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Articles 1 - 14 of 14
Full-Text Articles in Entire DC Network
Retrofit Of Corroded Corrugated Metal Culverts Using Gfrp Slip-Liner, Rahulreddy Chennareddy
Retrofit Of Corroded Corrugated Metal Culverts Using Gfrp Slip-Liner, Rahulreddy Chennareddy
Civil Engineering ETDs
Culverts are water conveyance structures, typically used to allow water flow and maintain a balance between the flow streams without interrupting structures such as highways and bridges. Corrugated metal pipes (CMPs) have been used as culverts in North America since the 1950s because of their low cost and simple construction method. Today, the corrosion of CMPs is a major problem faced by all U.S. Departments of Transportation. There is an urgent need to provide an efficient solution, one that is corrosion-resistant, to retrofit thousands of corroded CMPs across the country. High specific strength, high strength to weight ratio, corrosion resistance, …
Multi-Scale Analysis Of Multifunctional Composites And 3d Printed Polymers, Daniel Branden Perez
Multi-Scale Analysis Of Multifunctional Composites And 3d Printed Polymers, Daniel Branden Perez
Open Access Dissertations
Methods of multi-scale analysis through combined physical testing and computational FEM were used to investigate structural battery composites and 3D printed polymers. Multifunctional composite structural batteries are materials capable of storing electrical energy while providing structural rigidity. Two battery cell configurations were considered: a carbon paper based cell with copper and aluminum foils, and a woven carbon fiber-based battery with nickel and iron deposition coatings. Flexural simulations were performed through simulated and physical three-point bend testing. Unidirectional carbon fiber layers in the place of the carbon paper can lead to up to a 233.73 GPa stiffness, significantly greater than the …
Amorphous-Crystalline Brush Block Copolymers: Phase Behavior, Rheology And Composite Design, Gayathri Kopanati
Amorphous-Crystalline Brush Block Copolymers: Phase Behavior, Rheology And Composite Design, Gayathri Kopanati
Doctoral Dissertations
Bottlebrush block copolymers are polymers with chemically distinct polymer side chains grafted onto a common backbone. The unique architecture induced properties make these materials attractive for applications such as photonic materials, stimuli responsive actuators and drug delivery vehicles to name a few. This dissertation primarily investigates the phase transitions and rheological behavior of amorphous-crystalline bottlebrush brush block copolymers and their composites. The temperature induced phase behavior is investigated using time resolved synchrotron X-ray source. Irrespective of volume fraction and backbone length, the samples display strong segregation even at high temperatures (200 °C) and there is no accessible order-disorder transition in …
Molecular Weight And Thermal Properties Of Fiber Reinforced Polyamide-Based Composites Throughout The Direct Long-Fiber Reinforced Thermoplastic Process, Mingyu Yang
Electronic Thesis and Dissertation Repository
The D-LFT process is an efficient and cost-effective process and includes two twin-screwextruders, a conveyer, and a compression molding machine. It is imperative to understand how the process sequence affects molecular weight and thermal properties of composite materials during the D-LFT process. The main objective of this study was to characterize variation in molecular weight and thermal properties of two types of polyamide (PA)-based composite materials (glass fiber reinforced PA6 composites and carbon fiber reinforced PA66 composites) through the D-LFT process. Samples were taken from different locations along the D-LFT process and characterized using triple detection gel permeation chromatography (GPC), …
Adaptive Paddle Board, Alexander Holthaus, Alexander Holthaus, Garrett Holmes, Garett Jones
Adaptive Paddle Board, Alexander Holthaus, Alexander Holthaus, Garrett Holmes, Garett Jones
Mechanical Engineering
This Final Design Review (FDR) document outlines the Adaptive Paddle Board senior project, done by four Mechanical Engineering Students at California Polytechnic State University and provides detail on the project and what the team has accomplished. The goal was to create a universally adaptive paddle board that can be used by the Central California Adaptive Sports Center for a wide range of persons with disabilities. This document highlights current research from patents and existing products, details regarding customer specifications, results from concept generation, the manufacturing and testing that went into the final design, and the process taken to get there. …
