Applied Mechanics Commons^™

Using Controlled Curing In A Custom Stereolithography-Based 3d Printing Machine To Obtain Graded Property Variations, Evan S. Schwahn

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

In an effort to construct materially graded parts, a strategy was studied that is based on varying ratios of interpenetrating polymer networks (IPNs) in a manner that can be adapted to 3D printing. Using IPNs has the benefit of allowing access to a broad range of property variation. The strategy used involves controlled partial curing of the first network, followed by washing of that network to remove uncured components, then swelling of the structure with a second polymer component and curing.

This method was utilized to control final IPN properties by controlling the extent of crosslinking of the initial network, …

Parker Hannifin Chainless Challenge 2014-15 Senior Design Project, Matt Pallotta, Nathan Klammer, Kemper Whaley, Jack Rechtin

Mechanical Engineering

California Polytechnic State University has been invited to compete in the Parker Hannifin Chainless Challenge Competition in 2014-15. Cal Poly has chosen a team of mechanical engineering students to take part. We have named our team “Bike Under Pressure” and all references as such refer to the team.

The challenge is to build a bicycle which does not have a solid mechanical connection between the power input of the rider to the power output of the wheel(s). After conducting research into different previous designs and brainstorming designs of their own, Bike Under Pressure developed two conceptual designs. One design featured …

Asymptotic Modelling Of A Thermopiezoelastic Anisotropic Smart Plate, Yufei Long

Open Access Theses

Motivated by the requirement of modelling for space flexible reflectors as well as other applications of plate structures in engineering, a general anisotropic laminated thin plate model and a monoclinic Reissner-Mindlin plate model with thermal deformation, two-way coupled piezoelectric effect and pyroelectric effect is constructed using the variational asymptotic method, without any ad hoc assumptions. Total potential energy contains strain energy, electric potential energy and energy caused by temperature change. Three-dimensional strain field is built based on the concept of warping function and decomposition of the rotation tensor. The feature of small thickness and large in-plane dimension of plate structure …

Fully Electronic Method Of Measuring Post-Release Gap And Gradient/Residual Stress Of A Mems Cantilever, Andrew Stephen Kovacs

Open Access Dissertations

Smartphones and other wireless devices have become ubiquitous over the past decade, and the RF front-end inside of them has become more complex and disproportionately consumes more power compared to other components. Micro-electromechanical systems (MEMS) have a huge potential to reduce these problems while simultaneously offering superior performance compared to current leading-edge technology. However, MEMS technology has difficulty transitioning from the lab to large-scale manufacturing due to the unpredictability of device lifetime and manufacturability issues. This can be mitigated by investigating how critical material or physical parameters (gap, stress, Young's modulus, material thickness, etc.) vary from manufacturing uncertainties and how …

Validation Of Open Chain Model During Kinematic Analysis Of Joint Mobilization Of The Foot: An In Vitro Study, Anthony Ross Mcnally

Mechanical & Aerospace Engineering Theses & Dissertations

Joint mobilization techniques have been shown to improve dorsiflexion range of motion after ankle injury in multiple in vivo studies; however, the underlying arthrokinematic effects of this treatment still require clarification. Therefore, the purpose of this preliminary study was to determine the viability of an open kinetic chain in vitro model for applying Maitland Grade III anterior/posterior joint mobilizations to the talocrural joint while examining the osteokinematic and arthrokinematic changes at the talocrural, subtalar and hindfoot joints. Three fresh frozen cadaver lower legs had Maitland Grade III anterior-to-posterior joint mobilization applied to the talocrural joint in 2 sessions of 200 …

Benchmarking, Characterization And Tuning Of Shell Ecomarathon Prototype Powertrain, Eric J. Griess

Master's Theses

With the automotive industry ever striving to push the limits of fuel efficiency, the Shell EcoMarathon offers a glimpse into this energy conserving mindset by challenging engineering students around the world to design and build ultra-efficient vehicles to compete regionally. This requires synchronization of engineering fields to ensure that the vehicle and powertrain system work in parallel to achieve similar goals.

