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Heat Treatments For Minimization Of Residual Stresses And Maximization Of Tensile Strengths Of Scalmalloy® Processed Via Directed Energy Deposition, Rachel Boillat-Newport, Sriram Praneeth Isanaka, Jonathan Kelley, Frank Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Scalmalloy® is an Al-Mg-Sc-Zr-Based Alloy Specifically Developed for Additive Manufacturing (AM). This Alloy is Designed for Use with a Direct Aging Treatment, as Recommended by the Manufacturer, Rather Than with a Multistep Treatment, as Often Seen in Conventional Manufacturing. Most Work with Scalmalloy® is Conducted using Powder Bed Rather Than Powder-Fed Processes. This Investigation Seeks to Fill This Knowledge Gap and Expand Beyond Single-Step Aging to Promote an overall Balanced AM-Fabricated Component. for This Study, Directed Energy Deposition (DED)-Fabricated Scalmalloy® Components Were Subjected to Low-Temperature Treatments to Minimize Residual Stresses Inherent in the Material Due to the Layer-By-Layer Build Process. …

Compressive And Flexural Tensile Strength Impacts Of Aluminum Shavings In Concrete, Ian Smith

Construction Management

Concrete is one of the most utilized construction materials around the world, but new and cutting-edge methods are constantly pushing the envelope for concrete’s applications and feasibility as a construction material. Unfortunately, concrete has a general lack of resistance to bending and stretching. Studies have shown several successful attempts to enhance the mechanical properties of concrete through implementation of various admixtures and methods. Steel is widely considered the primary material capable of reinforcing concrete. This paper evaluates concrete’s change in strength of flexural tension and compression as a result of implementing aluminum as a reinforcing agent. To determine the full …

Searching For Unknown Material Properties For Am Simulations, Aaron Flood, Rachel Boillat, Sriram Praneeth Isanaka, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Additive manufacturing (AM) simulations are effective for materials that are well characterized and published; however, for newer or proprietary materials, they cannot provide accurate results due to the lack of knowledge of the material properties. This work demonstrates the process of the application of mathematical search algorithms to develop an optimized material dataset which results in accurate simulations for the laser directed energy deposition (DED) process. This was performed by first using a well-characterized material, Ti-64, to show the error in the predicted melt pool was accurate, and the error was found to be less than two resolution steps. Then, …

Characterization Of Residual Stress And Precipitate Evolution In Aluminum 2xxx Self-Reacting Friction Stir Welds, Benjamin Joe Wing

Doctoral Dissertations

2xxx series aluminum alloys possess attractive properties for structural aerospace applications including high strength to weight ratio, corrosion resistance, and stable cryogenic performance. Solid state joining processes are often employed to reduce weld defects and improve weld performance/consistency as many alloys of this range have poor weldability for traditional fusion based joining techniques. One such process, self-reacting friction stir welding (SRFSW) allows for consistent high-quality, welding of large and curved articles is often used in the construction of large structures such as launch vehicle liquid propellant tanks.

Despite the merits of this process, joint softening (a decrease in mechanical properties …

Creep Resistance And Microstructure In Binary Aluminum Cerium Alloy Produced By Laser Powder Bed Fusion, Jillian Ann Stinehart

Master's Theses (2009 -)

Currently, the only commercially available aluminum alloy for additive manufacturing (AM) is AlSi10Mg, which is not suitable for high temperature applications. Al-Ce based alloys have been shown to be highly printable, cost-efficient alloys. Compared to cast Al-Ce alloys, the eutectic features are refined (<1μm), which give AM Al-10Ce favorable strength and ductility at room temperature. The low diffusivity and solubility of cerium in aluminum improve the retention of mechanical properties at high temperatures. In order to quantify the effect of cerium on the thermal stability of AM aluminum and show its suitability for high-temperature applications, Al-10Ce was creep tested between 60-77% of its absolute melting temperature. The creep performance of AM Al-10Ce was favorable compared to that of cast binary Al-Ce and AM AlSi10Mg and was comparable to that of cast ternary Al-Ce alloys. The stress exponent, n, was approximately 1 in the low stress regime and 5-7 in the high stress regime. The activation energy was 231kJ/mol. In comparison, both cast binary Al-Ce and AM AlSi10Mg have higher stress exponents and lower activation energies, showing AM Al-10Ce to be more creep resistant. After creep testing, slight grain coarsening was observed, while grain orientation remained unchanged. The melt pool boundaries (MPBs) faded in appearance after creep testing, and the number of columnar grains decreased.