Structural Health Monitoring Of Composite Parts: A Review, Jacob Pessin
Structural Health Monitoring Of Composite Parts: A Review, Jacob Pessin
Honors Theses
Structural health monitoring has the potential to allow composite structures to be more reliable and safer, then by using more traditional damage assessment techniques. Structural health monitoring (SHM) utilizes individual sensor units that are placed throughout the load bearing sections of a structure and gather data that is used for stress analysis and damage detection. Statistical time based algorithms are used to analyze collected data and determine both damage size and probable location from within the structure. While traditional calculations and life span analysis can be done for structures made of isotropic materials such as steel or other metals, composites …
C6 Wheels, Samuel L. Pizot, Luke Martin, Josh Warner, Jonah Levis
C6 Wheels, Samuel L. Pizot, Luke Martin, Josh Warner, Jonah Levis
Mechanical Engineering
This document details the C6 Wheels project being undertaken for senior design. The objective is to design and manufacture carbon fiber reinforced polymer wheels for the Cal Poly Formula Society of Automotive Engineers (FSAE) team. The wheel shells will be used on FSAE’s competition vehicles. FSAE requested the wheels to improve the handling characteristics of their vehicles by reducing the unsprung and rotational mass. They have attempted carbon fiber wheels previously but have not yet run any on their vehicles. FSAE specifically proposed the design of carbon fiber shells with an aluminum center as opposed to full carbon fiber wheels …
Micromechanics-Enriched Finite Element Modeling Of Composites With Manufacturing Or Service-Induced Defects, Alden S. Hyde
Micromechanics-Enriched Finite Element Modeling Of Composites With Manufacturing Or Service-Induced Defects, Alden S. Hyde
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
Composite materials are increasingly used in many industries due to the high strength and low weight properties that they exhibit. Since composites are becoming more popular, they are being used in applications such as aircraft, boats, wind turbine blades, and even sports equipment. Composite behavior is complicated since they are made up of two completely different materials such as strong thin fibers and a relatively weaker resin material that hold the fibers together. It is becoming more important to understand how composites behave in different situations so that equipment designers have reliable material information in order to design safe products …
Silk Fibroin And Hydroxyapatite Composites For Bioresorbable Bone Fixation Devices, Bryant Heimbach
Silk Fibroin And Hydroxyapatite Composites For Bioresorbable Bone Fixation Devices, Bryant Heimbach
Doctoral Dissertations
Every year there are approximately 9 million bone fractures in the United States, and 30% of these require an internal fixation device to help heal. Currently, the gold standard for fixation devices relies on the use of metals because of their high mechanical properties and bioinertness. However, metal implants often require a second surgery to remove them because they cause stress shielding and metal ion leaching. Current bioresorbable fixation devices on the market have poor mechanical properties and are limited to use in non-load-bearing applications (i.e. maxillofacial fractures). As such, there remains a gap in the fracture fixation devices on …
Investigation Of Design, Manufacture, Analysis, And Test Of A Composite Connecting Rod Under Compression, Thomas Juhl Rohrbach
Investigation Of Design, Manufacture, Analysis, And Test Of A Composite Connecting Rod Under Compression, Thomas Juhl Rohrbach
Master's Theses
Composite materials hold great potential for the replacement of traditional materials in machines utilized on a daily basis. One such example is within an engine block assembly where massive components inherently reduce the efficiency of the system they constitute. By replacing metal elements such as connecting rods, cylinder caps, or a crank shaft with composite alternatives, a significant increase in performance may be achieved with respect to mechanical strength, thermal stability, and durability, while also reducing mass. Exploration of this technology applied to a connecting rod geometry was investigated through a combination of process development, manufacturing, numerical analysis and testing. …
Short Beam Shear Strength Evaluations Of Gfrp Composites: Correlations Through Accelerated And Natural Aging, William Todd Barker
Short Beam Shear Strength Evaluations Of Gfrp Composites: Correlations Through Accelerated And Natural Aging, William Todd Barker
