Open Access. Powered by Scholars. Published by Universities.®
- Discipline
-
- Aerospace Engineering (47)
- Materials Science and Engineering (40)
- Structures and Materials (17)
- Ceramic Materials (15)
- Metallurgy (15)
-
- Mechanical Engineering (3)
- Design of Experiments and Sample Surveys (2)
- Electrical and Computer Engineering (2)
- Physical Sciences and Mathematics (2)
- Statistics and Probability (2)
- Tribology (2)
- Chemical Engineering (1)
- Civil and Environmental Engineering (1)
- Controls and Control Theory (1)
- Electronic Devices and Semiconductor Manufacturing (1)
- Manufacturing (1)
- Other Aerospace Engineering (1)
- Polymer Science (1)
- Polymer and Organic Materials (1)
- Semiconductor and Optical Materials (1)
- Structural Engineering (1)
- Systems Engineering and Multidisciplinary Design Optimization (1)
- Keyword
-
- Ceramic-matrix composites--Fatigue (9)
- Composite materials (9)
- Metallic composites--Fatigue (8)
- Strains and stresses (8)
- Fretting corrosion (7)
-
- Materials--Fatigue (7)
- Damping (Mechanics) (6)
- Metals--Fatigue (5)
- Additive manufacturing (4)
- Fatigue (Mechanics) (4)
- Finite element method (4)
- Titanium (4)
- Aluminum alloys--Cracking (3)
- Composite materials--Fatigue (3)
- Mechanical properties (3)
- Silicon carbide (3)
- Titanium alloys--Fatigue (3)
- Aluminum--Fatigue (2)
- Axial loads (2)
- Ceramic matrix composite (CMC) (2)
- Ceramic-matrix composites--Creep (2)
- Fatigue (Materials) (2)
- Friction (2)
- Metal matrix composites (2)
- Metallic composites--Thermal fatigue (2)
- Metals--Impact testing--Mathematical models (2)
- Sandwich construction (2)
- Shot peening (2)
- Strain (Mechanics) (2)
- Titanium--Effect of temperature on (2)
- Publication Year
- Publication Type
Articles 1 - 30 of 103
Full-Text Articles in Mechanics of Materials
Tensile Creep Of A Hybrid Polymer-Matrix/Ceramic-Matrix Composite At Elevated Temperature, Waleed S. Alshehri
Tensile Creep Of A Hybrid Polymer-Matrix/Ceramic-Matrix Composite At Elevated Temperature, Waleed S. Alshehri
Theses and Dissertations
Advanced aerospace systems require structural materials that can perform reliably in high-temperature environments for long durations. The performance of standard polymer matrix composites (PMCs) in these conditions is often limited by their susceptibility to time-dependent deformation, such as creep. The objective of this research is to characterize the high-temperature creep behavior of a novel unitized material system comprising a polymer matrix composite (PMC) and a ceramic matrix composite (CMC) co-cured together. The PMC part consists of the polyimide matrix reinforced with laminated carbon fibers woven in an eight harness satin weave (8HSW). The CMC part consists of a zirconia-based ceramic …
Improvement Of Microcracking And Mechanical Properties Of Tungsten Fabricated Via Laser Powder Bed Fusion Through Alloying With Reactive Secondary Constituents, William S. Mockel
Improvement Of Microcracking And Mechanical Properties Of Tungsten Fabricated Via Laser Powder Bed Fusion Through Alloying With Reactive Secondary Constituents, William S. Mockel
Theses and Dissertations
Tungsten (W), a Group VI transition metal, possesses a number of advantageous properties, most notably its impressive mechanical performance at extreme temperatures. While tungsten's nature render traditional manufacturing methods difficult, additive manufacturing through laser powder bed fusion (LPBF) presents a promising avenue for fabricating tungsten components. However, the material’s high ductile-to-brittle transition temperature combined with the embrittling effect of impurities mean that the residual stresses imparted by LPBF result in microcracking in tungsten, degrading its usefulness. This study sought to improve the characteristics of LPBF-W through the removal of embrittling oxygen content via alloying with low concentrations of reactive elements, …
Mechanical Response Of Triply Periodic Minimal Surface Gyroid Structures Under Combined Loading, Jay B. Patel
Mechanical Response Of Triply Periodic Minimal Surface Gyroid Structures Under Combined Loading, Jay B. Patel
Theses and Dissertations
