Materials Science and Engineering Commons^™

Analysis Of The Cyclic Behavior And Fatigue Damage Of Low Alloy Steels, Zahra Salemi Najafabadi

Dissertations

Fatigue is the most common type of failure in many structures and components subjected to cyclic loading. Surface effects in fatigued materials are of particular importance, since in most cases the surface is the preferred site of fatigue crack initiation. Microcracks originate at the metal surface due to stress concentration introduced by macro notches and micro defects in the surface layers. The microcrack initiation and propagation are controlled by the localized plastic deformation in the surface layers especially in the initial stage of fatigue failure process. Therefore, the knowledge regarding the cyclically induced changes in deformation resistance at the metal …

Dynamic Response Of Elastic Two-Story Steel Moment Frame Scaled Structure Equipped With Viscous Dampers, Garrett L. Barker, Alexander L. Poirier

Architectural Engineering

The authors of this report are Architectural Engineering undergraduate students at California Polytechnic State University, San Luis Obispo. Damping is a complex, experimentally derived value that is affected by many structural properties and has a profound effect on the dynamic response of structures. Deducing the inherent damping of a steel moment frame and affecting the damping ratio with viscous dampers are two topics explored in this paper. Dampers are commonly implemented in resilient structures that perform better in a design basis earthquake, reducing the seismic cost and downtime. Undergraduate coursework does not delve into the factors that affect damping and …

Effects Of Release Materials And Temperature Ramp Rates On The Surface Finish Of Carbon-Fiber Composite Components, Sudeep Louis, Thucmy Dang, Ethan Schlocker

Materials Engineering

Toray Advanced Composites is interested in improving their carbon fiber reinforced polymers (CFRP) manufacturing process by enhancing their control on the amount of surface roughness for varied customer preference. Surface roughness of CFRP is important in post-production processes including coating, priming, and painting. This project seeks to determine the effects of three release materials and two temperature ramp rates on the surface finish of CFRP. The release materials used were Tooltech, FEP, and Frekote 770-NC. The two initial temperature ramp rates were 1°F/min and 2°F/min. Surface roughness was measured using a profilometer and analyzed using Ra values. Ra is an …

Analysis Of Novel Corrosion Resistant Maraging Steels For Use In Additive Manufacturing, Bradley Michael Samuel, James Knowlton Smith

Materials Engineering

Stainless maraging steel has been proven to be an industry standard material for plastic injection molds. Its high hardness and corrosion resistance extend the lifetime of the tool. This alloy system is also well-suited to additive manufacturing, which can be utilized to form internal cooling channels, further increasing tool life. Using Rapid Alloy Development (RAD) Oerilkon METCO is developing a new composition of stainless maraging tool steel that has high hardness/strength, is corrosion resistant, and has additive-capable melting and solidification properties. This study tests the hardness and corrosion resistance of the new RAD alloys against the current market competitor Corrax …

Processing And Characterization Of Silicon Nitride For Rapid And Low-Level Detection Of Water Pathogens, Arielle H. Buchanan, Logan A. Chai

Materials Engineering

Water sanitation is a serious issue affecting the lives of many, and methods for assessing water cleanliness have been a major research interest for decades. Rapid and accurate water pathogen detection methods that can be performed in field applications have been a growing research focus, especially in low-income countries most affected by poor water quality. Silicon nitride was explored as a material for colorimetric water-pathogen sensing due to the large body of knowledge around its processing, and its isoelectric point. A bioassay of chlorophenol red-β-Dgalactopyranoside (CPRG) and β-galactosidase (β-gal) enzymes with Escherichia coli (E. coli) bacteria was used to examine …

In Situ Marine Biodegradation Of Poly(Lactic) Acid And Thermoplastic Starch Blends, Brittany Denicholas

Materials Engineering

Marine life has been suffering from macro- and microplastics since the inception of petroleum-based plastic. Bio-based biodegradable polymers such as PLA and TPS can help mitigate the damage done by petroleum plastics. Blending PLA and TPS can reduce the cost while preventing a significant effect on the material properties. PLA/TPS blend compositions such as 90/10, 80/20, 70/30 could be candidates for a solution. The PLA/TPS blends have been submerged in a marine environment at the Cal Poly Pier in Avila Beach for 8 weeks. Three sample sets containing three of each blend composition were collected every week and tested in …

Non-Destructive Material Analysis Of Metals And Composites Via Thermography, Jonathan R. Doubt, James L. Chapman

Materials Engineering

The Naval Surface Warfare Center, Port Hueneme Division, is interested in the development of non-destructive damage assessment of shipboard materials via drones at distance. Long Pulsed Thermography (LPT), a method of non-destructive evaluation, was investigated as a possible method for detecting damage in metals (5005h24 Al alloy and 1008 carbon steel) and composites (aramid fiber honeycomb sandwich structure) at distances from 0.5 m to 3.0 m. LPT was conducted using two 1000 W can lights to heat the samples, and a FLIR E8-XT thermal camera. The images were then analyzed using ImageJ software to determine if damage could be detected …

