Mechanical Engineering Commons^™

Size Scaling Of Strength And Toughness For 3d Printed Polymer Specimens, Darren Thomas Bell

Open Access Theses

To find material systems that offer low density and high strength, stiffness or toughness, hierarchically designed material systems have provided a promising research area. This thesis lays the groundwork for designing efficient micro-architectured material systems by characterizing size effects for 3d printed polymer parts. Two methods were used to analyze data from 3-point bend tests for specimens of varying size: the load-separation method was used for finding the point of crack growth initiation and Bazant’s method was used to find shape independent strength at failure. The strength values were used as inputs for finding size independent material constants within a …

Thermal Transport In Lithium Ion Batteries: An Experimental Investigation Of Interfaces And Granular Materials, Aalok Jaisheela Uday Gaitonde

Open Access Theses

Increasing usage and recent accidents due to lithium-ion (Li-ion) batteries exploding or catching on fire has inspired research on the characterization and thermal management of these batteries. In cylindrical 18650 cells, heat generated during the battery's charge/discharge cycle is poorly dissipated to the surrounding through its metallic case due to the poor thermal conductivity of the jelly roll, which is spirally wound with many interfaces between electrodes and the polymeric separator. This work presents a technique to measure the thermal conduction across the metallic case-plastic separator interface, which ultimately limits heat transfer out of the jelly roll.

The polymeric separator …

Reaction Tuning Of Selectively Deposited Nano-Thermite Inks For Thrust And Heat Deposition, Raghav Ramachandran

Open Access Theses

Currently there is very little systematic work that quantifies the performance of energetic materials in terms of thrust or heat deposition applied to electronic circuits. A better understanding of the interactions between nano-scale energetic materials and electronic systems, as a function of stoichiometry is needed for enhanced defeat. Both of these needs are addressed in this research. Formulations of Al-CuO and Al-Bi2O3 nano-thermites were prepared at different equivalence ratios and selectively deposited onto silicon substrates and thrust and heat deposition of these materials was quantified. Both nano-thermite systems produced maximum thrust near stoichiometric ratios, and more fuel-rich mixtures led to …

Early Bearing Fault Analysis Using High Frequency Enveloping Techniques, Ilya Shulkin

Open Access Theses

High frequency acceleration enveloping is one of many tools that vibration analysts have at their disposal for the diagnosis of bearing faults in rotating machinery. This technique is believed to facilitate very early detection of potential failures by detecting low amplitude repetitive impacts in frequency ranges above conventional condition monitoring. One traditional enveloping method uses a mathematical operation known as the Hilbert transform along with other signal processing procedures such as band-pass filtering and full-wave rectification. For comparison, another method uses a proprietary algorithm included in National Instruments’ LabVIEWTM add-on package: Sound and Measurement Suite. Enveloping’s inherent problem with noise …

Investigation Of Thin Film Thermal Transport Using Micro-Raman Thermometry And Tip Enhanced Raman Spectroscopy, Mithun Srinivasan

Open Access Theses

In recent years, a steady increase in the need for packing more energy in smaller devices had driven the need for better understanding of thermal transport in thin films and designing methods to manipulate them. This can be attributed as the reason for numerous efforts made in the past decade to achieve temperature resolution at nanoscale. Such techniques can help us in understanding the thermal conductivity of thin films which can result in an improved performance of these devices. The temperature probing technique must be non-invasive to avoid damaging the vulnerable thin films, fast to study the energy transport and …

Free Edge Stress Analysis Of Laminated Structures With Arbitrary Cross Sections Using Mechanics Of Structure Genome, Lingxuan Zhou

Open Access Theses

Composite laminates have been increasingly used in advanced structural applications, due to their excellent strength-to-weight properties and considerable flexibility on designing with respect to the laminate layup. However, the heterogeneity and anisotropy of composite laminates have brought many challenges for analysis and numerous researches have been devoted in this field. A well known problem which has been studied intensively is the so-called free-edge problem. It states that due to the mismatch in elastic properties of adjacent layers, full-scale three-dimensional (3D) and highly concentrated stress fields will occur in the vicinity of the free edges. The interlaminar stresses grow very rapidly …

