Open Access. Powered by Scholars. Published by Universities.®
Engineering Science and Materials Commons™
Open Access. Powered by Scholars. Published by Universities.®
- Keyword
-
- Microcantilever (2)
- AFM (1)
- ANSYS/AUTODYN (1)
- Active Probe (1)
- Active Probes (1)
-
- Additive Manufacturing (1)
- Atmospheric boundary layer (1)
- Automotive (1)
- Belt-pulley inertial coupling (1)
- Black-box Variational Inference (1)
- Bond strength (1)
- Bond theory (1)
- Borehole (1)
- CFRP (1)
- CVT (1)
- Cap Plasticity (1)
- Carbon nanotube (1)
- Chain (1)
- Chemcial vapor deposition (1)
- Chirality (1)
- Computational Material Modeling (1)
- Continuously Variable Transmission (1)
- Control (1)
- Control theory (1)
- Crack control (1)
- DIC (1)
- Deformable (1)
- Displacement (1)
- Drucker-Prager (1)
- Dynamics (1)
Articles 1 - 29 of 29
Full-Text Articles in Engineering Science and Materials
Cfrp Delamination Density Propagation Analysis By Magnetostriction Theory, Brandon Eugene Williams
Cfrp Delamination Density Propagation Analysis By Magnetostriction Theory, Brandon Eugene Williams
All Dissertations
While Carbon Fiber Reinforced Polymers (CFRPs) have exceptional mechanical properties concerning their overall weight, their failure profile in demanding high-stress environments raises reliability concerns in structural applications. Two crucial limiting factors in CFRP reliability are low-strain material degradation and low fracture toughness. Due to CFRP’s low strain degradation characteristics, a wide variety of interlaminar damage can be sustained without any appreciable change to the physical structure itself. This damage suffered by the energy transfer from high- stress levels appears in the form of microporosity, crazes, microcracks, and delamination in the matrix material before any severe laminate damage is observed. This …
Machine Learning-Based Data And Model Driven Bayesian Uncertanity Quantification Of Inverse Problems For Suspended Non-Structural System, Zhiyuan Qin
All Dissertations
Inverse problems involve extracting the internal structure of a physical system from noisy measurement data. In many fields, the Bayesian inference is used to address the ill-conditioned nature of the inverse problem by incorporating prior information through an initial distribution. In the nonparametric Bayesian framework, surrogate models such as Gaussian Processes or Deep Neural Networks are used as flexible and effective probabilistic modeling tools to overcome the high-dimensional curse and reduce computational costs. In practical systems and computer models, uncertainties can be addressed through parameter calibration, sensitivity analysis, and uncertainty quantification, leading to improved reliability and robustness of decision and …
The Effects Of Laser Shock Peening On The Fatigue Life Of Additive Manufactured Alsi10mg, Jacob L. Biddlecom
The Effects Of Laser Shock Peening On The Fatigue Life Of Additive Manufactured Alsi10mg, Jacob L. Biddlecom
All Dissertations
Additive manufacturing (AM) is becoming a manufacturing process that is well established, even with all the resources and attention that has been brought to it, the field is still lacking some key understandings. Currently, there are certain aspects that are difficult to overcome. Some of the intrinsic obstacles include process-induced defects, such as porosity from lack of fusion and gaseous bubble entrapment, as well as complex thermal gradients. These defects can lead to altered material response especially when looking at the fatigue life. The fatigue behaviors of AM components can change from print to print as well as when compared …
Crack Control And Bond Performance Of Alternative Coated Reinforcements In Concrete, Sachin Sreedhara
Crack Control And Bond Performance Of Alternative Coated Reinforcements In Concrete, Sachin Sreedhara
All Dissertations
