Structural Materials Commons^™

A Study On High-Frequency Bending Fatigue, Microhardness, Tensile Strength, And Microstructure Of Parts Made Using Atomic Diffusion Additive Manufacturing (Adam) And Additive Friction Stir Deposition (Afsd), Hamed Ghadimi

LSU Doctoral Dissertations

This dissertation reports the findings of several studies on the mechanical and microstructural properties of parts made using atomic diffusion additive manufacturing (ADAM) and additive friction stir deposition (AFSD). The design of a small-sized bending-fatigue test specimen for an ultrasonic fatigue testing system is reported in Chapter 1. The design was optimized based on the finite element analysis and analytical solution. The stress–life (S–N) curve is obtained for Inconel alloy 718. Chapter 2 presents the findings of ultrasonic bending-fatigue and tensile tests carried out on the ADAM test specimens. The S-N curves were created in the very high-cycle fatigue regime. …

Physical Properties Of Copper Niobium Nanolamellar Composites Fabricated By Accumulative Roll Bonding, Jared Justice

Nuclear Engineering ETDs

Nanolamellar composites with high interface density have increased strength due to interfaces serving as barriers to dislocation movement and high radiation damage resistance. However, these interfaces also serve as barriers to electron motion, reducing the electrical resistivity and thermal conductivity. This work seeks to understand the inherent tradeoff between strength and physical properties of nanolamellar composites produced by accumulative roll bonding with layer thickness ranging from 25 nm to 193 nm. The electrical resistivity was investigated over temperatures ranging from 2 K to 300 K. The effect of longitudinal rolling and cross rolling was also investigated. Electrical resistivity results were …

Analysis Of Loading Rate, Fiber Orientation And Material Composition Through Image Processing And Digital Volume Correlation In High Performance Concrete, Aidan R. Carlson

Electronic Theses and Dissertations

Ultra High Performance Concrete (UHPC) and High Performance concrete (HPC) is characterized by high compressive strength and high toughness. This is achieved through maximizing the particle packing density in the matrix and the use of fibers to reinforce the matrix, increasing the materials toughness. The interactions of fibers and the matrix during loading is quite complex and involves several different energy dissipation mechanisms. The goal of this work and this thesis is to investigate these interactions and identify any changes in material response, and hope that these changes may be useful for the design of UHPC moving forward.

In this …

A Review On Ship Recycling Industry In Bangladesh From Global Perspective, Ahammad Abdullah, Zobair Ibn Awal, M Ziauddin Alamgir, Md. Jobayer Mia, Farihatul Mim, Utpal K. Dhar

Journal of Ocean and Coastal Economics

At present, the global center of the ship breaking and recycling industry is in South Asia, specifically Bangladesh, India, and Pakistan. These three countries account for 70–80 percent of the international recycling market for ocean-going vessels, with China and Turkey covering most of the remaining market. Only about 5 percent of global volume is scrapped outside these five countries. Bangladesh has environmentally beneficial coastal region and affordable labor that make the shipbreaking and recycling business as a potential sector for the country. In addition, ship recycling and its related businesses are helping to solve our nation’s unemployment issues at all …

Barriers To Use Of Cross-Laminated Timber In Maine, Shane R. O'Neill

Forest Resources Faculty Scholarship

To increase understanding of both the adoption rate and in-state manufacturing of mass timber In Maine, the 131^st Legislature and Governor Mills passed LD 881, a resolve directing a study of the barriers facing cross-laminated timber In Maine and provide recommendations to promote their use in construction. This study was developed in response to the resolve. The study engaged 108 unique participants to define available training, education, and experiences across the stakeholders throughout the building lifecycle process in the state.

From this information, the following five recommendations are proposed:

1. Understand the policies and initiatives of other states to develop …

Stress Relaxation Cracking In 347h Austenitic Steel Weldments Under Various Heat Treatments: Experiments And Modeling, Yi Yang

Doctoral Dissertations

347H austenitic stainless steel exhibits exceptional creep and corrosion resistance, rendering it an exemplary candidate for pipeline materials, particularly in mid- to high-temperature working conditions. However, due to constraints in component dimensions, welding has been chosen as the preferred method for joining pipeline systems extensively employed in nuclear power plants, fossil fuel plants, and petrochemical companies. The welding process entails the accumulation of residual stress during the cooling stage, along with the introduction of microstructure evolution. Moreover, the residual stress field and microstructure continuously evolve under service conditions, thereby intensifying the susceptibility of crack initiation and propagation. The initial residual …

3d Experimental Studies Of Temperature And Crystallographic Effects On Creep And Strength In Rock Salt, Amirsalar Moslehy

Doctoral Dissertations

Salt domes utilization as storage reservoirs in the energy sector has led to extensive studies on rock salt’s mechanical and geothermal behavior. These important facilities’ safety and serviceability rely on understanding rock salt’s compressive strength and creep behavior under various loading directions, water contents, in-situ stresses, and temperatures. Despite numerous studies on rock salt’s mechanical behavior in the literature, there are still many unanswered questions about rock salt’s behavior. This dissertation was aimed at utilizing state-of-the-art experimental techniques such as 3D synchrotron micro-computed tomography (SMT) and 3D x-ray diffraction (3DXRD) along with hundreds of compression and creep experiments to enhance …