Citric Or Acetic Acid Effects On The Crosslinking Of Pvoh, Samuel Carr, Erika Szaldobagyi

Materials Engineering

Transportation and shipping processes are the most dangerous times for food due to harsh handling and frequent temperature changes. Plain corrugated boxes cannot withstand the damp environment caused by melting ice that is used to keep foods cold and fresh. To minimize damage, a protective polymer film coating can be applied. These coatings can be unsafe when used with food and will lead to excess waste by limiting the recyclability of the boxes. The purpose of this project was to produce nontoxic crosslinked PVOH films to determine suitability for a cost effective, biodegradable, and repulpable corrugated box coating. Polyvinyl alcohol …

Determining The Efficacy Of A Silica And Bacterial Cellulose Composite Model System, Hannah Martin, Daisy Kamp

Materials Engineering

Bacterial cellulose (BC) is a sustainable alternative to petroleum-based polymer films for synthetic leather applications. Synthesized by a symbiotic culture of bacteria and yeast, BC is a three-dimensional structure composed of cellulose microfibrils. However, pure BC lacks certain desirable properties such as high tensile strength. Previous studies have shown that loading BC with nanoparticles to form nanocomposites has improved BC’s mechanical properties. However, this was not studied as a function of particle size. This study focuses on using silica/BC nanocomposites to model the impact that particle size and silica soaking concentrations have on the uptake efficiency of these particles into …

Soil Degradation Of A Plastic Blend Of Opuntia Ficusindica Juice, Animal Protein And Beeswax, Isabel A. Gamez, Daniel R. Kava

Materials Engineering

Since the introduction of single use plastics in the early 1900s, their usage has increased exponentially. Unfortunately, due to this exponential increase there are negative environmental implications of their production, which requires further consideration. Currently, there are various waste disposal practices for SUPs, including landfilling, incineration, and recycling. Recent data revealed that only 14 % of plastic waste was recycled, with 40% of plastic waste being landfilled, while the rest of the plastic waste was incinerated or released to the environment at 14 % and 32 %, respectively. A potential solution to the plastic waste issue is developing a polymer …

Effect Of Oxygen Equivalence On The Strength And Toughness Of Ti-6al-4v Forgings, Kira Baylor, Clarissa Drouillard

Materials Engineering

Tensile testing and fracture toughness testing were conducted to establish a numerical relationship between interstitial content and performance in forged Ti-6Al-4V. The value of oxygen equivalence was used to represent the interstitial content by combining the weight percent of oxygen, carbon, and nitrogen. The correlation between oxygen equivalence and mechanical properties can be used to accurately predict the performance of forged parts. Samples of forged parts with varying levels of interstitial content were subjected to a recrystallization anneal at 75 F below the beta transus temperature to decrease microstructure variability across parts with a second anneal at 1300 F to …

Investigation Of The Effects Of Cladding Layers On Longitudinal And Transverse Mechanical Properties In Composite Laminates, Rachel Potratz, Tiffany Foo, Joseph Kamlet

Materials Engineering

The addition of cladding layers to composite laminates is used in industry to improve bond adhesion and the ease of manufacturing. However, there is no public data on the effects of cladding layers on the mechanical properties of composite components. To directly observe how cladding layers affect mechanical properties, four laminates with zero, one, two, and three cladding layers of twill fabric were added symmetrically to a biased core. The mechanical testing performed was tensile, short beam strength, and compression testing in the longitudinal and transverse directions. The measured strengths were related to the longitudinal properties of the core, and …

Tini-Based Bi-Metallic Shape-Memory Alloy By Laser-Directed Energy Deposition, Yitao Chen, Cesar Ortiz Rios, Braden Mclain, Joseph William Newkirk, Frank W. Liou

Materials Science and Engineering Faculty Research & Creative Works

In this study, laser-directed energy deposition was applied to build a Ti-rich ternary Ti-Ni-Cu shape-memory alloy onto a TiNi shape-memory alloy substrate to realize the joining of the multifunctional bi-metallic shape-memory alloy structure. The cost-effective Ti, Ni, and Cu elemental powder blend was used for raw materials. Various material characterization approaches were applied to reveal different material properties in two sections. The as-fabricated Ti-Ni-Cu alloy microstructure has the TiNi phase as the matrix with Ti₂Ni secondary precipitates. The hardness shows no high values indicating that the major phase is not hard intermetallics. A bonding strength of 569.1 MPa …

In-Situ Defect Detection Using Acoustic Vibration Monitoring For Additive Manufacturing Processes, Ali Harake

Master's Theses

The world of additive manufacturing revolves around speed and repeatability. Inherently, the process of 3D printing is plagued with variability that fluctuates with every material and parameter modification. Without proper qualification standards, processes can never become stable enough to produce parts that may be used in aerospace, medical, and construction industries. These industries rely on high quality metrics in order to protect the lives of those who may benefit from them. To establish trust in a process, all points of variation must be controlled and accounted for every part produced. In instances where even the best process controls are enacted, …