Graduate Theses, Dissertations, and Problem Reports
Fiber Reinforced Polymers (FRP) composites have been materials of interest in replacing or reinforcing steel, wood, and concrete, but lack of understanding of degradation under physical and chemical aging is a main concern. Through many years of research, the understanding of aging or durability of GFRPs has improved. To be able to evaluate aging related degradation rates, an accelerated aging methodology under varying environments is introduced. Accelerated aging is a concept used to age composites in a lab controlled environment under varying pH conditions (2 to 13) and temperatures (~ -20° to +160°F). Once acceleratedly aged testing is completed, Arrhenius …
Bending Response Of Timber Mortise And Tenon Joints Reinforced With Filler-Modules And Frp Gussets, Andrew Robert Pacifico
Bending Response Of Timber Mortise And Tenon Joints Reinforced With Filler-Modules And Frp Gussets, Andrew Robert Pacifico
Graduate Theses, Dissertations, and Problem Reports
In 2013, the California Bay Area (CBA) passed a set of ordinances to ensure that their 10,000 plus timber soft-story buildings were prepared for seismic events, through nondestructive evaluation methods. Many property owners are searching for an affordable retrofitting system that will also meet CBA’s new laws focusing on installations by the mandated deadlines in 2020. Over the past three to four decades, Fiber Reinforced Polymer (FRP) composites have found their way into the civil infrastructure sector for rehabilitation. The objective of this study is to evaluate the bending behavior retrofitted mortise and tenon timber joints reinforced with engineered wood …
Freeform Extrusion Fabrication Of Advanced Ceramics And Ceramic-Based Composites, Wenbin Li
Freeform Extrusion Fabrication Of Advanced Ceramics And Ceramic-Based Composites, Wenbin Li
Doctoral Dissertations
"Ceramic On-Demand Extrusion (CODE) is a recently developed freeform extrusion fabrication process for producing dense ceramic components from single and multiple constituents. In this process, aqueous paste of ceramic particles with a very low binder content ( < 1 vol%) is extruded through a moving nozzle to print each layer sequentially. Once one layer is printed, it is surrounded by oil to prevent undesirable water evaporation from the perimeters of the part. The oil level is regulated just below the topmost layer of the part being fabricated. Infrared radiation is then applied to uniformly and partially dry the top layer so that the yield stress of the paste increases to avoid part deformation. By repeating the above steps, the part is printed in a layer-wise fashion, followed by post-processing. Paste extrusion precision of different extrusion mechanisms was compared and analyzed, with an auger extruder determined to be the most suitable paste extruder for the CODE system. A novel fabrication system was developed based on a motion gantry, auger extruders, and peripheral devices. Sample specimens were then produced from 3 mol% yttria stabilized zirconia using this fabrication system, and their properties, including density, flexural strength, Young's modulus, Weibull modulus, fracture toughness, and hardness were measured. The results indicated that superior mechanical properties were achieved by the CODE process among all the additive manufacturing processes. Further development was made on the CODE process to fabricate ceramic components that have external/internal features such as overhangs by using fugitive support material. Finally, ceramic composites with functionally graded materials (FGMs) were fabricated by the CODE process using a dynamic mixing device"--Abstract, page iv.
Composites Of Poly(Dimethylsiloxane) And Silica Nanoparticles As An Approach To Manipulating The Conductivity Of Stretchable Gold Films, Brittany Ives
Composites Of Poly(Dimethylsiloxane) And Silica Nanoparticles As An Approach To Manipulating The Conductivity Of Stretchable Gold Films, Brittany Ives
Electronic Theses and Dissertations
Stretchable conductors play a fundamental role in wearable electronics as device electrodes and interconnects. Polydimethylsiloxane (PDMS) is conventionally used as the platform for stretchable conductors which are fabricated by depositing a thin layer of gold metal onto the surface. These gold films fail electrically under minimal strains (15-20% linear elongation) due to uncontrolled crack propagation through the metal film. Adding a rough microstructured polymer layer onto the PDMS surface preserves electrical conductivity in metal films to higher elongations of 60% due to the numerous sites for strain localization. However, such heterogeneous layered systems are vulnerable to delamination, leading to device …