The Design And Construction Of A Radio Telescope, Avery Elizabeth Bunting, Kira Hope Tolman

Architectural Engineering

Two architectural engineering students and an electrical engineering student worked together to design and build a radio telescope that is capable of using hydrogen line astronomy to map the galaxy. The telescope is made entirely out of aluminum, which, combined with small deflection limits, made for an iterative design process that focused primarily on constructability and supporting the desired outcomes of the electrical side.

Numerical Simulation Of The Donor-Assisted Stir Material For Friction Stir Welding Of Aluminum Alloys And Carbon Steel, Joseph Maniscalco, Abdelmageed A. Elmustafa, Srinivasa Bhukya, Zhenhua Wu

Mechanical & Aerospace Engineering Faculty Publications

In this research effort, we explore the use of a donor material to help heat workpieces without wearing the tool or adding more heat than necessary to the system. The donor material would typically be a small piece (or pieces) of material, presumably of lower strength than the workpiece but with a comparable melting point. The donor, a sandwich material, is positioned between the tool head and the material to be welded, where the tool initially plunges and heats up in the same manner as the parent material that is intended for welding. The donor material heats up subsequent to …

Effect Of Sc On Recrystallization Resistance Of Aa7050, Keaton Schmidt

Dissertations, Master's Theses and Master's Reports

The extrusion process involves high temperatures and strains that can result in undesirable microstructures, especially along the surface. Extruded alloys tend to exhibit surface recrystallization during heat treating at regions of higher strains, which can lead to reduced fatigue strength and corrosion resistance. By adding Sc to AA7050, nano-sized dispersoids are formed with Sc cores and Zr shells that restrict recrystallization more than the base alloy that only utilizes Zr. Billets with varying Sc content and a control with only Zr were cast, and extrusions were made in order to compare surface microstructures at varying strains in the as-extruded and …

Intergranular And Pitting Corrosion Mechanisms Of Sensitized Aluminum Alloy Aa5083, Clayton Egleston

Williams Honors College, Honors Research Projects

The motivation and objectives of this project is to examine the mechanisms of intergranular corrosion (IGC) and pitting corrosion of sensitized AA5083. In this regard, different characterization techniques were used, including optical analysis of microstructure, cyclic potentiodynamic polarization with Tafel fitting, electrochemical impedance spectroscopy with electrical equivalent circuit (EEC) fitting, and potentiostatic current transient monitoring. The transition from IGC to pitting corrosion occurs when the grain boundaries become saturated with the β-phase (Mg₂Al₃). It was found that AA5083 becomes more vulnerable to pitting corrosion as the degree of sensitization increases.

An Investigation Into Aluminum’S Torsional Behavior Of Circular, Rectangular, And Square Cross-Sections, Marly Mcclintock

Honors Theses

The Specifications for Aluminum Structures (2020) provides the standards that structural engineers follow for aluminum design. Included in these specifications are limit state equations that use strength properties to calculate a member’s initial yield, full yield, and rupture values. One limit state that the standards currently neglect is the torsional failure of solid bars. Torsion is the act of rotation caused by a twisting force, otherwise known as torque. Future installments of the specifications hope to include torsional yielding and rupture equations, so this study investigates the validity of these proposed equations.

Two different aluminum alloys were investigated for this …

Structural Performance Of Single-Skin Glass Façade Systems Exposed To Fire, Mohamed Badr, Maged A. Youssef, Salah El-Din F. El-Fitiany, Ajitanshu Vedrtnam

Civil and Environmental Engineering Publications

Purpose

Understanding the structural performance of external glass curtain walls (façades) during fire exposure is critical for the safety of the occupants, as their failure can lead to fire spread throughout the entire building. This concern is magnified by the recent increase in fire incidents and wildfires. This paper presents the first simplified technique to model single skin façades during fire exposure, and, then utilizes it to examine the structural behaviour of vertical, inclined, and oversized façade panels.

