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Articles 1 - 12 of 12

Full-Text Articles in Applied Mechanics

Development Of A Data Acquisition System For Unmanned Aerial Vehicle (Uav) System Identification, Donald Joseph Lear Oct 2017

Development Of A Data Acquisition System For Unmanned Aerial Vehicle (Uav) System Identification, Donald Joseph Lear

Mechanical & Aerospace Engineering Theses & Dissertations

Aircraft system identification techniques are developed for fixed wing Unmanned Aerial Vehicles (UAV). The use of a designed flight experiment with measured system inputs/outputs can be used to derive aircraft stability derivatives. This project set out to develop a methodology to support an experiment to model pitch damping in the longitudinal short-period mode of a UAV. A Central Composite Response Surface Design was formed using angle of attack and power levels as factors to test for the pitching moment coefficient response induced by a multistep pitching maneuver.

Selecting a high-quality data acquisition platform was critical to the success of ...


Meshless Mechanics And Point-Based Visualization Methods For Surgical Simulations, Rifat Aras Jul 2014

Meshless Mechanics And Point-Based Visualization Methods For Surgical Simulations, Rifat Aras

Modeling, Simulation & Visualization Engineering Theses & Dissertations

Computer-based modeling and simulation practices have become an integral part of the medical education field. For surgical simulation applications, realistic constitutive modeling of soft tissue is considered to be one of the most challenging aspects of the problem, because biomechanical soft-tissue models need to reflect the correct elastic response, have to be efficient in order to run at interactive simulation rates, and be able to support operations such as cuts and sutures.

Mesh-based solutions, where the connections between the individual degrees of freedom (DoF) are defined explicitly, have been the traditional choice to approach these problems. However, when the problem ...


Computational Dynamics For The Flexible Multi-Body System, Yu Liu Apr 2013

Computational Dynamics For The Flexible Multi-Body System, Yu Liu

Mechanical & Aerospace Engineering Theses & Dissertations

Research in computational dynamics has tremendously developed in the recent years because of the demand for analysis and simulation of various multi-body systems in the growing bio-medical, mechanical and aerospace industries. These multi-body systems are made of individual bodies that are interconnected via mechanical joints. Mathematically, these joints that connect the bodies can be described as constraint equations imposed upon the motions of the involved free bodies. This process will result in an equation of motion expressed in the form of a differential-algebraic equation (DAE). This is one of the main difficulties when dealing with the multi-body system because these ...


Design And Implementation Of A Z-Axis Mems Gyroscope With A Symmetric Multiple-Mass Mechanical Structure, Yujie Zhang Apr 2012

Design And Implementation Of A Z-Axis Mems Gyroscope With A Symmetric Multiple-Mass Mechanical Structure, Yujie Zhang

Mechanical & Aerospace Engineering Theses & Dissertations

This thesis presents a z-axis MEMS gyroscope with a symmetric mechanical structure. The multiple-mass design prioritizes the sense-mode Quality Factor (Q) and thus improves its scale factor. The proposed mechanically coupled, dynamically balanced anti-phase sense-mode design minimizes energy dissipation through the substrate in order to maximize the Q. Numerical simulation is implemented in a finite element analysis software, COMSOL, to identify the two operation modes of the gyroscope: drive-mode and sense-mode. The multiple-mass gyroscope design is further fabricated using a one-mask process. Experimental characterization of frequency response in both drive-mode and sense-mode of the device are conducted, proving the design ...


Parallel Mpi/Fortran Finite Element Symmetrical/Unsymmetrical Domain Decomposition, Siroj Tungkatara Apr 2008

Parallel Mpi/Fortran Finite Element Symmetrical/Unsymmetrical Domain Decomposition, Siroj Tungkatara

Civil & Environmental Engineering Theses & Dissertations

MPI/FORTRAN finite element analysis software based on Domain Decomposition (DD) formulas has been developed in this work. Efficient input data storage/data communication schemes, domain partitioning, fast symbolical and numerical sparse assembly, symmetrical/unsymmetrical sparse solver and robust symmetrical/unsymmetrical iterative solvers algorithms are all incorporated into the developed code. Parallel Precondition Conjugated Gradient (PCG) and Flexible Generalized Minimum Residual (FGMRES) are developed. Efficient computational techniques used in the developed code are explained. Numerical performance and the accuracy of the developed code are conducted on acoustic examples with medium to large grid sizes. The results obtained from ODU Wilbur ...


Dedication To Pierre Lallemand On The Occasion Of His Retirement, Dominque D'Humieres, Manfred Krafczyk, Li-Shi Luo, Robert Rubinstein Jan 2008

Dedication To Pierre Lallemand On The Occasion Of His Retirement, Dominque D'Humieres, Manfred Krafczyk, Li-Shi Luo, Robert Rubinstein

Mathematics & Statistics Faculty Publications

The fourth international conference for mesoscopic methods in engineering and science (http://www.icmmes. org), held in Munich, Germany, 16–20 July 2007, was closed with a celebration honouring Dr Pierre Lallemand on the occasion of his retirement from the Centre National de la Recherche Scientifique (CNRS) after more than 40 years of service.


