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Articles 1 - 12 of 12
Full-Text Articles in Engineering Science and Materials
Investigation Of Compressive Behavior For Metal Matrix Composites With A Circular Hole, Janet L. Gooder
Investigation Of Compressive Behavior For Metal Matrix Composites With A Circular Hole, Janet L. Gooder
Theses and Dissertations
This study investigated the notched and unnotched macromechanical response due to micromechanical behavior of [0/±45/90]S SCS-6/β 21 S and [0/90] 2S Sigma/β 21S subjected to static compressive loads at room temperature. The stress-strain behavior and mechanical response in the presence of a circular hole was examined. A clear description of the progressive nature of damage, which ultimately resulted in failure, was provided. The effect of elevated temperature was shown for SCS-6/β 21S. The ultimate compressive strength and elastic modulus were reported for both MMCs. Sigma/β 21S and SCS-6/β 21S were mildly notch sensitive at room temperature. Notch sensitivity of …
A Study Of Graphite Peek Composite With Central Elliptical Holes Under Tension, Bill J. Lau
A Study Of Graphite Peek Composite With Central Elliptical Holes Under Tension, Bill J. Lau
Theses and Dissertations
This study investigated the stress-strain response and failure modes of Graphite/Polyetheretherketone (Gr/PEEK) tension specimens containing a central elliptical hole. Both experiments and finite element numerical analyses were conducted. Test specimens included seven layups and three hole geometries; three of each combination were tested. The holes consisted of an ellipse with major axis aligned with the load axis, an ellipse with major axis transverse to the load axis, and a circle. Strain gages were located adjacent to the hole and midway between the hole and tab on all specimens. Strain data was used to plot stress-strain response. The analysis utilized a …
Fatigue Behavior Of A Cross-Ply Ceramic Matrix Composite At Elevated Temperatures Under Tension-Tension Loading, Richard J. Tuznik
Fatigue Behavior Of A Cross-Ply Ceramic Matrix Composite At Elevated Temperatures Under Tension-Tension Loading, Richard J. Tuznik
Theses and Dissertations
A study was conducted which investigated the behavior of a Nicalon/ Calcium-Aluminosilicate (Nicalon/CAS) cross-ply [0/90]2S ceramic matrix composite at elevated temperatures under tension-tension fatigue loading. Tension-tension fatigue tests were performed with a load ratio of R = 0.10 and a frequency of 10 Hertz at 700°C and 850°C. These results were compared to results from a previous study conducted at room temperature. Material behavior and damage was recorded by fatigue life curves, elastic modulus' maximum and minimum strain, acetate replication techniques, and post-mortem fractography. Analysis of these results showed identical matrix dominated damage behavior at RT and 700°C. Ultimate …
Simultaneous Design Of Active Vibration Control And Passive Damping, Michele Lynn Devereaux Gaudreault
Simultaneous Design Of Active Vibration Control And Passive Damping, Michele Lynn Devereaux Gaudreault
Theses and Dissertations
A modified form of the standard linear quadratic regulator LQR cost functional is used to optimally blend active vibration control and passive structural damping, whether viscous or viscoelastic. Viscoelastic damping is first modelled by a standard linear model, and then by a fractional derivative model. For the viscous damping case and the classically modelled viscoelastic damping case, a sub-optimal closed form solution is derived that is independent of the initial conditions. An iterative technique that minimizes the average value of the cost functional and one that minimizes the maximum value are developed. Both techniques are applicable to viscous and viscoelastic …
Investigation Of Tension-Compression Fatigue Behavior Of A Cross-Ply Metal Matrix Composite At Room And Elevated Temperatures, Elizabeth A. Boyum
Investigation Of Tension-Compression Fatigue Behavior Of A Cross-Ply Metal Matrix Composite At Room And Elevated Temperatures, Elizabeth A. Boyum
Theses and Dissertations