This work explored combined tensile and torsional loads applied to additively manufactured Inconel 718 specimens employing Triply Periodic Minimal Surface (TPMS) structures. The gyroid TPMS unit cell was selected with two variations of cylindrical cell maps, a rectangular cell map, and a spherical cell map. All four variants were tested in an axial-torsion test frame at room temperature using equal parts of vertical and angular displacement control until failure. The combined loading in these tests utilized tension and torsion. The data from the tests were compared to finite element analysis (FEA) models to visualize when yielding was predicted. Finally, the …
Fatigue Behavior Of Two Advanced C/Sic Composites At 1200°C In Air, Conner A. Adams
Fatigue Behavior Of Two Advanced C/Sic Composites At 1200°C In Air, Conner A. Adams
Theses and Dissertations
High-temperature tension-tension fatigue behavior of two advanced carbon/silicon carbide (C/SiC) ceramic matrix composites (CMCs) was investigated. Both composites were reinforced with T300 carbon fibers. Laminated carbon fiber preforms consisted of 24 plies of plain weave fabric in a 0/90 layup. The first composite, C/CVI-SiC, was processed by chemical vapor infiltration (CVI) of SiC into the fiber preform. Prior to the CVI process, the fiber preforms were coated with a duplex pyrolytic carbon and boron carbide fiber coating to create a weak fiber- matrix interphase. The second composite, C/HYPR-SiC, was also processed via CVI, but had an oxidation inhibited matrix comprising …
Fatigue Behavior Of An Advanced Sic/Sic Composite With An Array Of Small Cooling Holes At 1200°C, Tess K. Panchyshyn
Fatigue Behavior Of An Advanced Sic/Sic Composite With An Array Of Small Cooling Holes At 1200°C, Tess K. Panchyshyn
Theses and Dissertations
Tension-tension fatigue behavior of an advanced melt-infiltrated (MI) silicon carbide/silicon carbide (SiC/SiC) composite was evaluated, and basic tensile properties measured, at 1200°C in laboratory air. The composite consists of a melt-infiltrated SiC matrix reinforced with laminated Hi-Nicalon Type-S fibers woven in a 5-harness satin weave. The Hi-Nicalon-S fiber preforms were coated with a boron nitride (BN) fiber coating by chemical vapor infiltration (CVI). The melt-infiltrated matrix was consolidated by combining CVI-SiC with SiC particulate slurry and molten silicon infiltration. The finished ceramic matrix composite (CMC) had a fiber volume fraction of 33%. Additionally, the effect of multiple small holes on …
Tension–Compression Fatigue Of A Hybrid Polymer-Matrix/Ceramic-Matrix Composite At Elevated Temperature, Marina B. Ruggles-Wrenn, Joshua Schmidt
Tension–Compression Fatigue Of A Hybrid Polymer-Matrix/Ceramic-Matrix Composite At Elevated Temperature, Marina B. Ruggles-Wrenn, Joshua Schmidt
Faculty Publications
Fully reversed tension–compression fatigue of a hybrid material comprising polymer matrix composite (PMC) co-cured with a ceramic matrix composite (CMC) was investigated. The PMC portion had a polyimide matrix reinforced with 15 plies of carbon fibers woven in an eight-harness satin weave (8HSW). The CMC portion had three plies of a quartz-fiber 8HSW fabric in a zirconia-based ceramic matrix. The hybrid PMC/CMC was developed for use in aerospace thermal protection systems (TPS). Hence, the experimental setup aimed to simulate the TPS service environment—the CMC side was kept at 329 °C, whereas the PMC side was open to laboratory air. Compression …
A First Step Towards Understanding Thermomechanical Behavior Of The Nb-Cr System Through Interatomic Potential Development And Molecular Dynamics Simulations, Lucas A. Heaton, Adib J. Samin
A First Step Towards Understanding Thermomechanical Behavior Of The Nb-Cr System Through Interatomic Potential Development And Molecular Dynamics Simulations, Lucas A. Heaton, Adib J. Samin
Faculty Publications
Utilizing a preliminary interatomic potential, this work represents an initial exploration into the thermomechanical behavior of NbCr solid solutions. Specifically, it examines the effect of different amounts of Cr solute, for which information in the literature is limited. The employed interatomic potential was developed according to the embedded atom model (EAM), and was trained on data derived from density functional theory calculations. While the potential demonstrated reasonable accuracy and predictive power when tested, various results highlight deficiencies and encourage further development and training. Mechanical strength, heat capacities, thermal expansion coefficients, and thermal conductivities were found to decrease with Cr content. …
