Mechanical Engineering Commons^™

Investigation Into Strain Sensing With Reduced Graphene Oxide, And Applications In Low-Cost Leak Detection And Health Monitoring Of Water Equipment, Armin Yazdi

Theses and Dissertations

Strain gauges are one of the most important transducers that can be used in many applications such as robotics, structural health monitoring, medicine etc. The expensive mass production, as well as lack of high sensitivity, high strain tolerance or high quality can be some of the challenges with the current strain gauges. The reduced graphene oxide possesses many of the excellent properties of graphene while being easy and inexpensive to be mass-produced. However, its electromechanical behavior under strain (especially large strains) has not been well studied. In this dissertation, strain sensing by reduced graphene oxide with Polydimethylsiloxane substrate is investigated …

Bonding Evaluation Of Graphene-Oxide Layers On Flexible Substrates, Maysam Rezaee

Theses and Dissertations

Flexible electronics are getting interest in development of field effects transducers such as biomedical health screening tools, structural health monitoring in infrastructures, aerospace, vehicular industries and cell phones. As a promising candidate for flexible electronics, graphene-based devices have been developed through exceptional electrochemical and thermomechanical properties of graphene. Reducing the graphene oxide enables creation of large scale devices through its high manufacturability. Same as other types of electronics, the bonding of sensing units to the substrate is significantly dependent to the deposition method used for the fabrication of device. In this study, the mechanical strength of reduced graphene oxide (rGO) …

Numerical And Experimental Investigation Of Aeration Self Mixing By Using Pulsating And Continuous Air Flow, Ahmed Ali Alkhafaji

Theses and Dissertations

Wastewater treatment is considered one of the most common forms of pollution control in the united states. Considered as an integral part of the wastewater treatment, the aeration process is the most energy-consuming process among all the processes that take place in any wastewater treatment plant. According to the United States Environmental Protection Agency (EPA), a wastewater treatment plant is expected to remove at least 85% of the suspended solids and dissolved organic compounds from the wastewater before discharging it to a river or a lake. The normal operation of the aeration process is by compressing air continuously to basin …

Application Of Survival Analysis Techniques To Probabilistic Assessment Of Fatigue In Steel Bridges, Azam Nabizadehdarabi

Theses and Dissertations

The fatigue of engineering materials under repetitive loading is a significant issue affecting the design and durability of components and systems in a variety of engineering-related applications including civil, mechanical, aerospace, automotive, and electronics. Many factors can affect the service life of a component or system under repetitive loading, such as the type of structure, loading, connection details, stress state, peak stress or stress range, surface condition, temperature, and environmental exposure. Currently, there is no comprehensive probabilistic approach that can systematically address all the factors that contribute to fatigue on a single mathematical platform. However, advanced analysis techniques developed for …

Structural Health Monitoring Of Laminate Structures Using Shear-Mode Piezoelectric Sensors, Hussain Altammar

Theses and Dissertations

Structural health monitoring (SHM) employing embedded piezoelectric transducers has shown potential as a promising solution for inspection of different engineering structures such as aircraft, bridges, and renewable energy structures. Despite advancements in the field of ultrasonic SHM, inspection of laminate structures is still a major challenge due to their susceptibility to various joint defects. This thesis presents a novel approach to tackle the challenge of inspecting laminate structures using shear-mode (d35) piezoelectric transducers that are made of lead zirconate titanate (PZT).

This study begins with the characterization of d35 piezoelectric transducers using analytical, numerical, and experimental approaches. The results were …

Dynamic Moving Load Identification Using Optimal Sensor Placement And Model Reduction, Paul Augustine

Theses and Dissertations

A structure in service can be subjected to static, dynamic or moving loads. Several situations in practice involve estimation of moving loads which induce vibrations in the structure on which they are applied. An accurate estimation of these loads will ensure product quality and reliability of the final design, and mitigate the cost of structural health monitoring systems. The moving nature of dynamic loads increases the computational difficulty of the problem. One of the types of Inverse Problems involves estimation of the applied load from measured structural response such as strain or accelerations.

Measuring response at a limited number of …

Damage Detection Of Mixed-Mode Cracks In Large Truss Structures Using Wavelet Transform, Hussain Altammar

Theses and Dissertations

The use of dynamic response in damage identification has been gaining considerable attention over the last two decades. The aim of these methods is to detect the presence of a defect or a crack in components or structures. This study focuses on using modal properties for the damage detection of mixed-mode cracks in truss structures. The behavior of a mixed-mode crack is simulated by developing a macroscopic model that is integrated with the finite element model of a truss structure. The modal properties obtained from the model of the damaged structure are found to be comparable to the results of …

Aqueous Turbulence Structure Immediately Adjacent To The Air - Water Interface And Interfacial Gas Exchange, Binbin Wang

Theses and Dissertations

Air-sea interaction and the interfacial exchange of gas across the air-water interface are of great importance in coupled atmospheric-oceanic environmental systems. Aqueous turbulence structure immediately adjacent to the air-water interface is the combined result of wind, surface waves, currents and other environmental forces and plays a key role in energy budgets, gas fluxes and hence the global climate system. However, the quantification of turbulence structure sufficiently close to the air-water interface is extremely difficult. The physical relationship between interfacial gas exchange and near surface turbulence remains insufficiently investigated. This dissertation aims to measure turbulence in situ in a complex environmental …