Prediction of structural parameters and air permeability of cotton woven fabric

2017 ◽  
Vol 88 (14) ◽  
pp. 1650-1659 ◽  
Author(s):  
Guocheng Zhu ◽  
Yuan Fang ◽  
Lianying Zhao ◽  
Jinfeng Wang ◽  
Weilai Chen
Keyword(s):  
Pressure Drop ◽  
Pore Diameter ◽  
Structural Parameters ◽  
Air Permeability ◽  
Experimental Results ◽  
Woven Fabric ◽  
Analytical Models ◽  
Yarn Diameter ◽  
Poiseuille Equation ◽  
Good Agreement

Air permeability is a very important property influencing the performance of clothing comfort and technical textiles particularly in applications for protective products, including airbags, parachutes, and tents. Several analytical models for predicting air permeability have been made by considering porosity and pore diameter or porous area. However, the connection between fabric structure and air permeability with analytical models has not been well reported as yet. In this work, the diameter of cotton yarn was predicted by considering yarn count, twist, and packing density. Subsequently, the pore area and equivalent pore diameter of fabric were predicted after finding the warp and the weft densities of fabric. The predicted values had very good agreement with the experimental results in yarn diameter and other structural parameters of fabric. The air permeability of fabrics was measured and several well-known analytical models for predicting air permeability were compared. The results revealed that the Hagen–Poiseuille equation had much better prediction than other models and also had good agreement with the experimental results, especially when it was applied for tight fabrics at low pressure drop (≤60 Pa). The Hagen–Poiseuille equation could be improved by considering the Reynolds number, interfiber interstices, and the deformation of pores under higher pressure drop.

scholarly journals Inlet and Exit-Header Shapes for Uniform Flow Through a Resistance Parallel to the Main Stream

1961 ◽  
Vol 83 (3) ◽  
pp. 361-368 ◽  
Author(s):  
Morris Perlmutter
Keyword(s):  
Experimental Study ◽  
Pressure Drop ◽  
Total Pressure ◽  
Experimental Results ◽  
Main Stream ◽  
Height Ratio ◽  
Large Length ◽  
Flow Through ◽  
Pass Through ◽  
Good Agreement

An analytical and experimental study of flow in headers with a resistance parallel to the turbulent and incompressible main stream has been made. The purpose was to shape the inlet and exit headers, which had a large length-to-height ratio, so that the fluid would pass through the resistance uniformly. Analytical wall shapes and estimated total pressure drop through the headers were compared with experimental results. Good agreement between analysis and experiment was found for the cases compared.

Modeling and Simulation of a Parametrically-Excited Micro-Mirror With Duty-Cycled Square-Wave Excitation

2013 ◽  
Author(s):  
Wajiha Shahid ◽  
Zhen Qiu ◽  
Xiyu Duan ◽  
Haijun Li ◽  
Thomas D. Wang ◽  
...  
Keyword(s):  
Experimental Results ◽  
Analytical Models ◽  
Control Analysis ◽  
Square Wave ◽  
Optical Scanning ◽  
Electrostatically Actuated ◽  
Resonance Behavior ◽  
Potential Use ◽  
Good Agreement

Electrostatically-actuated MEMS mirrors are used in a variety of applications involving fast optical scanning, with endoscopic microscopy an area of particular interest for miniaturization of advance optical imaging systems. In this paper, analytical and experimental characterization of the dynamics and stability of a 1D torsional micro-mirror is described. The micro-mirror being studied is intended for use in biomedical imaging, in which operation strictly by duty-cycled square waves at one or more voltages can be convenient for practical mirror operation and/or control. Analysis focuses on a Hill’s equation approach to predicting stability regions of parametric resonance behavior when input is a duty-cycled square wave, using an approximation for nonlinear capacitance behavior of the mirror. An analytical approach is compared to experimental results. In results to date, analytical models show good agreement with stability predictions, particularly at small voltages, over the range of duty cycled excitations. Additionally, the paper explores how phase delay varies over a range of micro-mirror frequencies for a 50% duty cycle, also compared with experimental results, for potential use in feedback control.

