The yarn suction efficiency of an air suction gun is closely related to the airflow patterns, which are strongly affected by the geometry of the gun. To obtain basic data for the optimum design of a gun, we investigated the airflow patterns in the gun with different geometrical parameters by numerical simulation and discussed the relation between the flow patterns and yarn suction force F_m. Compressed-air inflow angle plays an important role in generating a helical flow by controlling circumferential velocity component v_c in a yarn propulsion tube. This helical airflow greatly promotes yarn suction capacity. F_m has a closer relationship to the distribution of air velocity than air pressure, and strongly depends on v_c. The airflow patterns are weakly dependent on a passage diverging angle of nozzle and a converging angle of de Laval tube. A reduction in throat diameter of de Laval tube causes a rapid extension of the supersonic flow area near the throat accompanied by increasing axial velocity component in the de Laval tube. However, it leads to decreases in v_c in the yarn propulsion tube and air velocity in the yarn inhalation tube, which hinders the promotion of F_m.

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The geometrical effects of an air suction gun on yarn motion were clarified by measuring postures of a running yarn with a still camera in order to promote the suction performance by controlling the yarn motion appropriately. The relation between the yarn posture and yarn suction force was also discussed. The yarn posture is a helix. This helical motion greatly improves the suction efficiency of the air suction gun owing to high concentration of air drag on the yarn. Helix diameter of yarn posture d_y and helix pitch of yarn posture p_y decrease with an increase in the compressed-air inflow angle and a decrease in the throat diameter of de Laval tube, and are almost independent of the passage diverging angle of nozzle and the converging angle of de Laval tube. Unfavorable values of the geometrical parameters cause large fluctuations in yarn postures, i.e. violent yarn motion. A stable yarn posture with appropriately small d_y decreases the friction between the yarn and the wall of tube, and an appropriately small p_y increases the contact area between the yarn and the air. Hence the yarn suction force is promoted.

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There are various seat-type pressure sensors but there are no seats, which fulfill all the conditions such as flexibility, expandability, thinness and low cost. Then we developed a new pressure sensor using the compression property of fabric.
In this report, we evaluated the respondent properties of the fabric sensor. It turned out its response time when to detect pressure is about 0.1 ms. Also it turned out that the frequency range of detection is about 30 Hz considering the strain of fabric when to pressure the fabric repeatedly. And depending on the conditions of the finished work such as sandwiching the fabric between rubber boards, the frequency range even decreases.

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In this study, a method for FE analysis of woven angle ply laminates has been proposed. It is important to characterize the effect of laminate angle of woven fabrics on the mechanical behaviors because woven angle ply laminates has been widely used as quasi-isotropic material in many fields. Though FE analysis of on-axis woven fabric composite has been able to carry out, FE analysis of woven angle ply laminates has been difficult for its complicated non-periodic structure. As the method to solve the problems of generating FE model, mesh superimposing method with three scale models has been proposed. We have generated FE model of homogenized off-axis woven fabric laminate as the global model, matrix as meso model, and fiber bundles as local model. By using this method, woven fabric laminates with arbitrary laminate angle can be analyzed considering the effect of lamination of woven fabrics on the strains in the fiber bundles. The accuracy of the method has been verified when using 64 Gaussian points for integrations.

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In this study, compressive creep behaviors of staple fiber assemblies made of polyester fibers with heteromorphic section, round section and hollow section, PTT fibers and regenerated fibers such as cupra and lyocell fibers are investigated under two different stress conditions, and results are obtained as follows.
(1) Creep deformation ratio of regenerated fiber assembly is larger than that of synthetic fiber assembly for each stress condition within the range of samples used here.
(2) Creep deformation ratio of fiber assemblies that have same fineness and same fiber length is compared. For polyester fibers with heteromorphic and round sections, and cupra fiber, the order of magnitude is as follows; (cupra) > (round) > (heteromorphic). For polyester fibers with round and hollow sections, the order is (round) > (hollow).
(3) Creep deformation ratio at high stress condition is twice as large as that of low stress condition for fine polyester fiber with hetermorphic section and thick polyester fiber with round and hollow sections. In contrast, creep deformation ratio at high stress is smaller than that of low stress condition for cupra and lyocell fibers with large length.
(4) Compressive creep phenomena of staple fiber assembly is expressed by the creep equation derived from non-linear three element model as follows,
ε_t =Y₀ ln(vt+1)
where, Y₀ and v are constants determined by material properties, measurement condition and compressive stress. Y₀ value has good correlation with apparent Young′s modulus, number of crimp and crimp ratio, and v value has good correlation with bending rigidity of fiber.

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