Mechanical Engineering Commons^™

Novel Peridynamic Models For Material Degradation And Mass Transport, Jiangming Zhao

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

Fracture and corrosion are two major causes of structure failure. They can interact with each other, leading to faster material degradation. They are also under the influence of environmental conditions. The corrosion rate highly depends on the transportation rate of involving substances, while the fracture can be accelerated significantly due to fluid flow. These complex mechanisms involved in structure failure have troubled classical models for decades. The peridynamic (PD) theory introduced in 2000 has shown great potential in modeling such problems. In this work, we develop novel PD models for fracture, corrosion, mass transport, and viscous flow, which are building …

A Single Cell Pair Mechanical Interrogation Platform To Study Cell-Cell Adhesion Mechanics, Amir Monemianesfahani

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

Cell-cell adhesion complexes are macromolecular adhesive organelles that integrate cells into tissues. Perturbations of the cell-cell adhesion structure or relatedmechanotransduction pathways lead to pathological conditions such as skin and heart diseases, arthritis, and cancer. Mechanical stretching has been used to stimulate the mechanotransduction process originating from the cell-cell adhesion and cell-extracellular matrix (ECM) complexes. The current techniques, however, have limitations on their ability to measure the cell-cell adhesion force directly and quantitatively. These methods use a monolayer of cells, which makes it impossible to quantify the forces within a single cell-cell adhesion complex. Other methods using single cells or cell …

Toward An Understanding Of Fundamental Mechanisms In Transitional And Turbulence Flow Control, Ethan A. Davis

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

Turbulence is an emergent phenomenon found throughout nature and engineering, alike. It plays a vital role in the aquatic locomotion of organisms, scalar mixing, fluid transport, shipping and transportation, and even the flow of biological fluids in the human body. Therefore, it is of utmost importance in both a practical and engineering sense to better understand turbulence with the goal of better controlling it. This dissertation focuses broadly on better understanding the underlying mechanisms behind wall-bounded turbulent flows, with an emphasis on exploiting those mechanisms for turbulence flow control.

We developed a numerical simulation to study the effect of slip …

Thermomechanical Modeling In Laser Powder Bed Fusion Additive Manufacturing Using Graph Theory: Application To Prediction Of Recoater Crash, Md Humaun Kobir

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

This work pertains to the laser powder bed fusion (LPBF) additive manufacturing process. The objective of this thesis is to predict a frequently occurring type of thermal-induced process failure in LPBF called recoater crash. To ascertain the likelihood of a recoater crash before the part is printed, we develop and apply a computationally efficient thermomechanical modeling approach based on graph theory.

Despite its demonstrated ability to overcome the design and processing constraints of conventional subtractive and formative manufacturing, the production-level scaleup of LPBF is hindered by frequent build failures. For example, the part often deforms as it is being printed …

Development Of A Mash Tl-3 Compliant Parapet Mounted Fence, Luis Rodriguez Alvizo

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

When roadways pass over railway tracks, there is a risk that debris from the roadway or pedestrians may fall onto the tracks and interfere with railway operations. Because of this, state Departments of Transportation (DOTs) commonly install debris fences in conjunction with bridge rails over railway tracks. However, the safety performance of debris fence systems when impacted by an errant vehicle has not been demonstrated through full-scale crash testing. Thus, the objective of this research was to develop a new, parapet-mounted debris fence for the Iowa DOT according to safety performance guidelines included in the American Association of State Highway …

Reduced-Order Modeling Of Loosening In Bolted Joints And Dynamic Interactions Between Axially Aligned Threaded Joints, Sandro Aldana

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

Maintaining effective preload in bolted joints is critical for ensuring long-term performance and safety throughout the operation of any assembled structure. The loosening of bolted joints has been studied since the Industrial Revolution, but modeling approaches have only emerged over the past three decades. Although existing approaches are capable of simulating or predicting loosening in a single joint consisting of a single bolt, they are too computationally expensive to be used to model loosening in large structures consisting of many bolts. The objective of this thesis is to construct and employ a reduced-order modeling (ROM) approach that treats the internal …

Thermal & Mechanical Analysis Of Bombyx Mori Silk Nanofibers, Justin Busnot

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

This thesis presents a study on the thermomechanical properties of Bombyx Mori silk nanofibers. These nanofibers were obtained from silkworm cocoons which were degummed to separate the fibroin and the sericin, the two proteins that make up silk. The fibroin was then centrifuged to remove insoluble particles and stored and 4°C before the electrospinning process. A parametric study of the electrospinning process was carried out in order to identify the factors allowing to obtain optimal mechanical properties. The current as well as the flow rate applied, the diameter of the syringe, the distance separating the syringe from collector or even …

