Mechanical Engineering Commons^™

Computational Comparison Of Medializing Tibial Tubercle Osteotomy And Trochleoplasty In Patients With Trochlear Dysplasia, Clare K. Fitzpatrick, Robert N. Steensen, Oliver Alvarez, Amy E. Holcomb, Paul J. Rullkoetter

Mechanical and Biomedical Engineering Faculty Publications and Presentations

Medial patellofemoral ligament reconstruction (MPFLR) has emerged as the procedure of choice for recurrent patellar dislocation. This addresses soft tissue injury but does not address underlying anatomic factors, including trochlear dysplasia, that are commonly present and increase risk of dislocation. Quantification of the stability offered by other surgical interventions, namely, medializing tibial tubercle osteotomy (mTTO) and trochleoplasty, with and without MPFLR, may provide insight for surgical choices in patients with trochlear dysplasia. We developed subject-specific finite element models based on magnetic resonance scans from a cohort of 20 patients with trochlear dysplasia and recurrent patellar dislocation. The objectives of this …

Experimental And Numerical Investigation Of Fluid Flow Behavior Through Fractured Wellbore Cement, Mahya Hatambeigi

Civil Engineering ETDs

Leakage from wellbores has been a major challenge in the energy industry, leading to groundwater contamination, reduced productivity, safety hazards, and increased operating costs. Cemented annulus fractures are a common type of leakage pathway in wellbores that can form due to various physical and chemical conditions. The number of wellbore leaks continues to increase globally, making it imperative to develop a better understanding of the complex mechanisms governing fluid flow through fractured wellbore cement. Understanding the behavior of fluid flow through a leaky cemented annulus is crucial for evaluating the leakage potential and risk assessments in wellbore systems, as well …

Influence Of Swirl And Turbulence In The Particle Removal Using Fog In A Pipe Flow, Nisarg T. Patel

All Theses

Fog-and-tube scrubbers are employed to remove harmful ultrafine aerosols, such as Diesel particulate matter (DPM), from an airflow. The underlying principle of this removal process involves enlarging the aerosol particles by coagulating them with fog drops, which are subsequently eliminated through inertial impaction onto the tube wall. Previous research conducted by Tabor et al. (2021) demonstrated an increase in scavenging of ultrafine DPM particles, ranging from 11.5 nm to 154 nm, by as large as 45% over the no fog case. This finding is crucial in addressing the challenges associated with conventional filtration methods for capturing ultrafine particles.

The present …

Investigation Of Pool Boiling Heat Transfer On Modified Copper And Aluminum Surfaces, Mariam Khaled Zaghloul

Theses

This thesis presents an investigation of pool-boiling heat transfer using the surfacemodification method. The studied boiling surfaces were smooth and rough pin-fins embedded on the copper and aluminum surfaces. This study visualizes bubble formation and departure diameter. Experimental testing aims to predict the heat transfer coefficients for different heat fluxes over smooth and rough pin-finned surfaces. The surface modification method allows changing the boiling surface characteristics, which can lead to enhanced heat transfer. Several factors were studied, including the heat-transfer coefficient, heat flux, bubble departure diameter, and formation time. Four surfaces were used for conducting the pool boiling experiment: a …

Laser-Induced Forward Transfer (Lift) Based Bioprinting Of The Collagen I With Retina Photoreceptor Cells, Md Shakil Arman, Ben Xu, Andrew Tsin, Jianzhi Li

Manufacturing & Industrial Engineering Faculty Publications

This study focuses on the 3D bioprinting of retina photoreceptor cells using a laser-induced forward transfer (LIFT) based bioprinting system. Bioprinting has a great potential to mimic and regenerate the human organoid system, and the LIFT technique has emerged as an efficient method for high-resolution micropatterning and microfabrication of biomaterials and cells due to its capability of creating precise, controlled microdroplets. In this study, the parameters for an effective femtosecond laser-based LIFT process for 3D bioprinting of collagen biomaterial were studied. Different concentrations of collagen I solutions were tested and 0.75 mg/ml to 1 mg/ml collagen Ⅰ was identified as …