Analysis Of Composite Plates By Using Mechanics Of Structure Genome And Comparison With Ansys, Banghua Zhao

Open Access Theses

Motivated by a recently discovered concept, Structure Genome (SG) which is defined as the smallest mathematical building block of a structure, a new approach named Mechanics of Structure Genome (MSG) to model and analyze composite plates is introduced. MSG is implemented in a general-purpose code named SwiftComp™, which provides the constitutive models needed in structural analysis by homogenization and pointwise local fields by dehomogenization. To improve the user friendliness of SwiftComp™, a simple graphic user interface (GUI) based on ANSYS Mechanical APDL platform, called ANSYS-SwiftComp GUI is developed, which provides a convenient way to create some common SG models or …

An Investigation Of Composite Failure Analyses And Damage Evolution In Finite Element Models, Ann M. Frappier

Open Access Theses

This paper presents a composite conical structure used commonly in flight-qualification testing. This structure’s overall load-displacement behavioral response is characterized. Mixed-mode multidelamination in a layered composite specimen is considered in Abaqus/Explicit through both the Virtual Crack Closure Technique and Cohesive Elements. The Virtual Crack Closure Technique and Cohesive Elements are compared against experimental test results presented in literature. Further, a thorough comparison in which the effects of failure criteria type, through-thickness mesh density, and finite element type on the progressive failure response of this composite assembly is discussed. Lastly, Abaqus/Standard and Helius PFA are compared in order to gain confidence …

Uncertainty Quantification On Industrial High Pressure Die Casting Process, Jiahong Fu

Open Access Theses

High pressure die casting (HPDC) is a famous manufacturing technology in industry. This manufacturing process is simulated by commercial code to shed the light on the quality of casting product. The casting product quality might be affected by the uncertainty in the simulation parameter settings. Thus, the uncertainty quantification on HPDC process is significant to improve the casting quality and the manufacturing efficiency.

In this work, three uncertainty quantifications and sensitivity analyses on the A380 aluminum alloy HPDC process of intermediate speed plate are performed. The material thermophysical properties, boundary conditions of the model, and operational as well as artificial …

Passive Thermal Management Using Phase Change Materials, Yash Yogesh Ganatra

Open Access Theses

The trend of enhanced functionality and reducing thickness of mobile devices has led to a rapid increase in power density and a potential thermal bottleneck since thermal limits of components remain unchanged. Active cooling mechanisms are not feasible due to size, weight and cost constraints. This work explores the feasibility of a passive cooling system based on Phase Change Materials (PCMs) for thermal management of mobile devices. PCMs stabilize temperatures due to the latent heat of phase change thus increasing the operating time of the device before threshold temperatures are exceeded. The primary contribution of this work is the identification …

Liquid Metal Particle Popping: Nanoscale To Macroscale, Trevor R. Lear

Open Access Theses

Liquid metal nanoparticles can be used to produce stretchable electronic devices. Understanding the mechanical properties of liquid metal nanoparticles is crucial to optimizing their use in various applications, especially printing of flexible, stretchable electronics. Smaller nanoparticles are desired for high-resolution printing and compatibility with existing scalable manufacturing methods; however, they contain less liquid metal and are more difficult to rupture than larger particles, making them less desirable for post-processing functionality. This study investigates the mechanics of liquid metal particle rupture as a function of particle size. We employ compression of particle films to characterize the composition of the particle core …

In-Situ Particle Sizing Of Agglomerates In Aluminized Solid Composite Propellants Using Digital Inline Holography (Dih), Michael S. Powell

Open Access Theses

Aluminized ammonium perchlorate composite propellants (APCP) form large molten agglomerated particles that can result in poor combustion performance and increased two-phase flow losses. Quantifying agglomerate size distributions is important for assessing these losses for different types of aluminum fuels that can help improve rocket performance. It is highly desirable to measure particle sizes in-situ using non-intrusive optical methods, rather than conventional particle collection, which can have large uncertainties. Regular high-speed microscopic imaging suffers from a limited depth of field. Digital inline holography (DIH) is an alternative approach that results in 3D information through numerical reconstruction. In this paper, DIH approach …

