Investigation of Yarn Twist Propagation in Rotor Spinning

2002 ◽  
Author(s):  
BinGang Xu ◽  
XiaoMing Tao
Keyword(s):  
Dynamic Equilibrium ◽  
Dynamic Coupling ◽  
Coupling Effects ◽  
Forming Process ◽  
Dimensionless Parameters ◽  
Yarn Tension ◽  
Rotor Spinning ◽  
Yarn Twist ◽  
Mechanical Approach ◽  
Dimensionless Variables

This paper proposed an integrated mechanical approach for yarn dynamics in rotor spinning, especially the twist propagation in the yarn forming process from fibers collected in a rotor groove to the twisted yarn at the twist stopper. Equations of dynamic equilibrium in different yarn forming regions were established, and further, expressed in terms of dimensionless variables. Then the yarn tension and twist distribution, considering the dynamic coupling effects between different regions under the steady spinning conditions, were numerically simulated, in which influences of various dimensionless parameters of rotor spinning on the yarn tension and twist distributions were discussed in details.

An investigation on the distribution of massive fiber granules in rotor spinning units

2016 ◽  
Vol 87 (7) ◽  
pp. 865-877 ◽  
Author(s):  
Yuzhen Jin ◽  
Jingyu Cui ◽  
Xiangdong Li ◽  
Hongli Chen
Keyword(s):  
Numerical Study ◽  
Distribution Characteristics ◽  
Rotor Speed ◽  
Fiber Morphology ◽  
Forming Process ◽  
Transport Channel ◽  
Rotor Spinning ◽  
Yarn Strength ◽  
Yarn Twist ◽  
Simulation Results

Rotor spinning is an open-end spinning method that uses air as the medium to transform the fibers into yarn. Nowadays, the properties of its final product—yarn—such as yarn strength and yarn twist, are not satisfied due to the fiber morphology, which greatly depends on the distribution of the massive fibers in the rotor spinning unit (RSU). In this paper, theoretical analysis is given to describe the trajectory of fiber on the slide wall. A numerical study is performed with the massive fibers being simplified into granules to study their distribution characteristics in the RSU. According to our numerical results, the forming process of the fibrous ring is discussed and the effects of two variables, the rotor speed and the angle of the slide wall, on the distribution of fiber granules were also studied. The simulation results indicate that the fiber granules are not evenly distributed during their transport in the fiber transport channel (FTC) and they tend to accumulate on the upper and lower edge of the FTC. The distribution of fiber granules in the groove (fibrous rings) is closely related to the rotor speed. The higher the rotor speed, the longer and thinner the fibrous ring. The distribution of fiber granules on the slide wall is related to the angle of the slide wall such that a smaller angle leads to a scattered distribution on the slide wall, while a larger angle tends to bring a concentrated one. The simulation results show good agreements with our experimental results.

scholarly journals Seakeeping Tests of a FOWT in Wind and Waves: An Analysis of Dynamic Coupling Effects and Their Impact on the Predictions of Pitch Motion Response

2021 ◽  
Vol 9 (2) ◽  
pp. 179
Author(s):  
Giovanni Amaral ◽  
Pedro Mello ◽  
Lucas do Carmo ◽  
Izabela Alberto ◽  
Edgard Malta ◽  
...  
Keyword(s):  
Frequency Domain ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Dynamic Coupling ◽  
Coupling Effects ◽  
Mooring Lines ◽  
Scaled Model ◽  
Wave Basin ◽  
Domain Models ◽  
Catenary System

The present work highlights some of the dynamic couplings observed in a series of tests performed in a wave basin with a scaled-model of a Floating Offshore Wind Turbine (FOWT) with semi-submersible substructure. The model was moored by means of a conventional chain catenary system and an actively controlled fan was used for emulating the thrust loads during the tests. A set of wave tests was performed for concomitant effects of not aligned wave and wind. The experimental measurements illustrate the main coupling effects involved and how they affect the FOWT motions in waves, especially when the floater presents a non-negligible tilt angle. In addition, a frequency domain numerical analysis was performed in order to evaluate its ability to capture these effects properly. The influence of different modes of fan response, floater trim angles (changeable with ballast compensation) and variations in the mooring stiffness with the offsets were investigated in the analysis. Results attest that significant changes in the FOWT responses may indeed arise from coupling effects, thus indicating that caution must be taken when simplifying the hydrodynamic frequency-domain models often used as a basis for the simulation of FOWTs in waves and in optimization procedures for the design of the floater and mooring lines.