Development, Experimental Validation, And Progressive Failure Modeling Of An Ultra-Thin High Stiffness Deployable Composite Boom For In-Space Applications, Jimesh D. Bhagatji

Mechanical & Aerospace Engineering Theses & Dissertations

To maximize the capabilities of nano- and micro-class satellites, which are limited by their size, weight, and power, advancements in deployable mechanisms with a high deployable surface area to packaging volume ratio are necessary. Without progress in understanding the mechanics of high-strain materials and structures, the development of compact deployable mechanisms for this class of satellites would be difficult. This research focuses on fabrication, experimental testing, and progressive failure modelling to study the deformation of an ultra-thin composite beam. The research study examines deformation modes of a boom under repetitive pure bending loads using 4-point bending setup. The material and …

Chemical And Physical Interaction Mechanisms And Multifunctional Properties Of Plant Based Graphene In Carbon Fiber Epoxy Composites, Daniel W. Mulqueen

Mechanical & Aerospace Engineering Theses & Dissertations

Graphene has generated substantial interest as a filler due to its exceptional strength, flexibility, and conductivity but faces obstacles in supply and implementation. A renewable, plant-based graphene nanoparticle (pGNP) presents a more accessible and sustainable filler with the same properties as mineral graphenes. In this study, the mechanisms of graphene reinforcement in carbon fiber reinforced plastic (CFRP) were examined, along with the resulting improvements to mechanical strength, resistance to crack propagation, electrical and thermal conductivity at elevated temperatures. pGNP, produced from renewable biomass, was shown to have a graphitic structure with flakes 3-10 layers thick and a median lateral size …

The Effect Of Deployment And Optimal Dispatch Of Shared Electric Shuttles On The Energy Efficiency Of Campus Transit, Robert Smith

All Theses

A problem facing most public transit systems is low energy efficiency and the continued cycling of large transport vehicles such as buses at low occupancy when low demand for transport exists, wasting energy to no benefit. To remedy this issue, we propose a hybrid system consisting of existing diesel buses and automated electric shuttles to augment the system during off-peak hours. Due to their smaller size, higher occupancy, and more efficient powertrains, these shuttles could reduce the system energy used per passenger-mile-traveled. Automation removes the labor cost of drivers and, thus, eliminates the need to employ more drivers for the …

The Influence Of Diversity Dimensions On Student’S Collaboration Success: What It Means For Workforce Development In Manufacturing, Oyinkansola Adeite

All Theses

Manufacturing productivity is measured by labor productivity which is the hourly output of the manufacturing economy. The recent reduction in productivity numbers by the United States Bureau of Labor Statistics emphasizes the need for workforce development. With globalization and technological advancements, diversity has emerged as a critical aspect for the workplace. By encompassing dimensions such as education, race, and age, diversity creates a tapestry of unique perspectives and experiences. This study’s aim is to figure out the effect of a diversity dimension on team performance using intelligent systems, and in addition, if extra dimensions of diversity further impact team performance. …

A Unit-Load Approach For Reliability-Based Design Optimization Of Linear Structures Under Random Loads And Boundary Conditions, Robert James Haupin, Gene Jean-Win Hou

Mechanical & Aerospace Engineering Faculty Publications

The low order Taylor’s series expansion was employed in this study to estimate the reliability indices of the failure criteria for reliability-based design optimization of a linear static structure subjected to random loads and boundary conditions. By taking the advantage of the linear superposition principle, only a few analyses of the structure subjected to unit-loads are needed through the entire optimization process to produce acceptable results. Two structural examples are presented in this study to illustrate the effectiveness of the proposed approach for reliability-based design optimization: one deals with a truss structure subjected to random multiple point constraints, and the …

Multiscale Modeling And Gaussian Process Regression For Applications In Composite Materials, Joshua Arp

All Dissertations

An ongoing challenge in advanced materials design is the development of accurate multiscale models that consider uncertainty while establishing a link between knowledge or information about constituent materials to overall composite properties. Successful models can accurately predict composite properties, reducing the high financial and labor costs associated with experimental determination and accelerating material innovation. Whereas early pioneers in micromechanics developed simplistic theoretical models to map these relationships, modern advances in computer technology have enabled detailed simulators capable of accurately predicting complex and multiscale phenomena.

