Processing-structure-property relationships of a polymer-templated cholesteric liquid crystal exhibiting dynamic selective reflection Thesis Submitted to The School of Engineering of the UNIVERSITY OF DAYTON In Partial Fulfillment of the Requirements for The Degree Master of Science in Materials Engineering 共111页。 摘要： Cholesteric liquid crystals (CLCs) are chiral-structured materials that exhibit selective reflection color. While methods to switch off this color with external stimuli have been established, the use of external stimuli to change the reflection color is currently under development. This work explores processing-structure-property relationships of a polymer-templated CLC system that exhibits large-scale reflection color changes with temperature. The effects of heating rate, curing intensity, and cell geometry on the magnitude of these color changes were investigated by collecting transmission spectra of the system during heating and cooling. The system exhibited a constant color change of 500-600 nm at heating rates up to 10°C/min. Samples cured at intensities below 1.00 mW/cm2 displayed larger color changes. The cell geometry was largely unaffected by the cell thickness. However, for cell thicknesses between 10 and 50 μm, as cell thickness increased, the magnitude of the color change decreased. The potential impact of attaching, or tethering, the chiral-structured polymer/liquid crystal gel to the cell su***ce was also considered. Both tethered and untethered systems displayed large-scale color changes with temperature. 下载地址： http://www.pipipan.com/file/22167070
THE EFFECT OF DWELL LOADING ON THE ***ALL FATIGUE CRACK GROWTH AT NOTCHES IN IN100 Thesis Submitted to The School of Engineering of the UNIVERSITY OF DAYTON In Partial Fulfillment of the Requirements for The Degree of Master of Science in Materials Engineering 共115页。 摘要： Dwell loaded components are common in the turbine engine section of gas turbine engines. The turbine components are subjected to high stresses and high loads for up to 2 min during a pilots take-off, cruise and landing. Understanding the mechanisms of crack initiation while the turbine components are subjected to dwell loading is essential for fatigue life predictions. Previously conducted research includes the fatigue testing and life prediction of dwell specimens with an evenly distributed stress that is representative of a smooth location on the turbine disk. However, turbine disks have notches and fillets that change the stress concentration. This thesis utilizes the techniques and testing strategies that have been successful in predicting fatigue life in smooth bar dwell specimens and applies them to dwell notched specimens that are more representative of actual fielded components. The notch fatigue study indicates that the minimum fatigue life prediction method is applicable for various geometries and therefore, its applicability to actual fielded components holds reasonable promise. 下载地址： http://www.pipipan.com/file/21740496
标签: 材料工程