Adiabatic Shear Banding In Nickel And Nickel-Based Superalloys: A Review, Russell A. Rowe, Paul G. Allison, Anthony N. Palazotto, Keivan Davami
Adiabatic Shear Banding In Nickel And Nickel-Based Superalloys: A Review, Russell A. Rowe, Paul G. Allison, Anthony N. Palazotto, Keivan Davami
Faculty Publications
This review paper discusses the formation and propagation of adiabatic shear bands in nickel-based superalloys. The formation of adiabatic shear bands (ASBs) is a unique dynamic phenomenon that typically precedes catastrophic, unpredicted failure in many metals under impact or ballistic loading. ASBs are thin regions that undergo substantial plastic shear strain and material softening due to the thermo-mechanical instability induced by the competitive work hardening and thermal softening processes. Dynamic recrystallization of the material’s microstructure in the shear region can occur and encourages shear localization and the formation of ASBs. Phase transformations are also often seen in ASBs of ferrous …
Evaluation Of Additively Manufactured Lattices Under High Strain Rate Impact, Derek G. Spear
Evaluation Of Additively Manufactured Lattices Under High Strain Rate Impact, Derek G. Spear
Theses and Dissertations
Several additively manufactured lattice designs and configurations were evaluated under compression loads under various strain rates from quasi-static to highly dynamic. These experiments examined how the mechanical behavior of the lattice changed based on the lattice design properties and the applied strain rates. The modulus of elasticity, yield strength, plateau stress, and toughness were observed to decrease with an increase in strain rate, revealing that the lattice designs exhibit a negative strain rate sensitivity. A new lattice flow stress model was developed to account for the mechanical response of the lattice and was incorporated into a computational model for simulation. …
Investigation And Statistical Modeling Of The Mechanical Properties Of Additively Manufactured Lattices, Derek G. Spear, Anthony N. Palazotto
Investigation And Statistical Modeling Of The Mechanical Properties Of Additively Manufactured Lattices, Derek G. Spear, Anthony N. Palazotto
Faculty Publications
This paper describes the background, test methodology, and experimental results associated with the testing and analysis of quasi-static compression testing of additively manufactured open-cell lattice structures. The study aims to examine the effect of lattice topology, cell size, cell density, and surface thickness on the mechanical properties of lattice structures. Three lattice designs were chosen, the Diamond, I-WP, and Primitive Triply Periodic Minimal Surfaces (TPMSs). Uniaxial compression tests were conducted for every combination of the three lattice designs, three cell sizes, three cell densities, and three surface thicknesses. In order to perform an efficient experiment and gain the most information …
Shock Migration On An Oscillating Straked Delta Wing Using An Unsteady Euler Solver, Alexander J. Brown
Shock Migration On An Oscillating Straked Delta Wing Using An Unsteady Euler Solver, Alexander J. Brown
Theses and Dissertations
This research contributes to the understanding of Shock Induced Trailing Edge Separation (SITES) as a driver of Limit Cycle Oscillation (LCO) by performing a computational investigation of nonlinear aerodynamic phenomena on a straked delta wing in transonic flow, oscillating in pitch. ZEUS, an Euler-based aeroelastic solver with a boundary layer coupling scheme meant to capture viscous flow effects within the boundary layer, was used to analyze aerodynamic flow around the wing for various mean incidence angles, oscillation amplitudes, and Mach numbers within the transonic region. The dynamic characteristics of the airflow around the wing were investigated in order to characterize …
Experimental And Computational Analysis Of Progressive Failure In Bolted Hybrid Composite Joints, John S. Brewer