This work advances domain knowledge via two means: firstly, through the development of high-fidelity, physics-based finite …

Investigation Of Fatigue Response With Analytical And Machine Learning Models And Hygroscopic Analysis Of Asymmetric Bistable Cfrp Composites, Shoab Ahmed Chowdhury

All Dissertations

Asymmetric bistable carbon fibre reinforced plastic (CFRP) composites enable a broad range of applications as they can sustain multiple stable configurations and have small snap-through load requirements. These unique features, coupled with their light strength-to-weight and stiffness-to-weight ratios, have made them preferred options for multifunctional systems. This study investigates the fatigue and hygroscopic response of 2-ply, [0/90] bistable CFRP laminates and proposes predictive modeling approaches for improved performance.

While previous studies widely researched and documented the fatigue of general composites in axial loading, fatigue analysis of asymmetric bistable composites in the out-of-plane snap-through direction is inadequate. This study performs fatigue …

Co-Simulation Of Active Magnetic Bearing Rotors Using Adams, Msc Apex, And Simulink, Shea A. Charkowsky

Master's Theses

Apex-Adams-Simulink co-simulation is applied to active magnetic bearing (AMB) rotors, demonstrating results unshown in literature, including continuous frequency response, and unavailable in known rotor dynamics software, including touchdown bearing impact. AMBs levitate rotors without contact, so they involve no friction, wear, lubrication, pollution, or shaft speed limits and are thus valuable for large, high-speed applications. Modeling of such rotors, necessary for safety and performance, simultaneously requires flexible body dynamics and advanced control design, but simulation programs tend to specialize in only one or the other. The co-simulation method combines multiple such programs—MSC Apex (finite element modeling), Adams (multibody dynamics), and …

Theoretical And Experimental Study Of Active Magnetic Bearing Control Integrated On Bently's Rotor Kit, Arturo Mario Flores

Master's Theses

This thesis focuses on the comprehensive study of controlling a customized Active Magnetic Bearing (AMB) installed on Bently Nevada’s RK4 rotor kit in Cal Poly’s Vibrations and Rotordynamics Lab. The AMB was uniquely designed and manufactured by a Cal Poly senior project team to fit Bently’s rotor kit and the results of this research are distinctive to the custom system. To achieve practical functionality of the AMB system, we designed a controller a Virtual Instrument (VI) using the National Instrument software, LabVIEW. From the experimental study, we calibrated the programming to find unknown parameters of the AMB system and validated …

Trust-Based Runtime Verification Of Autonomous Robotic Systems, Maziar Fooladi Mahani

All Dissertations

 Trust plays a crucial role in enabling effective collaboration and decision-making within human-multi-robot teams. In this context, runtime verification techniques and trust inference models have emerged as valuable tools for assessing and quantifying the trustworthiness of individual robots. This dissertation presents a study on trust-based runtime verification and introduces a Bayesian trust inference model for human-multi-robot teams. Firstly, we discuss the concept of runtime verification, which involves monitoring and analyzing the behavior of robots during their operation. We highlight the importance of trust as a key factor in determining the reliability and credibility of robot actions. By integrating trust metrics …

Measurement Of Conduction, Radiation, And Convection Thermal Energy To Assess Baking Performance In Residential Ovens., Sean Simpson