Design/methodology/approach

The proposed technique is based on conducting simplified heat transfer calculations, and, then utilizing a widely used structural analysis software to …

Influence Of Aluminum Addition On The Laser Powder Bed Fusion Of Copper-Aluminum Mixtures, Nada Kraiem, Loic Constantin, A. Mao, Fei Wang, Bai Cui, Jean-François Silvain, Yongfeng Lu

Department of Electrical and Computer Engineering: Faculty Publications

The high optical reflectivity of copper (Cu) in the near infrared (NIR) domain and its elevated heat dissipation make Cu a challenging metal for laser powder bed fusion (LPBF), even with high energy densities (EDs). In this study, we demonstrated that adding aluminum (Al) powder by as little as 0.75, 1.5, and 3 wt.% substantially enhances Cu processability, leading to denser (up to 98%) and smoother (Ra = 3.3 𝜇m) Cu-Al parts as compared to 95% and 18 𝜇m, respectively, for the parts printed using pure Cu. In addition, this method reduces the ED required by a factor of two …

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 …

Prediction Of Springback In Aa6016-T4 Sheets Using Isotropic Finite Element And Epsc Modeling Approaches, Dane Roger Sargeant

Theses and Dissertations

Strain path changes are common in complex automotive stampings, where sheet materials undergo a combination of drawing, stretching, and bending to achieve a desired part shape. Aluminum sheet alloys are increasingly used in vehicle structure light-weighting efforts, but limited formability and high levels of springback present challenges to the manufacturing and assembly processes. The current work explores springback levels in AA6016-T4 sheet after various pure bending operations, where sheets were first pre-strained in uniaxial, plane-strain, and biaxial tension. Finite element modeling of the pre-straining and subsequent bending operations will be performed using both isotropic and elasto-plastic self-consistent (EPSC) crystal plasticity …

Design And Fabrication Of Aluminum Based Ws2 Nano-Composite Through Powder Metallurgy, Umida Ziyamuhamedov, M Wani

Technical science and innovation

In this research paper, experimental studies on the fabrication of Aluminum based metal matrix composites composed are presented. The Aluminum based metal matrix composite was developed with varying percentage of WS₂. Physical and mechanical properties were measured to assess the influence of addition of WS₂ on density and micro hardness of composite.

A Study Of The Effect Of Load And Displacement Control Strategies On Joint Strength In Friction Bit Joining Of Ga Dp 1180 Steel And Aa 7085-T71, Taylor George Berg

Theses and Dissertations

Friction Bit Joining (FBJ) is a new technology that can be used to join dissimilar materials together. This ability makes it a good candidate for creating lightweight structures for the automotive industry by combining lightweight materials such as aluminum to stronger materials like advanced high-strength steels. The automotive industry is putting significant effort into interest in reducing vehicle structure weight to increase fuel efficiency and reduce greenhouse gas emissions. Joining of dissimilar materials is a challenge they face in the light weighting the body of the vehicle. The purpose of the current research is to employ FBJ in the joining …

Development Of Superior Energy Absorbing Devices With Adaptive Capabilities Utilizing Hybrid Cutting/Clamping Deformation Modes, John Magliaro

Electronic Theses and Dissertations

The primary objective of this research was to investigate cutting deformation modes, employing higher-bladed cutters (i.e. 6 or more evenly space blades), with an emphasis on superior energy absorbing capabilities in comparison to axial crushing, the current state-of-the-art. A series of test cases involving AA6061 extrusions were identified utilizing analytical models of the steady-state cutting force and mean crushing force and selecting geometries where the ratio of the former force normalized with respect to the latter exceeded unity. Quasi-static testing confirmed that the total energy absorbing capacity could be exceeded while simultaneously reducing the peak force under quasi-static loading for …

Thermal Deformation In High Pressure Die Casting Shot Sleeves, Ross Crowley

Dissertations (1934 -)

Replacement of shot sleeves represents a significant cost in cold chamber high pressure die casting (HPDC) processes. It is well known that the service life of a shot sleeve is closely related to its thermomechanical deformation behavior, so an improved understanding of this behavior is needed to guide the design of shot sleeves for increased service life. Prior research efforts have analyzed shot sleeve deformation but were based on 2D representations and did not consider transient effects from the molten metal’s flow behavior. This objective of this study was to analyze thermo-mechanical deformation during the injection sequence by using a …