Concrete cracking in structures is a ubiquitous problem which can lead to the deterioration of the structure. Other than affecting the strength aspect of a structure, cracking impacts the serviceability criteria as well. Although cracking phenomenon in any structure is highly inevitable, it has to be minimized in order to maintain a structure’s life effectively. Cracking in reinforced concrete structures is related to the bond strength developed between the bar and the concrete. It also depends on an ability of the bar to resist the stresses due to shrinkage to minimize the crack. Another important aspect is the resistance offered …
Investigation Of Subgrid-Scale Mixing And Turbulence-Chemistry Interaction In Turbulent Partially Premixed Flames Using Experimental Data, Jian Cai
All Dissertations
The filtered mass density function (FMDF) of mixture fraction, temperature and species used in large eddy simulation (LES) of turbulent combustion is studied experimentally using line images obtained in turbulent partially premixed methane flames (Sandia flames D and E). Cross-stream filtering is employed to obtain the FMDF and other filtered variables. The mean of the FMDF conditional on the subgrid-scale (SGS) scalar variance at a given location are found to vary from unimodal to bimodal, corresponding to quasi-equilibrium distributed reaction zones and laminar flamelets (including extinguished flamelets), respectively. The conditionally filtered mixture fraction dissipation for small SGS variances has a …
Development Of A Finite Element Model To Predict The Behavior Of A Prototype Wheel On Lunar Soil, Marisa Orr
Development Of A Finite Element Model To Predict The Behavior Of A Prototype Wheel On Lunar Soil, Marisa Orr
All Dissertations
The All-Terrain Hex-Limbed Extra-Terrestrial Explorer (ATHLETE) is a mobile lunar lander under development by the National Aeronautics and Space Administration's Lunar Architecture Team. While previous lunar missions have lasted only a few days, the ATHLETE is designed to last for 10 years, which will enable a sustained U.S. presence on the moon and exploration of the more treacherous regions which are not suitable for landing. Because the ATHLETE will carry entire astronaut habitats, its six wheels must be carefully designed to support a large load on soft lunar soil efficiently.
The purpose of this thesis is to develop a finite …
Modeling Of Cell Transfer And Process-Induced Cell Damage In Laser-Assisted Cell Direct Writing, Wei Wang
Modeling Of Cell Transfer And Process-Induced Cell Damage In Laser-Assisted Cell Direct Writing, Wei Wang
All Dissertations
Laser-assisted cell direct-write technique has been obtaining more and more attention in different biomaterial direct writing applications. A typical laser-assisted cell direct-write process can be divided into two main stages: the cell droplet ejection and cell droplet landing. The objective of this study is to model the cell mechanical profile during the cell droplet ejection and cell landing and further model the cell damage.
The possible cell damage during the droplet ejection process in laser-assisted cell direct writing may come from two different sources: the phase explosion-induced bubble expansion and the thermoelastic stress wave. The bubble expansion-induced stress wave is …
Friction Measurement In Precision Glass Molding, Peiman Mosaddegh
Friction Measurement In Precision Glass Molding, Peiman Mosaddegh
All Dissertations
Extensive growth of state-of-the-art technologies has created a demand for high quality lenses and has driven the industry toward an inexpensive process for manufacturing of aspheric glass lenses called Precision Glass Molding (PGM). Finite Element Analysis (FEA) has been used to predict the right mold geometry. Having a realistic simulation to predict mold geometry depends on the correct model of material behavior and friction coefficient at elevated temperature.