This research, the first load-controlled tension-compression fatigue testing to be performed on a MMC, extends the existing knowledge of MMC fatigue damage mechanisms to include the tension compression loading condition. To accomplish this, a (0/90)2, SCS-6/Ti-15-3 laminate was subjected to tension- tension fatigue at room temperature, and tension-compression fatigue at both room temperature and 427°C. Stress and strain data was taken to evaluate the macro-mechanic behavior of the material. Microscopy and fractography were performed to characterize the damage on a micro-mechanic level. On a maximum applied stress basis, the room temperature tension-tension specimens had longer fatigue lives than the room …
Influence Of Embedded Optical Fibers On Compressive Strength Of Advanced Composites, Stefan B. Dosedel
Influence Of Embedded Optical Fibers On Compressive Strength Of Advanced Composites, Stefan B. Dosedel
Theses and Dissertations
This study investigated the effects of embedding optical fibers into advanced composite materials. This combination was meant to simulate 'smart structures' that have been shown to sense several different variables in the composite including strain, temperature, and damage. A laminate orientation taken from an existing aircraft structure was used to fabricate sixteen groups of specimens which were subjected to compression testing in an IITRI fixture to determine the ultimate compressive strength and modulus of elasticity. Ten of these groups were fabricated with optical fibers while the other six were control groups and contained no optical fibers. This study showed that …
Fatigue Behavior Of A Cross-Ply Ceramic Matrix Composite Under Strain Controlled Tension-Tension And Tension-Compression Loading, James J. Gudaitis
Fatigue Behavior Of A Cross-Ply Ceramic Matrix Composite Under Strain Controlled Tension-Tension And Tension-Compression Loading, James J. Gudaitis
Theses and Dissertations
This stuidy investigates the fatigue response of a cross-ply [0/90]2s Nicalon/Calcium Aluminosillicate (Nicalcc/CAS) ceramic matrix composite at room temperature under strain controlled tension-tension and tension-compression fatigue loading. The primary objectives were to determine strain fatigue limits for both loading cases and to complete a fatigue life diagram (Δe-N) for all tests. Failure mechanisms were also studied. The average initial modulus value for this lay-up was 120 GPa. The ultimate tensile strain was 0.00988 mn/mm (285 MPa). Eight tests were conducted with maximum strains that ranged from 0.00300 mm/mm to 0.00722 mm/mm. The tension-tension fatigue limit was found to be …
Electrorheological Fluids And Their Application In Automotive Clutches: Design Procedures And Recommendations, Ihab Fahmy
Archived Theses and Dissertations
No abstract provided.
Characterization Of Fatigue Damage In A Metal Matrix Composite (Scs-6/ Ti-15-3) At Elevated Temperature, Brian P. Sanders
Characterization Of Fatigue Damage In A Metal Matrix Composite (Scs-6/ Ti-15-3) At Elevated Temperature, Brian P. Sanders
Theses and Dissertations
The fatigue characteristics of a unidirectional titanium based metal matrix composite (MMC) were investigated at elevated temperature (427°C). A hybrid strain controlled loading mode was used to subject the 0° and 90° laminas to fatigue. Along with the fatigue tests, microscopy and analytical modeling ware also conducted. This combination of activities led to defining the initiation and progression of damage and deformation in the MMC. Hen loading was parallel to the fiber on, the fatigue behavior was initially dominated by creep deformation of the matrix. Then, depending on the maximum strain, specimen failure was the result either fiber fractures or …
Behavior Of Concrete Masonry Prisms Under Axial Compression, Tarek Ghoneim Mohamed Ghoneim
Behavior Of Concrete Masonry Prisms Under Axial Compression, Tarek Ghoneim Mohamed Ghoneim
Archived Theses and Dissertations
No abstract provided.
Evaluation Of Dynamic Stresses And Fatigue Life Prediction For Randomly Loaded Structure, Walied Ahmed Moussa
Evaluation Of Dynamic Stresses And Fatigue Life Prediction For Randomly Loaded Structure, Walied Ahmed Moussa
Archived Theses and Dissertations
No abstract provided.
A Comprehensive Fully Integrated Finite Element Analysis Of Metal Flow And Die Stresses In Forward Cold Extrusion, Tarek Hamdi Farid
A Comprehensive Fully Integrated Finite Element Analysis Of Metal Flow And Die Stresses In Forward Cold Extrusion, Tarek Hamdi Farid
Archived Theses and Dissertations
No abstract provided.