Global ETD Search
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Showing 1 to 20 of 48 for “"Fatigue cracks"”.
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Closure of fatigue cracks at high strains
… specimens to study the closure behavior of short cracks at high cyclic strains under completely reversed cycling. Testing procedures and methodology, and closure measurement techniques, are described in detail. The strain levels chosen for the study cover from predominantly elastic to grossly …
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The microstructural evolution of fatigue cracks in FCC metals
The microstructural evolution during fatigue crack propagation was investigated in a variety of planar and wavy slip FCC metals. The planar materials included Haynes 230, Nitronic 40, and 316 stainless steel, and the wavy materials included pure nickel and pure copper. Three different sets of …
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Eddy current detection of fatigue cracks in drill pipes
… corrosion have tended to cause circumferential fatigue cracks to develop on the outside surface of the drill pipe and propagate inwards. As no early warning system exists, these cracks propagate undetected until failure occurs. High operational costs and losses associated with down time, provide …
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Analysis of acoustic emission waveforms from fatigue cracks on a steel bridge hanger
Fatigue cracks on a steel bridge hanger were monitored for acoustic emission in conjunction with strain gage monitoring. Waveforms of emissions were collected and classified using source location, strain magnitude, position on strain cycle and uniqueness of waveforms as the primary criteria. A vast …
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Classification of In-Flight Fatigue Cracks in Aircraft Structures using Acoustic Emission and Neural Networks
… deals with the analysis and classification of fatigue cracks in aircraft structures. The particular structure that was examined was the vertical tail section of a Cessna T-303 Crusader aircraft. The analysis was performed using the nondestructive evaluation technique known as acoustic emission …
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Accurate characterisation of surface fatigue cracks (in steels) using the AC potential drop NDT technique
… variously shaped and oriented surface breaking fatigue cracks. The ACPD method was reviewed to establish its viability as an NDT technique, and to understand the response of the output to fatigue cracking. The proposed system using a mains power source with a frequency of 50Hz was investigated …
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Crack coalescence in rock-like material under cycling loading
… arranged at different distances and angles. Wing cracks and secondary cracks are observed in both monotonic and cyclic tests. Wing cracks, which are tension cracks, initiate at (or near) the tips of the flaws and propagate parallel to the compressive loading axis. Secondary cracks always appear …
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A microstructure based fatigue life prediction framework and its validation
Fatigue crack initiation in polycrystalline materials can be attributed to various mechanistic and microstructural features acting in concert like the elastic stress anisotropy, plastic strain accumulation, resolved shear stress, normal stress, slip-system length, and grain boundary character. In …
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The Fatigue of Weldments Subjected to Complex Loadings
Cruciform and double-strap lap weldments were fatigue tested under constant amplitude axial load and SAE Bracket Spectrum load conditions. For the cruciform weldments, fatigue cracks generally initiate at the root but may initiated the toe if higher bending stresses are induced by joint distortion. …
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Detection of Fatigue Crack Growth in a Simulated Aircraft Fuselage
… emission (AE) nondestructive testing can detect fatigue cracks as they occur in complex structures. One use for AE has been in-flight detection of fatigue cracks in aircraft. The KC-135 aircraft were successfully monitored as early as 1979. The main problem with this and subsequent applications …
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Development of Multi-Axial Fatigue Retrofits for Lock Gate Components
… intensity of cyclic loads and the environment, fatigue cracks have become a prominent issue. Developed cracks near the pintle region (a joint which the gate rotates and rests upon) have shown to be difficult to mitigate due to the complex stresses that flow through this area. Mitigation methods …
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A fatigue design parameter for spot welds
The development of fatigue cracks in galvanized low carbon and high-strength-low-alloy tensile-shear-spot weldments was investigated using the AT & T Microhmeter. The boundaries between the three stages of the fatigue life were determined based on the resistivity measurements of the Microhmeter. …
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Influence of weld profile on fatigue crack growth in tubular welded joints
… investigates the influence of weld profile on fatigue crack growth in tubular welded joints used in the construction of offshore platforms. An experimental strain analysis has been conducted on three multiplanar steel joints having the same overall geometry but different weld profiles and …
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Experimental assessment of cracked steel beams under mechanical loading and elevated temperatures
… fire is further aggravated by the presence of fatigue cracks in steel bridges. Various experimental and numerical studies have been conducted to evaluate the response of steel beams under elevated temperature. However, to date, there is lack of information on the response of steel beams with …
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Neural Network Fatigue Life Prediction in 7075-T6 Aluminum from Acoustic Emission Data
… acoustic emission (AE) -data associated with fatigue cracks in aluminum fatigue specimens and to use early cycle life AE data to predict failure in such members. An AE data acquisition system coupled with a Kohonen self organizing map and a back propagation neural network were used to perform …
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Condition Monitoring of Structures by Using Ambient Dynamic Responses
… to detect the existence and extent of small fatigue cracks in a simulated railway bridge.
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Numerical study of solder joint failure under fast loading conditions
… from those of monotonic loading. The two fatigue cracks, one at (or very close to) each interface, have both grown to a significant length with one responsible for final failure of the joint.
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Vibration- and Impedance-based Structural Health Monitoring Applications and Thermal Effects
… and detection of damage (in the form of a fatigue crack) in these specimen and to quantify the smallest detectable crack size in aluminum structures. This is done by applying the electrical impedance-based SHM method and using piezoceramic sensors and actuators. Moreover, in order to better …
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