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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 30 for “"Load ratio"”.
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The Effects of Load Ratio on Threshold Fatigue Crack Growth of Aluminum Alloys
… cracks can grow to failure under fatigue loading, called fatigue crack growth (FCG). Because it is impossible or impractical to prevent subcritical crack growth in most applications, a damage tolerant design philosophy was developed for crack sensitive structures. Design engineers have …
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Effect of strength, load ratio and environment on near-threshold fatigue crack propagation of 2 1/4 Cr - 1 Mo steel
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1980.
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Experimental investigation on the dynamics of inflatable dams
… membranes are predominantly studied. Load combinations are considered without any water, with impounding water, and with water overflow. The two major experimental variables are the dam's internal pressure and the stream's flow rate or the impounded water height. The existence of …
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Hydrogen degradation and microstructural effects of the near-threshold fatigue resistance of pressure vessel steels
… steel the crack propagation rates at high load ratio (R = Kmin-Kmax) are increased in the presence of water vapor and the opposite effect is observed at low load ratio. It is proposed that water vapor-containing environments give rise to two mechanisms affecting crack growth rates: …
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Seismic Behavior of concrete filled steel Tubular Built-up columns
… adopted in structural members with larger load eccentricity ratio and slenderness ratio, such as stadium, industrial buildings, bridge pier and pillar, and electrical transmission tower. However, the research is mainly focused on static performance, seldom research has been reported on the …
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Fatigue crack growth in ceramics containing a viscous grain boundary phase at elevated temperatures
… composite was examined under tensile static loading (static fatigue) and tension-tension cyclic loading (cyclic fatigue). The study was carried out at temperatures of 700-900$\sp\circ$C, where the vitreous grain boundary phase flowed viscously. Experimental results have shown the existence of …
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Fatigue crack growth in hydrogen pipeline steels
… are carried out for a variety of API steels at load ratios for a given initial crack depth. The load ratio R equals where and are respectively the minimum and maximum stress intensity factors in a pressure cycle the crack experiences due to the pressure fluctuations. In particular for API X42 …
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Comparison of SLR predictions to monitored performance of six Virginia passive solar houses
… fuel used. Predictions were made using the Solar Load Ratio (SLR) method for the expected use of auxiliary heating fuel. Comparisons were then made between actual performance and predicted performance. The SLR method is used for predictions because it is a widely used tool in the design of passive …
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Reliability of reinforced concrete beams in torsion
… an increase in beam reinforcement. When the live load is reduced for members having a load influence area greater than 400 ft 2, the reliability index is found to increase with increase in basic live load to nominal dead load ratio.
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Voltage and Reactive Power Control in Islanded Microgrids
… such as: 1) The ability of the distributed generation (DG) units to maintain equal reactive power sharing in a distribution system; 2) The ability of the DG units to maintain acceptable voltage boundary in the entire IMG; 3) The functionality of the existing voltage and reactive power (Volt/Var) …
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Transfer lubrication techniques in a stick slip situation.
… rotationally via an elastic member and radially loaded by two diametrically opposed pistons pneumatically pressed against the disc circumference. A metal piston pressed against the metal disc induced the stick slip motion whilst the other piston consisted of a dry lubricant compact providing for …
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Effect of Severe Corrosion on Lateral Strength of Square RC Bridge Columns
… corrosion of steel bars decreases the lateral load-carrying capacity of reinforced concrete members, causes loss in the mechanical properties of reinforcement and cross-sectional area of steel bars and concrete cover, bond deterioration, reduces anchorage of steel bars, and decreases the …
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High resolution fatigue crack growth analysis of crack closure and slip irreversibility using digital image correlation
… crack tip displacement fields during the fatigue loading cycles. During this study, a least-squares regression algorithm using the vertical and horizontal displacements was developed, and the stress intensity factors, KI and KII, and the T-stress for the isotropic and anisotropic cases were …
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Fatigue crack growth in polycrystalline alumina at high temperatures
… was examined under monotonic tensile loading (static fatigue) and under Mode-I tension-tension cyclic loading (cyclic fatigue). The investigation of fatigue crack growth in polycrystalline Al$\sb2$O$\sb3$ has confirmed the cyclic effect existing in ceramic materials, but this cyclic …
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The effect of loading frequency and loading level on the fatigue behavior of angle-ply carbon/PEEK thermoplastic composites
The effect of loading frequency and loading level on the fatigue behavior of ($\rm{\pm}45\rbrack\sb{4s}$ carbon/PEEK composite was investigated. Tention-tention load controlled fatigue tests were performed on straight sided samples using a 100-KN MTS machine. Three loading frequencies (1Hz, 5Hz, …
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Development of Hybrid Fire Simulation Methods and Their Applications to Column Fire Tests
… concrete columns to investigate the effect of load ratio and the axial constraint ratio on the performance of columns at elevated temperatures. The proposed method is also applied to a scaled steel braced frame that was subjected to fire following an earthquake. A set of temperature- and …
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Acoustic Emission Techniques and Cyclic Load Testing for Integrity Evaluation of Self-Compacting Normal and Self-Compacting Lightweight Prestressed Concrete Girders
… on the performance and validation of the 24h load test method (24h LT), the cyclic load test method (CLT), and acoustic emission (AE) techniques when used on self-compacting prestressed lightweight and normal weight concrete girders. The current investigation examines data obtained from the …
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Response of high strength concrete columns under fire-induced biaxial bending
… bending which can arise due to eccentricity in loading, uneven spalling, or due to significant thermal gradients generated through 1-, 2-, or 3-sides of fire exposure. High strength concrete (HSC) columns are especially prone to such biaxial bending due to fire induced spalling. However, there …
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Performance of Fouled Railroad Superstructure Subjected to Traversing Heavy Haul Trains
… transportation needs. Freight train passby loads increase the surface deformation of railroad substructure due to cumulative plastic strains, which lead to surface deviation of the railroad tracks. Correspondingly, railroad maintenance is necessary to sustain track geometry alignment and to …
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Micromechanical Simulation of Fatigue in Nodular Cast Iron
… in a void volume fraction with each cycle of loading. This is called void ratchetting. The hypothesis of this thesis is to explain the fatigue failure of NCI using void ratchetting mechanism. The strain-life, stress-life, notch support effect, and fatigue crack growth are studied using the …
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