High-Frequency Yarn Tension Variations in Spinning

1980 ◽  
Vol 102 (1) ◽  
pp. 45-50
Author(s):  
E. Dyson ◽  
G. Afshari
Keyword(s):  
Experimental Investigation ◽  
Periodic Structure ◽  
Coefficient Of Variation ◽  
Rotational Speed ◽  
High Frequency ◽  
Ring Spinning ◽  
Statistical Parameters ◽  
Yarn Tension ◽  
Rotor Spinning

A description of an experimental investigation of the variations in yarn tension during both ring and rotor open-end spinning which have frequencies equal to, or greater than, the rotational speed of the system is given. Typical results are illustrated and discussed both in terms of statistical parameters such as the coefficient of variation and in terms of their spectra. Tension variations during rotor spinning are shown to have, in general, a much less pronounced periodic structure then the corresponding variations during ring spinning.

scholarly journals Clay profile in Greyzemic Phaeozems of the Pre-Carpathian region (Ukraine)

2018 ◽  
pp. 240-250
Author(s):  
Ihor Papish
Keyword(s):  
Humus Horizon ◽  
Dynamic Equilibrium ◽  
Soil Aggregates ◽  
Clay Material ◽  
Forming Process ◽  
Dual Nature ◽  
Carpathian Region ◽  
Humus Layer ◽  
Mineral Profile ◽  
Greyzemic Phaeozems

The aim of this article is to describe the formation of the chemic-mineralogical profile of Greyzemic Phaeozems on the various geomorphological surfaces in the Pre-Carpathian loess subprovince. The differentiation of the Greyzemic Phaeozems mineral mass is determined by the composition of soil-forming rocks, the nature of the formation of different geomorphological surfaces and the peculiarities of the soil-forming process. The mineral profile of Greyzemic Phaeozems is differentiated into two parts, the upper one is within the humus horizon and the lower one is a weakly humus layer. At the high Pliocene terraces of the Prut River, its dual nature is caused by lithologic heterogeneity of the soil-forming rocks, and within the limits of the San-Dnister Upland, the active development of the processes of the leaching of clay material due to podzolization and soil profile gleyzation. The common regularity of the mineral profile of the Greyzemic Phaeozems this region is the uniformity of the ratio of the main mineral phases of the fine material, the active eluviation from the humus horizon of the smectite material, the relative accumulation in the humus horizon illite minerals, and various clastogenic non-clay minerals. The negative trends in the clay profile evolution of Greyzemic Phaeozems cause the reduction of erosion resistance of these soils. The strength of the cohesion between soil aggregates is determined by the content of humus (humatic kind) and dominating smectite minerals in clay plasma. The processes of dehumification have been destabilized the mineral colloidal complex of Phaeozems and changed of smectite-illite dynamic equilibrium in soils. In Greyzemic Phaeozems the substantial loss of highly dispersive smectite material can be observed. The dominance of inactive bi-octahedral illite clay in the arable layer of Phaeozems reduces the role of clay plasma in the formation of water-stable micro- and macrostructure. Key words: chemic-mineralogical profile of soil, podzolization, gleyzation, content of humus, chemical equilibrium in soils.