The goal for Cal Poly – San Luis Obispo’s EcoMarathon vehicle for the 2015 competition is to analyze the unique operating mode that the powertrain undergoes during competition and improve their current package to increase fuel efficiency. In this …

A Contribution Toward Better Understanding Of Overbanking Tendency In Fixed-Wing Aircraft, Nihad E. Daidzic

Journal of Aviation Technology and Engineering

The phenomenon of overbanking tendency for a rigid-body, fixed-wing aircraft is investigated. Overbanking tendency is defined as a spontaneous, unbalanced rolling moment that keeps increasing an airplane’s bank angle in steep turns and must be arrested by opposite aileron action. As stated by the Federal Aviation Administration, the overbanking tendency may lead to a loss of control, especially in instrument meteorological conditions. It was found in this study that the speed differential over wing halves in horizontal turns indeed creates a rolling moment that achieves maximum values for bank angles between 45 and 55 degrees. However, this induced rolling moment …

Vibration Of Steel-Framed Floors Supporting Sensitive Equipment In Hospitals, Research Facilities, And Manufacturing Facilities, Di Liu

Theses and Dissertations--Civil Engineering

Floors have traditionally been designed only for strength and deflection serviceability. As technological advances have been made in medical, scientific and micro-electronics manufacturing, many types of equipment have become sensitive to vibration of the supporting floor. Thus, vibration serviceability has become a routinely evaluated limit state for floors supporting sensitive equipment. Equipment vibration tolerance limits are sometimes expressed as waveform peak acceleration, and are more often expressed as narrowband spectral acceleration, or one-third octave spectral velocity.

Current floor vibration prediction methods, such as those found in the American Institute of Steel Construction Design Guide 11, Floor Vibrations Due to Human …

Mechanistic Modeling Of Cutting Forces In Wavy-Edge Bull-Nose Helical End-Milling Of Inconel 718 Under Different Cooling-Lubrication Strategies, Abdulhakim Ali Sultan

Doctoral Dissertations

“This research presents the results of the development of a mechanistic cutting force prediction model for the wavy-edge bull-nose helical endmill (WEBNHE). The mechanistic model was developed to predict cutting force components and the resultant cutting force in high-speed end-milling of Inconel 718 under two cooling strategies: emulsion and Minimum Quantity Lubrication (MQL). The effects of the cooling strategies are incorporated into the mechanistic model through six cutting force coefficients (K_tc, K_rc, K_ac), and edge force coefficients (K_te, K_re, K_ae), which have been experimentally identified in a separate …

Structure-Thermal Coupling In Viscoelastic Material In Rubber Bushing Of Vehicle System, Zhengui Zhang

Open Access Dissertations

The objective of this research is to utilize the frequency-dependent viscoelastic material model and characterize the dynamic response of rubber bushing under external excitation. Furthermore, with appropriate modeling, two heat generation mechanisms of rubber bushing are explored and their thermal fields are investigated. Due to the nonlinear force-deflection relationship of the viscoelastic material, finding satisfactory mechanical properties of rubber components still poses a great challenge. However, industry nowadays is in urgent demand for precise finite element analysis (FEA) modeling of rubber components. For example, a proper constitutive relationship of rubber components is critical to providing a reliable and trustable simulation …

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

Department of 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 …

Effects Of Magnetic Field On The Shape Memory Behavior Of Single And Polycrystalline Magnetic Shape Memory Alloys, Ali S. Turabi

Theses and Dissertations--Mechanical and Aerospace Engineering

Magnetic Shape Memory Alloys (MSMAs) have the unique ability to change their shape within a magnetic field, or in the presence of stress and a change in temperature. MSMAs have been widely investigated in the past decade due to their ability to demonstrate large magnetic field induced strain and higher frequency response than conventional shape memory alloys (SMAs). NiMn-based alloys are the workhorse of metamagnetic shape memory alloys since they are able to exhibit magnetic field induced phase transformation. In these alloys, martensite and austenite phases have different magnetization behavior, such as the parent phase can be ferromagnetic and martensite …

High Temperature Flow Solver For Aerothermodynamics Problems, Huaibao Zhang

Theses and Dissertations--Mechanical and Aerospace 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 …

Shape Memory Behavior Of Single Crystal And Polycrystalline Ni-Rich Nitihf High Temperature Shape Memory Alloys, Sayed M. Saghaian

Theses and Dissertations--Mechanical and Aerospace Engineering

NiTiHf shape memory alloys have been receiving considerable attention for high temperature and high strength applications since they could have transformation temperatures above 100 °C, shape memory effect under high stress (above 500 MPa) and superelasticity at high temperatures. Moreover, their shape memory properties can be tailored by microstructural engineering. However, NiTiHf alloys have some drawbacks such as low ductility and high work hardening in stress induced martensite transformation region. In order to overcome these limitations, studies have been focused on microstructural engineering by aging, alloying and processing.