Modular Composite Sandwich Structures For Thermal And Structural Retrofitting Of Existing Buildings, Marc Al Ghazal

Masters Theses

Around 40% of global energy consumption and 30% of worldwide carbon dioxide (CO2) emissions are attributed to buildings. Most of this consumption is dedicated to ensuring thermal comfort. The goal of this research was to develop and field validate retrofit solutions to improve the energy efficiency of buildings. Exterior cladding panels were designed and tested to ensure adequate thermal and structural performance. Sandwich panels (glass fibers reinforced polymer (GFRP) skins and polymeric foam cores) were fabricated using the vacuum assisted resin transfer molding (VARTM) process. Extruded polystyrene (XPS) and polyurethane (PU) foams were compared as core materials through a series …

Cfrp Delamination Density Propagation Analysis By Magnetostriction Theory, Brandon Eugene Williams

All Dissertations

While Carbon Fiber Reinforced Polymers (CFRPs) have exceptional mechanical properties concerning their overall weight, their failure profile in demanding high-stress environments raises reliability concerns in structural applications. Two crucial limiting factors in CFRP reliability are low-strain material degradation and low fracture toughness. Due to CFRP’s low strain degradation characteristics, a wide variety of interlaminar damage can be sustained without any appreciable change to the physical structure itself. This damage suffered by the energy transfer from high- stress levels appears in the form of microporosity, crazes, microcracks, and delamination in the matrix material before any severe laminate damage is observed. This …

Thermo-Mechanical Instabilities In Next-Generation Friction Materials In High-Speed Sliding Systems, Kingsford Koranteng

Electronic Theses and Dissertations

For centuries, the manufacturing industry has incorporated metals like copper into friction materials to enhance thermal properties and minimize thermo-mechanical instabilities (TMI) in high-speed sliding systems. Unfortunately, these metals have adverse environmental effects due to the emission of hazardous particulate matter. As a result, there is a growing movement towards adopting next-generation friction materials as an alternative solution.

The study begins by conducting experimental and numerical investigations to examine the instabilities found in metal-based friction materials. The primary objective is to utilize the insights gained from the investigations to computationally explore effective strategies for mitigating various instabilities that may arise …

Mechanical Characterization Of Automated Fiber Placement And Additive Manufacturing Hybrid Composites, Lucan Haviland

Electronic Theses and Dissertations

This thesis presents the optimization of processing parameters based on the mechanical properties of Continuous Fiber-Reinforced Thermoplastic (CFRTP) Unidirectional (UD) consolidated tapes. The UD tapes were consolidated using an AFP head and a thermoforming press for comparison. The adhesive strength of hybrid parts consisting of CFRTP UD tape bonded to a 3D-printed substrate with the same matrix system were investigated. Large Area Additive Manufacturing (LAAM) was utilized for the 3D-printed parts. Different types of thermoplastic composite materials were explored, including Glass Fiber reinforced Polyethylene Terephthalate Glycol (GF/PETG), Carbon Fiber reinforced Polyethylene Terephthalate Glycol (CF/PETG), Carbon Fiber reinforced Polycarbonate (CF/PC), and …

Investigation Of Microstructure And Mechanical Behavior Of Novel Powder-Extruded Al-Ce-Mg Alloys, Mairym Vazquez

Doctoral Dissertations

Pursuing advanced structural materials with enhanced performance, reduced weight, and lower costs is a constant endeavor in the aerospace and automotive industries. Conventional structural alloys, such as cast irons, carbon steels, and titanium alloys, have strength, weight, and cost limitations. Aluminum-based alloys, known for their lightweight and high strength, have gained popularity in these industries. This dissertation focuses on investigating microstructure and mechanical behavior of novel powder-extruded Al-Ce-Mg alloys as potential candidates for high-performance structural materials.

This research explores using powder extrusion, a well-established forging methodology in the steel industry, to produce Al-Ce-Mg alloys with improved properties and aims to …

Fatigue And Fracture Of Electron Beam Melting Ti-6al-4v, William A. Grell

Electronic Theses and Dissertations

For applications in the aerospace field, selection of materials for a given design requires an understanding of critical properties, like fatigue and fracture, in addition to static mechanical and physical properties. With the ongoing advancements in metallic additive manufacturing techniques and the interest in applying the process to aerospace applications, there is a clear need to fully characterize properties. Arguably, the most attractive alloy for applications in aerospace is the Ti-6Al-4V alloy. The current dissertation examines the mechanical properties of the alloy, made by the Electron Beam Melting (EBM) Powder Bed Fusion (PBF) method. As illustrated in this work, the …

Refractory High-Entropy Alloys: Design, Fabrication, Characterization, And Nanoparticle Synthesis, John Hutson Whitlow

