The Start-up flow of viscoelastic fluids in three abrupt contraction-expansion channels was numerically studied using the Leonov model. A slit channel connects two parallel conduits, and the three contraction-expansion channels are different in the slit length. The analysis in terms of the stress power showed that the swell of the flow at the expansion region was related to the release of elastic energy which was stored in the upstream channel; when the slit length is shorter, more elastic energy should be released at the expansion region, hence the swell occurred more greatly.
Bending vibrational properties of polyester Shingosen fabrics were measured and analyzed by using the new mechanical parameters of bending vibration. It was shown that bending vibration of New Silky, Rayon Touch, and Peach Face type Shingosen fabrics continued longer than New Worsted type in the conventional classification, however, shorter than natural silk filament fabrics. In the classification of production characteristics, yarn-processing type Shingosen fabrics damped sooner than fabric-finishing and fiber-production type in bending vibration. In the classification of fiber characteristics, bending vibration of contractile fibers type Shingosen fabrics continued the longest and ultra-fine fibers type the shortest. Those features of Shingosen fabrics in bending vibrational properties became more distinct by discriminant analysis using the parameters of bending vibration as variables.
We made interlacers with which yarns could be always exposed to air jets, and tried to produce interlaced yarns for the purpose of verifying whether or not the results obtained in the previous model experiment are effective in practical interlacing process. As a result, it was found that a continuous blowing of air jets can produce intermittent tangling and opening parts in practical interlacers. Furthermore, we studied the yarn motion in the yarn path using an optical fiber sensor system, and it was confirmed that there is no relationship between the production of interlaced yarns and the yarn motion.
Alumina ceramics precursor was coated on the glass fibers by sol-gel method using metal alkoxide solution. The optimum coating condition for the concentration of metal alkoxide and silane coupling agent was investigated. Silane coupling agent makes it possible to uniformly coat alumina precursor film on the glass fiber. The organic contents in alumina precursor on the glass fiber increased with the concentration of metal alkoxide. The addition of silane coupling agent led adhesive force between glass fiber and ceramics precursor films to be higher. The alkali-resistance, heat-resistance and tensile strength of ceramics precursor coated glass fibers were superior to original glass fiber. The surface of glass fiber was eroded by curing in NaOH aqueous solution at 40°C. However, the morphology of fiber coated by alumina precursor was retained in NaOH aqueous solution. The crack on the surface of glass fiber was formed by heating at 800°C, but the crack was not observed in the glass fiber coated by alumina precursor. The tensile strength of glass fiber and alumina precursor coated fiber was 60×103 and 80×103kgf/cm2, respectively. The tensile strength of glass fiber and alumina precursor coated fiber increased with the concentration of silane coupling agent.