Experimental And Computational Analysis Of Progressive Failure In Bolted Hybrid Composite Joints, John S. Brewer
Theses and Dissertations
Composite materials are strong, lightweight, and stiff making them desirable in aerospace applications. However, a practical issue arises with composites in that they behave unpredictably in bolted joints, where damage and cracks are often initiated. This research investigated a solution to correcting the problem with composite bolted joints. A novel hybrid composite material was developed, where thin stainless steel foils were placed between and in place of preimpregnated composite plies during the cure cycle to reinforce stress concentrations in bolted joints. This novel composite was compared to control samples experimentally in quasi-static monotonic loading in double shear configuration in 9-ply …
Fatigue Of A Sic/Sic Ceramic Composite With An Ytterbium‐Disilicate Environmental Barrier Coating At Elevated Temperature, Marina B. Ruggles-Wrenn, Thaddeus M. Williams
Fatigue Of A Sic/Sic Ceramic Composite With An Ytterbium‐Disilicate Environmental Barrier Coating At Elevated Temperature, Marina B. Ruggles-Wrenn, Thaddeus M. Williams
Faculty Publications
Excerpt: Tension-tension fatigue performance of a SiC/SiC composite with an ytterbium-disilicate environmental barrier coating (EBC) was investigated at 1200°C in air and steam. The composite is reinforced with Hi-Nicalon™ SiC fibers and has a melt-infiltrated matrix processed by chemical vapor infiltration of SiC with subsequent infiltration with SiC particulate slurry and molten silicon. Abtract © American Ceramic Society
Fatigue Behavior Of An Advanced Melt-Infiltrated Sic/Sic Composite With Environmental Barrier Coating At 1200°C In Air And In Steam, Thaddeus M. Williams
Fatigue Behavior Of An Advanced Melt-Infiltrated Sic/Sic Composite With Environmental Barrier Coating At 1200°C In Air And In Steam, Thaddeus M. Williams
Theses and Dissertations
Advanced aerospace applications such as aircraft turbine engine components, hypersonic flight vehicles, and spacecraft reentry thermal protection systems require structural materials that have superior long-term mechanical properties under high temperature, high pressure, and varying environmental factors, such as moisture. Because of their low density, high strength and fracture toughness at high temperatures SiC fiber-reinforced SiC matrix composites are being evaluated for aircraft engine hot-section components. In these applications the composites will be subjected to various types of mechanical loadings at elevated temperatures in oxidizing environments. Because their constituents are intrinsically oxidation-prone, the most significant problem hindering SiC/SiC composites is oxidation …
Manufacture Of Fused Deposition Modeling Joints Using Ultem 9085, Zane A. Willburn
Manufacture Of Fused Deposition Modeling Joints Using Ultem 9085, Zane A. Willburn
Theses and Dissertations
The manufacture of joints between a base structure and a structure manufactured via Fused Deposition Modeling (FDM) will be investigated. ULTEM 9085, a high temperature plastic with potential aerospace applications, will be the material used. The specific application this research is focused on is a robotic and mobile FDM printer capable of building structures onto other structures in space. A joint will be formed by fusing the base layer of the printed structure and the top of the base structure together. Tensile testing will be performed to determine the strength of the bond between parts. Tensile specimens will be manufactured …
Creep Of Hafnium Diboride -20 Vol% Silicon Carbide At 1500°C In Air, Glen E. Pry
Creep Of Hafnium Diboride -20 Vol% Silicon Carbide At 1500°C In Air, Glen E. Pry
Theses and Dissertations
Refractory metal borides, commonly referred to as Ultra High Temperature Ceramics (UHTCs), exhibit a number of unique properties, such as extremely high melting temperature and hardness, chemical stability, high electrical and thermal conductivity and corrosion resistance. It has been demonstrated that the addition of SiC improves the oxidation resistance of ZrB2- and HfB2-based UHTCs above 1200°C by modifying the composition of the oxide scale. Addition of SiC retards the oxidation rate of ZrB2 and HfB2 by forming a protective layer of borosilicate glass. Creep deformation is one of the critical criterion for structural application of ceramics at elevated temperatures. Compression …