Warm forming process for an AA5754 train window panel

2021 ◽  
pp. 1-32
Author(s):  
Antonio Piccininni ◽  
Andrea Lo Franco ◽  
Gianfranco Palumbo
Keyword(s):  
Material Characterization ◽  
Room Temperature ◽  
Warm Forming ◽  
Railway Vehicle ◽  
Fe Model ◽  
Forming Process ◽  
Vehicle Component ◽  
Mechanical Approach ◽  
Thermal Simulations ◽  
Critical Regions

Abstract A warm forming process is designed for AA5754 to overcome low room temperature formability. The solution includes increased working temperature and is demonstrated with a railway vehicle component. A Finite Element (FE) based methodology was adopted to design the process taking into account also the starting condition of the alloy. In fact, the component's dent resistance can be enhanced if the yield point is increased accordingly: the stamping process was thus designed considering the blank in both the H111 (annealed and slightly hardened) and H32 (strain-hardened and stabilized) conditions that were preliminarily characterized. Tensile and formability tests were carried out at different temperature and strain rate levels, thus providing the data to be implemented within the FE model (Abaqus/CAE): the stamping was at first simulated at room temperature to evaluate the blank critical regions. Subsequently, the warm forming process was designed by means of an uncoupled thermo-mechanical approach. Thermal simulations were run to properly design the heating strategy and achieve an optimal temperature distribution over the blank deformation zone (according to the results of the material characterization). Such a distribution was then imported as a boundary condition into the mechanical step (Abaqus/Explicit) to determine the optimal process parameters and obtain a sound component (strain severity was monitored implementing an FLD-based damage criterion). The simulation model was validated experimentally with stamping trials to fabricate a sound component using the optimized heating strategy and punch stroke profile.

scholarly journals New Numerical Model of Composite Fabric Behaviour: Simulation of Manufacturing of thin Composite Part

2000 ◽  
Vol 9 (3) ◽  
pp. 096369350000900 ◽  
Author(s):  
J.L. Billoet ◽  
A. Cherouat
Keyword(s):  
Mechanical Properties ◽  
Tensile Tests ◽  
Woven Fabrics ◽  
Woven Fabric ◽  
Forming Process ◽  
Composite Part ◽  
Initial Shape ◽  
Shaping Process ◽  
Mechanical Approach ◽  
Behaviour Simulation

The present study concerns the modelling of the behaviour of pre-impregnated woven fabric during the forming process. The mechanical approach is based on a mesostructural model. It allows us to take into account the mechanical properties of fibres and resin and the various dominating mode of deformation of woven fabrics during the forming process. Shear and tensile tests of composite fabric specimens are proposed and compared with the experimental results in order to demonstrate the efficiency of our approach. Different numerical simulations and experiments of shaping process have been carried out in order to validate the proposed computational formulation. The various forming parameters examined have included the initial shape of fabric, fibre orientations and viscosity of resin.

scholarly journals Numerical Tools for Composite Woven Fabric Preforming

2013 ◽  
Vol 2013 ◽  
pp. 1-18 ◽  
Author(s):  
Abel Cherouat ◽  
Houman Bourouchaki
Keyword(s):  
Mechanical Properties ◽  
Composite Structures ◽  
Woven Fabrics ◽  
Woven Fabric ◽  
Angular Distortion ◽  
Geometrical Approach ◽  
Forming Process ◽  
Manufacture Process ◽  
Mould Surface ◽  
Mechanical Approach

An important step in the manufacturing processes of thin composite components is the layingup of the reinforcement onto the mould surface. The prediction of the angular distortion of the reinforcement during draping and the changes in fibre orientation are essential for the understanding of the manufacture process and the evaluation of the mechanical properties of the composite structures. This paper presents an optimization-based method for the simulation of the forming processes of woven fabric reinforced composites. Two different approaches are proposed for the simulation of the draping of woven fabric onto complex geometries: geometrical and mechanical approaches. The geometrical approach is based on a fishnet model. It is well adapted to predimensioning fabrics and to give a suitable quantification of the resulting flat patterns. The mechanical approach is based on a mesostructural model. It allows us to take into account the mechanical properties of fibres and resin and the various dominating mode of deformation of woven fabrics during the forming process. Some numerical simulations of the forming process are proposed and compared with the experimental results in order to demonstrate the efficiency of our approaches.

Sign in / Sign up

Export Citation Format

Share Document