Mechanical Engineering Commons^™

Design And Analysis Of Blast Induced Traumatic Brain Injury Mechanism Using A Surrogate Headform: Instrumentation And Outcomes, Eyitejumade A. Sogbesan

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

Brain injury cases in military personnel exposed to improvised explosive devices (IED) in combat have been on the rise. In Iraq and Afghanistan improved helmets and body armor are not enough protection against blast wave threats. The United States military are sponsoring researchers and scientists around the globe to find the associations between pressure waves and traumatic brain injury (TBI).

Lack of accurate data and blast wave exposure information in returning soldiers has slowed the innovation needed to effectively diagnose TBI and other related brain injury as a result of pressure waves. More detailed data will be required to gain …

Enabling And Understanding Failure Of Engineering Structures Using The Technique Of Cohesive Elements, H. Jiang, Xiaosheng Gao, T. S. Srivatsan

Mechanical Engineering Faculty Research

In this paper, we describe a cohesive zone model for the prediction of failure of engineering solids and/or structures. A damage evolution law is incorporated into a three-dimensional, exponential cohesive law to account for material degradation under the influence of cyclic loading. This cohesive zone model is implemented in the finite element software ABAQUS through a user defined subroutine. The irreversibility of the cohesive zone model is first verified and subsequently applied for studying cyclic crack growth in specimens experiencing different modes of fracture and/or failure. The crack growth behavior to include both crack initiation and crack propagation becomes a …

Mechanical Behavior Of Bio-Inspired Laminated Composites, Liang Cheng, Adam Thomas, James L. Glancey, Anette M. Karlsson

Mechanical Engineering Faculty Publications

To investigate if the relative high strength and stiffness of biological composites can be translated into man-made materials, innovative bio-inspired laminated composites with commercial materials (glass epoxy prepreg) were designed and manufactured by incorporating the distinctive helicoidal morphology observed in the exoskeletons of crustaceans. The helicoidal structure is characterized by a stacking sequence consisting of a gradual rotation of each lamina in the multi-layered laminated composites. Variations of the helicoidal structure were designed and produced to address some important issues encountered in the practical composites manufacturing process, including mid-plane symmetry. In addition, composite structures with a general quasi-isotropic configuration were …

A Virtual Supply Airflow Rate Meter In Rooftop Air Conditioning Units, Daihong Yu

Durham School of Architectural Engineering and Construction: Dissertations, Theses, and Student Research

Virtual sensing technology aims to estimate difficult to measure, expensive, or new quantities by using multifarious mathematical models along with non-invasive and low-cost measurements. Such embedded intelligence is a key to improving the performance of building systems in terms of functionality, safety, energy efficiency, environmental impacts, and costs. Considering the progress that has been achieved over many various fields (e.g., process controls, automobiles, avionics, autonomous robots, telemedicine) within the last two decades, numerous intelligent features have been incorporated and enabled that would otherwise not be possible or economical.

To identify the potential opportunities and research/development needs of virtual sensing technology …

3-D Terrain Mapping And Navigation Using A Laser Range Finder, Matthew L. Azevedo, Matthew Parilla, Kevin K. Parsons

Mechanical Engineering

The purpose of this Senior Project is to develop and implement a three-dimensional mapping and navigation system utilizing laser technology on a robotic platform.  The sponsor of this project, Synbotics® Incorporated, currently has an obstacle avoidance system only operating in a single horizontal plane.  This limits the mapping and navigation ability of the robot because objects below and above this plane are not accounted for.  A three-dimensional system is needed to allow the robot to better navigate and map an area by accounting for these objects in the third dimension and avoiding collisions.  Keith Guy, Synbotics® Chief Executive Officer, requested …

Nanostructured Substrate With Nanoparticles Fabricated By Femtosecond Laser For Surface-Enhanced Raman Scattering, Yukun Han, Zhi Liang, Huilai Sun, Hai Xiao, Hai-Lung Tsai

Electrical and Computer Engineering Faculty Research & Creative Works

A Simple and Fast Method to Fabricate Nanostructured Substrates with Silver Nanoparticles over a Large Area for Surface-Enhanced Raman Scattering (SERS) is Reported. the Method Involves Two Steps: (1) Dip the Substrate into a Silver Nitrate Solution for a Few Minutes, Remove the Substrate from the Solution, and Then Air Dry and (2) Process the Silver Nitrate Coated Substrate by Femtosecond (Fs) Laser Pulses in Air. the Second Step Can Create Silver Nanoparticles Distributed on the Nanostructured Surface of the Substrate by the Photoreduction of Fs Multiphoton Effects. This Study Demonstrates that an Enhancement Factor (EF) Greater Than 5x105, Measured …

Study Of Emission Turbulence-Radiation Interaction In Hypersonic Boundary Layers, L. (Lian) Duan, M. P. Martín, I. Sohn, D. A. Levin, M. F. Modest

