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Full-Text Articles in Engineering
Viscoplastic Characterization And Fatigue Modeling Of Titanium Based Metal Matrix Composites, Mark A. Foringer
Viscoplastic Characterization And Fatigue Modeling Of Titanium Based Metal Matrix Composites, Mark A. Foringer
Theses and Dissertations
Viscoplastic characterization and fatigue modeling of titanium-based metal matrix composites was accomplished by combining a unified viscoplastic theory, a nonlinear micromechanics model, and a linear damage accumulation model. First. Ti 15-3 was characterized using the Bodner-Partom viscoplastic theory. A micromechanics model was then employed in a linear damage accumulation fatigue model to predict the fatigue behavior of titanium based composites. The viscoplastic behavior predictions of the micromechanics model were used to eliminate separately defined time dependent terms in the fatigue model. Also, a new linear damage accumulation model was developed from the fatigue behavior of the composite constituents. Finally, it …
Fatigue Behavior Of A Cross-Ply Ceramic Matrix Composite At Elevated Temperature Under Tension-Tension Loading, Craig D. Steiner
Fatigue Behavior Of A Cross-Ply Ceramic Matrix Composite At Elevated Temperature Under Tension-Tension Loading, Craig D. Steiner
Theses and Dissertations
This study investigated the fatigue behavior and damage mechanisms of a [0-90]4s SiC-MAS ceramic matrix composite under tension-tension loading at two elevated temperatures and two frequencies. Stress and strain hystereses, maximum and minimum strain, and modulus of elasticity were evaluated to characterize the material behavior. Microscopy and fractography were used to evaluate damage progression and mechanisms. Fatigue life was independent of frequency at both temperatures.
Investigation Of Tension-Compression Fatigue Behavior Of A Notched Cross-Ply Metal Matrix Composite At Elevated Temperature, Matthew W. Yocum
Investigation Of Tension-Compression Fatigue Behavior Of A Notched Cross-Ply Metal Matrix Composite At Elevated Temperature, Matthew W. Yocum
Theses and Dissertations
This research extends the existing knowledge of MMC fatigue damage mechanisms by studying the tension-compression fatigue behavior of a notched cross-ply laminate MMC at elevated temperature. A [0-90]2S SCS-6-Ti-15-3 laminate with a center hole was subjected to tension-compression fatigue at 427 °C (800 °F). Stress and strain data was taken to evaluate macro-mechanic behavior of the material. Microscopy and fractography were performed to characterize the damage on a micro-mechanical level. Crack initiation and progression was monitored using acetate face replicas. Four cracks were found to develop around the periphery of the hole, two of which became dominant and proceeded …
Investigation Into The Behavior Of Geometrically Nonlinear Composite Arches, John C. Bailey
Investigation Into The Behavior Of Geometrically Nonlinear Composite Arches, John C. Bailey
Theses and Dissertations
This research modifies the existing finite element formulation of a potential energy based large deformation and moderate rotation theory. Hermitian shape functions replace the existing linear bending angle interpolations. Negligible differences between the two formulations indicate the underlying kinematics limit the accuracy, not the finite element interpolations. Using the new program, numerous nonlinear arch geometries are modeled to investigate the effects of arc length and thickness variations. Local and global snapping phenomena are captured as well as through the thickness shear driven nonlinearities.
Fatigue Behavior Of A Cross-Ply Ceramic Matrix Composite Subjected To Tension-Tension Cycling With Hold Time, Scott A. Grant
Fatigue Behavior Of A Cross-Ply Ceramic Matrix Composite Subjected To Tension-Tension Cycling With Hold Time, Scott A. Grant
Theses and Dissertations
This study was carried out to investigate the elevated temperature behavior of the SiC-MAS5 cross- ply [0-90]4S ceramic matrix composite manufactured by Corning Inc. to fatigue with loading waveforms that combine the characteristics of stress rupture and high cycle fatigue. The test results were compiled in the form of S-N (cycles to failure), S-T (exposure time versus cycles to failure), S-S (energy exposure versus cycles to failure), normalized modulus degradation, strain progression, and hysteresis loop progression. From the mechanical behavior demonstrated by these curves, relationships between the effect of the environment and loading waveform were developed. In addition, a …
Characterization Of Fatigue Behavior Of 2-D Woven Fabric Reinforced Ceramic Matrix Composite At Elevated Temperature, Daniel J. Groner
Characterization Of Fatigue Behavior Of 2-D Woven Fabric Reinforced Ceramic Matrix Composite At Elevated Temperature, Daniel J. Groner
Theses and Dissertations
This study investigated the fatigue behavior and associated damage mechanisms in notched and unnotched enhanced Sic-SiC ceramic matrix composite specimens at 1100°C. Stiffness degradation, strain variation, and hysteresis were evaluated to characterize material behavior. Microscopic examination was performed to characterize damage mechanisms. During high cycle-low stress fatigue tests, far less fiber-matrix interface debond was evident than in low cycle-high stress fatigue tests. Notched specimens exhibited minimal stress concentration during monotonic tensile testing and minimal notch sensitivity during fatigue testing. Damage mechanisms were also similar to unnotched.
Investigation Of Tension-Compression Fatigue Behavior Of A Unidirectional Metal Matrix Composite At Elevated Temperature, Darren L. Kraabel
Investigation Of Tension-Compression Fatigue Behavior Of A Unidirectional Metal Matrix Composite At Elevated Temperature, Darren L. Kraabel
Theses and Dissertations
This study investigated the fatigue behavior in a unidirectional metal matrix composite under tension-compression loading conditions. Stress-strain responses, modulus and strain trends were monitored to characterize damage. Fractography and microscopy were used to characterize failure modes. Fatigue life curves were plotted base on different parameters such as stress and strain. Tension-compression fatigue life was shorter than the obtained under tension-tension fatigue cycling. Creep, observed in tension-tension. fatigue cycling, and the effects of the compressive load on the plastic zone around the crack tip explain shorter life under tension-compression fatigue loading.
Fatigue Behavior Of A Cross-Ply Metal Matrix Composite At Elevated Temperature Under Strain Controlled Mode, Leon B. Dennis
Fatigue Behavior Of A Cross-Ply Metal Matrix Composite At Elevated Temperature Under Strain Controlled Mode, Leon B. Dennis
Theses and Dissertations
This research extends the existing knowledge of cross-ply metal matrix composites (MMC) to include fatigue behavior under strain-controlled fully reversed loading. This study investigated fatigue life, failure modes and damage mechanisms of the SCS-6-Ti-15-3, [O-9O]2s, MMC. The laminate was subjected to fully reversed fatigue at elevated temperature (427° C) at various strain levels. Stress, strain and modulus data were analyzed to characterize the macro-mechanical behavior of the composite. Microscopy and fractography were accomplished to identify and characterize the damage mechanisms at the microscopic level. Failure modes varied according to the maximum applied strain level showing either mixed mode …
Design And Analysis Of Constrained Layer Damping Treatments For Bending And Torsion, Kimberly J. Balkema
Design And Analysis Of Constrained Layer Damping Treatments For Bending And Torsion, Kimberly J. Balkema
Theses and Dissertations
In this dissertation, different aspects of constrained layer damping treatments on beams of various geometries are studied. First, the optimal length of a constrained layer damping treatment mounted on a surface in linear strain is identified as a function of the relative stiffnesses of the damping layers and the non-uniformity of the surface stain. The analysis extends previous work that considered the case of uniform surface strain. Sixth order sandwich beam theory is then modified for use with a rectangular beam covered with a segmented constrained layer damping treatment. Non-dimensional variables are used to simplify the form of the problem. …