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Full-Text Articles in Mechanical Engineering
Sources Of Quality Uncertainty In Laser Powder Bed Fusion Metal Additive Manufacturing, Zachary Young
Sources Of Quality Uncertainty In Laser Powder Bed Fusion Metal Additive Manufacturing, Zachary Young
Doctoral Dissertations
"Powder based additive manufacturing (AM) exhibits tremendous uncertainties, where variations in build quality is present despite utilizing similar build processing parameters. First, this work reports the features and formation mechanisms of five unique types of spatter during the LPBF process by in-situ high-speed, high-energy x-ray imaging. The unique physical characteristics of spatter are determined. The effect of laser scan speed and laser power on spatter formation, ejection, and mitigation are determined. Second, this work addresses the uncertainty challenge by identifying the sources of uncertainty in SLM by in-situ characterization due to variations from the additive manufacturing processing parameters needed for …
Implementing A Linear Quadratic Spacecraft Attitude Control System, Daniel Kolosa
Implementing A Linear Quadratic Spacecraft Attitude Control System, Daniel Kolosa
Masters Theses
This thesis implements a linear quadratic attitude control system for a low-thrust spacecraft. The goal is to maintain spacecraft alignment with a time-varying thrust vector needed for trajectory change maneuvers. A linear quadratic attitude control approach is used to maintain spacecraft pointing throughout flight. This attitude control strategy uses the thrust-acceleration input obtained from a linear quadratic optimal trajectory control model that simulates the trajectory of a spacecraft in orbit maneuvers. This attitude model simulates a CubeSat, a small satellite that is equipped with a low-thrust propulsion and attitude control system. An orbit raising and a plane change scenario is …
The Effect Of Sensor Mass, Sensor Location, And Delamination Location Of Different Composite Structures Under Dynamic Loading, Albert Darien Liu
The Effect Of Sensor Mass, Sensor Location, And Delamination Location Of Different Composite Structures Under Dynamic Loading, Albert Darien Liu
Master's Theses
This study investigated the effect of sensor mass, sensor location, and delamination location of different composite structures under dynamic loading. The study pertains to research of the use of accelerometers and dynamic response as a cost-effective and reliable method of structural health monitoring in composite structures. The composite structures in this research included carbon fiber plates, carbon fiber-foam sandwich panels, and carbon-fiber honeycomb sandwich panels. The composite structures were manufactured with the use of a Tetrahedron MTP-8 heat press. All work was conducted in the Cal Poly Aerospace Structures/Composites Laboratory. Initial delaminations were placed at several locations along the specimen, …