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Direct numerical simulations are conducted to study the effects of emission turbulence-radiation interaction in hypersonic turbulent boundary layers, representative of the Orion Crew Exploration Vehicle at peak-heating condition during reentry. A nondimensional governing parameter to measure the significance of emission turbulence-radiation interaction is proposed, and the direct numerical simulation fields with and without emission coupling are used to assess emission turbulence-radiation interaction. Both the uncoupled and coupled results show that there is no sizable interaction between turbulence and emission at the hypersonic environment under investigation. An explanation of why the intensity of emission turbulence-radiation interaction in the hypersonic boundary layer …

Fracture Analysis Of Kevlar-49/Epoxy And E-Glass/Epoxy Doublers For Reinforcement Of Cracked Aluminum Plates, Ananth Ram Mahanth Kasavajhala, Linxia Gu

Department of Mechanical and Materials Engineering: Faculty Publications

Adhesively bonded composite patch repair is an efficient means to regain load carrying capacity, alleviate the crack growth, and improve the service life of the damaged structure. In this paper, three dimensional finite element models are developed to ex­amine the fracture behavior of a single edge V-notched Aluminum plate repaired with Kevlar-49/epoxy or e-glass/epoxy pre-preg patches on both sides. Contour integral method was used for evaluating the stress intensity factor (SIF), an indicator of the crack stability. The load transfer mechanisms, stress distribution, damage variable (D), and crack mouth opening displacement (CMOD), were also presented to estimate the …

Design And Fabrication Of A Tapped Densification Apparatus For Bulk Solids, Joshua H. De Jong

Theses

Experiments are commonly used to ascertain the flow properties of bulk solids. One such property is a measurement quantity known as the tapped density. Here, a container of granular material is subjected to a long sequence of discrete taps, after which the bulk density - the total mass divided by the volume occupied –- is determined. Current technology exists to achieve the maximum tap density by subjecting a container to a user defined number of taps at a specific, predetermined amplitude and frequency. However, the final bulk density is known to be dependent on the tap parameters. It can therefore …

A Differential Planetary Gear Model With Backlash And Teeth Damage, Xi Wu, Jim Meagher, Andrew Sommer

Mechanical Engineering

Planetary gear trains can be more compact and efficient as power transmissions than fixed axis gear trains but are also more complicated and less understood in terms of vibration health monitoring. A practical differential planetary gear train, which combines two inputs and one output, is studied using multi-body dynamics software. Backlash between the sun gear and planet gears are precisely specified to avoid teeth interference and undercut. In order to calculate accurate impact forces, an impact model is chosen. Tooth geometry errors are created on the sun gear. Constraints and contact forces to the model are applied as close as …

An Advanced Numerical Model Of Gear Tooth Loading From Backlash And Profile Errors, Andrew Sommer, Jim Meagher, Xi Wu

Mechanical Engineering

This study demonstrates the early transient dynamic loading on teeth within a fixed-axis gear transmission arising from backlash and geometric manufacturing errors by utilizing a non-linear multi-body dynamics software model. Selection of the non-linear contact parameters such as the stiffness, force exponent, damping, and friction coefficients are presented for a practical transmission. Backlash between gear teeth which is essential to provide better lubrication on tooth surfaces and to eliminate interference is included as a defect and a necessary part of transmission design. Torsional vibration is shown to cause teeth separation and double-sided impacts in unloaded and lightly loaded gearing drives. …

Estimating The Yield Strength Of Thin Metal Films Through Elastic-Plastic Buckling-Induced Debonding, S Goyal, K Srinivasan, G Subbarayan, Thomas Siegmund

School of Mechanical Engineering Faculty Publications

In this paper, we propose a procedure to estimate the yield strength of thin films by debonding films from their substrate by elastic-plastic buckling under thermally-induced compressive loading. The out-of-plane displacement of the metal lines under conditions of elastic-plastic buckling is dependent on the yield strength of the film. Thus, an inverse estimate of the yield strength is made from measurements of the out-of-plane displacements of the buckled metal lines. The procedure is demonstrated to estimate the yield strength of aluminum lines consistent with measurements by other techniques.

Characterising 3d Soft Tissue Features On Joint Surfaces, Colm O'Kane

Conference Papers

A crucial aspect of orthopaedic implant design is the prediction of surgical outcomes when the shape of a bone is necessarily altered by the addition of the implant. Matching native kinematics as closely as possible is generally considered a core aim of joint replacement surgery. The overall hypothesis behind this research is that soft tissue geometry, including cartilage thickness distribution and ligament attachment sites, influences kinematics in the knee joint. In order to enable investigation of possible links between geometry and kinematics, the ability to characterise the shape variation of the soft tissue relative to the underlying bony geometry must …

A 3-D Chain Algorithm With Pseudo-Rigid-Body Model Elements, Robert Parley Chase, Robert H. Todd, Larry L. Howell, Spencer P. Magleby

