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 107 for “"Thermal Cycling"”.
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Effects of thermal cycling on epoxy bonded materials
Thermal cycling is a concern to those who use epoxy as an adhesion in space applications due to the mechanical and thermal properties of both the epoxy and adhered materials. These properties include the thermal expansion coefficient, a, and the stress at which the epoxy will yield fracture. An …
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Mechanical Behavior of Adhesive joints Subjected To Thermal Cycling
The effect of thermal cycling on the state of stress in polymeric materials bonded to stiff elastic substrates was investigated using numerical techniques, including finite element methods. The work explored the relationship between a cyclic temperature environment, temperature-dependent …
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Thermal and transport properties of layered silicate nanomaterials subjected to extreme thermal cycling
… of the composites after experiencing extreme thermal environments. Polymer-layered nanocomposites were studied to determine if they can reduce the permeation to the liquid nitrogen used as fuel in the next generation of space vehicles. Due to the non-permeable nature of the silicates and the …
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Conformal cooling and rapid thermal cycling in injection molding with 3D printed tools
… the application of this capability to improved thermal management for injection molding tooling through: i)cooling lines which are conformal to the mold surface which provide improved uniformity and stability of mold temperature and ii) tools with low thermal inertia which, in combination with …
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A STUDY OF THE THERMAL CYCLING PERFORMANCE OF SOLDER JOINTS IN AREA ARRAY PACKAGING
… to study the performance of solder joints under thermal cycling test. The quality of the solder joints in this research work from growth to failure was monitored by using a type of ultrasonic inspection called acoustic micro imaging (AMI). Results indicate that provided a suitable AMI parameters …
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The effects of thermal cycling on residual stresses in thick- walled stainless steel pipe
The effects of thermal cycling on residual stresses are studied in thick-walled 316L stainless steel pipe. A relatively small AT of 280°F is considered. The residual stresses are measured by an x-ray diffraction technique. The initial stress state of the pipe wall shows periodic and random …
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Effects Of Bond Coat Surface Preparation On Thermal Cycling Lifetime And Failure Characteristics Of Thermal Barrier Coatings
Thermal barrier coatings (TBCs) have been widely used in gas turbine engines to protect the underlying metal from high operating temperature so as to improve the durability of the components and enhance the engine efficiency. However, since the TBCs always operate in a demanding high-temperature …
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The Effect of Long-Term Thermal Cycling on the Microcracking Behavior and Dimensional Stability of Composite Materials
The effect of thermal-cycling-induced microcracking in fiber-reinforced polymer matrix composites is studied. Specific attention is focused on microcrack density as a function of the number of thermal cycles, and the effect of microcracking on the dimensional stability of composite materials. …
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Molecular Origins of Phase Stability in Phase-Change Nano-Emulsions for Thermal Energy Storage by NMR Spectroscopy
… heat storage materials that can store or release thermal energy during phase transitions. Organic PCM nano-emulsions are formed by emulsifying oil in water in the presence of surfactants, enhancing thermal conductivity and pumpability. However, PCMs nano-emulsions can become unstable due to …
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Numerical analysis of surface mount electronics with viscoelastic epoxy underfills and potting
… and strains generated during manufacturing and thermal cycling in addition to dynamic loading. The large disparity in the coefficients of thermal expansion (CTE) of polymers, ceramic components, metal solders, and PCBs can generate significant stress during thermal cycling. Cracking of …
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Nondestructive Evaluation Of Thermal Barrier Coatings With Thermal Wave Imaging And Photostimulated Luminescence Spectroscopy
… beyond material limits is by applying thermal barrier coatings (TBCs) to hot section components. TBCs provide a thermal gradient between the hot gases and metallic substrate, and allow an increase in turbine inlet temperatures of 100-150ºC. However, spallation of TBCs can cause …
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Corrosion resistance of NZP and aluminum titanate
To determine the feasibility of using low thermal expansion ceramics and aluminum titanate in diesel engine applications, the mechanical and thermal properties and corrosion resistance were evaluated. NZP (Ba<sub>1.25</sub>Zr₄P<sub>5.5</sub>Si<sub>.0.5</sub>0₂₄ and Ca<sub>0.5</sub> …
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Cycling studies of micro-tubular solid oxide fuel cells
… the degradation phenomena. The first was isothermal (steady state) ageing, which was performed to provide a benchmark of degradation for easy comparison with degradation under transient conditions (i.e. thermal, redox and load cycling). During this operation, sintering was found to dominate …
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Dislocation density reduction in multicrystalline silicon through cyclic annealing
… of multicrystalline silicon were subjected to thermal cycling at high temperatures. The stress levels induced by the thermal cycling were modeled using finite element analysis (FEA) on Abaqus CAE and compared to the dislocation density reductions observed in the lab. As too low of stress will …
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Accelerated tests of environmental degradation in composite materials
… damage. The effects of a realistic moisture and thermal environment on two high temperature polymer matrix composites (PETI-5 and PIXA-M) have been investigated in this work. An extensive test program was developed to test the response of the materials to this baseline environment and its …
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Microstructural Evolution in Thermally Cycled Large-Area Lead and Lead-Free Solder Joints
… describe the stresses accumulated due to thermal fatigue as a result of CTE mismatch within the system. By understanding the failure mechanisms related to lead-free solders, the application of lead- free solders could be more strategically designed for specific applications. The objective …
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