Shape memory properties and microstructure of four Ni-rich NiTiHf alloys (Ni50.3Ti29.7Hf20, Ni50.7Ti29.3Hf20, …

2015 Zips Sae Baja Brakes And Throttle System, Philip A. Bennett

Williams Honors College, Honors Research Projects

The SAE Baja student design team at The University of Akron is one of the longest-standing design teams at the university. The purpose of this team is to design, manufacture, test, and race an off-road vehicle within the guidelines of competition established by the Society of Automotive Engineers. The vehicle is made up of a small number of subsystems including frame, drivetrain, suspension, steering, and braking. The following will discuss all aspects of the design process of the braking and throttle system of the 2015 Zips Baja car. This process includes several steps and considerations such as design goals, system …

Design Of An Sae Baja Racing Off-Road Vehicle Powertrain, Eric T. Payne

Williams Honors College, Honors Research Projects

No abstract provided.

La0.7Sr0.3Fe0.7Ga0.3O3-Δ As Electrode Material For A Symmetrical Solid Oxide Fuel Cell, Zhibin Yang, Yu Chen, Chao Jin, Guoliang Xiao, Minfang Han, Fanglin Chen

Faculty Publications

In this research, La_0.7Sr_0.3Fe_0.7Ga_0.3O_3−δ (LSFG) perovskite oxide was successfully prepared using a microwave-assisted combustion method, and employed as both anode and cathode in symmetrical solid oxide fuel cells. A maximum power density of 489 mW cm⁻² was achieved at 800 °C with wet H₂ as the fuel and ambient air as the oxidant in a single cell with the configuration LSFG|La_0.8Sr_0.2Ga_0.83Mg_0.17O_3−δ|LSFG. Furthermore, the cells demonstrated good stability in H₂ and acceptable sulfur tolerance.

Stabilizing Electrochemical Carbon Capture Membrane With Al2O3 Thin-Film Overcoating Synthesized By Chemical Vapor Deposition, Jingjing Tong, Fengzhan Si, Lingling Zhang, Jie Fang, Minfang Han, Kevin Huang

Faculty Publications

Development of high-efficiency and cost-effective carbon capture technology is a central element of our effort to battle the global warming and climate change. Here we report that the unique high-flux and high-selectivity of electrochemical silver-carbonate dual-phase membranes can be retained for an extended period of operation by overcoating the surfaces of porous silver matrix with a uniform layer of Al₂O₃ thin-film derived from chemical vapor deposition.

La0.6Sr1.4Mno4+Δ Layered Perovskite Oxide: Enhanced Catalytic Activity For The Oxygen Reduction Reaction, Yarong Wang, Zhibin Yang, Fanliang Liu, Chao Jin, Jiao Wu, Ming Shen, Ruizhi Yang, Fanglin Chen

Faculty Publications

Efficient electrocatalysts for the oxygen reduction reaction (ORR) is a critical factor to influence the performance of lithium–oxygen batteries. In this study, La_0.6Sr_1.4MnO_4+δ layered perovskite oxide as a highly active electrocatalyst for the ORR has been prepared, and a carbon-coating layer with thickness <5 nm has been successfully introduced to enhance the electronic conductivity of the as-prepared oxide. XRD, XPS, Raman, SEM and TEM measurements were carried out to characterize the crystalline structure and morphology of these samples. Rotating ring-disk electrode (RRDE) technique has been used to study catalytic activities of the as-prepared catalysts for the ORR in 0.1 M KOH media. RRDE results reveal that carbon-coated La_0.6Sr_1.4MnO_4+δ exhibits better catalytic activity for the ORR. For the carbon-coated La_0.6Sr_1.4MnO_4+δ, the ORR proceeds predominately via a direct four electron process, and a maximum cathodic current density of 6.70 mA cm⁻² at 2500 rpm has been obtained, …

Investigation Of The Quenching Characteristics Of Steel Components By Static And Dynamic Analyses, Pratik Sarker

LSU New Orleans Theses and Dissertations

Machine components made of steel are subjected to heat treatment processes for improving mechanical properties in order to enhance product life and is usually done by quenching. During quenching, heat is transferred rapidly from the hot metal component to the quenchant and that rapid temperature drop induces phase transformation in the metal component. As a result, quenching generates some residual stresses and deformations in the material. Therefore, to estimate the temperature distribution, residual stress, and deformation computationally; three-dimensional finite element models are developed for two different steel components – a spur gear and a circular tube by a static and …