Finding the static and dynamic coefficient of friction experimentally between two flat surfaces at elevated temperature is the subject of this research. The equipment used in this study was originally designed for …
Vehicle Steering Systems - Hardware-In-The-Loop Simulator, Driving Preferences, And Vehicle Intervention, Jesse Black
Vehicle Steering Systems - Hardware-In-The-Loop Simulator, Driving Preferences, And Vehicle Intervention, Jesse Black
All Dissertations
The steering system is a critical component of all ground vehicles regardless of their propulsion source. Chassis directional control is provided by the steering system, which in turn relays valuable feedback about the road and vehicle behavior. As the primary feedback channel to the driver, the steering system also delivers the initial perception of a vehicle's handling and responsiveness to the consumer. Consequently, the steering system is an important aspect of the vehicle's evaluation and purchasing process, even if drivers are unaware of its direct influence in their decision making. With automobile purchases potentially hinging on the steering system, a …
Evaluation Of Fluid Diodes As Pulmonary Heart Valve Replacements, Tiffany Camp
Evaluation Of Fluid Diodes As Pulmonary Heart Valve Replacements, Tiffany Camp
All Dissertations
Children born with congenital heart disease often times suffer from severe chronic pulmonary insufficiency. Palliative treatments for this condition may come early on in the life of the patient; however, if it becomes severe enough, a pulmonary valve replacement may be required. There currently is not a permanent option for a replacements valve. Therefore, a need exists to develop a permanent solution. Knowing that the right heart circulation is more tolerant of moderate levels of regurgitation (0 - 35%) and pressure gradient (0 - 30 mmHg), this study investigates the hypothesis that a fluid diode, a motionless valve that offers …
Dynamics Of Ultrasonic Consolidation, James Gibert
Dynamics Of Ultrasonic Consolidation, James Gibert
All Dissertations
Ultrasonic consolidation (UC) is a solid state rapid manufacturing process derived from ultrasonic welding of thin metal foils coupled with contour milling to achieve functional accurate components. The bonding of metal is accomplished by the local application of high frequency vibration energy under pressure producing a metallurgical bond without melting the base material. Its unique nature allows the design and fabrication of structural panels for satellites, production of injection molding tools, functionally graded structures, metal-matrix composites, embedded sensors, armor, and fiber embedded adaptive structures. It is commonly theorized that interfacial motion and friction at the bonding interface play a prominent …
Development And Integration Of Geometric And Optimization Algorithms For Packing And Layout Design, Santosh Tiwari
Development And Integration Of Geometric And Optimization Algorithms For Packing And Layout Design, Santosh Tiwari
All Dissertations
The research work presented in this dissertation focuses on the development and application of optimization and geometric algorithms to packing and layout optimization problems. As part of this research work, a compact packing algorithm, a physically-based shape morphing algorithm, and a general purpose constrained multi-objective optimization algorithm are proposed. The compact packing algorithm is designed to pack three-dimensional free-form objects with full rotational freedom inside an arbitrary enclosure such that the packing efficiency is maximized. The proposed compact packing algorithm can handle objects with holes or cavities and its performance does not degrade significantly with the increase in the complexity …
Microcantilever-Based Force Sensing, Control And Imaging, Reza Saeidpourazar
Microcantilever-Based Force Sensing, Control And Imaging, Reza Saeidpourazar
All Dissertations
This dissertation presents a distributed-parameters base modeling framework for microcantilever (MC)-based force sensing and control with applications to nanomanipulation and imaging. Due to the widespread applications of MCs in nanoscale force sensing or atomic force microscopy with nano-Newton to pico-Newton force measurement requirements, precise modeling of the involved MCs is essential. Along this line, a distributed-parameters modeling framework is proposed which is followed by a modified robust controller with perturbation estimation to target the problem of delay in nanoscale imaging and manipulation. It is shown that the proposed nonlinear model-based controller can stabilize such nanomanipulation process in a very short …
