Prediction of curling distance of dry-relaxed cotton plain knitted fabric has been realized by using multiple regression analysis. One set of the parameters that are used in the multiple regression analysis is the moments on the loop that force the fabric to curl. There have been several studies of the moments on the loop, but the models developed are too complex for practical use. Thus; in the present study, moments on the loop have been determined by means of Castigliano Theorem, which leads to a more usable model. The following results have been obtained :
(1) Simple formulas for the moments, M_y and M_x These formulas depend on fabric and yarn parameters, such as course-wale spacing, yarn diameter and bending rigidity of yarn. M_y is the moment that affects the bending and sidecurling behavior around the oy axis (Figure 5 a). M_x is the moment that affects the bending and top/bottom-curling behavior around the ox axis (Figure 5 a).
(2) Good agreement between M_y, M_x as presented and those proposed by Postle and Munden was observed [11] (M_y0.0367gcm-0.04gcm and M_x : 0.1896gcm-0.175gcm).
(3) Equations 20, 23, 25 and Table 1 and also previous studies [1, 2, 4, 5, 7, 8, 10, 11] show that the values of M_yand MX increase as the tightness factor and bending rigidity of yarn increase. The values of moment around ox axis, M_y, are higher than those around oy axis, M_y.

抄録全体を表示

As mentioned in the Part 1 [9], many studies on the curling tendency of knitted fabrics have been done. However, until now, it was not possible to predict the exact curling distance of a fabric. Curling distance is very important in the garment industry where the glued-edge of a fabric is thought of as a material loss. Thus, the aim of present study is to determine the curling distance of fabrics before production. During this study, multiple regression analysis was done between fabric parameters that are know before production and curling distances that are measured by experimentally. In past experimental studies, the curling tendency has been measured because of the difficulties in measuring the curling distance. Thus, in this paper, a new method has been developed to measure the curling distance. The following results have been obtained :
(1) During the regression analysis, r² (r : coefficients of correlation) have been found to be 0.75 for both side curling and top/bottom curling (C_s-side curling, C_tb-top/bottom curling, Equation 1 and 2, respectively). Thus, it is possible to predict the curling distance before production, with in a reasonable approximation, using know fabric and yarn parameters.These parameters are loop length [7] that is determined before production, yam count to calculate yarn diameter and bending rigidity of the yarn. These properties are know before production by experimental, calculation or by definition.
(2) As pointed out in Part 1 [9] and seen from Table 2 : the values of the moments about the x axis (about an axis parallel to the courses) are higher than the values of the moments about the y axis (about an axis parallel to the wales) (M_x is bigger than M_y). But again as seen from Table 2 ; curling distance about the x axis (Crb-top/bottom curling) is lower then curling distance about the y axis (C_s-side curling), since bending rigidity of the fabric for bending about the x axis (about an axis parallel to the courses) is higher than the bending rigidity of the fabric about the y axis [3 - 5].

抄録全体を表示

Polypropylene fabrics were dyed under various conditions by supercritical carbon dioxide technology. Amounts of dye absorbed by polypropylene fibers were calculated from the visible spectrum and penetration of dye was observed by microscopy.The result showed dye had diffused into fibers and dye uptake values of carbon dioxide dyeing obtained from visible analysis were much higher than that of water. X-ray and DSC analysis indicated that dyeing behavior of polypropylene with disperse dyes obeyed the free volume model. No obvious damage had happened while fabrics dyeing at 120°C in accordance with the TGA and mechanical properties test. Wash fastness was the major problem to be necessary to overcome on this dyeing method.

抄録全体を表示

This paper ctescriDes a new methociology for FEA of composites with geometrical non-linearity due to reorientation of fabrics. Textile composites have more ductility than uni-directional fiber reinforced composite. Especially, woven and knitted fabric composites have high ductility at high temperature, and they therefore have the advantage in the processing such as deep drawing. However, it is difficult to evaluate the characteristics of the composites because of its microscopic complexity. In addition, the analysis for macroscopic deformation of fabric composites is not carried out so easily since the geometry of fiber bundle varies with the changing of macroscopic strain field.
In macroscopic analysis, the influence of reorientation of fabrics is adopted as the change of equivalent mechanical properties. It is assumed that fiber bundles of woven or knitted fabric composites are in-plane periodic, but not three-dimensional. The method which the stress and strain are obtained by the boundary condition with in-plane deformation under applied loading is proposed. We obtain the representative stress/strain vectors for RVE (Representative Volume Element) from the proposed method. The equivalent mechanical properties for RVE can be calculated by those stress/strain vectors. Therefore this phenomenon have to be taken into consideration when the deformation for composites is calcu- lated. The reoriented fabric structures after deformation are also determined based on the above periodic boundary condition under the applied loading, the original fabric is deformed. By the above procedure, the database of mechanical properties for each deformation patterns are made, and are used in macroscopic analysis. As an example, the off-axis tensile analysis for lamina plate of woven fabric composite is carried out.

抄録全体を表示

An air jet loom equipped with a profile reed and sub-nozzles is able to weave wider fabrics at higher speed than other types. A study on the characteristics of air flow and behavior of the weft yarn in the weft passage area of the profile reed during inserting the weft yarn is very important. The velocity distributions of air flow issued from a sub-nozzle in the weft passage were measured in detail by a hot-wire anemometer. The motion of a weft yarn in the weft passage was also observed by photography.
The experimental results indicate that the shape of the lower jaw part of the profile reed affects positions of the maximum velocity of the air jet in a cross-section until the air jet runs into the bottom of the reed. When the front side of the profile reed is closed, the value of the maximum velocity in the weft passage is smaller than that under the normal condition because of increasing of flow leakage behind the profile reed. The position of the maximum velocity in the weft passage is found to coincide with the position of the maximum leakage from the profile reed. It is confirmed by photograph that a yarn tip is led through the weft passage by the jet issued from a sub-nozzle.

抄録全体を表示