Development Of Superior Energy Absorbing Devices With Adaptive Capabilities Utilizing Hybrid Cutting/Clamping Deformation Modes, John Magliaro

Electronic Theses and Dissertations

The primary objective of this research was to investigate cutting deformation modes, employing higher-bladed cutters (i.e. 6 or more evenly space blades), with an emphasis on superior energy absorbing capabilities in comparison to axial crushing, the current state-of-the-art. A series of test cases involving AA6061 extrusions were identified utilizing analytical models of the steady-state cutting force and mean crushing force and selecting geometries where the ratio of the former force normalized with respect to the latter exceeded unity. Quasi-static testing confirmed that the total energy absorbing capacity could be exceeded while simultaneously reducing the peak force under quasi-static loading for …

Feedstock Powders For Reactive Structural Materials, Daniel Hastings

Dissertations

Metals as fuels have higher energy density per unit mass or volume compared to any hydrocarbon. At the same time, metals are common structural materials. Exploring metals as reactive structural materials may combine their high energy density with attractive mechanical properties. Preparing such materials, however, is challenging. Requirements that need to be met for applications include density, strength, and stability enabling the component to sustain the structure during its desired operation; added requirements are the amount and rate of the energy release upon impact or shock. Powder technology and additive manufacturing are approaches considered for design of reactive structural materials. …

Strengthening Of 7175 Aluminum Alloy Through Multi-Step Aging Process, Colin E. Masterson, Ryland W. Jolliffe

Materials Engineering

7175 is a heat-treatable aluminum alloy commonly used in aerospace forgings. This alloy is aged with a multi-step heat treatment. This treatment must balance strength with stress corrosion cracking resistance through a degree of overaging. The team was tasked by Weber Metals to increase the strength of this treatment without sacrificing stress corrosion cracking resistance. Both two-step and retrogression and reaging treatments were tested in experiments to find a heat treatment that could increase the yield and tensile strength by 1-2 ksi while maintaining a minimum electrochemical conductivity equivalence of 38% relative to copper. Two-step aging is the more conventional …

The Effect Of Nanostructures In Aluminum Alloys Processed Using Additive Manufacturing On Microstructural Evolution And Mechanical Performance Behavior, Rachel Boillat, Sriram Praneeth Isanaka, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper reviews the status of nanoparticle technology as it relates to the additive manufacturing (AM) of aluminum-based alloys. A broad overview of common AM processes is given. Additive manufacturing is a promising field for the advancement of manufacturing due to its ability to yield near-net-shaped components that require minimal post-processing prior to end-use. AM also allows for the fabrication of prototypes as well as economical small batch production. Aluminum alloys processed via AM would be very beneficial to the manufacturing industry due to their high strength to weight ratio; however, many of the conventional alloy compositions have been shown …

Correlating Fracture Toughness And Surface Roughness For A Ductile Epoxy Adhered To Aluminum Substrates, Kurt Ryan Smith

Masters Theses

Adhesively bonded joints are used across multiple disciplines as an efficient and cost effective method for reinforcing, repairing, or creating new structures. Sufficient understanding of the bond line characteristics of the adhesive is necessary to properly design a reliable bonded joint and ensure a long service life. It is well understood that surface preparation has a significant impact on these interface characteristics as a given level of surface roughness achieves mechanical interlocking between the resin and metal and is important to prevent premature interfacial failure [1]. The goal of this study is to characterize the fracture toughness values for an …

Research Of The Process Of Continuous Hydrogenation Of Benzene In The Presence Of Modified Catalysts, B Kedelbaev Dr. Professor, K Lakhanova Phd, G Iztleuov, Sadritdin Turabdzhanov Dr., Professor

Technical science and innovation

The technology has been developed for the production of unsaturated alloy nickel hydrogenation catalysts. The results of the study of the phase, chemical compositions and structure of nickel alloys and catalysts showed that the ferroalloy introduction as a modifying additive affects the NiAl₃ / Ni₂Al₃ ratio. The studied alloying metals are practically insoluble in alkali and exist in the catalyst in dissolved states. All these changes favorably affect the catalytic properties of modified nickel catalysts in the benzene hydrogenation reaction. A systematic study of the stationary catalyst activity with addition of ferroalloys in the continuous catalytic …

