Engineering Commons^™

Fluid Modeling And Analysis Of A Mash Tl-6 Vehicle Model, Elisa Vasquez

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

The objective of this research project was to replicate the dynamic behavior of a truck-tank trailer combination vehicle using representative dimensions, properties, and inertias of the trailer/fluid ballast combination. A literature review was completed describing techniques for modeling fluids and fluid-container interactions using finite element analysis. Various fluid modeling techniques were identified, and parameters associated with those models were archived. Next, researchers utilized the tank geometry of the elliptical straight-frame 5949 trailer produced by LBT Inc. to generate a finite element mesh using finite element analysis preprocessors HyperMesh and LS PrePost. Material properties were taken from reference guides, research papers, …

Toward Understanding Underlying Mechanisms Of Drag Reduction In Turbulent Flow Control, Alex Rogge

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

The underlying mechanisms of three different flow-control strategies on drag reduction in a turbulent channel flow are investigated by direct numerical simulations. These strategies include the addition of a small concentration of long-chain polymers into a fluid, the incorporation of slip surfaces, and the application of an external body force. While it has been believed that such methods lead to a skin-friction reduction by controlling near-wall flow structures, the underlying mechanisms at play are still not as clear. In this study, a temporal analysis is employed to elucidate underlying drag-reduction mechanisms among these methods. The analysis is based on the …

Machine Learning Augmentation Micro-Sensors For Smart Device Applications, Mohammad H. Hasan

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Novel smart technologies such as wearable devices and unconventional robotics have been enabled by advancements in semiconductor technologies, which have miniaturized the sizes of transistors and sensors. These technologies promise great improvements to public health. However, current computational paradigms are ill-suited for use in novel smart technologies as they fail to meet their strict power and size requirements. In this dissertation, we present two bio-inspired colocalized sensing-and-computing schemes performed at the sensor level: continuous-time recurrent neural networks (CTRNNs) and reservoir computers (RCs). These schemes arise from the nonlinear dynamics of micro-electro-mechanical systems (MEMS), which facilitates computing, and the inherent ability …

Wavelength Decomposition Of Hybrid Additive Manufacturing Power Signals And Their Relationship With Surface Integrity, Xingtao Wang

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Additive Manufacturing (AM) has been a promising manufacturing technology in industrial applications and gained a massive amount of attention from researchers all over the world. Directed Energy Deposition (DED) is an AM process in which focused thermal energy is used to fuse materials by melting as they are deposited. One of the most significant challenges involved in current metal AM processes is improving repeatability and consistency. Substantial effort has already been invested in this area of research.

In this dissertation, a milling tool not only played a role in subtractive manufacturing but also acted as a method of monitoring the …

In-Service Performance Evaluation Of Concrete Sloped End Treatments In Iowa, Jessica Lingenfelter

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Sloped end treatments were historically developed as low-cost, low-maintenance end treatments for rigid features like concrete barriers and bridge rails. Crash testing indicated that sloped end treatments are associated with significant instability for impacting vehicles. However, the in-service performance of these features has not been evaluated. An in-service performance evaluation (ISPE) was performed to evaluate vehicle crashes with sloped end treatments in Iowa between 2008 and 2017. Researchers generated a geographic inventory of sloped end treatment locations, reviewed crash narratives and scene diagrams for crashes near these sloped end treatments, and calculated an estimated crash rate and crash cost for …

Development Of A Novel Vehicle Guidance System: Vehicle Risk Mitigation And Control, Michael Sweigard

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Over a half of fatal vehicular crashes occur due to vehicles leaving their designated travel lane and entering other lanes or leaving the roadway. Lane departure accidents also result in billions of dollars in cost to society. Recent vehicle technology research into driver assistance and vehicle autonomy has developed to assume various driving tasks. However, these systems are do not work for all roads and travel conditions. The purpose of this research study was to begin the development a novel vehicle guidance approach, specifically studying how the vehicle interacts with the system to detect departures and control the vehicle

A …

Evaluation And Update Of Mash Test Vehicles, Kellon B. Ronspies

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

The Manual for Assessing Safety Hardware (MASH) requires full-scale crash testing of roadside features using worst practical impact conditions. Vehicle selection for full-scale crash testing is intended to be representative of the contemporary passenger vehicle fleet. Researchers at the Midwest Roadside Safety Facility (MwRSF) investigated attributes of passenger vehicle sales to determine if the vehicle selection criteria shown in MASH should be revised to accommodate changes in the vehicle fleet. A methodology was considered to affordably re-analyze the vehicle fleet when necessary to ensure MASH vehicle selection criteria are reflective of vehicles currently on roadways.

Representative vehicles were documented using …

Thermal Modeling Of Additive Manufacturing Using Graph Theory: Validation With Directed Energy Deposition, Jordan Severson

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Metal additive manufacturing (AM/3D printing) offers unparalleled advantages over conventional manufacturing, including greater design freedom and a lower lead time. However, the use of AM parts in safety-critical industries, such as aerospace and biomedical, is limited by the tendency of the process to create flaws that can lead to sudden failure during use. The root cause of flaw formation in metal AM parts, such as porosity and deformation, is linked to the temperature inside the part during the process, called the thermal history. The thermal history is a function of the process parameters and part design.

Consequently, the first step …

Anomalous Eutectic Microstructures In Mg-Al Structural Alloy Prepared By Rapid Solidification, Soodabeh Azadehranjbar, Jian Wang, Jeffrey E. Shield

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Magnesium is the lightest engineering metal 1 However, conventional Mg alloys typically suffer from low strength and poor deformability due to very few slip systems and easy twinning 3 Alloying Mg with other materials and microstructural engineering are promising approaches to increase ductility and strength of Mg In the current work, non equilibrium solidification conditions were applied to induce a transition from regular to anomalous eutectic in Mg Al eutectic alloy such that four distinguished microstructures were acquired and the corresponding formation mechanisms were investigated

On Geometric Design Rules And In-Process Build Quality Monitoring Of Thin-Wall Features Made Using Laser Powder Bed Fusion Additive Manufacturing Process, Aniruddha Gaikwad

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

The goal of this thesis is to quantify the link between the design features (geometry), in-process signatures, and build quality of parts made using the laser powder bed fusion (LPBF) additive manufacturing (AM) process. This knowledge is the foundational basis for proposing design rules in AM, as well as for detecting the impending build failures using in-process sensor data.

As a step towards this goal, the objectives of this work are two-fold:

1) Quantify the effect of the geometry and orientation on the build quality of thin-wall features. To explain further, the geometry related factor is the ratio of the …