Model-Based Design Of An Optimal Lqg Regulator For A Piezoelectric Actuated Smart Structure Using A High-Precision Laser Interferometry Measurement System, Grant P. Gallagher

Master's Theses

Smart structure control systems commonly use piezoceramic sensors or accelerometers as vibration measurement devices. These measurement devices often produce noisy and/or low-precision signals, which makes it difficult to measure small-amplitude vibrations. Laser interferometry devices pose as an alternative high-precision position measurement method, capable of nanometer-scale resolution. The aim of this research is to utilize a model-based design approach to develop and implement a real-time Linear Quadratic Gaussian (LQG) regulator for a piezoelectric actuated smart structure using a high-precision laser interferometry measurement system to suppress the excitation of vibratory modes.

The analytical model of the smart structure is derived using the …

Synthesis Of Dysprosium Oxychloride (Dyocl), Saehwa Chong, Brian J. Riley, José Marcial, Charmayne E. Lonergan, Derek A. Cutforth

Materials Science and Engineering Faculty Research & Creative Works

Dysprosium oxychloride, DyOCl, was synthesized using a simple hydrolysis method with DyCl₃·6H₂O. X-ray powder diffraction (XRD) data was used to determine the crystal structure. The DyOCl compound is isostructural to the matlockite (PbFCl) crystal structure and crystallizes in the tetragonal P4/nmm (#129) space group. The crystal structure contains the alternating cationic layers of (DyO)_n and anionic layers of nCl⁻ along the c-axis. The structural data including unit cell, volume, and density of DyOCl were compared to other rare-earth oxychloride data from the Inorganic Crystal Structure Database (ICSD) and our previous study on TbOCl. Fourier-transform …

Tini-Based Bi-Metallic Shape-Memory Alloy By Laser-Directed Energy Deposition, Yitao Chen, Cesar Ortiz Rios, Braden Mclain, Joseph William Newkirk, Frank W. Liou

Materials Science and Engineering Faculty Research & Creative Works

In this study, laser-directed energy deposition was applied to build a Ti-rich ternary Ti–Ni–Cu shape-memory alloy onto a TiNi shape-memory alloy substrate to realize the joining of the multifunctional bi-metallic shape-memory alloy structure. The cost-effective Ti, Ni, and Cu elemental powder blend was used for raw materials. Various material characterization approaches were applied to reveal different material properties in two sections. The as-fabricated Ti–Ni–Cu alloy microstructure has the TiNi phase as the matrix with Ti2Ni secondary precipitates. The hardness shows no high values indicating that the major phase is not hard intermetallic. A bonding strength of 569.1 MPa was obtained …

Influence Of Materials And Design Parameters On Zinc Oxide Surface Acoustic Devices, Samuel B. Dewhitt

Theses and Dissertations

This thesis presents research into Zinc Oxide (ZnO) based resonators to include Width Extensional Mode (WEM), Length Extensional Mode (LEM), and Surface Acoustic Wave (SAW) devices. The design and operation of ZnO based SAW devices are investigated further to characterize design parameters and operating modes. Their design, fabrication, and results are discussed in detail. SAW device testing in conjunction with X-Ray Diffractometry (XRD) and Atomic Force Microscopy (AFM) are utilized to characterize ZnO and its deposition parameters on a variety of different substrates and interlayers, with different deposition temperatures and annealing parameters. These substrates include silicon, silicon oxide-on-silicon, and sapphire …

Identification And Characterization Of Point Defects In Nonlinear Optical Crystals: Barium Gallium Selenide And Lithium Triborate, Brian C. Holloway

Theses and Dissertations

Increased interest in developing new nonlinear optical materials has led to 3rd generation materials, such as BaGa4Se₇ and LiB₃O₅. These two nonlinear optical crystals have the potential to enable development of tunable lasers operating across the mid-wave infrared and the ultraviolet regions, respectively. Coherent light sources are used in the development of enhanced technologies with commercial and defense-based applications such as: health and environmental monitoring devices, next-generation infrared countermeasures, and ballistic missile booster exhaust plume characterization. The performance of optical materials in high-powered military applications is largely limited by the presence of defects. These defects …

Stabilization Of Palm Wood Using Water-Based Impregnation, David A. Barnes

Materials Engineering

Impregnation is a technique for stabilizing wood that involves saturating the material in a liquid and allowing it to cure before use. Stabilization methods such as this are employed for a variety of reasons; chiefly, the low dimensional stability of wood and palm means that they are subject to several failure modes that arise from changing environmental conditions, such as cracking, warping, and bending. Samples of Borassus flabellifer, black palm, provided by DuraPalm were impregnated with solvent-based and water-based stabilizers, and untreated wood samples used as a control group. Kop-Coat WoodYouth® Plus was used as a solvent-based stabilizer, and impregnation …