Electronic Theses and Dissertations

Residential ovens are complicated thermal environments capable of delivering convection, conduction, and radiation heat transfer to food. The amount and mode of heat transfer can change based on the design of the oven cavity, cooling systems, and oven cycle algorithms. Studies have shown that the changes in one heat transfer mode can have an impact on the quality of baked goods. The many variables involved make designing residential ovens a time consuming and costly process. The goal of this study is to adapt thermal energy sensing technology to collect energy data from a residential oven and develop correlations to quality …

Aerodynamic Flow Control Using Micro Rotating Cylinders, Alejandro Daniel Carrizales

Theses and Dissertations

This research investigates the aerodynamic and flow field characteristics of a NACA 0010 airfoil equipped with rotating cylinders near the leading edge, subjected to a flow with a freestream turbulence intensity of 4.3%. The airfoil was modified to integrate five micro-DC motors positioned at 14.5% of the chord length from the leading edge. The cylinders, with dimensions of 0.75 inches in diameter and 0.5 inches in width, exposed 3mm of their length to the incoming flow. A modified leading edge with eight sinusoidal protrusions (tubercles) was employed to compare the performance of the micro-rotating cylinder airfoil with an unmodified baseline …

Phase Stability Of Lead Phosphate Apatite, Jiahong Shen, Dale Gaines Ii, S. Shahabfar, Zi Li, Dohun Kang, Sean Griesemer, Adolfo Salgado-Casanova, Tzu-Chen Liu, Yi Xia, Multiple Additional Authors

Mechanical and Materials Engineering Faculty Publications and Presentations

Recently, Cu-substituted lead apatite LK-₉₉ was reported to have room-temperature ambientpressure superconductivity. Here we utilize density functional theory (DFT) total energy and harmonic phonon calculations to investigate the thermodynamic and dynamic stability of two lead phosphate apatites in their pure and Cu-substituted structures. Though Pb₁₀(PO₄)₆O and Pb₁₀(PO₄)₆(OH)₂ are found to be thermodynamically stable (i.e., on the T=₀K ground state convex hull), their Cu-substituted counterparts are above the convex hull. Harmonic phonon calculations reveal dynamic instabilities in all four of these structures. Oxygen vacancy formation …

Double Cantilever Beam Mode-I Testing Validation In Large-Scale Additive Manufacturing Carbon Composite, Luis Alfonso Camacho

Open Access Theses & Dissertations

Testing for mechanical properties for additive manufacturing has been based on already existing standards for traditional manufacturing methods. For composites in large scale additive manufacturing there is a research gap in bond strength and fracture toughness for a single layer interface. By using Double cantilever beam Mode I, this thesis manuscript validates testing parameters and protocols to describe the intricacies of ABS matrix 20 wt.% carbon filled composite, specifically on the layer-to-layer interface. Studies suggest that fracture toughness is sensitive to process parameters, like deflection speed and sharpened crack tip at the layer interface of BAAM 3D printed part and …

The Effects Of Process Parameters On The Cyclical Life Of Ti-6al-4v Manufactured Via Laser Powder Bed Fusion, Brandon Ramirez

Open Access Theses & Dissertations

Additive manufacturing via Laser Powder Bed Fusion (LPBF) has already proven revolutionary technology. Due to its favorable strength-to-weight ratio, ti-6Al-4V, a popular titanium alloy, has already been implemented in the aerospace industry for various components. However, the quality validation in additively manufactured parts has always been an issue of concern, specifically under cyclic loading. Ti-6Al-4V samples were printed using LPBF with various process parameters to investigate these conditions further. The build was stress-relieved; however, the samples underwent no other post-processes maintaining their as-built surface. The process parameters were separated into five categories, including various laser powers and printing speeds, allowing …

Geometrical And Surface Texture Characterization For Laser Powder Bed Fusion Process, Jesus Alfredo Rivas

Open Access Theses & Dissertations

Laser powder bed fusion (LPBF) is one of the most widely used additive manufacturing (AM) methods for metal parts. Geometrical tolerances required for industry applications are determined by geometrical measuring methods and process capability calculations. However, geometry characterization presents challenges for LPBF because measuring uncertainty values are not defined and the standardized measurement framework Geometric Tolerancing and Dimension (GD&T) is not fully adopted.

