With the innovation of spinning method and Lycra® fiber, wool elastic core-spun yarn is applied for more industrial end-uses, which make it meaningful to study the mechanical property of wool/spandex core-spun yarn. Tensile property of staple yarns has been studied by many researchers. However, no research is reported on the tensile property of elastic core-spun yarn. In this paper, a new approach is introduced to calculate and predict tensile property of a wool/ spandex core-spun yarn. The theoretical model introduces a fiber utilization coefficient β to specify the slippage length of fiber. The force on a single fiber is first worked out and then these fiber forces are combined to obtain forces acting on each element. Yarn stress—strain curve is obtained on the basis of wool fiber tensile curve and yarn cross-section structure. Factors, such as dimensions and properties of fiber and yarn, fiber slippage effect, and fiber orientations in the yarn are included in the model. Comparisons of experimental and theoretical tensile curves show that the theoretical model has very good agreement with experimental curves. So this method is valid in predicting the tensile behavior of the wool/spandex core-spun yarn.
Precision glass molding (PGM) is an efficient process used for manufacturing high-precision micro lenses with aspheric surfaces, which are key components in high-resolution systems, such as endoscopes. In PGM, production costs are significantly influenced by the lifetimes of elaborately manufactured molding tools. Protective coatings are applied to the molding tools to withstand severe cyclic thermochemical and thermomechanical loads in the PGM process and, in this way, extend the life of the molding tools. This research focuses on a new method which combines metallographic analysis and finite element method (FEM) simulation to study the interaction of three protective coatings—diamond-like carbon (DLC), PtIr and CrAlN—each in contact with the high Abbe number glass material S-FPM3 in a precision glass molding process. Molding tools are analyzed metallographically using light microscopy, white light interferometry, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX). The results show that the DLC coating improved process durability more than the PtIr and CrAlN coatings, in which the phenomenon of coating delamination and glass adhesion can be observed. To identify potential explanations for the metrological results, FEM is applied to inspect the stress state and stress distribution in the molding tools during the molding process.
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