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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 33 for “"Surface Cracks"”.
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Analysis of the interaction of two parallel surface cracks
… is to analyze and predict the interaction of surface cracks that occur in parallel planes. Multiple cracks may form in aging aircraft that forms at stress concentrations such as fastener holes and notched components by stress corrosion and fatigue cracking. The lifetime of the structures are …
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A Fracture Mechanics Analysis of Surface Cracks in Bending
Made available in DSpace on 2014-12-12T00:25:46Z (GMT). No. of bitstreams: 1 7206938.pdf: 2569563 bytes, checksum: 8040d0da07cc857abf8c56ceeacc6624 (MD5) Previous issue date: 1971
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The dual boundary element method applied to semi-infinite surface cracks in two-dimensions
… evaluate the stress intensity factors (SIF) for surface cracks in semi-infinite solids via the DBEM. We first detail the derivations of the boundary element and dual boundary element methods. The main difficulty with these methods are integrations of the singular integrals which cannot be …
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Study of surface cracks in a simulated solid rocket propellant grain with an internal star perforation
… the three-dimensional fracture mechanism of the surface cracks which are the most common defects detected in the real rocket motor grain. After a brief evaluation of the current status of solid propellant research, stress analysis of a star grain model under internal pressure was performed by …
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A new empirical model to predict stress intensity factor for double interacting surface cracks located in hollow cylinder
… and severe operational conditions, etc., cracks exist. The cracks could be detected in single or multiple form, where multiple cracks considered among the significant concerns that cylinders expected to experience. This is because in the existence of multiple neighboring cracks, crack …
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Fatigue growth of surface flaws in finite plates
… most commonly observed structural defect is the surface crack. The primary difficulty in analyzing the growth of surface cracks is the stress intensity factor which varies from point to point along the crack due to crack front curvature and the complex local geometry. The study of surface cracks …
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Thermal -Mechanical Model of Solidifying Steel Shell Behavior and Its Applications in High Speed Continuous Casting of Billets
… casting speed to avoid hot off-corner sub-surface cracks, and the optimal mold taper.
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Theoretical analysis and experimental investigation of contact fatigue and surface damage in prealloyed and diffusion bonded sintered steels
The contact fatigue and surface damage of prealloyed (Fe-0.85Mo, Fe-1.5Mo) and diffusion bonded (Ni-free, low-Ni, high-Ni) powder metallurgy (PM) steels were investigated. Materials subjected to contact stress fail due to the nucleation of subsurface cracks (contact fatigue cracks), nucleation of …
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Three-dimensional boundary element and experimental analysis of lubricant ceramic surface ring cracks in rolling contact.
Surface defects such as ring cracks are located on silicon nitride ceramic rolling elements.The random nature of ring crack position creates difficulties in predicting rolling contact fatigue (RCF) life. The influence of the lubricant, contact pressure and crack geometry on the RCF mechanism is …
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Failure modes of silicon nitride rolling elements with ring crack defects
… and machining the material may result in surfacedefects,such as surface ring cracks. It is difficult to detect surface ring cracks during high volume production processes and hence it is crucially important to understand their influence and the fundamental mechanism of the failures they …
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Coupled Thermal-Mechanical Fixed-Grid Finite-Element Model With Application to Initial Solidification
… contributing to the formation of transverse surface depressions and short longitudinal surface cracks associated with severe liquid level fluctuations.
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Polyurethane Sealant to Mitigate Crack Effects in Glass-to-Metal Sealed Underwater Connectors
… reliability of the insulation is reduced due to surface cracks formed during manufacturing. In this thesis, we propose and test a sealant to overcome limitations associated with internal cracks. The need for a sealant was identified following a series of experimental tests simulating …
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Investigations into deep cracks in rocket motor propellant models
… for several decades. Although a large number of surface cracks are detected in the rocket motor propellants, the mechanism of these cracks is sull not well known due to the complex geometry of the grain. A stress-freezing photoelastic investigation has been performed to study the deep cracks …
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Parameters Influencing the Corrosion Protection Service Life of Epoxy Coated Reinforcing Steel in Virginia Bridge Decks
… A chloride solution was applied to the surface on a weekly cycle (for a total duration of 3.06 years) and a nondestructive electrochemical testing was performed on each core on a monthly cycle. Cores were also inspected for surface cracks, the thermal properties of the epoxy coating, and …
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Development of active microwave thermography for structural health monitoring
… a microwave excitation to generate heat and the surface thermal profile of the material or structure under test is subsequently measured using a thermal camera (or IR camera). Utilizing a microwave heat excitation provides advantages over traditional thermal excitations (heat lamps, etc.) …
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Grinding of advanced ceramic materials: experimental and theoretical investigation into crack initiation and propagation
… from shaping ceramics whilst conserving their surface integrity, strength and high quality surface finish. Manufacturing processes such as grinding with diamond bonded wheels present one solution. The use of a diamond grinding wheel on the surface of ceramics, creates a complex system of …
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Development of an end-effector system for autonomous spraying applications and radiation surveying
… autonomous shotcrete spray pattern control and surface radiation surveying. The work of this thesis is part of a joint project known as the Mobile Autonomous Scanning and Shotcreting (MASS) robot that is currently under development at the University of Ontario Institute of Technology in …
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Analysis of the conform process: a specific form of aluminium extrusion.
… methods which predict microstructure and surface cracks in the extrudate. The author suggests innovative techniques to improve the efficiency of finite element analysis in metal forming. Finally the author recommends procedures for the study of structural integrity and the optimisation of …
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Roles of surface finish and hydrogen availability on the tensile properties of 1018 steel in hydrogen environments
… charging. Specimens with three different surface finishes were tested at various cathodic charging current densities. The tensile deformation was initiated only after the specimen was charged to at least 95% with hydrogen. The data presented in this study show that very low cathodic …
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Microstructural degradation of bearing steels
… in particular whether damage in the form of cracks precedes hard “white-etching matter" formation, which is carbon supersaturated nanoscaled ferrite. Heat treatments have been designed to create four different crack types and distributions: scarce martensite plate cracks, fine grain boundary …
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