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Full-Text Articles in Mechanical Engineering
Construction And Characterization Of A Single Stage Dual Diaphragm Gas Gun, Nathaniel Steven Helminiak
Construction And Characterization Of A Single Stage Dual Diaphragm Gas Gun, Nathaniel Steven Helminiak
Master's Theses (2009 -)
In the interest of studying the propagation of shock waves, this work sets out to design, construct, and characterize a pneumatic accelerator that performs high-velocity flyer plate impact tests. A single stage gas gun with a dual diaphragm breach allows for a non-volatile, reliable experimental testing platform for shock phenomena. This remotely operated gas gun utilizes compressed nitrogen to launch projectiles down a 14 foot long, 2 inch diameter bore barrel, which subsequently impacts a target material of interest. A dual diaphragm firing mechanism allows the 4.5 liter breech to reach a total pressure differential of 10ksi before accelerating projectiles …
A Parametric Investigation And Optimization Of A Cylindrical Explosive Charge, Logan Ellsworth Beaver
A Parametric Investigation And Optimization Of A Cylindrical Explosive Charge, Logan Ellsworth Beaver
Master's Theses (2009 -)
Explosive device design has a wide impact in the space, manufacturing, military, and mining industries. As a step toward computer assisted design of explosives, an optimization framework was developed using the Design Analysis Kit for Optimization and Terrascale Applications (Dakota). This software was coupled with the hydrocode CTH. This framework was applied to three exploding cylinder models, two in 1D and one in 2D. Gradient descent, dividing rectangles, and a genetic algorithm were each applied to the one-dimensional models. Parametric studies were performed as a basis for comparison with the optimization algorithms, as well as qualifying the 1D model's accuracy. …
Direct Numeric Simulation Of Shock Wave Structures Without The Use Of Artificial Viscosity, Kenneth Bernard Jordan
Direct Numeric Simulation Of Shock Wave Structures Without The Use Of Artificial Viscosity, Kenneth Bernard Jordan
Dissertations (1934 -)
The purpose of this work is to directly simulate shock wave structures without the use of artificial viscosity. The commonly used artificial viscosity model is replaced with an irreversibility model. Irreversibilities are not typically taken into account when modeling the shock processes because shocks are resolved in a large domain where the thickness of the shock is thin compared to the numeric grid resolution. The result is the shock is poorly resolved. In addition processes other than shock processes are adiabatic and reversible. The result is artificial viscosity, a form of irreversibility, is added to the numeric cells near the …
One-Dimensional Strain Initiated By Rapid Compaction Of A Heterogenous Granular Mixture Consisting Of Cu, Fe, Sio2, C, Mos2, And Sn, Cullen Braun
Master's Theses (2009 -)
The dynamic compaction of metal powders is of great interest to the metallurgical and military communities. The compaction of a heterogeneous granular mixture consisting of copper, iron, silica, graphite, molybdenum-disulde, and tin predominately used in aviation break-pad creation is presented. The initial density of the material was on average 2.756 g/cm3 . The research also required developing a working projectile velocity measurement system and a proper target assembly for pressure measurements. Manganin gages were used to record the shock wave transit time and the pressure of the transmitted waveform into the powder mixture. An impedance matching technique was utilized to …
Mesoscale Behavior Of An Aluminum-Manganese Dioxide-Epoxy Mixture Under Shock Loading: From Milli To Nano-Sized Aluminum Particles, Andrew Fraser
Mesoscale Behavior Of An Aluminum-Manganese Dioxide-Epoxy Mixture Under Shock Loading: From Milli To Nano-Sized Aluminum Particles, Andrew Fraser
Master's Theses (2009 -)
The main focus of this thesis is to explore the dynamic shock compaction of multiple component mixtures, specifically Al-MnO2-Epoxy. This will be facilitated by initially simulating the bulk dynamic response in a mesoscale configuration and then comparing these results to experimental data. The mesoscale simulations were performed in the shock code CTH. The first section will discuss the matching of experimental data to computational results. With the goal of determining the bulk shock Hugoniot, a one-dimensional flyer plate configuration was created while using a grain-geometry imported from an scanning electron microscope (SEM) micrograph of the mixture. Both the …