The bending behavior of yarn is affected by mechanical properties, arrangement and interaction between its constituent fibers and yarn geometry. In this study the yarn bending rigidity was obtained from the tensile modulus of its constituent fibers and yarn geometry and structural parameters and it was shown that the dimensionless yarn bending rigidity decreased as the ratio of tensile modulus to the shear modulus of the constituent fibers increased. Furthermore, the yarn bending rigidity decreased as the surface helix angle of the yarn increased. When compared with previous research, there was good agreement between the findings of Owen, Zurek, and Platt’s and the results of this study.

In this paper, a coercive couple due to the friction between strands during two-ply yarn bending deformation is derived in terms of the strand and two-ply yarn structural factors using an energy method. The experimental and theoretical results are compared for the multifilament yarn and for various structural parameters as well.

This research studied how to develop tight upper sportswear from 3D scan data considering fabric stretch property. Subjects were five Korean men of average figure in their 20's. Scanning was done for ten postures via vitus smart/pro(Techmath LTD). Analyzing from 3D scan data, more than 70% of the upper body surface showed surface change rate under 20%. It was shoulder and under arm side part that showed most noticeable body surface change when moving. A parametric model with convex surface was generated and flattened onto the plane, resulting 2D pattern. The error rate occurring in the process of 3D to 2D conversion was 0.2% for outline and 0.13% for area, respectively. Thirteen kinds of stretchable fabrics in the market were collected for this study. Stretch property was in the range of 16.0~58.2% for wale direction; 23.1~78.4% for course. Based on wear trial test, four fabrics were chosen for making the 1st experimental garment and finally one fabric was chosen for the 2nd one, which was developed applying 4 kinds of crosswise reduction rate on 2D pattern: 0, 5, 10, and 15%. Through wear trial test and garment pressure measurement, experimental garment applied with 10% pattern reduction rate was evaluated as most comfortable and considerable.

We present an optimal cutter location (CL) data computation for face-milling of large marine propellers composed of CL point optimization and CL path optimization on a given tool path. The CL point optimization at a single cutter contact (CC) point is conducted by maximizing the effective radius of the face milling cutter, while the CL path optimization on a series of CC points is performed by conforming deviation of the tool-swept surface from the design surface between consecutive CL data to a given machining tolerance. The proposed algorithm was implemented and applied to the machining of a large marine propeller which proved effective from a quantitative point of view, and is used on the shop floor in a Korean ship building company.

No abstract