Measurement uncertainty is influenced by this process's high surface roughness (10 µm < Ra ⩽ 80 µm). As an example, when using multiple probing points or scanning pathways on a LPBF surface with the most accurate (+/- 0.004 mm) and traceable measurement method, the coordinate measuring machine (CMM), the results can vary by up to 0.050 mm to 0.070 mm. This measurement uncertainty leads to an imprecise benchmark reference for comparison with optical or X-ray computed tomography (XCT). These measurement variations also make it difficult to accurately characterize parts for automotive, aerospace, medical and other high-tech industries, such as a turbine blade geometry used in aircraft engines with a blade height tolerance of +/- 0.15 mm, which required a measurement uncertainty less than 30% of the tolerances. Mechanical properties such as tensile testing assessments useful in comparisons of materials, alloy development, quality control, and design under certain circumstances are also affected by this imprecise geometry characterization. Overestimating the diameter of the ASTM E8 sample by 0.100 mm can make up to a difference in stress results of 7%.

This research aimed to evaluate various measurement approaches (contact and non-contact) for surface texture and geometrical size dimension characterization and provide information regarding measurement uncertainty …

Measurement Of Vapour Pressure, Miscibility And Thermal Conductivity For Binary And Ternary Refrigerant Lubricant Mixtures In The Context Of Heat Pump Tumble Dryers, Katharina Stockel, Ramona Nosbers, Riley Barta, Christiane Thomas

School of Mechanical Engineering Faculty Publications

Household appliances need to be both efficient and cost-effective. As a result, electrically driven tumble dryers were converted to heat pump driven ones several years ago in order to comply with energy directives, in this case in Germany. In order to increase the efficiency of heat pumps of different performance classes, the use of zeotropic refrigerant mixtures can be useful, since the temperature glide during the phase change of the refrigerant mixture can be adapted to the temperature gradients of the secondary fluids. In order to take advantage of this unique property, a refrigerant mixture selection was carried out by …

Design And Implementation Of A Load Sensor In A Bearing Adapter Assembly For Freight Railcar Applications, Prince E. Mensah

Theses and Dissertations

The U.S. freight rail network, which covers approximately 140,000 route miles, is commonly regarded as the largest, safest, and most economical freight system in the world. It generates more than 167,000 jobs nationwide and has additional advantages over other modes of transportation, such as lower costs for logistics, public infrastructure upkeep, and decreases in traffic congestion, highway deaths, fuel consumption, and greenhouse gas emissions. Knowing the exact weight of cargo hauled by freight railcars can help avoid exceeding the loading thresholds set by the Association of American Railroads (AAR). Moreover, knowing the exact load applied to each bearing on the …

Vibration-Based Machine Learning Models For Condition Monitoring Of Railroad Rolling Stock, Sergio M. Martinez

Theses and Dissertations

One of the primary causes of rail rolling stock derailments is attributed to bearing and wheel axle failures. The health of train bearings is primarily monitored at target locations through wayside detection systems. This practice is susceptible to bearing failure and potential derailments at points in between these wayside systems. To remedy this, the University Transportation Center for Railway Safety (UTCRS) has developed a wireless onboard monitoring system that can continuously monitor the vibration response, which directly correlates to the health of bearings. This data is used to train regression-based machine learning algorithms and long-term prediction neural networks to predict …

Two-Dimensional Nanomaterials And Nanocomposites For Sensing, Separation, And Energy Applications, Md Ashiqur Rahman

