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Full-Text Articles in Engineering
Prediction Of Springback In Aa6016-T4 Sheets Using Isotropic Finite Element And Epsc Modeling Approaches, Dane Roger Sargeant
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 …
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
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 …
Friction Bit Joining Of Similar Alloy Sheets Of High-Strength Aluminum Alloy 7085, Matthew R. Okazaki
Friction Bit Joining Of Similar Alloy Sheets Of High-Strength Aluminum Alloy 7085, Matthew R. Okazaki
Theses and Dissertations
Friction Bit Joining (FBJ) is a new technology used primarily in joining dissimilar metals. Its primary use has been focused in the automotive industry to provide an alternative joining process to welding. As automotive manufacturing has continually pushed toward using dissimilar materials, new joining processes have been needed to replace traditional welding practices that do not perform well when materials are not weld compatible. FBJ meets these needs perfectly as it provides strength as well as the ability to join materials of almost any kind.The purpose of this research was to explore different applications of the FBJ process. Traditionally FBJ …
Toward A Production Ready Fbj Process For Joining Dissimilar Combinations Of Gadp 1180 Steel And Aa 7085-T76, Kevin Alexander Shirley
Toward A Production Ready Fbj Process For Joining Dissimilar Combinations Of Gadp 1180 Steel And Aa 7085-T76, Kevin Alexander Shirley
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 light weight structures for the automotive industry by combining lightweight materials such as aluminum to stronger materials like advanced high-strength steels. The automotive industry and many other industries have great interest in reducing structure weight to increase fuel efficiency. The purpose of this research is to make FBJ of GADP 1180 to AA 7085-T76 a production ready process by (1) better understanding the effects of process parameters, bit design and tool design on joint …
Manipulation And Automation Of Fbj Short-Axis Fasteners, Shane Forrest Wood
Manipulation And Automation Of Fbj Short-Axis Fasteners, Shane Forrest Wood
Theses and Dissertations
Legislative and market pressures are pushing automakers to achieve new fuel economy requirements in the coming years. To help achieve these goals automakers are reducing the overall weight of the vehicle by increasing the use of high-strength aluminum and advanced high-strength steels, and with this increased use comes the desire to quickly, and securely, join these materials within the vehicle. Friction bit joining is a process that lends itself well to joining these materials. This process uses consumable fasteners that need to be used in an automated production line. The geometry of these fasteners causes two main problems: the bits …
Friction Bit Joining Of Dissimilar Combinations Of Gadp 1180 Steel And Aa 7085 – T76 Aluminum, Lorne Steele Atwood
Friction Bit Joining Of Dissimilar Combinations Of Gadp 1180 Steel And Aa 7085 – T76 Aluminum, Lorne Steele Atwood
Theses and Dissertations
Friction Bit Joining (FBJ) is a method used to join lightweight metals to advanced high-strength steels (AHSS). The automotive industry is experiencing pressure to improve fuel efficiency in their vehicles. The use of AHSS and aluminum will reduce vehicle weight which will assist in reducing fuel consumption. Previous research achieved joint strengths well above that which was required in three out of the four standard joint strength tests using DP980 AHSS and 7075 aluminum. The joints were mechanically tested and passed the lap-shear tension, cross-tension, and fatigue cycling tests. The t-peel test configuration never passed the minimum requirements. The purpose …
Friction Bit Joining Of Dissimilar Combinations Of Dp 980 Steel And Aa 7075, Rebecca Hilary Peterson
Friction Bit Joining Of Dissimilar Combinations Of Dp 980 Steel And Aa 7075, Rebecca Hilary Peterson
Theses and Dissertations
Friction Bit Joining (FBJ) is a new technology that allows lightweight metals to be joined to advanced high-strength steels (AHSS). Joining of dissimilar metals is especially beneficial to the automotive industry because of the desire to use materials such as aluminum and AHSS in order to reduce weight and increase fuel efficiency. In this study, FBJ was used to join 7075 aluminum and DP980 ultra-high-strength steel. FBJ is a two-stage process using a consumable bit. In the first stage, the bit cuts through the top material (aluminum), and in the second stage the bit is friction welded to the base …
Friction Bit Joining Of Dissimilar Combinations Of Advanced High-Strength Steel And Aluminum Alloys, Lile P. Squires
Friction Bit Joining Of Dissimilar Combinations Of Advanced High-Strength Steel And Aluminum Alloys, Lile P. Squires
Theses and Dissertations
Friction bit joining (FBJ) is a new method that enables lightweight metal to be joined to advanced high-strength steels. Weight reduction through the use of advanced high-strength materials is necessary in the automotive industry, as well as other markets, where weight savings are increasingly emphasized in pursuit of fuel efficiency. The purpose of this research is twofold: (1) to understand the influence that process parameters such as bit design, material type and machine commands have on the consistency and strength of friction bit joints in dissimilar metal alloys; and (2) to pioneer machine and bit configurations that would aid commercial, …
A Material System For Reliable Low Voltage Anodic Electrowetting, Mehdi Khodayari, Jose Carballo, Nathan B. Crane
A Material System For Reliable Low Voltage Anodic Electrowetting, Mehdi Khodayari, Jose Carballo, Nathan B. Crane
Faculty Publications
Electrowetting on dielectric is demonstrated with a thin spin-coated fluoropolymer over an aluminum electrode. Previous efforts to use thin spin-coated dielectric layers for electrowetting have shown limited success due to defects in the layers. However, when used with a citric acid electrolyte and anodic voltages, repeatable droplet actuation is achieved for 5000 cycles with an actuation of just 10 V. This offers the potential for low voltage electrowetting systems that can be manufactured with a simple low-cost process.