Novel And Fast Peridynamic Models For Material Degradation And Failure, Siavash Jafarzadeh

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

Fracture is one of the main mechanisms of structural failure. Corroded surfaces with chemically-induced damage are, notably, potential sites for crack initiation and propagation in metals, which can lead to catastrophic failure of structures. Despite some progress in simulating fracture and damage using classical models, realistic prediction of complex damage progression and failure has been out of reach for many decades. Peridynamics (PD), a nonlocal theory introduced in 2000, opened up new avenues in modeling material degradation and failure. Existing numerical methods used to discretize PD equations, however, are quite expensive as the PD nonlocal interactions make them unaffordable for …

Mash 2016 Test Level 3 And Test Level 4 Evaluation Of Roadside Safety Barrier With Pedestrian Features, Miguel Angel Hinojosa Palacios

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

The Minnesota Department of Transportation (MnDOT) desires to use a vehicle, bicycle, and pedestrian combination bridge railing system along pedestrian and bicycle bridge paths. The system was evaluated per MASH 2016.

In full-scale crash test no. MNPD-3, the system was evaluated according to MASH test designation no. 3-11. The 2014 Dodge Ram 1500 crew cab pickup truck impacted the system 71¼ in. upstream from the centerline of post no. 4 with a speed of 63.4 mph at an angle of 25.3 degrees. The combination railing system was found to meet the AASHTO MASH 2016 TL-3 impact safety criteria.

MnDOT uses …

Device Development For Long-Term Systemic Oral Biologic Drug Delivery, Benjamin Wankum

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

A biologic drug is a drug that is produced by a living organism. Biologic drugs are used to treat various medical conditions such as arthritis, diabetes, or certain forms of cancers due to their high potency and high selectivity of action. Drawbacks of biologics include their poor stability in the gastrointestinal tract and their poor absorption. In effect, this gives the drugs very low bioavailability and short therapeutic half-lives. To combat these obstacles, current delivery methods include subcutaneous injections at home or intravenous or intramuscular injections in a medical facility.

The overall scientific goal of the research was to utilize …

Development Of An Intraperitoneal Catheter Placement Device For Use On The Battlefield, Riley Reynolds

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

The objective of this project was to simplify peritoneal cavity access so an Airforce field medic can safely infuse oxygen microbubbles (OMBs) into the intraperitoneal space for the emergency treatment of hypoxia due to lung damage. To solve this problem, we created an intraperitoneal catheter placement device for use on the battlefield. The three common methods and some of the most common devices for peritoneal cavity access were reviewed. Injury frequencies for each of the three methods were analyzed. The results showed that each of the access techniques gives a similar rate of iatrogenic injury.

The battlefield conditions where the …

Evaluation Of Flared Approach Guardrail Transitions And Mash 2270p Ram Vehicle Model Improvements, Ryan F. Bickhaus

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

The objective of this research study was to use computer simulation to identify the critical flare rate for flaring approach guardrail transitions (AGTs) away from the primary roadway. AGTs installed with a flared configuration result in a length of need (LON) reduction as well as an increase in the clear zone area in front of the barrier, which would reduce both installation cost and crash frequency. The research focused on the determination of the maximum allowable flare rate that could safely be utilized with 31-in. (787-mm) tall thrie-beam AGTs without concrete curbs that utilize the Midwest Guardrail System (MGS) upstream …

In-Service Performance Evaluation And Installation Recommendations For Cable Median Barriers On Non-Continuously Shielded, Divided-Median Kansas Freeways, Nathan Dowler

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

The Kansas Department of Transportation (KDOT) installed 7.95 miles of cable median barrier (CMB) along K-10, K-96, and US-75 freeways in 2011 and 2012. In January 2020, KDOT funded a study to determine the in-service performance of its CMBs. In addition, KDOT sought to determine if it was cost-effective to modify guidelines for installing median barriers, which were based on annual daily traffic and median width.

Researchers reviewed every crash within approximately ¼ mile of a CMB installation and extracted crashes which involved a CMB impact. Researchers analyzed the critical details of each CMB crash, with particular emphasis on penetrations, …

On Road Coordinates For Autonomous Vehicle Guidance, Ricardo Jacome

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

A new roadmap framework is proposed to improve the guidance and trajectory prediction capabilities of connected and automated vehicles (CAVs). Independent of road shape determination through external sensors, the system serves as a backup for challenging conditions, such as low sensor visibility and adverse environmental effects (e.g., rain, fog, snow). Based on the fusion of vehicle dynamics principles, differential geometry, and road design standards, the roadmap framework provides a consolidated collection of critical reference points of roadway centerlines and information about the shape of the roadway in the vicinity of a vehicle, including curvature, optimal travel velocity, and road alignment …