Masters Theses

High-Entropy Alloys have been a highly researched area of metals ever since their introduction in 2004 by Brian Cantor and Jien-Weh Yeh. In the continued research of High-Entropy Alloys (HEAs), a specific area concerning Refractory High-Entropy Alloys (RHEAs) has emerged for their high-temperature applications. Although RHEAs have maintained high strength and toughness at high temperatures, their low ductility still needs to be addressed. A dataset was created to find correlations between various characteristics of RHEAs and their composition. A set of seven compositions were selected and fabricated. Mechanical tests were run on the seven compositions, and a proposal was written …

A Spike-Shaped Anchorage For Steel Reinforced Polymer (Srp)-Strengthened Concrete Structures, Xingxing Zou, Keenan L. Mcburney, Lesley H. Sneed

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Steel reinforced polymer (SRP) composite has recently emerged as an effective and economical solution for strengthening of reinforced concrete (RC) structures. Premature debonding failure of unanchored SRP at low load levels generally governs the performance of RC structures strengthened with externally bonded SRP. Therefore, a novel yet simple spike-shaped anchorage system was proposed in this study to prevent the debonding failure of SRP and to improve the interfacial shear capacity. Experimental investigation through single-lap shear tests of SRP-concrete joints showed that the anchorage system changed the failure mode from composite debonding to fiber rupture. In addition, the anchorage system substantially …

Interlaminar Tensile Properties Of Unidirectional And Woven Carbon Fiber Reinforced Toughened Epoxy Laminates, Eric Timothy Casey, Sean Mckalip Thompson

Materials Engineering

This project aims to develop a dataset on interlaminar tensile strength comparing unidirectional and woven thermoset matrix carbon fiber composites keeping ply count, matrix material, and fiber diameter constant. The interlaminar tensile strength is an important property relating to the delamination failure mode. Interlaminar tensile strength is determined using the ASTM D6415 testing standard. This test is a modified four-point bend test using a 90° curved beam test specimen. Laminates were produced by laying up pre-impregnated carbon fiber sheets onto a curved beam tooling. The unidirectional laminate was produced with 20 plies in a [0,0,90,0,0]₄ layup pattern. The woven …

Experimental Characterization And Computer Vision-Assisted Detection Of Pitting Corrosion On Stainless Steel Structural Members, Riley J. Muehler

Master's Theses

Pitting corrosion is a prevalent form of corrosive damage that can weaken, damage, and initiate failure in corrosion-resistant metallic materials. For instance, 304 stainless steel is commonly utilized in various structures (e.g., miter gates, heat exchangers, and storage tanks), but is prone to failure through pitting corrosion and stress corrosion cracking under mechanical loading, regardless of its high corrosion resistance. In this study, to better understand the pitting corrosion damage development, controlled corrosion experiments were conducted to generate pits on 304 stainless steel specimens with and without mechanical loading. The pit development over time was characterized using a high-resolution laser …

Evaluating The Potential Of Geopolymer Concrete As A Sustainable Alternative For Thin White-Topping Pavement, Sathvik S. Chandra, Pshtiwan Shakor, Sarwar Mohmmad, Bankole O. Awuzie, Atul K. Singh, Abishek Rauniyar, M Karakouzian

Civil and Environmental Engineering and Construction Faculty Research

Introduction:

The construction industry uses a large quantity of natural materials in the production of concrete. Although attempts to incorporate green materials in concrete began years ago, not every building uses such materials today, and roadways, particularly, still rely on unsustainable materials.

Methods:

Therefore, this study used alternative materials, including fly ash, manufactured sand aggregates, and different molarities of alkaline activators, to incorporate waste byproducts in a geopolymer concrete white-topping pavement layer. Recent developments have led to the emergence of geopolymers as distinct classes of materials. In the 1990s, fly ash-based geopolymers became more popular than other kinds, as they …

Synthesis And Characterization Of Sodium Cathode Materials, He Zhou

McKelvey School of Engineering Theses & Dissertations

As sodium batteries hold great promise as a next-generation energy storage device to replace lithium batteries, the development of sodium battery materials has become increasingly urgent. The current study aims to investigate two potential sodium-ion battery cathode materials, Sodium Vanadium Phosphate, and Sodium Manganese Hexacyanoferrate, optimize the experimental procedures, conduct a systematic analysis of material properties and characterization, and ultimately determine the ideal synthesis conditions for these materials.

In the first part of the study, we focused on optimizing the synthesis of Sodium Vanadium Phosphate. By investigating various synthesis conditions, such as annealing temperature, pressure, ascorbic acid content, and material …

Study Of A Carbon Fiber Reinforced Polymer Composite Using A Biobased Polyurethane As A Thermosetting Resin, Teddy Mageto

Electronic Theses & Dissertations

Carbon Fiber Reinforced Polymer composites (CFRP) have garnered increasing interest in recent years especially in the aerospace and automobile industries where they are gradually replacing metals as structural materials. This is owing to their light weight, high strength, high modulus, and excellent strength-to-weight ratio. Polymers are typically used as thermosetting resins in these composites. However, the synthesis of polymers currently is conducted via petrochemical processes which leads to adverse effects on the environment. To this end, in this work a biobased Polyurethane (PU) was used as a thermosetting resin in a CFRP. The biobased PU was synthesized by the reaction …