ORCID Profile
0000-0003-3761-7103
Current Organisations
Northumbria University
,
University of Nottingham
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Publisher: Elsevier BV
Date: 06-2014
Publisher: Springer Science and Business Media LLC
Date: 11-2014
Publisher: SAGE Publications
Date: 22-05-2014
Abstract: Before being processed into composites, reinforcement fabrics may undergo repeated involuntary deformation, the complete sequence of which is here referred to as specimen history. To mimic its effect, fabric specimens were subjected to sequences of defined shear operations. For single fabric layers with unconstrained thickness, quantitative evaluation of photographic image data indicated that repeated shear deformation results in a residual increase in inter-yarn gap width. This translates into an increase in measured fabric permeabilities in multi-layer lay-ups at given compaction levels. The extent of both interrelated effects increases with increasing yarn density in the fabric and with increasing maximum angle in the shear history. Additional numerical permeability predictions indicated that the increase in permeability may be partially reversed by through-thickness fabric compression. The observations suggest that the effect of involuntary deformation of the fabric structure can result in variations in the principal permeability values by factors of up to 2.
Publisher: SAGE Publications
Date: 02-2012
Abstract: Woven fabric permeability is relevant to many applications, such as airbags, textile composites processing, paper making and air and water filtration. This paper proposes an analytical model to predict through-thickness fabric permeability based on viscous and incompressible Hagen–Poiseuille flow. The flow is modeled through a unit cell of fabric with a smooth fluid channel at the center with slowly varying cross-section. The channel geometry is determined by yarn spacing, yarn cross-section and fabric thickness. The shape of the channel is approximated by a parabolic function. Volumetric flow rate ( Q) is formulated as a function of pressure drop and flow channel geometry for woven fabric. The permeability ( K) is calculated thereafter according to Darcy’s law. The air permeability of nine different fabrics has been measured to verify the analytical model. A sensitivity study was carried out to understand how geometric parameters influence the fabric permeability. The analytical model shows very close agreement with the experimental data: within 5% for most fabrics. The sensitivity study on permeability indicates the importance of flow channel geometry in obtaining accurate predictions.
Publisher: Elsevier BV
Date: 06-2008
Publisher: Elsevier BV
Date: 06-2019
Publisher: Elsevier BV
Date: 12-2018
Publisher: Elsevier BV
Date: 2014
Publisher: SAGE Publications
Date: 18-01-2012
Abstract: Dynamic permeability is relevant to textile applications subjected to fluid/gas flow under high pressure, such as automotive airbags, wearable airbags and parachute fabrics. Dynamic permeability can be determined when a porous medium is tested under transient pressure conditions. This paper utilizes a reliable approach to measure and characterize dynamic permeability for woven fabrics. The experimental principle is based on the ideal gas law and the non-linear Forchheimer equation. Compared with static permeability measured under a constant low pressure, the dynamic permeability is an intrinsic property determined by change of fabric geometry and structure due to a high-pressure load. The pressure-induced deformation is identified, including effects on fiber and yarn arrangement, yarn porosity and fabric thickness. The level of deformation is a function of the number of fabric layers and initial pressure drop. The experimental results show that the dynamic permeability is higher than the static permeability for loose fabric, while it is lower for tight fabrics. For tight fabric, more fabric layers and a lower initial pressure can reduce the difference between the static and the dynamic permeability. Analytical models are used to explain and predict both static and dynamic permeability.
Publisher: Elsevier BV
Date: 10-2015
Publisher: Springer Science and Business Media LLC
Date: 30-07-2014
Publisher: SAGE Publications
Date: 30-01-2015
Abstract: Through-thickness permeability (TTP) is one primary property of technical textiles used in air-related applications, such as filtration and protection. The TTP depends on the textile geometrical factors and usually varies according to the test conditions. In this article, the effect of low air pressure compression (LPC) on TTP of woven fabric was investigated. Nine woven fabrics were measured for the relationships of LPC and thickness, LPC and fabric in-plane dimensions, air pressure drop (APD) and air velocity, as well as LPC and fabric TTP. A dramatic decrease of woven fabric thickness was found below the APD value of 200 Pa and less decreased thickness was observed with a continued increase of APD. The variation of fabric in-planar dimensions was found to be negligible during LPC. The plot relationship of the APD and measured air velocity was presented in linearity for most fabric s les. The fabric TTP showed a linear proportion to the fabric thickness, indicating the fabric to be more permeable with the increase of thickness. A sensitivity study showed an evident difference between using fabric constant and decreased (LPC) thickness in calculating TTP, disclosing the importance of compression in fabric TTP evaluation.
Publisher: SAGE Publications
Date: 05-07-2016
Abstract: Many technical applications of woven fabric are subject to increasing high pressure from air transport through the fabric. The through-thickness permeability (TP) of woven materials exhibits a dynamic response to increased air pressure. This paper presents an analytical model for predicting the steady TP of woven fabric. The approach was based on Darcy’s law and the Poiseuille equation, using the flow boundary of an idealized plain-weave unit cell. The unit cell model consists of a gradual converging- erging (GCD) duct with a rectangular cross-section. Further, the dynamic TP of the GCD duct was established analytically as a function of increasing pressure, which correlates to the separation of air flow from the GCD duct wall. Air flow separation from the duct wall led to a quadratic relationship between the increasing pressure and air flow velocities. This dynamic TP and air flow nonlinearity were simulated numerically in the computational fluid dynamics solver CFX. Five GCD ducts under increasing air pressure were analyzed numerically and analytically. The comparison showed good agreement between the proposed analytical model and the CFD simulation, with a maximum error up to 12%. A sensitivity study showed that an increase in porosity or a decrease in the thickness of weave materials could result in a larger dynamic TP value.
Publisher: SAGE Publications
Date: 15-05-2012
Abstract: An automated approach (TexGen) for modeling the geometry of textile structures is presented. This model provides a generic approach to the description of yarn geometry and yarn interlacement for all types of weaving. One feature of this model is that the shape and size of the cross sections may change locally this is exploited in the functions for interference correction, which modify the textile according to geometric considerations to avoid penetration of yarns. Another feature of this model is that it acts as a pre-processor for finite element simulations by generating a mesh, definition of contact, materials orientation and boundary conditions, thus providing an automatic procedure. This paper describes the modeling techniques, algorithms and concepts implemented in TexGen and examines the functionality of their implementation for a range of two-dimensional/three-dimensional commercial fabrics. Comparisons between the images of real fabrics and modeled fabric structures confirm that the software is capable of modeling sophisticated fabric architectures, including twisted yarns with varied yarn cross sections. Accurate input measurements of fabric geometry are critical for successful results. The paper also discusses directions for further development of the approach to overcome current limitations.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Andrew Long.