Tensile Properties And Fatigue Behavior Of Geopolymer Matrix Composites With Carbon Fiber Reinforcement At Elevated Temperature, Steffan M.L. Wilcox
Tensile Properties And Fatigue Behavior Of Geopolymer Matrix Composites With Carbon Fiber Reinforcement At Elevated Temperature, Steffan M.L. Wilcox
Theses and Dissertations
The tensile stress-strain and tension-tension fatigue of geopolymer matrix composites reinforced with 0/90 carbon fibers was investigated at 23 and 300°C in laboratory air. Geopolymers are inorganic polymeric materials composed of alumina, silica, and alkali metal oxides. Because geopolymers are synthesized as a fluid mixture or particles and liquid, they can be cast into a desired shape, and cured at only slightly elevated temperatures. The relative ease of synthesis and low processing temperatures make geopolymers an attractive choice as a matrix material for composite materials. Geopolymers also offer resistance to heat and oxidizing environments. Currently, geopolymer matrix composites are being …
Stressed Oxidation Of Hafnium Diboride In Air At 1500°C, Thomas A. Bowen
Stressed Oxidation Of Hafnium Diboride In Air At 1500°C, Thomas A. Bowen
Theses and Dissertations
Hypersonic vehicles with narrow airfoils produce thin boundary layers and shock temperatures in excess of 2000°C, exceeding the operating limits of traditional aerospace materials. The use of ultra-high temperature ceramics (UHTCs) allows for operating temperatures far exceeding those of metallic alloys. One such UHTC is hafnium diboride (HfB2). Transition metal diborides generally experience significant oxidation degradation at elevated temperatures. The use of additives, such as silicon carbide (SiC) has been shown to reduce the oxidation of transition metal diborides. This research focused on the compressive creep of HfB2 with varying amounts of SiC in air at 1500°C. …
Experimental Investigation Of Mechanical Behavior Of An Oxide/Oxide Ceramic Composite In Interlaminar Shear And Under Combined Tension-Torsion Loading, Skyler R. Hilburn
Experimental Investigation Of Mechanical Behavior Of An Oxide/Oxide Ceramic Composite In Interlaminar Shear And Under Combined Tension-Torsion Loading, Skyler R. Hilburn
Theses and Dissertations
Creep behavior in interlaminar shear of an oxide-oxide ceramic composite, Nextel 720™/aluminosilicate (N720/AS), was investigated at 1100°C in laboratory air and in steam. The interlaminar shear strength (ILSS) was determined as 7.65 MPa. The creep behavior was examined for interlaminar shear stresses in the 2-6 MPa range. Primary and secondary creep regimes were observed in all tests conducted in air and in steam. Tertiary creep was noted in the tests performed at 6 MPa. Larger creep strains and higher creep strain rates were produced in steam. Surprisingly, the presence of steam had a beneficial effect on creep lifetimes. It appears …
Effect Of Steam Environment On Creep Behavior Of Nextel720/Alumina-Mullite Ceramic Matrix Composite At Elevated Temperature, Tolga Kutsal
Effect Of Steam Environment On Creep Behavior Of Nextel720/Alumina-Mullite Ceramic Matrix Composite At Elevated Temperature, Tolga Kutsal
Theses and Dissertations
The tensile creep behavior of an oxide-oxide ceramic matrix composite (CMC) was investigated at 1000 and 1100° C in laboratory air and steam. The oxide-oxide CMC studied in this research was Nextel™ 720/alumina-mullite (N720/AM). The composite consists of N720/fibers with 0°/90° fiber orientation and a porous alumina-mullite matrix. Tensile-strain behavior was investigated and tensile properties measured at 900, 1000 and 1100° C. The effect of loading rate on tensile properties of N720/AM ceramic matrix composite at 1100° C in steam was also examined. Creep-rupture tests were performed at 1100° C in laboratory air and steam, and at 1000° C only …
A Finite Element Evaluation Of An Experiment Related To Coating Damping Properties, Armando Deleon
A Finite Element Evaluation Of An Experiment Related To Coating Damping Properties, Armando Deleon
Theses and Dissertations