Fuel Type Estimation Using Fuel System Parameters, Shambhavi Balasubramanian

Open Access Theses

A number of factors are responsible for an increased interest in alternative fuels for transportation and other uses. Among the most widely available alternative fuels are biodiesel and vegetable oil, both of which can be used to power a diesel engine. Biodiesel has higher density, viscosity, surface tension, sound velocity, and bulk modulus of elasticity than regular diesel fuel. This affects the fuelling, injection timing, and fuel spray and consequently the emission characteristics.

Estimation of fuel type is critical to the performance of the engine. Knowing the fuel type allows the engine controller to determine the proper fuel quantity and …

Experimental Characterization Of Scroll Expander For Small-Scale Power Generation In An Organic Rankine Cycle, Felipe Airoldi Accorsi

Open Access Theses

Organic Rankine Cycles (ORC) are thermodynamic power cycles designed to generate work from low temperature sources. The low temperature heat input, typically between 80 °C to 270 °C, allows them to recover energy from industrial waste heat, exhaust gas from diesel, engines, solar systems, geothermal systems, and others. This technology already is commercialized in large-to-medium-scale power plants; however, it is still in development for small-to-micro scale.

The operating principle of ORC comprises four major steps. First, the working fluid evaporates at high pressure using the heat transfer from the low temperature heat source. Then, the working fluid reduces its enthalpy …

Algorithms For Lidar Based Traffic Tracking: Development And Demonstration, Vamsi K. Bandaru

Open Access Theses

The current state of the art of traffic tracking is based on the use of video, and requires extensive manual intervention for it to work, including hours of painstaking human examination of videos frame by frame which also make the acquisition of data extremely expensive. Fundamentally, this is because we do not have observability of the actual scene from a camera which captures a 2D projection of the 3D world. Even if video were to be automated, it would involve such algorithms as RANSACK for outlier elimination while matching features across frames or across multiple cameras. This results in algorithms …

Design And Analysis Of A High Performance Valve, Jordan M. Garrity

Open Access Theses

Most valves available in the fluid power industry today are capable of achieving either a large flow rate or a quick response time; however, often they are unable to deliver both simultaneously. Commercially available valves that can produce both at the same time require complex geometries with multiple actuation stages and piloting pressures, making them expensive components. To establish their active usage in applications across the fluid power industry, a reduction in price for these components is paramount. The Energy Coupling Actuated Valve (ECAV) is capable of solving the large flow rates with fast actuation speeds trade-off by utilizing a …

A Novel Mode-Switching Hydraulic Hybrid For An On-Highway Vehicle: A Study Of Architecture And Control, Hiral Jayantilal Haria

Open Access Theses

Increasing demand for fossil fuels, their limited reserves and the environmental effects resulting from the transportation sector has raised severe concerns to government agencies, transportation industry as well as the end-users. This has raised interests in improving the fuel economy of road vehicles. One of the promising technologies in this regard is hybridization of vehicle transmission. Hydraulic hybrids have progressively gained acceptance due to their high power density and low component costs relative to their electric counterpart.

Many different hydraulic hybrid architectures have been developed to achieve better power management and regenerative braking and have been tested for performance and …

Improving Fuel Economy During High Load Diesel Engine System Operation Through Valve Train Flexibility, Xueting Lu

Open Access Theses

As emission regulations getting more stringent and the demand for fossil fuel growing, it is crucial to develop advanced technologies for internal combustion engine to lower emissions and fuel.

Strategies such as diesel oxidation catalysts (DOC) for UHC, diesel particulate filters (DPF) for PM, and selective catalytic reduction (SCR) for NOx have been developed and implemented to convert harmful emissions to innocuous species. However, the efficiencies of these after-treatment systems are heavily temperature dependent.