Pressure Drop Analysis of Pilot-Control Globe Valve With Different Structural Parameters

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
Zhi-jiang Jin ◽  
Zhi-xin Gao ◽  
Ming Zhang ◽  
Jin-yuan Qian
Keyword(s):  
Pressure Drop ◽  
Structural Parameters ◽  
Loss Coefficient ◽  
Spring Stiffness ◽  
Before And After ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
Globe Valve ◽  
Good Agreement ◽  
Pilot Valve

Pilot-control globe valve (PCGV) can use the pressure drop caused by fluid flowing through the orifice located at valve core bottom to open or close the main valve using a small pilot valve. In this paper, computational fluid dynamics (CFD) method is adopted to analyze the pressure drop before and after valve core of PCGV and minor loss of orifice under different structural parameters and inlet velocities, and the simulation results show a good agreement with the experimental results. It turns out that the valve diameters, orifice diameters, and pilot pipe diameters have great influences on the pressure drop and the loss coefficient. Moreover, an expression is proposed which can be used to calculate minor loss coefficient, then to estimate the pressure drop and driving force of a PCGV within limited conditions. This paper can be referenced as guidance for deciding the dimension of structural parameters and spring stiffness during design process of a PCGV.

Multiple regression analysis of a woven fabric sound absorber

2018 ◽  
Vol 89 (5) ◽  
pp. 855-866 ◽  
Author(s):  
Xiaoning Tang ◽  
Deyi Kong ◽  
Xiong Yan
Keyword(s):  
Multiple Regression ◽  
Regression Models ◽  
Structural Parameters ◽  
Air Permeability ◽  
Woven Fabrics ◽  
Woven Fabric ◽  
Physical Parameters ◽  
Acoustic Absorption ◽  
Linear Regression Models ◽  
Absorption Properties

In this study, the effects of physical parameters on the acoustic absorption properties of woven fabrics were studied. The acoustic absorption properties of 24 kinds of woven fabrics with different structural parameters were measured and analyzed. Multiple linear regression models have been established to characterize the relationship between acoustic behavior and various physical parameters. It has been found that the acoustic absorption properties were mainly determined by the perforation ratio and air permeability. The decrease in perforation ratio and air permeability results in an increase of acoustic absorption properties of woven fabrics. Furthermore, three woven fabrics were used to validate the proposed multiple regression models. The established models could well predict the acoustic absorption properties of woven fabrics where the correlation coefficient is higher than 0.77 with air gaps of 1, 2, and 3 cm, respectively.

Structural investigation of spunlace nonwoven

2018 ◽  
Vol 22 (3) ◽  
pp. 158-179 ◽  
Author(s):  
Ravi Kumar Jain ◽  
Sujit Kumar Sinha ◽  
Apurba Das
Keyword(s):  
High Speed ◽  
Structural Changes ◽  
Structural Integrity ◽  
Pore Diameter ◽  
Structural Parameters ◽  
Water Pressure ◽  
Air Permeability ◽  
Strong Positive Correlation ◽  
Content Type ◽  
Significance Level

Purpose Spunlacing is a promising nonwoven technology for the production of fabric with good handle and better structural integrity. Structural parameters such as pore size, thickness and number of binding point/entanglement between fibres are decisive for good mechanical and comfort properties of nonwoven fabrics. This study aims to focus on the effect of different process parameters on the structural change in spunlace fabrics. Design/methodology/approach Spunlacing is purely a mechanical bonding technology where high-speed jets of water strike a web to entangle the fibres. Different spunlace nonwoven structures were produced by varying processing parameters such as waterjet pressure, delivery speed, web mass and web composition as per four-factor, three-level Box–Behnken design. The effect of these parameters on the structural arrangement was studied using scanning electron microscopy. An attempt has also been made to study the changes in pore geometry and thickness of the fabrics by using response surface methodology with backward elimination. Findings Significant structural changes were observed with variation in water pressure, web mass and web composition. The test results showed that fabric produced at higher waterjet pressure has lower mean pore diameter and lower thickness. The variation in mean pore diameter and mean thickness due to waterjet pressure is around 26 and 34 per cent, respectively, at 95 per cent significance level. The web composition and web mass also significantly influence the mean pore diameter and thickness at 95 per cent significance level. There is a strong positive correlation (r = 0.523) between mean air permeability and mean pore diameter of fabric, and this correlation is significantly linear. A strong negative correlation (r = −0.627) is found between weight and air permeability of fabric. Research limitations/implications The delivery speed failed to show any significant effect; this is in contrary to the general expectation. Originality/value The effect of concurrent variation in waterjet pressure, web mass, delivery speed and web composition on the structure of spunlace nonwoven is studied, which was not reported in the literature. The effect of web composition on pore diameter of spunlace nonwoven is interesting finding. This study is expected to help in designing the spunlace nonwoven as per end uses and specifically for apparel application.