Modeling Solid Propellant Ignition Events, Daniel A. Smyth
Modeling Solid Propellant Ignition Events, Daniel A. Smyth
Theses and Dissertations
This dissertation documents the building of computational propellant/ingredient models toward predicting AP/HTPB/Al cookoff events. Two computer codes were used to complete this work; a steady-state code and a transient ignition code Numerous levels of verification resulted in a robust set of codes to which several propellant/ingredient models were applied. To validate the final cookoff predictions, several levels of validation were completed, including the comparison of model predictions to experimental data for: AP steady-state combustion, fine-AP/HTPB steady-state combustion, AP laser ignition, fine-AP/HTPB laser ignition, AP/HTPB/Al ignition, and AP/HTPB/Al cookoff. A previous AP steady-state model was updated, and then a new AP …
Friction Bit Joining Of 5754 Aluminum To Dp980 Ultra-High Strength Steel: A Feasibility Study, Britney Weickum
Friction Bit Joining Of 5754 Aluminum To Dp980 Ultra-High Strength Steel: A Feasibility Study, Britney Weickum
Theses and Dissertations
In this study, the dissimilar metals 5754 aluminum and DP980 ultra-high strength steel were joined using the friction bit joining (FBJ) process. The friction bits were made using one of three steels: 4140, 4340, or H13. Experiments were performed in lap shear, T-peel, and cross tension configurations, with the 0.070" thick 5754 aluminum alloy as the top layer through which the friction bit cut, and the 0.065" thick DP980 as the bottom layer to which the friction bit welded. All experiments were performed using a computer controlled welding machine that was purpose-built and provided by MegaStir Technologies. Through a series …
The Composition And Distribution Of Coal-Ash Deposits Under Reducing And Oxidizing Conditions From A Suite Of Eight Coals, David R. Brunner
The Composition And Distribution Of Coal-Ash Deposits Under Reducing And Oxidizing Conditions From A Suite Of Eight Coals, David R. Brunner
Theses and Dissertations
Eighteen elements, including: carbon, oxygen, sodium, magnesium, aluminum, silicon, phosphorus, sulfur, chlorine, potassium, calcium, titanium, chromium, manganese, iron, nickel, strontium, and barium were measured using a scanning electron microscope with energy dispersive spectroscopy from deposits. The deposits were collected by burning eight different coals in a 160 kWth, staged, down-fired, swirl-stabilized combustor. Both up-stream and down-stream deposits from an oxidizing region (equivalence ratio 0.86) and reducing region (equivalence ratio 1.15) were collected. Within the deposits, the particle size and morphology were studied. The average particle cross-sectional area from the up-stream deposits ranged from 10 - 75 µm2 and had a …
Multidimensional Modeling Of Solid Propellant Burning Rates And Aluminum Agglomeration And One-Dimensional Modeling Of Rdx/Gap And Ap/Htpb, Matthew Wilder Tanner
Multidimensional Modeling Of Solid Propellant Burning Rates And Aluminum Agglomeration And One-Dimensional Modeling Of Rdx/Gap And Ap/Htpb, Matthew Wilder Tanner
Theses and Dissertations
This document details original numerical studies performed by the author pertaining to solid propellant combustion. Detailed kinetic mechanisms have been utilized to model the combustion of the pseudo-propellants RDX/GAP and AP/HTPB. A particle packing model and a diffusion flame model have been utilized to develop a burning rate and an aluminum agglomeration model. The numerical model for RDX/GAP combustion utilizes a "universal" gas-phase kinetic mechanism previously applied to combustion models of several monopropellants and pseudo-propellants. The kinetic mechanism consists of 83 species and 530 reactions. Numerical results using this mechanism provide excellent agreement with RDX and GAP burning rate data, …
An Investigation Of Wear-Resistant Coatings On An A390 Die-Cast Aluminum Substrate, D. Adam Mower
An Investigation Of Wear-Resistant Coatings On An A390 Die-Cast Aluminum Substrate, D. Adam Mower
Theses and Dissertations