Heavy-duty over-the-road trucks require periodic active diesel particulate filter regeneration to clean the filter of stored particulate matter. These events require sustained temperatures between 500 and …

Parametric And Design Analysis On Thermoelectric Generators, Shouyuan Huang

Open Access Theses

In facing the limited energy source reserves and environmental problems, thermoelectric generators (TEGs) are one of the promising waste heat recovery systems. The modern TEGs for exhaust stream (e.g. from automobiles) can improve the fuel economy by around 5%, taking advantage of the recent developed thermoelectric (TE) materials.

In this work, we aimed at designing a TEG as an add-on module for a gas-phase heat exchanger with maximized power output, and without negative impact (e.g. maintaining a minimum heat dissipation rate from the hot side). We first developed a parametric optimization algorithm using response surface method (RSM) and genetic algorithm …

The Effect Of Static And Dynamic Aging On Fatigue Behavior Of Sn3.0ag0.5cu Solder Alloy, Yiran Li

Open Access Theses

In microelectronic assemblies, solder joints serve as interconnection between different packaging levels and are an important cause for the failure of microelectronic products. Sn-Ag-Cu solder alloys became important after lead-based solder alloys were caused to be discarded by regulations in European Union and Japan. However, the constitutive behavior of Sn-Ag-Cu alloys is not as well understood as lead-based solder alloys, and many studies confirm the aging of these alloys with time. The aging of Sn-Ag-Cu alloys and its effect on mechanical behavior challenges the reliability prediction of microelectronic assemblies. In this study, the effect of pretest isothermal aging and in-test …

Cyclic Tensile Response Of A Polyurethane Material, Yizhou Nie

Open Access Theses

Polyurethane is one of the most widely used polymer materials in the world. With the increasing demand of polyurethane, its mechanical behaviors are particularly of interest. In particular, the response of the material under a quasi-static loading being subject to an impact load. To delineate the effect of rate change on the mechanical response of polyurethane, a tensile experiment was designed where the specimen is initially subjected to quasi-static tensile loading and then to high-rate cyclic tension within the same experiment. Constant strain-rate experiments at both quasi-static and high strain rates are also conducted. The analysis of the results leads …

Phase Field Damage Simulations Of Debonding Between Matrix And Spherical Inclusions, Johanna B. Palsdottir

Open Access Theses

Polymer-bonded explosives (PBX) are complicated composites, and it is important for practical applications to know how they deform and fracture. PBX consists of large volume fraction of energetic particles and experiments show that the interface is a critical region for structural stability since particles are often weakly bonded to the polymer and cracks initiate there and the composite fractures. This study focuses on the interface between a particle and a binder and how the particle inclusion starts to debond from the polymer binder in compressive and tensile loading.

A phase field damage model is used to model the response of …

Control-Oriented Modeling, Validation, And Analysis Of A Natural Gas Engine Architecture, Chaitanya Panuganti

Open Access Theses

In order to improve performance and meet increasingly tight emissions regulations, engine manufacturers must improve algorithms used to control the engine. One possible strategy is to utilize centralized control algorithms that take into account the coupled interactions between inputs and outputs. Implementing a centralized control strategy often requires some kind of dynamic model of the system, which is a primary motivation for modeling efforts in this thesis. In a methodical fashion, this thesis derives a control model for a natural gas engine architecture and validates this control model against reference data in simulation. Additionally, this thesis performs control-oriented analysis on …

Analysis Of Feedback Control Applied With Command Shaping To Minimize Residual Vibration, Nicholas L. Jacobs

Open Access Theses

Joint flexibility is a physical trait that affects all robotic systems to some degree. This characteristic has been shown to be very detrimental to the performance of these robotic systems when implementing fast point-to-point motion. During such motion, the robot will induce vibrations in its structure that will extend past the completion of the move. Many techniques have been applied over the years in order to minimize these residual vibrations. One such method is known as command shaping, which will construct the input profile so as to avoid exciting the natural frequencies of the system. This work seeks to extend …

Advanced Hydraulic Systems For Next Generation Of Skid Steer Loaders, Mrudula Uday Orpe

Open Access Theses

Fluid power systems have been extensively used in off highway applications like skid steer loaders, wheel loaders, excavators since many years. Work has been done by both industry and academia to improve efficiency, reduce noise and leakages in these systems. With increasing competition in the market, importance is now also given to operator comfort and machine productivity in off highway applications.