scholarly journals THE ANALYSIS CONSTRUCTION PREPARATION OF WOMEN’S PANTS AND PROPERTIES WOVEN FABRIC IMPORTANT FOR COMFORT OF CLOTHES

2019 ◽  
Vol 34 (3) ◽  
pp. 745-750
Author(s):  
Marija Savić ◽  
Danijela Paunović ◽  
Enisa Nokić
Keyword(s):  
Water Absorption ◽  
Conventional Method ◽  
Structural Parameters ◽  
Air Permeability ◽  
Woven Fabrics ◽  
Woven Fabric ◽  
Cad System ◽  
Fabric Density ◽  
Material Characteristics ◽  
Preparation Work

In this paper was analysed the tasks of construction preparation in the production of women’s pants and the properties of woven fabrics, which affect the thermophysiological and ergonomic comfort. Five different models were observed, which have different cutting lines at the front and back of the sock, different pockets and other details. The duration of construction preparation work in the conventional method and application of CAD system OptiTex were analysed. The ergonomic comfort of the tested models was subjectively evaluated in six differnt body positions, and the results were presented as mean with a number on a scale of 1 to 5. Seven woven fabric samples were used of same composition cotton 67 % and polyester 33 %, the same weave of canvas-rips. The correlatio of structural parameters was analysed: woven fabric density, warp and weft density, with material characteristics that are essential for thermophysiological comfort - air permeability and power of water absorption. It was noticed an increase air permeability, with a decrease in the density of the woven fabric, in most of the samples tested. This is explained by the existence of larger chamber in the structure of the lower density woven fabrics. With decreasing woven fabric density there is a tendency to slightly increase the power of water absorption.

Magnetorheological Fluid Flow in Microchannels

2010 ◽  
Vol 77 (4) ◽  
Author(s):  
Joseph Whiteley ◽  
Faramarz Gordaninejad ◽  
Xiaojie Wang
Keyword(s):  
Magnetic Field ◽  
Fluid Flow ◽  
Pressure Drop ◽  
Dynamic Pressure ◽  
Magnetorheological Fluid ◽  
Fused Silica ◽  
Experimental Results ◽  
Microchannel Flow ◽  
Roughness Effects ◽  
Good Agreement

This study presents experimental results on the flow of magnetorheological grease (MRG) through microchannels. MR materials flowing through microchannels create microvalves. The flow is controlled by injecting the MRG through microchannels with controlled adjustable rates. To study the effect of different channel diameters and surface roughnesses, microchannels made of stainless steel, PEEK, and fused silica materials with nominal internal diameters ranging from 1 mm to 0.075 mm (75 μm) are tested. A magnetic field is applied perpendicular to the microchannel flow and is controlled by an input electric current. The pressure drop of the flow is measured across the length of the microchannels. The dynamic pressure drop range and surface roughness effects are also discussed. The Herschel–Bulkley model for non-Newtonian fluid flow is employed to the experimental results with good agreement. The results show a significant pressure drop for different magnetic field strengths.