In this investigation, four coatings were tested for their ability to increase the wear life of A390 aluminum primary clutch sheaves used in continuously variable transmission (CVT). The coatings tested were: hard chrome, electroless nickel metal, hard coat anodizing and composite ceramic coating. The primary clutch sheave material is a die-cast A390 aluminum. A wear test stand was developed to duplicate wear found on CVTs currently in use. The wear was evaluated using four methods. First, the change in shift characteristics of the CVT while running on the wear test stand, second a change in performance using an ATV and …
A Torque Based Power Input Model For Friction Stir Welding, Jefferson W. Pew
A Torque Based Power Input Model For Friction Stir Welding, Jefferson W. Pew
Theses and Dissertations
For decades models have been developed for predicting the size of the weld nugget and heat affected zones in fusion welded structures. The basis for these models is the welding heat input, which is fairly well understood for most arc welding processes. However, this traditional approach is not as straightforward for Friction Stir Welding (FSW). To date, there is no definitive relationship to quantify the heat input for FSW. An important step to establish a heat input model is to identify how FSW process parameters affect weld power. This study details the relationship between FSW process parameters and torque for …
Grain Boundary Property Determination Through Measurement Of Triple Junction Geometry And Crystallography, Brent L. Adams, D. Casasent, M. Demirel, Bassem S. El-Dasher, D. Kinderlehrer, C. Liu, I. Livshits, F. Manolache, D. Mason, A. Morawiec, W. W. Mullins, S. Ozdemir, Gregory S. Rohrer, Anthony D. Rollett, David M. Saylor, Shlomo Ta'asan, A. Talukder, Chialin T. Wu, C. C. Yang, W. Yang
Grain Boundary Property Determination Through Measurement Of Triple Junction Geometry And Crystallography, Brent L. Adams, D. Casasent, M. Demirel, Bassem S. El-Dasher, D. Kinderlehrer, C. Liu, I. Livshits, F. Manolache, D. Mason, A. Morawiec, W. W. Mullins, S. Ozdemir, Gregory S. Rohrer, Anthony D. Rollett, David M. Saylor, Shlomo Ta'asan, A. Talukder, Chialin T. Wu, C. C. Yang, W. Yang
Faculty Publications
This work was supported primarily by the MRSEC program of the National Science Foundation under Award Number DMR-0079996. Microstructure controls the properties of most useful materials. Thus an ability to control microstructure through the processing of materials is a key to optimization of materials performance. Most materials are polycrystalline and their grain structure is a very important aspect of their microstructure. Thanks to their complexity there is a great variety of grain boundary types even in relatively isotropic materials such as the cubic metals. Simply describing the crystallography requires five (macroscopic) parameters (e.g. disorientation and inclination). Evidently, acquiring a knowledge …
An Investigation Of Improving Wear Of 390 Die-Cast Aluminum Through Hardcoat Anodizing, Michael J. Whiting
An Investigation Of Improving Wear Of 390 Die-Cast Aluminum Through Hardcoat Anodizing, Michael J. Whiting
Theses and Dissertations
The objectives of this research were to investigate the wear that occurs on the surface of a Hardcoat anodized die-cast aluminum surface, which was sliding against a composite rubber belt. This research investigated known wear theories and the results for previous testing to understand the mechanisms that were likely occurring in this application. These theories indicated that the wear occurring may be reduced by changing the hardness of the materials involved. Archard's equation gave tangible evidence of this fact, but related to the base material and not a surface coating. It was hypothesized that Hardcoat anodizing would follow the theory …
Experimental And Numerical Investigation Of Tool Heating During Friction Stir Welding, Joshua L. Covington
Experimental And Numerical Investigation Of Tool Heating During Friction Stir Welding, Joshua L. Covington
Theses and Dissertations
The heat input to the tool has been investigated for friction stir welding (FSW) of aluminum alloy AL 7075-T7351 over a wide range of process operating parameters using a combined experimental/numerical approach. In a statistical Design of Experiments fashion, 54 experimental welds (bead-on-plate) were performed at 27 different parameter combinations. Measured outputs during each of the welds included forces in all three coordinate directions and internal temperature of the rotating tool at three locations near the tool/workpiece interface. The heat input to the tool was also identified for each weld using infrared imaging temperature measurement techniques and the portion of …
