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 84 for “"Coefficient of Thermal Expansion"”.
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High-Throughput Measurements of Thermal Conductivity and the Coefficient of Thermal Expansion
… junction (DEJ) in a human tooth. The thermal conductivity and Young's modulus are uniform in dentin and enamel, respectively, and change abruptly across the dentin-enamel interface. The CTE changes gradually in dentin near the DEJ over a transition width of ≈ 100 mum.
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Material Coefficient of Thermal Expansion Investigation for Use in Additive Manufacturing Fused Deposition Modeling for Composite Tooling
… aircraft structures. These structures are often manufactured from carbon fiber reinforced epoxy. When these structures are damaged, they must be repaired to restore strength to the component to avoid the cost and logistics of having replacements parts. Occasionally, these repairs require …
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Analytical and Computational Micromechanics Analysis of the Effects of Interphase Regions, Orientation, and Clustering on the Effective Coefficient of Thermal Expansion of Carbon Nanotube-Polymer Nanocomposites
… have been used to determine the effective coefficient of thermal expansion (CTE) of carbon nanotube-epoxy nanocomposites containing aligned nanotubes. Both techniques have been used in a parametric study of the influence of interphase stiffness and interphase CTE on the effective CTE of the …
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Finite element analysis of damaged cross-ply composite laminates
The problem of transverse cracks in T300/5208 graphite-epoxy cross-ply laminates was studied using generalized plane strain finite element analysis. The degradation of elastic modulus, Poisson's ratio, shear modulus, and coefficient of thermal expansion was predicted and then compared with …
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A new class of auxetic lattices
In this work we have studied the mechanical and thermal behavior of a new class of auxetic lattices. We have started introducing a novel two-dimensional lattice family with three different realizations that leads to a Poisson's ratio arbitrarily close to the thermodynamic limit corresponding to ν = …
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The design, analysis, construction, and testing of a multifunctional composite satellite structure
… Inc. in conjunction with MIT. The design goal of this project is to use existing technology to gather ground data from low earth orbit at a minimal cost. A structure was constructed at MIT that allows the satellite to survive launch loads and maintains the optical stability of the satellite. …
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Mechanical and thermo-mechanical properties of particulate reinforced composites made from dry powder-power blends
… The process was designed to exploit the nature of fine powder constituent materials, such that the energy input during the molding process could be reduced. Polymer and reinforcement materials were chosen, characterized, and molded into composite plaques. These composites were characterized in …
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Effect of the interphase on the thermo-mechanical response of unidirectional fiber-reinforced epoxies: modeling, analyses and experiments
The complexity of the fiber-matrix interphase in a composite is largely due to the myriad of variables (material, processing, and design) that affect its formation. The interphase, thus formed, has to be characterized at several levels (micro-structural, chemical, and mechanical) in order for one …
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Atomic Structures of Metallic and Semiconducting Nanocrystals by Coherent Electron Diffraction
The third application of the single-particle diffraction technique is to measure the temperature-dependent structures of individual nanocrystals. Again, Au nanocrystals were studied for this experiment. Experimentally, we recorded diffraction patterns from the same Au nanocrystals at different …
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Application of similarity theory to forecasting the mixed-layer depth of the ocean
The thermal structure of the ocean, especially the uppermost mixed layer, greatly affects sonar ranges. In this paper, similarity theory is applied to the problem of forecasting the depth of the mixed layer during the warm season, assuming the controlling processes are secular, non-advective , and …
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Mems approaches in infrared imaging
The design and performance simulation of a novel Microelectromechanical System (MEMS) based infrared detector, that utilizes coefficient of thermal expansion, is discussed. The detector design uses a variety of thermal expansion coefficient materials, including alloys which are connected to ambient …
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Determination of the CTE tensor of materials from high temperature X-ray diffraction
Thermal expansion is historically reported as an average coefficient to estimate the change in dimensions of a material as it is heated or cooled. This average works well for approximating thermal expansion in high-symmetry crystals, but for low-symmetry crystals (monoclinic, triclinic), anisotropy …
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Thermomechanical properties of novel lanthanum zirconate based thermal barrier coatings - an integrated experimental and modeling study
<p>Thermal barrier coatings (TBCs) are refractory materials deposited on gas turbine components, which provide thermal protection for metallic components at operating conditions. The current state-of-art TBC material is yttria-stabilized zirconia (YSZ), whose service temperature is limited to 1200 …
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Thermomechanical property evaluation of molybdenum alloys
… molybdenum and its alloys were studied for their thermal properties and correlated to the material microstructure. Thermal expansion tests were carried out using thermo-mechanical analyzer (TMA). Thermo cycling tests were conducted around 650°C for spinel dispersed molybdenum alloys with 3% wt …
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Isotope effect for diffusion of tin in beta-titanium
The isotope effect for diffusion of in Ti has been measured at five temperatures in the bcc G-phase. Separation of the Sn isotopes was effected by 3-spectroscopy on electroplated sources. The effect is small and highly temperature-dependent, varying from 0.18 ± 0.03 at 9720 C to 0.37 ± 0.03 at …
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Mechanical properties of degraded PMR-15 resin
… properties from the inner material. A set of material tests was designed to separate the properties of the oxidized surface layer from the properties of interior material. Test specimens were aged at 316°C in either air or nitrogen, for durations of up to 800 hours. The thickness of the …
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Thermal expansion of chemically modified mullite
… solid solutions in an effort to lower their thermal expansion coefficients. TiO₂, B₂O₃, CrPO₄, P2O₅, Ga₂O₃, Cr2O₃, and WO₃ and the half-breed SiO₂ compounds AlPas, BPO₄, GaPO₄, BAsO₄, AIAsO₄, GaAsO₄, and GeO₂ were chosen as the modifiers. The results indicate that, apart from TiO₂, none of …
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Analysis of Composite Laminates with Matrix Cracks
Analysis of the effects of matrix cracking on composite laminates is a well-known problem which has attracted considerable attention for the past decade. An approximate analytical solution is introduced in this thesis to study this type of problem. The subjects of primary concern are the …
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Mechanical and Thermal Properties of Linear Carbon Chains Encapsulated by Multi- and Double -Walled Carbon Nanotubes
As a field of study, optics have been a critical to the development of material’s science. The interaction between light and matter is often non-destructive and non-invasive; making it powerful in the determination of materials’ compositions, and their properties at the electronic and vibrational …
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Silicon infiltration of silicon carbide selective laser sintered preforms
… infiltrated with an epoxy to decrease slumping of the part. They are then infiltrated using high temperature pressureless infiltration of a silicon matrix. This materials system can be applied in a wide variety of industries, including military, aircraft, tooling and automotive. The silicon …
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