The paper presents a fragment of a research project aimed at defining the dynamics and tribology of the real twisting system of a ring spinning frame, i.e. a system with regular and/or random occurrence of faults in its operation. The object of study are the dynamic disturbances and their tribological consequences, which occur in the operation of the twisting system of a worsted spinning ring-frame due to faulty rotation of the spindle caused by play in its bearing. Studied was a twisting system provided with a taper ring (HZ) and 'J' steel traveller. The forces were determined, for a case of three-contact inter-action between the traveller and ring, which act on the traveller and yarn if the spindle axis deviates from the vertical so that its tip traces an ellipse or a circle. It is shown that this faulty operation of the twisting system has a destructive effect on the inter-action of the traveller-ring-yarn (TRY) trio, which aggravates with time and has a deteriorating effect on the performance of the system

View full abstract

This paper presents a study on the development of stainless steel/polyester (SS/PET), stainless steel/rayon (SS/RS), and stainless steel/Kevlar (SS/KS) woven fabrics for shielding the power leakage of microwave oven applications. To facilitate weaving of stainless steel wires and to reduce the material cost initially the core-spun yarns of stainless steel and man-made staple fibers were produced by a DREF III open-end spinning method. The core-spun yarns were woven into a variety of woven structures that woven from a Picanol Rapier loom successfully. Primary objects of this research are to develop new conductive core-spun yarns and fabrics, which could be suitable for shielding home electronic and electrical appliance from electrical and magnetic fields at high frequency. Using a coaxial transmission line holder system set-up, the electromagnetic shielding effectiveness (EMSE) of various woven fabrics. was determined in the frequency range from 300kHz to 3GHz. The leakage power detector measures the leakage power density (LPD) of the microwave oven. The variations of EMSE and LPD with the yarn constructions, woven structures and the blend ratio of stainless steel to the man-made fiber in the yarns are also described.

View full abstract

The objective of this study is to well understand the interaction between the configuration of flexible fibers and flow kinematics in fiber suspension flows. In this framework, the evolution of the configuration of a single fiber in a simple shear flow at low Reynolds number was numerically analyzed on the basis of an 'immersed boundary method' developed by Peskin. In the computations fibers with force-free configuration of being straight were used. While deformation of a fiber is fundamentally three-dimensional, stretching/compression and bending deformations in the plane of flow were simply assumed.
In Part 2 of the series of papers, the effects of fluid viscosity and shear rate on the evolution of the configuration of a single fiber and flow kinematics were described. The behavior of a fiber becomes more complex as the fluid viscosity increases. Furthermore, it was confirmed that a flow-induced bending parameter, which is a function of fiber length, bending stiffness, fluid viscosity and shear rate, is a useful dimensionless parameter for classification of rotation of an elastic fiber, such as rigid rotation, springy rotation, S-turn, snake turn and complex rotation.

View full abstract

The objective of this study is to investigate the possibility on the variable thermal resistance of fiber bulk materials as a heat insulating bedquilt for keeping a human being warm and comfortable independent upon the change in the environmental temperature. The system for maintaining the optimum thermal condition in the bed was realized by varying the porosity of the fiber bulk materials using the deformation of the thin wires of shape memory alloy by the temperature change.
The relations between the porosities and the apparent thermal resistances of the typical three kinds of fiber bulk materials were measured. As a result, it was clarified that the possible variable range of the apparent thermal resistance is about the double for the cotton fiber bulk materials with polyester fibers. Mixing of the fine metal wires, which is a substitute for shape memory alloy, had little effect on the thermal resistance in the range of the mixing fraction.
Furthermore, the considerations on the thermal characteristics of the fiber bulk materials were performed using the numerical analysis assuming heat conduction and radiation heat transfer. Finally, the experiment on the change in the volume of fiber bulk materials and in the thermal resistance was carried out actually by mixing the fine wires of shape memory alloy..

View full abstract

The flow rate balance of viscoelastic fluids through a branching channel with two exits, which were different in width, was studied. Numerical simulations of the viscoelastic flow in branching channels were carried out by the stream-upwind finite element method. The Giesekus model with a single relaxation time was used for a constitutive equation. The Carreau model which was one of generalized Newtonian models was also used in order to separate the contribution of elasticity. The shear-thinning property in viscosity causes the increase in the ratio of the flow rate in the wider slit to the total flow rate with increasing flow rate. Furthermore, the stretch-thickening property in elongational viscosity promotes the tendency. Therefore, for viscoelastic fluids, both the shear viscosity and the elongational viscosity affect the flow rate balance.

View full abstract

The applicability of various fibrous wastes such as textile fabrics, non woven-fabrics and fishing net as insulating material in the enclosure filled with a liquid containing fibrous wastes was investigated. The heat transfer rates were measured in the enclosure bounded by vertical isothermal walls at different temperatures and filled with the waste and pure water. The polyester fiber was used for the experiments as a representative synthetic fiber. The void ratio in the enclosure with fibrous wastes was varied in the wide range. The permeability of fibrous wastes was also measured to discuss the heat transfer rate in detail. It was clarified that the configuration of the fibrous waste affected largely on the heat transfer rate. Namely, the sheet type waste such as non-woven fabrics suppressed the heat transfer rate largely in comparison with the case of cord-type waste such as fishing net under the condition of constant void ratio. Moreover, it was cleared that the configuration of the fibrous wastes affected largely on the permeability of the wastes and the heat transfer rate largely dependent on the permeability of fibrous wastes. The results obtained in this paper shows promise for contributing to the establishment of recycling system for wastes of various synthetic fabrics.

View full abstract