corrosion behavior of A₃ steel by sulfate-reducing bacteria(SRB)(biotic media)and corrosion product(abiotic media)were studied.The results showed that biofilms and corrosion product films play different role during different stages.Biofilms were easier flaky with increasing of its thickness.Non-uniform biofilms reduced pitting corrosion of the specimens.The corrosion product films formed under abiotic conditions were more adherently to the surface of the metal than those formed in biogenic media.

In-Situ Detection Of The Effect Of Brighter In The Solution For Nickel And Phosphor Alloy, Jian Zheng, Ning Li, De-Yu Li, Guo-Feng Cui

Journal of Electrochemistry

In this work,the gold-plated mica was used for the substrate,the concentration of 5% of normal plating solution for the nickel was used as the mother solution,and the effect for the deposition by the brighter with ECSTM was in-situ detected.The solution for deposition without the brighter has no brightness,though the values of the roughness and the H_(A-V) have reduced in evidence after deposition;the solution for deposition with the complete brighter although has great brightness,the values of the roughness and the H_(A-V) have increased(after) deposition;the solution for deposition with the half brighter has a moderate effect on the H_(A-V) and (brightness).Hence,the brighter …

Preparation Of Spinel Limn2O4 Cathode Materials For Li-Ion Batteries Based On Sol-Gel Process, Xiang-Ming He, Li Wang, Guo-Yun Zhang, Chang-Yin Jiang, Chun-Rong Wan

Journal of Electrochemistry

Spinel LiMn₂O₄ was prepared from CH₃COOLi·2H₂O,Mn(CH₃COO)₂ and adipic acid based on sol-gel process.XRD analysis showed that when the sintering temperature increased,the crystallinity increased,and the capacity also increased.However,its cycleability reached a maximum value at 750 ℃.The sintering duration also influenced on the capacity.The optimized performance was obtained when the sintering was carried out at 750 ℃ for 20 h.Under these conditions,as-prepared spinel LiMn₂O₄  presented the initial discharge capacity of 130 mAh·g^-1 and 125 mAh·g^-1 at 15^th cycle.

Special Photoelectrochemical Response Of Nano-Crystalline Tio2 Electrode, Bi-Bo Lan, Jian-Zhang Zhou, Yan-Yan Xi, Hong-Xiang Chen, Guang-Hua Yao, Zhong-Hua Lin

Journal of Electrochemistry

The nano-crystalline TiO₂ electrodes were prepared by spread method,electrodeposition and sol-gel method.The experimental results show that the nano-crystalline TiO₂ electrodes have special photoelectrochemical response-the photocrrent-potential curves appear peaks.The special photoelectrochemical behaviors of nano-(crystalline) TiO₂  electrodes are ascribed to nano-structure as well as special light induced redox reaction mechanism of nano-crystalline semiconductor electrodes.

Degradation Of Aniline Wastewater By Electro-Heterogeneous Catalysis Reactor, Wei-Li Liu, Ai-Li Zhang, Ji-Ti Zhou, Bao-Jun Jia, Qun-Li Zhu

Journal of Electrochemistry

The treatment of aniline wastewater was investigated using novel electro-heterogeneous catalysis reactor.The effects of applied cell voltage,electrolysis lime,pH value and the electrolyte on electrolysis were investigated.The experimental results show that the reactor with a cell voltage of 30 V,an electrolysis time of 1 h,pH value of 7 and a salinity of 800 mg/L can achieve the best removal efficiency on aniline,which is more efficient than the sole electrochemical reactor.