Microstructure Design Of A Two Phase Composite Using Two-Point Correlation Functions, Brent L. Adams, H. Garmestani, G. Saheli
Microstructure Design Of A Two Phase Composite Using Two-Point Correlation Functions, Brent L. Adams, H. Garmestani, G. Saheli
Faculty Publications
This work has been funded under the AFOSR Grant no. F49620-03-1-0011 and Army Research Lab contract no. DAAD17-02-P-0398 and DAAD 19-01-1-0742. Two-point distribution functions are used here as to introduce "Microstructure Sensitive Design" in two-phase composites. Statistical distribution functions are commonly used for the representation of microstructures and also for homogenization of materials properties. The use of two-point statistics allows the composite designer to include the morphology and distribution in addition to the properties of the individual phases and components. Statistical continuum mechanics is used to make a direct link between the microstructure and properties (elastic and plastic) in terms …
Advances In Experimental Method And Analysis For Estimation Of Geometrically-Necessary Dislocations, Brent L. Adams, Bassem S. El-Dasher, Anthony D. Rollett
Advances In Experimental Method And Analysis For Estimation Of Geometrically-Necessary Dislocations, Brent L. Adams, Bassem S. El-Dasher, Anthony D. Rollett
Faculty Publications
The authors wish to thank The Alcoa Technical Research Center for supplying the specimens and performing the compression tests. This work was supported by the MRSEC program of the National Science Foundation under DMR-0079996 as well as Lawrence Livermore Laboratory DOE/DoD Joint Program. An behavior of grain boundaries of the polycrystalline materials over a wide range of length scales during plastic deformation is considered. Electron backscattering diffraction and orientation imaging microscopy provide automated scanning measurements of the lattice orientation near grain boundaries. These methods are useful to set the necessary length scales. The data are presented for directionally-solidified pure Al …
Viewpoint: Experimental Recovery Of Geometrically Necessary Dislocation Density In Polycrystals, Brent L. Adams, Bassem S. El-Dasher, Anthony D. Rollett
Viewpoint: Experimental Recovery Of Geometrically Necessary Dislocation Density In Polycrystals, Brent L. Adams, Bassem S. El-Dasher, Anthony D. Rollett
Faculty Publications
The authors wish to thank The Alcoa Technical Research Center for supplying the specimens and performing the compression tests. This work was supported primarily by the MRSEC program of the National Science Foundation under DMR-0079996. Application of electron backscattering diffraction methods to recover estimates of the geometrically necessary dislocation density is described. The limitations of the method arising from the opacity of crystalline materials and the spatial and angular resolution limits are discussed.
Determination Of Effective Strain For The Strainhardening Of Aluminum Subjected To Completely Reversed Strain Combinations, Navin M. Patani
Determination Of Effective Strain For The Strainhardening Of Aluminum Subjected To Completely Reversed Strain Combinations, Navin M. Patani
Theses and Dissertations
It is known that subrecrystallization plastic deformation increases the strength of a metal. The amount of strengthening that may be acquired can be approximated using a strainhardening equation and a simple given strain. The purpose of this thesis was to determine the effective strain for predicting strainhardening for annealed aluminum subjected to completely reversed strain combinations.
The Enrichment Of Hydro-Carbon Fuel By Aluminum Powder In An Open-Hearth Furnace, Rick Sung-Tao Lee
The Enrichment Of Hydro-Carbon Fuel By Aluminum Powder In An Open-Hearth Furnace, Rick Sung-Tao Lee
Theses and Dissertations
The objective of this thesis was to study theoretically the enrichment of hydrocarbon fuels with aluminum powder for an open-hearth furnace.