Faculty Publications

A chain algorithm element is created from pseudo-rigid-body segments and used in a chain calculation that accurately predicts the force deflection relationship of beams with large 3-D deflections. Each chain element is made up of three pseudo-rigid-body models superimposed on each other acting orthogonally in relation to each other. The chain algorithm can predict large displacements and the force-deflection relationship of lateral torsional buckled beams significantly faster than the finite element method. This approach is not intended to compete with finite element analysis, but rather is a supplement tool that may prove particularly useful in the early phases of design …

Intelligibility Of Electrolarynx Speech Using A Novel Hands-Free Actuator, Brian Madden, Mark Nolan, Ted Burke, James Condron, Eugene Coyle

Conference Papers

During voiced speech, the larynx provides quasi-periodic acoustic excitation of the vocal tract. In most electrolarynxes, mechanical vibrations are produced by a linear electromechanical actuator, the armature of which percusses against a metal or plastic plate at a frequency within the range of glottal excitation. In this paper, the intelligibility of speech produced using a novel hands-free actuator is compared to speech produced using a conventional electrolarynx. Two able-bodied speakers (one male, one female) performed a closed response test containing 28 monosyllabic words, once using a conventional electrolarynx and a second time using the novel design. The resulting audio recordings …

Short-Term Curtailment Of Hvac Loads - Executive Summary, Florida Solar Energy Center, Lixing Gu

FSEC Energy Research Center®

Rapidly increasing requirements placed on utilities to reduce peak loads has led to utility customer incentives to shift peak demand to non-peak times or reduce peak loads when notified by the utility that the grid is close to capacity. This study investigates methods used to reduce building demand during a fixed time window near a utilities on-peak period. The window was chosen to be 5-9 A.M. in winter and 2-5 P.M. in summer. The most common methods for reducing building peak demand were reviewed and categorized by their usefulness and wide-spread availability. These strategies were reductions in lighting power density, …

Investigation Of Dc Motors For Electric And Hybrid Electric Motor Vehicle Applications Using An Infinitely Variable Transmission, Benjamin Carson Groen

Theses and Dissertations

Since the early 1900's demand for fuel efficient vehicles has motivated the development of electric and hybrid electric vehicles. Unfortunately, some components used in these vehicles are expensive and complex. AC motors, complex electronic controllers and complex battery management systems are currently used in electric (EV) and hybrid vehicles. This research examines various motors and speed control methods in an attempt to help designers identify which motors would be best suited for an EV powertrain application. The feasibility of using DC motors coupled with an Infinitely Variable Transmission (IVT), to obtain an innovative new electric or hybrid electric powertrain is …

Arra Advanced Weatherization Training Center - Quarterly Report (September 2010-December 2010), Florida Solar Energy Center, Neil Moyer

FSEC Energy Research Center®

The 4th quarter of 2010 was the initialization of the contract with DOE. During this time period, there were two major events that occurred. First, representatives from UCF-FSEC attended the three day Atlanta Weatherization Training Center Grantee Training Workshop with DOE representatives and the various organizations that were awarded funding. Secondly, the project management plan (PMP) was finalized and submitted to the Project Manager.

A Full-Depth Amalgamated Parallel 3d Geometric Multigrid Solver For Gpu Clusters, Dana A. Jacobsen, Inanc Senocak

Mechanical and Biomedical Engineering Faculty Publications and Presentations

Numerical computations of incompressible flow equations with pressure-based algorithms necessitate the solution of an elliptic Poisson equation, for which multigrid methods are known to be very efficient. In our previous work we presented a dual-level (MPI-CUDA) parallel implementation of the Navier-Stokes equations to simulate buoyancy-driven incompressible fluid flows on GPU clusters with simple iterative methods while focusing on the scalability of the overall solver. In the present study we describe the implementation and performance of a multigrid method to solve the pressure Poisson equation within our MPI-CUDA parallel incompressible flow solver. Various design decisions and algorithmic choices for multigrid methods …

Scalability Of Incompressible Flow Computations On Multi-Gpu Clusters Using Dual-Level And Tri-Level Parallelism, Dana A. Jacobsen, Inanc Senocak

Mechanical and Biomedical Engineering Faculty Publications and Presentations

High performance computing using graphics processing units (GPUs) is gaining popularity in the scientific computing field, with many large compute clusters being augmented with multiple GPUs in each node. We investigate hybrid tri-level (MPI-OpenMP-CUDA) parallel implementations to explore the efficiency and scalability of incompressible flow computations on GPU clusters up to 128 GPUS. This work details some of the unique issues faced when merging fine-grain parallelism on the GPU using CUDA with coarse-grain parallelism using OpenMP for intra-node and MPI for inter-node communication. Comparisons between the tri-level MPI-OpenMP-CUDA and dual-level MPI-CUDA implementations are shown using computationally large computational fluid dynamics …