Foundations Of Design Method Development, Sudhakar Teegavarapu
Foundations Of Design Method Development, Sudhakar Teegavarapu
All Dissertations
A systematic procedure for developing design methods, tools, and/or processes, referred to as meta-method, is proposed. It is hypothesized that design methods developed without following a systematic procedure are not effective and thus are not widely accepted by industry and academia likewise. The systematic framework provided by the meta-method will ensure 1) faster development of design methods, 2) enable tracking of requirements throughout the development process, 3) facilitate efficient exploration and selection of alternatives, 4) document the development process for future reuse, 5) help in testing and validation of design methods, and 6) bridge gap between multiple disciplines by forming …
Development, Parameterization And Validation Of Dynamic Material Models For Soil And Transparent Armor Glass, Bhaskar Pandurangan
Development, Parameterization And Validation Of Dynamic Material Models For Soil And Transparent Armor Glass, Bhaskar Pandurangan
All Dissertations
Despite the signing of several mine ban treaties in the 1990's, it is widely recognized that there is a landmine crisis. The following are some of the main aspects of this crisis: (a) Millions of unexploded landmines remain deployed all over the world; (b) Thousands of civilians are killed or maimed every year by unintended detonations of the mines; (c) The cost of medical treatment of landmine injuries runs into the millions; (d) the ability of the international community to provide the humanitarian relief in terms of medical services, safe drinking water and food, etc., is greatly hampered by landmine …
Modeling And Control Of Piezoactive Micro And Nano Systems, Saeid Bashash
Modeling And Control Of Piezoactive Micro And Nano Systems, Saeid Bashash
All Dissertations
Piezoelectrically-driven (piezoactive) systems such as nanopositioning platforms, scanning probe microscopes, and nanomechanical cantilever probes are advantageous devices enabling molecular-level imaging, manipulation, and characterization in disciplines ranging from materials science to physics and biology. Such emerging applications require precise modeling, control and manipulation of objects, components and subsystems ranging in sizes from few nanometers to micrometers. This dissertation presents a comprehensive modeling and control framework for piezoactive micro and nano systems utilized in various applications.
The development of a precise memory-based hysteresis model for feedforward tracking as well as a Lyapunov-based robust-adaptive controller for feedback tracking control of nanopositioning stages are …
Computional Modeling Of Precision Molding Of Aspheric Glass Optics, Balajee Ananthasayanam
Computional Modeling Of Precision Molding Of Aspheric Glass Optics, Balajee Ananthasayanam
All Dissertations
In this dissertation, research in two parallel directions is presented; the first involves the prediction of the final size and shape of a glass lens during a precision glass lens molding process and the second introduces a method to compute and quantify the importance of higher order terms in fracture mechanics for different modes of fracture.
The process of precision lens molding has received attention in recent years due to its potential to mass produce aspherical lenses. Aspherical lenses have significantly better optical properties and conventional lens making techniques are limited to manufacturing of spherical lenses only. The conventional technique …
Similarity Metrics Applied To Graph Based Design Model Authoring, Srinivasan Anandan
Similarity Metrics Applied To Graph Based Design Model Authoring, Srinivasan Anandan
All Dissertations
Model reuse is typically facilitated by search and retrieval tools, matching the sought model with models in a database. This research aims at providing similar assistance to users authoring design exemplars, a data structure to represent parametric and geometric design problems. The design exemplar represents design problems in the form of a bi-partite graph consisting of entities and relations. Authoring design exemplars for relatively complex design problems can be time consuming and error prone. This forms the motivation of developing a search and retrieval tool, capable of retrieving exemplars that are similar to the exemplar that a user is trying …
A Comprehensive Multiphysics, Multiscale Modeling Framework For Carbon Nanotube Fabrication Process By Chemical Vapor Deposition, Mahmoud Reza Hosseini
A Comprehensive Multiphysics, Multiscale Modeling Framework For Carbon Nanotube Fabrication Process By Chemical Vapor Deposition, Mahmoud Reza Hosseini