Effect Of Surface Roughness And External Loading On Embedment In Steel And Aluminum Bolted Joints, Nathan Stang

Electronic Theses and Dissertations

Embedment in bolted joints is defined as the local deformation of surfaces into one another due to uneven contact. Embedment that occurs after the tightening of a bolted joint can cause loss of preload in the joint potentially leading to failure. VDI 2230, a German standard for bolted joint design, is currently the main source for engineers regarding embedment. It related expected embedment to the surface roughness in steel bolted joints. This research expands on the VDI standard by performing tests on a commonly used aluminum alloy and a steel alloy. Both cold rolled 1045 steel and 6061- T6511 aluminum …

Thermomechanical Mechanisms That Cause Adhesion Of Aluminum High Pressure Die Castings To The Die, Alex Monroe

Dissertations, Master's Theses and Master's Reports

In high pressure die casting (HPDC) of aluminum, cast material adhering to die is a significant defect. Adhesion occurs in two primary ways. The casting may stick preventing its removal from the die. Aluminum can also adhere to the die and buildup in local areas on the die surface with additional casting cycles. This second form of adhesion is called soldering. Lubricant is the best technology to control all forms of adhesion, but it comes at the cost of casting porosity, blisters, reduced die life, and increased die casting machine wear. New strategies to prevent adhesion are desired to eliminate …

Analyzing Variation In Dispersoid Formation In Aluminum Alloys By Minor Changes In Homogenization Temperature, Brendan Treanore

Dissertations, Master's Theses and Master's Reports

The homogenization of billets in the aluminum extrusion industry is a critical step that removes chemical segregation from casting, dissolves low melting point phases, forms nanoscale dispersoid phases, and promotes the beta to alpha transformation of iron particles in the matrix. With ever increasing use of aluminum extrusion in the automotive industry there is a constant need for increased efficiency and consistency in processing of extruded aluminum. The work in this thesis explores the effects of 10°C differences in the homogenization temperature on the formation of dispersoids in 6082 alloys used in the automotive industry. The role of dispersoids is …

Atmospheric Corrosion Of Galvanically Coupled Aluminum Alloys And Carbon Steel, Mitchell Felde

Williams Honors College, Honors Research Projects

Aluminum alloys are a steadily growing material being commonly used in lieu of typical steels. Additional alloying, heat treatment, and other property enhancing processes are expanding the use of these alloys. However, with this expansion, galvanic corrosion is becoming more of an issue in the design stage due to the combination of these alloys with steels. The automotive industry is one industry where the use of aluminum alloys is becoming common practice. Aluminum alloys provide a lightweight aspect over the conventional carbon steel that was used previously. As a result of this transition towards more lightweight materials, galvanic coupling is …

Development Of A Novel Casting Alloy Composed Of Aluminum And Cerium With Other Minor Additions, Zachary Cole Sims

Doctoral Dissertations

Eutectic casting alloys of aluminum and cerium are a recent discovery and early research describes an alloy with great potential to meet the growing demand for a lightweight, economical, high specific strength material for use in high-temperature or extremely corrosive environments. The broad application of aluminum alloys across industry sectors is driven by their collection of balanced properties including economical cost, high specific strength, and flexibility of their production pathways. Additionally, their high corrosion resistance makes them a good choice for structural materials. Despite this, the push to use aluminum alloys in ever more extreme environments with higher temperatures, stresses, …

Boron Nitride Nanotube Based Lightweight Metal Matrix Composites: Microstructure Engineering And Stress-Transfer Mechanics, Pranjal Nautiyal

FIU Electronic Theses and Dissertations

Lightweight metals, such as Aluminum, Magnesium and Titanium, are receiving widespread attention for manufacturing agile structures. However, the mechanical strength of these metals and their alloys fall short of structural steels, curtailing their applicability in engineering applications where superior load-bearing ability is required. There is a need to effectively augment the deformation- and failure-resistance of these metals without compromising their density advantage.

This dissertation explores the mechanical reinforcement of the aforementioned lightweight metal matrices by utilizing Boron Nitride Nanotube (BNNT), a 1D nanomaterial with extraordinary mechanical properties. The nanotubes are found to resist thermo-oxidative transformations up to ~750°C, establishing their …