Global ETD Search
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 31 for “"mean stress"”.
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Experimental investigation of the combined effects of corrosion and mean stress on fatigue strength of low carbon steel
… of the combined effects of corrosion and mean stress on the fatigue strength of a low carbon steel.;Corrosion fatigue is a large problem in many engineering fields, which also affects the mining and oil and gas industries, hence the interest from Weir Group. This phenomenon can …
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Tensile, Creep, and Fatigue Behaviors of Thermoplastics Including Thickness, Mold Flow Direction, Mean Stress, Temperature, and Loading Rate Effects
… study include mold flow direction, thickness, mean stress, temperature, and loading rate. Specimens were subjected to monotonic tension, creep, and load-controlled fatigue tests. The two materials considered were a neat impact polypropylene and a mineral and elastomer reinforced polyolefin. A …
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Experimental and seismological constraints on the rheology, evolution, and alteration of the lithosphere at oceanic spreading centers
… rates are linearly dependent on effective mean stress when the effective mean stress is low and non-linearly dependent on effective mean stress when it is high. Microearthquakes recorded above an inferred magma reservoir along the TAG segment of the Mid-Atlantic Ridge delineate for the …
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Numerical investigation of polymer injection effects on geomechanical reservoir properties during enhanced oil recovery
… of polymer injection on the geomechanical stress distribution within a reservoir. Specific objectives include sensitivity analysis of the polymer rheology to determine changes in reservoir stress magnitudes. A coupled fluid flow-geomechanics numerical reservoir simulator is used to …
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Enhanced strain-based fatigue methodology for high strength aluminum alloys
… obtained in this study, studying the effects of mean stresses on fatigue life and investigating cyclic mean stress relaxation of two aluminum alloys, 7075-T6511 and 7249-T76511, used in structural aircraft applications. The two aluminum alloys were tested and their fatigue behavior characterized. …
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Experimental and seismological constraints on the rheology, evolution, and alteration of the lithosphere at oceanic spreading centers
… rates are linearly dependent on effective mean stress when the effective mean stress is low and non-linearly dependent on effective mean stress when it is high. Microearthquakes recorded above an inferred magma reservoir along the TAG segment of the Mid-Atlantic Ridge delineate for the …
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Modeling cycle and time dependent creep/relaxation effects on fatigue lives of notched members
Mechanical cyclic variations in mean stress and strain amplitude is a well-known occurrence for metals even at room temperature. Many fatigue analysis procedures ignore these variations. Fatigue analysis which included both time and cycle dependent mechanical material behavior for metals at room …
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Fully electronic method of measuring post-release gap and gradient/residual stress of a MEMS cantilever
… critical material or physical parameters (gap, stress, Young's modulus, material thickness, etc.) vary from manufacturing uncertainties and how they change during a device's repeated use. State-of-the-art methods used to measure these parameters are limited by the fact that they must be made …
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Multiaxial fatigue damage model for random amplitude loading histories
… analysis incorporating the multiaxial state of stress is conducted along a critical orientation assuming a constant strain ratio. The dominant deformation direction is chosen to be the critical orientation which is selected with the help of a principal strain histogram generated from the given …
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An investigation into thermomechanical fatigue of metal matrix composites
… strain-temperature phasing conditions. Based on stress range, substantial improvements in fatigue life have been observed. However, based on strain range, the effect of reinforcement on fatigue lives differs depending on the mechanical strain-temperature phasing, temperature, and strain rate. …
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The strength of glulam beams with holes - A probabilistic fracture mechanics method and experimental tests
… of Weibull weakest link theory and the mean stress method which is a generalization of linear elastic fracture mechanics. Combining these two methods means that the fracture energy and the stochastic nature of the material properties are taken into account. The probabilistic fracture …
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An active-path-dissolution model for corrosion-fatigue cracking of drill-pipe steels in offshore drilling environments
… electrochemical potential (E$\rm\sb{bulk}$), mean stress and stress ratio (R) effects, fluid temperatures (T), material yield strengths (S$\rm\sb{y}$), pre-existing notch (K$\rm\sb{t}$) effects, and test frequencies (f) were studied to provide data to validate the predictions of the APD model. …
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DEVELOPMENT OF FATIGUE MODELS FOR COPPER TRACES ON PRINTED WIRING ASSEMBLIES UNDER QUASI-STATIC CYCLIC MECHANICAL BENDING
… tests, finite element (FE) modeling of the stresses generated during the cyclic bending tests, and response surfaces (RS) to facilitate iterative assessment of the model constants. Cyclic three-point bend tests were conducted on land grid array (LGA) components during this investigation. …
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Occupational stress, well-being, and pediatric occupational therapists: A mixed-methods study
Occupational stress is a risk factor for the sustainability of occupational therapy. This mixed methods study aimed to investigate the self-reported stress levels of pediatric occupational therapists. A qualitative descriptive approach followed a quantitative descriptive correlational study. The …
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Examining the Relationship Between Physical Activity and Stress
… between physical activity participation and stress among undergraduate students at a private East Coast Catholic and Jesuit university. Specifically, the relationship between physical activity participation and stress was investigated using secondary data collected from the 2017 American …
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Understanding the deformation mechanisms in nanostructured metals by a novel discrete crystal plasticity finite element model
… anisotropy as a result of the increase in mean stress to emit dislocations. In addition, it was revealed that a heterogeneous lamellar structure consisting of a nanocrystalline layer sandwiched between two coarse-grained lamellae could effectively homogenize plastic strain in the …
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Geomechanical characterizations and correlations to reduce uncertainties of carbonate reservoir analysis
… strength and confining pressure, maximum shear stress and mean stress, and internal friction angle and unconfined compressive strength (UCS) are systematically investigated based on the compiled database. New correlations to predict the UCS and Young's modulus of each carbonate type have been …
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DEM [Discrete Element Method] simulations of drained and undrained behaviour
… using DEM A servo-control mode with constant mean stress is used to model drained simulations, and a strain-control model with constant volume is used to model undrained simulations. A periodic cell is used for all the simulations. For the drained simulations, the results of both dense and …
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Wave-current interaction in water of finite depth
… is modified by the waves due to an effective mean shear stress on the free surface. Surface distortion of the eddy viscosity is shown to be important for the change of the mean velocity profile by waves. Both wave-following and wave-opposing current are studied. Comparisons are made with some …
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The fatigue of welded butt joints in low carbon steel
… experimental results should be presented in a meaningful way to aid the safe design of welded connections.<br/><br/>Fatigue tests were conducted on specimens cut from Jin. thick plate of medium carbon steel, over a range of alternating and mean stress levels. The welds were produced using …
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