Theses and Dissertations

Two-dimension (2D) nanomaterials have gained popularity for the last few decades due to their excellent mechanical, electrical and thermal properties. These unique properties of 2D nanomaterials can be exploited in various applications specially in sensor, energy, and separation devices. In this study, the sensing and energy generation performance of PVDF/PAni fiber mat systems made by the forcespinning method with and without graphene coating. The graphene-coated nanocomposites show an average output voltage of 75 mV (peak-to-peak) which is 300% higher compared to bare fiber mats and an output current of 24 mA (peak-to-peak) by gentle finger pressing. Moreover, the graphene-coated PVDF/PAni …

Developing Control System For Manufacturing Processes, Md Shahriar Forhad

Theses and Dissertations

Process control has been a critical component in today's manufacturing industry. Industrialists nowadays want reliable control to assure precision manufacturing. Modern control systems must be more dynamic, so that any needed modifications may be made quickly to accomplish the desired product change. For innovative research and development, system customization is critical to ensure freedom for experimental works. In addition, full control of manufacturing systems is necessary to realize and implement Industry 4.0. Often, it is difficult to achieve such control due to limited access to proprietary equipment. To this end, this thesis focuses on developing a custom control platform for …

Integrated Energy-Aware Motion Planning And Charge Scheduling Of Unmanned Aerial Vehicles, Hayleyesus Alemayehu

All Theses

The growing demand for unmanned aerial vehicles (UAVs) is driven by their operational convenience, cost-effectiveness, availability, and adaptability to various scenarios. In energy-constrained environments, optimizing energy consumption and ensuring a continuous power supply for UAVs is crucial for mission success. The objective of this thesis is to address this issue by integrating energy-aware motion planning and charge scheduling for UAVs by utilizing a charger hosted on an unmanned ground vehicle (UGV), whose rendezvous locations and routes are jointly computed to minimize overall energy consumption.

This thesis proposes a hierarchical trajectory and control framework comprising local and global planners for each …

Characterization Of Mechanically Recycled Polylactic Acid (Pla) Filament For 3d-Printing By Evaluating Mechanical, Thermal, And Chemical Properties And Process Performance, Mahsa Shabani Samghabady

All Theses

Polylactic acid (PLA) is a biopolymer made from renewable resources such as sugar and corn. PLA filament is a popular material used in Fused Deposition Modeling (FDM) 3D-printing. While this material has many advantages, all the failed parts, support structures, rafts, nozzle tests, and the many prototype iterations during the 3D-printing process contribute to the plastic pollution and release of greenhouse gases. Although PLA is biodegradable, it can take years to degrade in landfills. Instead of throwing away PLA waste and buying new filaments, PLA can be recycled. Amongst the different recycling technologies, mechanical recycling is the most environmentally friendly. …

Dynamics And Steering Of A Vibration-Driven Bristle Bot In A Pipe System, Ian Stewart

All Theses

Soft vibrational robots are robots that incorporate compliant structures into their design and are driven by oscillating actuators. A recent, popular version of a soft vibrational robot is the bristle bot, which uses flexible bristles and a vibration motor to propel itself across surfaces and through pipes. This motion is primarily driven by stick-slip dynamics resulting from asymmetric frictional forces applied at the bristle tips. Depending on the frequency of vibration of the motor, the robot experiences various resonance regions allowing it to maneuver in different directions. Attaching bristles to all sides of the robot and placing it in a …

Development Of Pre-Magnetized Magnetorheological Elastomer For Bidirectionally Variable Stiffness Applications, Choonghan Lee

UNLV Theses, Dissertations, Professional Papers, and Capstones

Magnetorheological elastomers (MREs) utilize magnetic forces between ferromagnetic particles to cause variable stiffness properties and damping with external magnetic fields. In the MREs, the particles are embedded in a cured elastomer matrix, and an external magnetic field makes the stiffness change due to induced magnetic forces among particles. A disadvantage of the conventional MREs is that they cannot be softened (reduced stiffness) under an external magnetic field. Considering that there are many engineering applications where fast changes of stiffness in both directions (stiffening and softening) are required, embedding magnetically biased particles in the MRE can provide potential solutions. In this …