All Dissertations
Carbon nanotubes (CNTs) are among the most promising nanosize materials as evidenced by the attention they have received since their discovery in 1991 and a wide range of scientific and industrial applications. Each of these applications requires unique CNTs with specific length, diameter and chirality. However, control of these parameters is considered as one of the main challenges for large scale production of CNTs. Furthermore, these processes are not well designed so as to limit the number of CNT defect sites or the production of unwanted byproducts such as amorphous carbon. Therefore, it is crucial to develop a controlled CNTs …
Modeling Of The Effect Of Tool Wear On Cutting Forces In Turning, Yu Long
Modeling Of The Effect Of Tool Wear On Cutting Forces In Turning, Yu Long
All Dissertations
Machining is the most widely used and efficient material removal process, and tool wear in machining is usually of great interest in order to improve machining efficiency and effectiveness. Cutting tool wear patterns such as the flank and crater wear and the dead metal zone (DMZ) may induce the cutting tool geometry variation in machining. As a result, cutting forces may increase or decrease due to the change of tool effective cutting geometry during machining operations. A quantitative understanding of and the ability to predict cutting forces in relation to tool wear are important to the tool life estimation, chatter …
Physics-Based Shape Morphing And Packing For Layout Design, Hong Dong
Physics-Based Shape Morphing And Packing For Layout Design, Hong Dong
All Dissertations
The packing problem, also named layout design, has found wide applications in the mechanical engineering field. In most cases, the shapes of the objects do not change during the packing process. However, in some applications such as vehicle layout design, shape morphing may be required for some specific components (such as water and fuel reservoirs). The challenge is to fit a component of sufficient size in the available space in a crowded environment (such as the vehicle under-hood) while optimizing the overall performance objectives of the vehicle and improving design efficiency. This work is focused on incorporating component shape design …
Vibration Analysis Of Piezoelectric Microcantilever Sensors, Amin Salehi-Khojin
Vibration Analysis Of Piezoelectric Microcantilever Sensors, Amin Salehi-Khojin
All Dissertations
The main objective of this dissertation is to comprehensively analyze vibration characteristics of microcantilever-based sensors with application to ultra small mass detection and low dimensional materials characterization. The first part of this work focuses on theoretical developments and experimental verification of piezoelectric microcantilevers, commercially named Active Probes, which are extensively used in most today's advanced Atomic Force Microscopy (AFM) systems. Due to special geometry and configuration of Active Probes, especially multiple jump discontinuities in their cross-section, a general and comprehensive framework is introduced for forced vibration and modal analysis of discontinuous flexible beams. More specifically, a general formulation is obtained …
A Comparative Fault Diagnosis Methodology Based On Time Series Analysis Of System's Signals, Hany Bassily
A Comparative Fault Diagnosis Methodology Based On Time Series Analysis Of System's Signals, Hany Bassily
All Dissertations
The detection of system anomalies represents an important task in safety critical systems. Over the past two decades, advances in data manipulation techniques and sensor technology have contributed to the widespread application of signal processing concepts for fault diagnosis. However, the majority of these signal processing, or data driven, diagnostics do not possess the redundancy level exhibited in conventional model-based methods. Among signal processing methods, time series analysis is advantageous since it offers insight into the underlying dynamics and forecasts system behavior. Furthermore, the data driven method allows the depiction of system dynamics with an increased level of redundancy. This …
Measurement And Analysis Of Hydromechanical Effects In Fractured Rock, Todd Schweisinger
Measurement And Analysis Of Hydromechanical Effects In Fractured Rock, Todd Schweisinger
All Dissertations
Fractures in rock hold important stores of water and petroleum, and slight changes in fracture aperture accompanying drawdown from pumping wells play a key role in recovering these resources. Four accomplishments are described that advance insight into the behavior and characterization of fractured crystalline rock.