Performance of Electrospun Polyvinylidene Fluoride Nanofibrous Membrane in Air Filtration

2020 ◽  
Vol 20 (4) ◽  
pp. 552-559
Author(s):  
Yuanxiang Xiao ◽  
Enlong Wen ◽  
Nazmus Sakib ◽  
Zhonghua Yue ◽  
Yan Wang ◽  
...  
Keyword(s):  
Pore Size ◽  
Polyvinylidene Fluoride ◽  
Fiber Diameter ◽  
Structural Parameters ◽  
Solution Concentration ◽  
Air Permeability ◽  
Filtration Efficiency ◽  
Experimental Results ◽  
Fibrous Membrane ◽  
Predicted Values

AbstractPolyvinylidene fluoride (PVDF) fibrous membranes with fiber diameter from nanoscale to microscale were prepared by electrospinning. The structural parameters of PVDF fibrous membrane in terms of fiber diameter, pore size and its distribution, porosity or packing density, thickness, and areal weight were tested. The relationship between solution concentration and structural parameters of fibrous membrane was analyzed. The filtration performance of PVDF fibrous membrane in terms of air permeability and filtration efficiency was evaluated. The results demonstrated that the higher solution concentration led to a larger fiber diameter and higher areal weight of fibrous membrane. However, no regular change was found in thickness, porosity, or pore size of fibrous membrane under different solution concentrations. The air permeability and filtration efficiency of fibrous membrane had positive correlations with pore size. The experimental results of filtration efficiency were compared with the predicted values from current theoretical models based on single fiber filtration efficiency. However, the predicted values did not have a good agreement with experimental results since the fiber diameter was in nanoscale and the ratio of particle size to fiber diameter was much larger than the value that the theoretical model requires.

scholarly journals Depressurization System by Coiled Pipes Applied to a High Pressure Process: Experimental Results and Modeling

2017 ◽  
Vol 11 (1) ◽  
pp. 17-32
Author(s):  
J. M. Benjumea ◽  
J. Sánchez-Oneto ◽  
J. R. Portela ◽  
E. J. Martínez de la Ossa
Keyword(s):  
Experimental Data ◽  
High Pressure ◽  
Pressure Drop ◽  
Friction Factor ◽  
Pilot Plant ◽  
Single Step ◽  
Experimental Results ◽  
Industrial Scale ◽  
High Pressure Process ◽  
Good Agreement

Background:The use of backpressure regulator valves is widespread in high-pressure processes both at laboratory and pilot plant scales, but being a single step for effluent depressurization, such valves may have some limitations at industrial scale. In an effort to improve the depressurization step, this work studies a system based on the pressure drop of a fluid that circulates through coiled pipes.Method:The equipment, based on three series of variable length coiled pipes, was installed to achieve depressurization of 240 bars in a SCWO pilot plant.Results:The experimental results were compared with those obtained by the modeling carried out using different friction factor correlations from the literature.Conclusion:Among all the correlations tested, the Lockhart–Martinelli correlation showed the best agreement with experimental data. However, it was necessary to obtain an appropriate C parameter to achieve a good agreement with experimental data.

scholarly journals EXPERIMENTS AND FEM MODELS ON SEMI-COMPOSITE BEHAVIOR OF SRC STRUCTURES

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Takayuki Matsuta ◽  
Mikio Kitajima ◽  
Koji Maegawa
Keyword(s):  
Reinforced Concrete ◽  
Maximum Load ◽  
Experimental Results ◽  
Analytical Models ◽  
Contact Conditions ◽  
Steel Reinforced Concrete ◽  
Concrete Members ◽  
Load Carrying ◽  
Loading Tests ◽  
Good Agreement

Analytical models were prepared and results from these models were compared with experimental results to confirm the adequate modeling of steel-reinforced concrete members used in rockfall-protection galleries or rock-sheds. Static loading tests of steel-reinforced concrete members (a girder and a slab) were conducted on a simply supported beam. The analytical models have different contact conditions to verify which condition can express a semi-composite behavior and shear slide. Three types of contact conditions were applied: normal, tied, and tiebreak contact. Tiebreak contact can express the occurrence of gaps by defining shear bond strength. Consequently, analytical models that applied tiebreak contact showed comparatively good agreement with experimental results. Analytical models that applied the tiebreak contact condition showed a correlation of 97% (girder) and 101% (slab) with the experimental results for the maximum load-carrying capacity. Therefore, considering that slippage occurs between different materials, the model is good for expressing the behavior of complicated structures such as steel-reinforced concrete members that are used as a rock-shed.

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