Typically turbine engine blades gain protection from thermal damage by the use of hard coatings, such as magnesium aluminate spinel. Known as Thermal Barrier Coatings (TBC's), they have material properties that include several nonlinearities. These TBC's create damping primarily due to their nonlinear dissipation of energy. In order to effectively represent their damping properties, it is necessary to create a method which combines experimentation and analysis. Previous work has shown the need for a beam bounded and loaded in such a fashion that external support energy dissipation functions i.e. boundary conditions and aerodynamics are eliminated. Thus, a new experimental apparatus …
Effects Of Prior Aging At 316°C In Argon On Inelastic Deformation Behavior Of Pmr-15 Polymer At 316°C: Experiment And Modeling, Ozgur Ozmen
Theses and Dissertations
The inelastic deformation behavior of PMR-15 neat resin, a high-temperature polymer, was investigated at 316 deg C. The experimental program was designed to explore the influence of strain rate on tensile loading, unloading, and strain recovery behaviors. In addition, the effect of the prior strain rate on the relaxation response of the material, as well as on the creep behavior following strain controlled loading were examined. The material exhibits positive, nonlinear strain rate sensitivity in monotonic loading and unloading. Early failures occur in the inelastic regime. The recovery of strain at zero stress and creep response are strongly affected by …
Thermomechanical Properties Of Center-Reinforced Aluminum, Geofrey S. Cox
Thermomechanical Properties Of Center-Reinforced Aluminum, Geofrey S. Cox
Theses and Dissertations
The rule of mixture approach was shown to produce an accurate theoretical prediction of the room temperature elastic modulus values when compared to the experimental results. The laminate's modulus value remained relatively constant over the -55C to 80C temperature range, indicating stable behavior despite temperature changes. Blunt notch tests also revealed that the laminate's strength was not significantly reduced due to the presence of small holes. Finally, fatigue testing demonstrated that the laminate retains its stiffness properties throughout its fatigue life, until failure.
A Novel Method Characterizing The Impact Response Of Functionally Graded Plates, Reid A. Larson
A Novel Method Characterizing The Impact Response Of Functionally Graded Plates, Reid A. Larson
Theses and Dissertations
Functionally graded material (FGM) plates are advanced composites with properties that vary continuously through the thickness of the plate. Metal-ceramic FGM plates have been proposed for use in thermal protection systems where a metal-rich interior surface of the plate gradually transitions to a ceramic-rich exterior surface of the plate. The ability of FGMs to resist impact loads must be demonstrated before using them in high-temperature environments in service. This dissertation presents a novel technique by which the impact response of FGM plates is characterized for low-velocity, low- to medium-energy impact loads. An experiment was designed where strain histories in FGM …
The Effect Of Elevated Temperature On The Fretting Fatigue Behavior Of Nickel Alloy In-100, John F. Ownby
The Effect Of Elevated Temperature On The Fretting Fatigue Behavior Of Nickel Alloy In-100, John F. Ownby
Theses and Dissertations
This thesis studied the effect of elevated temperature (600 C) on the fretting fatigue behavior of IN-100. First, fretting and plain fatigue S-N curves were determined over a large range of applied stress at an identical stress ratio of 0.03 at 600 C and for fretting tests, with a constant contact load. The partial slip condition was verified by using hysteresis between shear force and axial stress techniques. The contact width and the crack initiation location were observed for all of the fretting specimens. The contact widths were consistent with expected values and the crack initiation location was at the …
An Experimental Technique For Developing Intermediate Strain Rates In Ductile Metals, Hugh E. Gardenier Iv
An Experimental Technique For Developing Intermediate Strain Rates In Ductile Metals, Hugh E. Gardenier Iv
Theses and Dissertations
