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Articles 1 - 9 of 9
Full-Text Articles in Mechanical Engineering
Image Based Processing For Weld Defect Detection, Shems-Eddine Belhout
Image Based Processing For Weld Defect Detection, Shems-Eddine Belhout
Masters Theses
There is a growing need for automation in the welding industry due to a growing shortage in skilled welders. TIG [Tungsten Inert Gas] welding, a method of welding that uses an electrode shielded by gas and is fed externally by a wire, is incredibly advantageous for its precise heat control. TIG welding is considered the standard for nuclear application which requires highly precise welds to be performed. Robotic welding can address this issue, and one major problem that occurs during welding is welding defects. Typical weld defect detection requires a highly knowledgeable welder or destructive and nondestructive evaluation. Destructive evaluation …
Repeatability And Reproducibility Analyses For Structured Light Scanning, Leah Jacobs
Repeatability And Reproducibility Analyses For Structured Light Scanning, Leah Jacobs
Masters Theses
Structured light scanning is used to create a digital twin of a manufactured part. Features can be extracted from this digital twin to determine if the part meets the designer’s intent and required tolerances. This paper describes a repeatability and reproducibility study for a selected structured light scanning system and measurement artifact.
Path Planning For Additive Manufacturing Of Wire Arc Additive Manufacturing And Blue Light Fringe Projection Scanning, Tiffany Patricia Quigley
Path Planning For Additive Manufacturing Of Wire Arc Additive Manufacturing And Blue Light Fringe Projection Scanning, Tiffany Patricia Quigley
Masters Theses
Current methods of manufacturing large scale parts can take up to six months to generate the objective product. The objective of the wire arc additive manufacturing (WAAM) hybrid cell is to significantly reduce lead time associated with large scale parts. The WAAM process utilizes a 6 degree-of-freedom (DOF) robot manipulator in addition to a 2 DOF part positioner. 5 degrees of freedom are necessary for an effective WAAM process, leaving 3 DOF as redundant in this cell. This thesis serves to prove successful implementation of redundant kinematics on a WAAM robotic system. This is accomplished by maintaining a gravity aligned …
Optimized 3d-Printing Of Carbon Fiber-Reinforced Polyether-Ether-Ketone (Cfr-Peek) For Use In Overmolded Lattice Composite, Ryan C. Ogle
Optimized 3d-Printing Of Carbon Fiber-Reinforced Polyether-Ether-Ketone (Cfr-Peek) For Use In Overmolded Lattice Composite, Ryan C. Ogle
Masters Theses
Current orthopedic implants are overwhelmingly composed from metallic materials. These implants show superior mechanical properties, but this can additionally result in stress shielding due to a modulus mismatch between the bone tissue and implanted device. Polymeric implants reduce this stress shielding effect but have much lower mechanical properties, limiting their use. Polylactic acid (PLA) is a widely used biodegradable thermoplastic polymer, however, its use has been limited by the polymer’s mechanical properties and rapid loss of strength during degradation in vivo. Polyether-ether-ketone (PEEK) is another common biocompatible polymer , with chemical and mechanical properties which make it a popular alternative …
Upscaling And Development Of Linear Array Focused Laser Differential Interferometry For Simultaneous 1d Velocimetry And Spectral Profiling In High-Speed Flows, Kirk Davenport
Masters Theses
In this research a new configuration of linear array-focused laser differential interferometry (LA-FLDI) is described. This measurement expands on previous implementations of LA-FLDI through the use of an additional Wollaston prism. This additional prism expands the typical single LA-FLDI column into two columns of FLDI point pairs. The additional column of probed locations allows for increased spatial sampling of frequency spectra as well as the addition of simultaneous wall normal velocimetry measurements. The new configuration is used to measure the velocity profile and frequency content across a Mach 2 turbulent boundary layer at six wall normal locations simultaneously. Features of …
Design, Fabrication, And Validation Of A Three-Zone Cell For Absorption Spectroscopy, Derek W. Burkhart
Design, Fabrication, And Validation Of A Three-Zone Cell For Absorption Spectroscopy, Derek W. Burkhart
Masters Theses
Spectroscopic databases such as HITRAN and HITEMP are required to characterize the spectral parameters of chemical species to ensure accurate calculations of gas concentrations and temperatures from laser absorption spectroscopy. These databases are populated by performing spectroscopic experiments at controlled conditions. Databases lack spectral parameters for combustion species such as CO, CO2, and H2O at temperatures combustion temperatures in the mid-IR wavelength range due to difficulties in creating an experimental absorption cell capable of surviving combustion temperatures. A high temperature absorption cell was previously used at the University of Tennessee Space Institute (UTSI) for high temperature spectroscopic experiments with combustion …
Sensor Comparison For Low-Cost Dynamic Force Measurement In Milling, Zachary Mason
Sensor Comparison For Low-Cost Dynamic Force Measurement In Milling, Zachary Mason
Masters Theses
Machine cutting forces are commonly measured using piezoelectric dynamometers. Such dynamometers can be prohibitively expensive and may still require extensive post processing. Previous work used a low-cost single degree of freedom constrained motion dynamometer (CMD) in conjunction with a knife edge sensor to determine the cutting forces through inverse force filtering. In that approach, the measured displacement of the CMD was transformed into the frequency domain by the fast Fourier transform (FFT) and convolved with the inverted receptance frequency response function (FRF) to yield force in the frequency domain. The force was then converted to the time domain using the …
A Numerical Optimization Study Of A Novel Electrospray Emitter Design, Joshua H. Howell
A Numerical Optimization Study Of A Novel Electrospray Emitter Design, Joshua H. Howell
Masters Theses
The low thrust and high specific impulse of electric propulsion has been brought to the forefront for CubeSat and small spacecraft applications. Electrospray thrusters, which operate via electrostatic principles, have seen much research, development, and application in recent years. The small sizes of the spacecraft that utilize electrospray thrusters has focused development into the miniaturization of this technology to the micro-scale. Miniaturization introduces design challenges that must be addressed, including power supply mass and footprint requirements. This consequence requires investigation into the effects of design choices on the thruster onset voltage, defined as the voltage at which ion emission begins. …
Redundant Kinematics Solution For A Combined 6dof Robotic Manipulator And 2dof Part Positioner In A Waam Application, Ethan C. Vals
Redundant Kinematics Solution For A Combined 6dof Robotic Manipulator And 2dof Part Positioner In A Waam Application, Ethan C. Vals
Masters Theses
A typical wire arc additive manufacturing (WAAM) robot cell consists of a 6 DOF robot manipulator and a 2 DOF part positioner. Since the WAAM process requires a minimum of 5 DOFs, there are three redundant DOFs in the system that can be utilized to improve the robot manipulator positioning during part printing. In this thesis, the redundant kinematics of a manipulator and part positioner robot system are solved and then implemented on an actual robot system. The inverse kinematics of the manipulator and part positioner are solved as a kinematic chain using the pseudo-inverse Jacobian method. The two DOFs …