Mobile, off – highway vehicles like Skid-steer loaders are widely used in labour saving applications like loading earth into a truck, dig and move material on construction sites to, clean roads, clear snow from roads etc. To carry out …

Modelling And Control Of A Parallel Through-The-Road Plug-In Hybrid Vehicle, Rohinish Gupta

Open Access Theses

With an increasing number of passenger vehicles, automotive emissions has become a major challenge. Among other pollutants, green house gas (GHG) emissions form a majority of the exhaust coming out of the tail-pipe and are blamed for the rising temperature of the earth. The net carbon emissions due to running a lightduty passenger vehicle are studied in the present thesis. Hybrid electric vehicles have been proven to have lower green house gas emissions than conventional vehicles as electricity is cleaner than fossil fuels.

Using a parallel-through-the-road hybrid architecture vehicle, different power management strategies are studied. To begin with, a detailed …

High-Throughput Mechanical Characterization Methods For Composite Electrodes And In-Situ Analysis Of Li-Ion Batteries, Luize Scalco De Vasconcelos

Open Access Theses

Electrodes in commercial rechargeable batteries are microscopically heterogeneous materials. The constituents often have large variation in their mechanical properties, making the characterization process a challenging task. In addition, the mechanical properties and mechanical behaviors of electrodes are closely coupled with the electrochemical processes of lithium insertion and extraction. There is an urgent need to develop an experimental platform to characterize the chemomechanical response of electrodes under the in-situ conditions of charge and discharge.

In the first part of this thesis, instrumented grid indentation is employed to determine the elastic modulus and hardness of the constituent phases of a composite cathode. …

Test Cell Set-Up To Enable Drive-Cycle Testing Of A Variable Valve Actuation Enabled Camless Diesel Engine, Alexander Harrison Taylor

Open Access Theses

The previous facility which was used for engine testing at Purdue's Ray W. Herrick Laboratories utilized an eddy current dynamometer which is only suited for steady-state testing and throttle snaps. To better utilize a pre-existing camless diesel engine, which is is enabled via variable valve actuation, it was desired to perform transient drive-cycle tests. To accomplish this goal, a variable frequency drive AC dynamometer was required. Given that a brand new facility was constructed, the team was presented with an opportunity for ground up design of a test cell.

The new test cell's operation was proved out using a cammed …

Utilizing Tunable Signal Interference Control Topologies With Electromechanical Resonators, Bryce A. Geesey

Open Access Theses

Exploiting knowledge gained from previous investigations of channelized and trans-versal filters, signal interference filters use transmission line differences to generate transmission zeros through phase-shifted combinations of signals at the output of a device. The transmission lines used in these circuits are straightforward to design, but are limited to high-frequency signals (on the order of a few gigahertz) due to the necessity for spatial compactness and low loss. More recent studies have used electromechanical resonators to achieve phase shifting and quality factor improvements at slightly-lower frequencies. These concepts may prove useful if extended to micro- and nanoscale resonators.

To explore signal …

Mixed Mesh/Nodal Magnetic Equivalent Circuit Modeling Of A Six-Phase Claw-Pole Automotive Alternator, Daniel C. Horvath

Open Access Theses

Magnetic equivalent circuits (MECs) have been employed by many researchers to model the relationship between magnetic flux and current in electromagnetic systems such as electric machines, transformers and inductors [1] ,[2]. Magnetic circuits are analogous to electric circuits where voltage, current, resistance and conductance are the respective counterparts of magneto-motive force (MMF), magnetic flux, reluctance and permeance. The solution of MECs can be accomplished with the plethora of techniques developed for electrical circuit analysis. Specifically, mesh analysis, based on Kirchoff’s Voltage Law (KVL), and nodal analysis, based on Kirchoffs Current Law (KCL), are two very common solution techniques. Once an …