Quantifying the strain-rate sensitive dynamic properties of structural materials is an important area of research in the solid mechanics field. Property evaluation is typically accomplished using dynamic tests which involve rapid loading or impact of specimens. In these tests, inertial forces and wave propagation make it difficult to accurately record the material response to a loading condition at an equivalent location. Furthermore, these tests typically generate high strain rates (in excess of 103 s−1) and an experimental method for generating rates of strain in the intermediate strain rate regime which is relatively simple, low cost, and reliable …
Investigation Into Fretting Fatigue Under Cyclic Contact Load And In Conjuction With Fatigue Of Titanium Alloy, Abdulla A. Al-Noaimi
Investigation Into Fretting Fatigue Under Cyclic Contact Load And In Conjuction With Fatigue Of Titanium Alloy, Abdulla A. Al-Noaimi
Theses and Dissertations
Fretting fatigue is the surface damage that occurs at the interface between two components that are undergoing a small amplitude oscillatory movements. It results in a reduction of the material life comparing to the plain fatigue. Most of the previous works were accomplished under a constant applied contact load and a little effort has been done under a variable contact load, while none of these studies have taken the phase difference between the axial and the contact load. The primary goal of this study is to investigate the effect of phase difference between axial and contact loads on fretting fatigue …
An Experimental Technique For The Evaluation Of Strain Dependent Material Properties Of Hard Coatings, Shad A. Reed, Anthony N. Palazotto, William P. Baker
An Experimental Technique For The Evaluation Of Strain Dependent Material Properties Of Hard Coatings, Shad A. Reed, Anthony N. Palazotto, William P. Baker
Faculty Publications
A novel vibration experiment consisting of a free-free boundary condition, an electromagnetic excitation source, a vacuum chamber, and a laser vibrometer based surface measurement system has been developed that permits high levels of excitation on highly damped specimens with a minimal amount of unwanted systematic error. While some of the aspects of this experiment are not unique, when combined with a processing technique that accounts for the nonlinearities present in the system, this experiment permits, accurate measurement of strain dependent stiffness and damping properties of hard coatings at high strain levels. This procedure has been demonstrated using a titanium beam …
Cyclic Creep And Recovery Behavior Of Nextel™ 720/Alumina Ceramic Matrix Composite At 1200° C In Air And Steam Environments, Bridgett A. Whiting
Cyclic Creep And Recovery Behavior Of Nextel™ 720/Alumina Ceramic Matrix Composite At 1200° C In Air And Steam Environments, Bridgett A. Whiting
Theses and Dissertations
The cyclic creep and recovery behaviors of the N720/Al2O3 composite were investigated in this research. The ceramic matrix composite (CMC) contains a porous alumina matrix with laminated, woven mullite/alumina (NextelTM 720) fibers. The composite does not have an interface between the fiber and matrix. The CMC relies on the porous nature for flaw tolerance. The objective of this study the influences of monotonic creep and cyclic creep loading histories on the creep lifetime, creep strain rate, accumulated creep strain as well as on the recovery of creep strain at near zero stress. The cyclic creep and …
Effects Of Prior Aging At 191°C On Creep Response Of Im7/Bmi 5250-4, Robert A. Salvia
Effects Of Prior Aging At 191°C On Creep Response Of Im7/Bmi 5250-4, Robert A. Salvia
Theses and Dissertations
The creep behavior of IM7/BMI 5250-4 with fiber orientations of [± 45] and [0/90] that were aged in air at 191 °C for up to 1000 hours was evaluated. The total weight loss during the aging process was also evaluated. Weight loss due to aging was 0.64% for the [0/90] fiber orientation and 0.72% for the [± 45] fiber orientation. Tensile tests to failure were conducted to establish tensile properties. The [0/90] specimens have a much higher stiffness and Ultimate Tensile Strength (UTS) values than the [± 45] specimens. The tensile tests of the aged specimens revealed that the Ultimate …