First was the development of two removable borehole extensometers that enable small axial displacements to be measured during hydraulic well tests. The extensometers consist of four major components: 1.) a pair of anchors; 2.) a displacement transducer 3.) a registration system, and; 4.) a temperature-compensated reference rod. One extensometer uses an axial reference rod with …
Nonlinear Vibration And Frequency Response Analysis Of Nanomechanical Cantilever Beams, Seyed Nima Mahmoodi
Nonlinear Vibration And Frequency Response Analysis Of Nanomechanical Cantilever Beams, Seyed Nima Mahmoodi
All Dissertations
Microcantilevers are one the most commonly utilized microelectromechanical systems in a variant of the ultra-precise scanning and characterization application. Of particular interest, the problem of vibrations of microcantilevers has recently received considerable attention due to its application in several nanotechnological instruments such as atomic force microscopy, nanomechanical cantilever sensors and friction force microscopy. For applications such as these, the problem of coupled flexural-torsional nonlinear vibrations of a piezoelectrically-actuated microcantilever beam is considered in this dissertation. The actuation and sensing are both facilitated through bonding a piezoelectric layer (here, ZnO) on the microcantilever surface. The beam is considered to have simultaneous …
Modeling Of The Transient Behavior Of Heat Pipes With Room-Temperature Working Fluids, Pascal Brocheny
Modeling Of The Transient Behavior Of Heat Pipes With Room-Temperature Working Fluids, Pascal Brocheny
All Dissertations
The heat pipe is a capillary-driven and two-phase flow device, capable of transporting and converting large amounts of energy with minimal losses. As a means of thermal management, uses of heat pipe technology not only include thermal control of satellites and spacecrafts in aerospace applications, but also the cooling of electronic components for ground applications. Recently, there has been a flourishing interest in exploring the use of heat pipe technology in the automotive field. However, in many thermal control applications, heat pipes using room-temperature working fluids, such as water or ammonia, with operating temperatures between 200 K (-73ºC) and 550 …
A Robust Conjugate Heat Transfer Methodology With Novel Turbulence Modeling Applied To Internally-Cooled Gas Turbine Airfoils, William York
A Robust Conjugate Heat Transfer Methodology With Novel Turbulence Modeling Applied To Internally-Cooled Gas Turbine Airfoils, William York
All Dissertations
Computational fluid dynamics and heat transfer (CFD) has become a viable, physics-based analysis tool for complex flow and/or heat transfer problems in recent years due, in large part, to rapid advances in computing power. CFD based on the Reynolds-averaged Navier-Stokes (RANS) equations is starting to enter the mainstream design environment in certain industries where rapid and reliable predictive capability is necessary. One such application is the gas turbine industry, where thermal management of airfoils at extremely high temperatures is one of the most critical components in engine design for reliability. The problem is complicated by the need for advanced airfoil …
Modeling And Simulation Of Friction-Limited Continuously Variable Transmissions, Nilabh Srivastava
Modeling And Simulation Of Friction-Limited Continuously Variable Transmissions, Nilabh Srivastava
All Dissertations
Over the last few decades, a lot of research effort has increasingly been directed towards developing vehicle transmissions that accomplish the government imperatives of increased vehicle efficiency and lower exhaust (greenhouse gaseous) emissions. These exhaust emissions can be regulated or lowered by increasing the fuel economy of a vehicle, and CVTs (continuously variable transmissions), indubitably, play a crucial role in this plan to improve the fuel economy. A continuously variable transmission is an emerging automotive transmission technology that offers a continuum of gear ratios between desired limits. A CVT offers numerous advantages over the conventional multi-step gear transmissions such as …
Investigation Of The Effects Of Subgrid-Scale Turbulence On Resolvable-Scale Statistics, Qinglin Chen
Investigation Of The Effects Of Subgrid-Scale Turbulence On Resolvable-Scale Statistics, Qinglin Chen
All Dissertations
The effects of the subgrid-scale (SGS) turbulence on the resolvable-scale statistics and the effects of SGS models on large-eddy simulation (LES) are studied. It is shown that the SGS turbulence evolves the resolvable-scale joint probability density function (JPDF) through the conditional means of the SGS stress, the SGS scalar flux, and their production rate, which must be reproduced by the SGS model for LES to predict correctly the one-point resolvable-scale statistics, a primary goal of LES. This necessary condition is used as the basis for studying SGS physics and for testing SGS models. Theoretical predictions, measurements data obtained in a …