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Mechanical Engineering

Marquette University

Theses/Dissertations

2015

Articles 1 - 8 of 8

Full-Text Articles in Engineering

Optimizing A Hammer Forging Progression For A Large Hand Tool, Edgar Espinoza Oct 2015

Optimizing A Hammer Forging Progression For A Large Hand Tool, Edgar Espinoza

Master's Theses (2009 -)

In the forging industry of today the need for United States based companies to reduce cost and maintain or improve the quality of a product has become essential in order to remain competitive. A company such as Green Bay Drop Forge (GBDF), a manufacturer of standard and custom steel forgings, was tasked with improving the forging process of one of their large hand tool products. A large wrench, forged at GBDF was noticed to contain a large amount of flash and excessive amount of hammer blows required to forge the part. The large amounts of flash and excessive hammer blows …

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Investigation Of Surface Topography Effects On Metal Flow Under Lubricated Hot Compression Of Aluminum, Justin Irvin Kurk Oct 2015

Investigation Of Surface Topography Effects On Metal Flow Under Lubricated Hot Compression Of Aluminum, Justin Irvin Kurk

Master's Theses (2009 -)

An investigation was conducted to study the effects of die surface topography, specifically surface roughness and lay, on metal flow and the friction factor under lubricated hot compression. 6061-T6 aluminum rings and square bar stock specimens were compressed on H-13 tool steel platens machined with a unidirectional lay pattern to six different roughnesses between a R 10 and 240 μin. A lab based hydraulic press mounted with an experimental die set was used for all testing. Repeated trials were conducted using high temperature vegetable oil and boron nitride lubricants. Metal flow was quantified as a function of surface roughness, lay …

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Health Condition Monitoring And Fault-Tolerant Operation Of Adjustable Speed Drives, Jiangbiao He Oct 2015

Health Condition Monitoring And Fault-Tolerant Operation Of Adjustable Speed Drives, Jiangbiao He

Dissertations (1934 -)

Adjustable speed drives (ASDs) have been extensively used in industrial applications over the past few decades because of their benefits of energy saving and control flexibilities. However, the wider penetration of ASD systems into industrial applications is hindered by the lack of health monitoring and fault-tolerant operation techniques, especially in safety-critical applications. In this dissertation, a comprehensive portfolio of health condition monitoring and fault-tolerant operation strategies is developed and implemented for multilevel neutral-point-clamped (NPC) power converters in ASDs. Simulations and experiments show that these techniques can improve power cycling lifetime of power transistors, on-line diagnosis of switch faults, and fault-tolerant …

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A Hybrid Controller For Stability Robustness, Performance Robustness, And Disturbance Attenuation Of A Maglev System, Feng Tian Apr 2015

A Hybrid Controller For Stability Robustness, Performance Robustness, And Disturbance Attenuation Of A Maglev System, Feng Tian

Dissertations (1934 -)

Devices using magnetic levitation (maglev) offer the potential for friction-free, high-speed, and high-precision operation. Applications include frictionless bearings, high-speed ground transportation systems, wafer distribution systems, high-precision positioning stages, and vibration isolation tables. Maglev systems rely on feedback controllers to maintain stable levitation. Designing such feedback controllers is challenging since mathematically the electromagnetic force is nonlinear and there is no local minimum point on the levitating force function. As a result, maglev systems are open-loop unstable. Additionally, maglev systems experience disturbances and system parameter variations (uncertainties) during operation. A successful controller design for maglev system guarantees stability during levitating despite system …

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Dynamic Modeling Of Human Gait Using A Model Predictive Control Approach, Jinming Sun Apr 2015

Dynamic Modeling Of Human Gait Using A Model Predictive Control Approach, Jinming Sun

Dissertations (1934 -)

This dissertation aims to develop a dynamic model of human gait, especially the working principle of the central nervous system (CNS), using a novel predictive approach. Based on daily experience, it should be straightforward to understand the CNS controls human gait based on predictive control. However, a thorough human gait model using the predictive approach have not yet been explored. This dissertation aims to fill this gap. The development of such a predictive model can assist the developing of lower limb prostheses and orthoses which typically follows a trial and error approach. With the development of the predictive model, lower …

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Mechatronics Design Process With Energy Optimization For Industrial Machines, Aderiano Medeiros Da Silva Apr 2015

Mechatronics Design Process With Energy Optimization For Industrial Machines, Aderiano Medeiros Da Silva

Dissertations (1934 -)

The need for designing industrial machines with higher energy efficiency, reliability, flexibility, and accuracy has increased to satisfy market demand for higher productivity at reduced costs in a sustainable manner. As machines become more complex, model-based design is essential to overcome the challenges in mechatronic system design. However, a well-designed mechanical system with a well-designed and tuned control system are not sufficient for machines to operate at high-performance conditions; this also heavily depends on trajectory planning and the appropriate selection of the motors controlling the axes of the machine. In this work, a model-based design approach to properly select motors …

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Verification Of A Dual-State Extended Kalman Filter With Lidar-Enabled Autonomous Hazard-Detection For Planetary Landers, Peter Joseph Jorgensen Apr 2015

Verification Of A Dual-State Extended Kalman Filter With Lidar-Enabled Autonomous Hazard-Detection For Planetary Landers, Peter Joseph Jorgensen

Master's Theses (2009 -)

This thesis presents a mathematical model for a LIDAR-enabled Terrain- and Hazard-Relative Navigation sensor and the design and implementation of a dual-state extended Kalman filter. The extended Kalman filter equations are presented in summary. Mathematical models for an altimeter, a velocimeter, a star tracker, and a lidar-enabled mapping/tracking sensor are presented in depth. An explanation of the software designed for computer simulation is included. It is proved through this analysis that, when implemented as part of a well-tuned extended Kalman Filter and in combination with other sensors, the proposed model for a lidar-enabled mapping/tracking sensor significantly reduces estimation error. This …

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Solid Lubrication Bearing Design Through Analytical And Empirical Vibration Analysis Of Characteristic Frequencies, Christopher A. Schultz Apr 2015

Solid Lubrication Bearing Design Through Analytical And Empirical Vibration Analysis Of Characteristic Frequencies, Christopher A. Schultz

Master's Theses (2009 -)

Ball bearings with solid lubrication lack the damping mechanisms of oil and produce well-defined vibration characteristics based upon given geometry and speed of operation. This work takes advantage of the high signal to noise ratio in x-ray bearings and develops an algorithm to statistically track bearing performance based upon fundamental bearing theory, Monte Carlo simulation, Order Analysis, and Weibull statistics. The technique gathers vibration data solely related to the theoretical operation of a bearing, negates the background noise, and provides descriptive vibration amplitude statistics of individual bearing components for evaluation. The practical implications of the thesis described herein allow the …

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