Mechanical Engineering Commons^™

Liquid-Vapor Distributions In Evacuated Small Diameter Channels For Improved Accuracy Of Initial Conditions In Modeling Of Oscillating Heat Pipes, Travis Mayberry

Mechanical Engineering Research Theses and Dissertations

Oscillating heat pipes, also known as pulsating heat pipes, are increasingly becoming a preferred high-performance thermal ground plane in a variety of heat spreading applications due to a number of advantages over traditional copper-water wicked heat pipes, including their lighter weight, thinner profiles, simpler fabrication, and greater variety of material and working fluid options. A major barrier to even wider adoption, however, is the lack of comprehensive analytical models to simulate their performance. A key input to first principles models simulating the fundamental physics of the devices is the initial condition of liquid and vapor segment lengths and their distribution …

Geometrically Complex Planar Heat Exchangers, Derli Dias Do Amaral Junior, Jose Lage

Mechanical Engineering Research Theses and Dissertations

In this study, geometrically complex planar heat exchangers, designed in line with the Constructal Law and operating at steady-state, are investigated numerically. The work is divided into two parts, one focusing on diffusion heat transfer in a rectangular plane and another on conjugate diffusion-convection heat transfer in a circular plane heat exchanger.

In the first part, a heat generating rectangular solid volume made of a low conductivity material is cooled through a small, isothermal side-section of the domain. The diffusion cooling process is improved by distributing within the heat generating material a fixed amount of a high conductivity material. The …

Anisotropic Plasticity Modeling Of Thin Sheets And Its Application To Micro Channel Forming Of Steel Foils, Jie Sheng

Mechanical Engineering Research Theses and Dissertations

Thin sheet metals and ultrathin metal foils produced by industrial rolling processes are textured polycrystalline materials and their mechanical behaviors may depend strongly on the orientation of applied loading. Consideration of such plastic anisotropy in advanced modeling of these materials is of the paramount importance in designing optimal manufacturing processes for automotive and other applications using finite element methods. This research addresses several critical issues in anisotropic plasticity modeling and its applications in analyzing micro channel forming of ultrathin stainless-steel foils. An experimental study has first been carried out on the accuracy and sensitivity of measuring the plastic strain ratios …

Magnetic Gradient-Based Magnetic Tweezer System For 3d And Swarm Control Of Microswimmer, Xiao Zhang

Mechanical Engineering Research Theses and Dissertations

Microscale manipulation has very promising potential in medical applications such as drug delivery, minimal and invasion surgery. Contactless control is preferable as remote manipulation is necessary for in vivo applications. Among different control methods, magnetic power source is more suitable and robust for the applications mentioned above. Presented here is a magnetic tweezer system, which manipulates microscale magnetic particles using magnetic forces created by magnetic field gradient. The proposed system has three advantages: First, force applied by the magnetic tweezer system does not contact with the target object and can be generated in different directions. Second, the magnetic tweezer system …

Context-Aware Sensing And Fusion For Structural Health Monitoring And Night Time Traffic Surveillance, Xinxiang Zhang

Electrical Engineering Theses and Dissertations

Rapid developments in computer vision technologies have been transforming many traditional fields in engineering and science in the last few decades, especially in terms of diagnosing problems from visual images. Leveraging computer vision technologies to inspect, monitor, assess infrastructure conditions, and analyze traffic dynamics, has gained significant increase in both effectiveness and efficiency, compared to the cost of traditional instrumentation arrays to monitor, and manually inspect civil infrastructures and traffic conditions. Therefore, to construct the next-generation intelligent civil and transportation infrastructures, this dissertation develops a comprehensive computer-vision based sensing and fusion framework for structural health monitoring and intelligent transportation systems. …

Rehology And Electrical Conductivity Of Particulate Composites In Additive Manufacturing, Bin Xia

Mechanical Engineering Research Theses and Dissertations

Extrusion-based multi-functional additive manufacturing (AM) has been a rapidly developing area in AM recently. Particulate composites are widely used in this area to provide different functionalities with different types of particulate additives. However, there is no systematic understanding of the behavior of particulate composites during extrusion (especially in small nozzles) or of their properties once deposited in the build. This work investigates the properties of the type of particulate composites usually used in additive manufacturing, composed of a polymer matrix material and particulate additives within the micrometer scale. The focus is on the material rheology in the nozzle/capillary (for the …

Actuation And Control Methods For Individual And Swarm Multiscale Mechanical Systems, Pouria Razzaghi

Mechanical Engineering Research Theses and Dissertations

Robotic mechanisms can be driven by different internally and externally applied inertial and magnetic actuations. These actuations are utilized to regulate the dynamics of robots and move them in different locomotion modes. The first part of this dissertation is about using an external magnetic actuation to move a simple-in-design, small-scale robot for biomedical applications. The robots can be steered in different locomotion modes such as pivot walking and tumbling. The control design of this system consists of a swarm algorithm under a global control input, and a vision-based closed-loop controller to navigate in 2D environments.

Secondly, I propose a new …

Damage Evolution And High-Rate Response Of High-Strength Concrete Under Triaxial Loading, Brett Williams

Mechanical Engineering Research Theses and Dissertations

The research presented in this study focuses on understanding fundamental mechanisms that drive material response under dynamic loading conditions. The objectives of the research were to: (1) to understand damage initiation and propagation in the bulk geomaterial under a variety of loading conditions and (2) to systematically investigate the strain rate effects on the triaxial compressive response of cementitious materials through the development of an innovative, first of its kind large-diameter (50 mm) triaxial Kolsky bar system.

The triaxial compressive response of high-strength concrete is needed to understand pressure-dependent material behavior, which is important for modeling extreme loading events. However, …

Rheology Of Particulate Suspensions With Non-Newtonian Fluids In Capillaries, Bin Xia, Paul Krueger

Mechanical Engineering Research

This resource contains the processed experimental measurements of the flow consistency index and flow behavior index, along with their trendlines, for the particulate suspensions investigated in "Rheology of Particulate Suspensions with Non-Newtonian Fluids in Capillaries" by Bin Xia and Paul S. Krueger.