Multidisciplinary Sensitivity Analysis And Design Optimization Of Flexible Wings Using The Euler Equations On Unstructured Grids, Arunkumar Satyanarayana Jan 1999

Multidisciplinary Sensitivity Analysis And Design Optimization Of Flexible Wings Using The Euler Equations On Unstructured Grids, Arunkumar Satyanarayana

Mechanical & Aerospace Engineering Theses & Dissertations

Aeroelasticity is a classical discipline. However, even with recent advancement in computational technology, it still remains a challenging discipline. This is particularly true when aeroelasticity problems are solved in a loosely coupled manner. The advantage of a loosely coupled scheme is that the legacy codes of computational fluid dynamics (CFD) and computational structural mechanics (CSM) can be preserved and used as independent modules in solving the desired aeroelasticity problems. In such a scheme, maintaining proper data transfer (load transfer and deformation tracking between CFD and CSM codes) is crucial in ensuring successful coupled solutions. This can be a challenging task ...


Vortex Wake And Exhaust Plume Interaction, Including Ground Effect, Ihab Gaber Adam Jul 1998

Vortex Wake And Exhaust Plume Interaction, Including Ground Effect, Ihab Gaber Adam

Mechanical & Aerospace Engineering Theses & Dissertations

Computational modeling and studies of the near-field wake-vortex turbulent flows, far-field turbulent wake-vortex/exhaust-plume interaction for subsonic and High Speed Civil Transport (HSCT) airplane, and wake-vortex/exhaust-plume interaction with the ground are carried out. The three-dimensional, compressible Reynolds-Averaged Navier-Stokes (RANS) equations are solved using the implicit, upwind, Roe-flux-differencing, finite-volume scheme. The turbulence models of Baldwin and Lomax, one-equation model of Spalart and Allmaras and two-equation shear stress transport model of Menter are implemented with the RANS solver for turbulent-flow modeling.

For the near-field study, computations are carried out on a fine grid for a rectangular wing with a NACA-0012 airfoil ...


Reduction Of Thermal Deflection And Random Response Of Composite Structures With Embedded Shape Memory Alloy At Elevated Temperature, Zhiwei Zhong Apr 1998

Reduction Of Thermal Deflection And Random Response Of Composite Structures With Embedded Shape Memory Alloy At Elevated Temperature, Zhiwei Zhong

Mechanical & Aerospace Engineering Theses & Dissertations

A feasibility study on the reduction of thermal deflection and random response of the composite structures using shape memory alloys (SMA) at elevated temperatures is presented in this dissertation. The characteristics of SMA are introduced and the structural problems, static and dynamic, of SMA fiber reinforced composites are investigated. The stress-strain relations are developed for a composite lamina with embedded SMA fibers. The finite element system equations including shape memory effect are derived. A consistent two-step solution procedure is developed for solving the static and dynamic problems of composite structures with embedded SMA fibers subjected to combined acoustic and thermal ...


Numerical Simulation Of The Nonlinear Response Of Composite Plates Under Combined Thermal And Acoustic Loading, Jayashree Moorthy Jan 1994

Numerical Simulation Of The Nonlinear Response Of Composite Plates Under Combined Thermal And Acoustic Loading, Jayashree Moorthy

Mechanical & Aerospace Engineering Theses & Dissertations

A time-domain study of the random response of a laminated plate subjected to combined acoustic and thermal loads is carried out. The features of this problem also include given uniform static inplane forces. The formulation takes into consideration a possible initial imperfection in the flatness of the plate. High decibel sound pressure levels along with high thermal gradients across thickness drive the plate response into nonlinear regimes. This calls for the analysis to use von Karman large deflection strain-displacement relationships. A finite element model that combines the von Karman strains with the first-order shear deformation plate theory is developed. The ...


An Apparatus For Measuring The Thermal Conductivity Of Cast Insulation Materials, Christine A. Wilkins, Robert L. Ash Jul 1980

An Apparatus For Measuring The Thermal Conductivity Of Cast Insulation Materials, Christine A. Wilkins, Robert L. Ash

Mechanical & Aerospace Engineering Faculty Publications

A steady-state apparatus has been developed for measuring the thermal conductivity of cast materials. The design has employed a novel thermal symmetry arrangement which can permit total electrical isolation of the test material from its surroundings. © 1980 American Institute of Physics


Effect Of Compliant Wall Motion On Turbulent Boundary Layers, Dennis M. Bushness, Jerry N. Hefner, Robert L. Ash Jan 1977

Effect Of Compliant Wall Motion On Turbulent Boundary Layers, Dennis M. Bushness, Jerry N. Hefner, Robert L. Ash

Mechanical & Aerospace Engineering Faculty Publications

A critical analysis of available compliant wall data which indicated drag reduction under turbulent boundary layers is presented. Detailed structural dynamic calculations suggest that the surfaces responded in a resonant, rather than a compliant, manner. Alternate explanations are given for drag reductions observed in two classes of experiments: (1) flexible pipe flows and (2) water-backed membranes in air. Analysis indicates that the wall motion for the remaining data is typified by short wavelengths in agreement with the requirements of a possible compliant wall drag reduction mechanism recently suggested by Langley. Copyright © 1977 American Institute of Physics.