Relevant bibliographies by topics / Fibre suspension

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  1. Journal articles
  2. Dissertations / Theses
  3. Books
  4. Book chapters
  5. Conference papers

Academic literature on the topic 'Fibre suspension'

Author: Grafiati
Published: 4 June 2021
Last updated: 20 February 2023

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Journal articles on the topic "Fibre suspension"

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Redlinger-Pohn, Jakob D., Melanie Mayr, Gregor Schaub, David Gruber, and Stefan Radl. "Fines mobility and distribution in streaming fibre networks: experimental evidence and numerical modeling." Cellulose 27, no. 16 (September 23, 2020): 9663–82. http://dx.doi.org/10.1007/s10570-020-03443-9.

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AbstractThe motion of flocculated fibres in a streaming suspension is governed by the balance of the network strength and hydrodynamic forces. With increasing flow rate through a channel, (1) the network initially occupying all space, (2) is then compressed to the centre, and (3) ultimately dispersed. This classical view neglects fibres-fines: we find that the distribution of these small particles differs in streaming suspensions. While it is known that fibre-fines can escape the fibre network, we find that the distribution of fibre-fines is non-homogenous in the network during compression: fibre-fines can be caged and retarded in the streaming fibre network. Hence, the amount of fibre-fines is reduced outside of a fibre network and enriched at the network’s interface. Aiming on selectively removing fibre-fines from a streaming network by suction, we identify a reduction of the fines removal rate. That documents a hindered mobility of fibre-fines when moving through the network of fibres. Additionally, we found evidence, that the mobility of fibre-fines is dependent on the fibre-fines quality, and is higher for fibrillar fines. Consequently, we suggest that the quality of fibre-fines removed from the suspension can be controlled with the flow regime in the channel. Finally, we present a phenomenological model to compute the length dependent fibre distribution in an arbitary geometry. For a fibre suspension channel flow we are able to predict a length-dependent fibre segregation near the channel’s centre. The erosion of a plug of long fibres was however underestimated by our model. Interestingly, our model with parameters fitted to streaming fibre suspension qualitatively agreed with the motion of micro-fibrillated cellulose. This gives hope that devices for handling flocculated fibre suspensions can be designed in the future with greater confidence.
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Sridang, P. Choksuchart, M. Heran, and A. Grasmick. "Influence of module configuration and hydrodynamics in water clarification by immersed membrane systems." Water Science and Technology 51, no. 6-7 (March 1, 2005): 135–42. http://dx.doi.org/10.2166/wst.2005.0631.

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Different immersed membrane systems were compared according to the module configuration. Filtering concentrated aqueous suspensions under constant permeate flux, the hydraulic performances of the systems were evaluated and compared through parameters such as critical permeate flux notion and trans-membrane pressure variation rates. Operational variables were membrane size and module fibre density, aeration inside or outside the fibre network, suspension concentration and physico-chemical conditioning. When using hollow fibres including a possible air injection inside the fibre network, results pointed out the positive role of the aeration on the fouling control. But too high a fibre density did not allow an optimal control when the aqueous suspension was very concentrated. On the other hand, when working with capillary membranes showing sufficient space between fibres, the major parameters were the transversal suspension flow circulation through the fibre network and the FeCl3 conditioning of the suspension. Experimental results show a possible working at a 0.07 m3.m2.h1 permeate flow rate under low TMP evolutions, 0.02 Pa/s, even if the filtration was operated under high concentrated suspension, 5 kgSS/m3.
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Manikantan, Harishankar, Lei Li, Saverio E. Spagnolie, and David Saintillan. "The instability of a sedimenting suspension of weakly flexible fibres." Journal of Fluid Mechanics 756 (September 9, 2014): 935–64. http://dx.doi.org/10.1017/jfm.2014.482.

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AbstractSuspensions of sedimenting slender fibres in a viscous fluid are known to be unstable to fluctuations of concentration. In this paper we develop a theory for the role of fibre flexibility in sedimenting suspensions in the asymptotic regime of weakly flexible bodies (large elasto-gravitation number). Unlike the behaviour of straight fibres, individual flexible filaments rotate as they sediment, leading to an anisotropic base state of fibre orientations in an otherwise homogeneous suspension. A mean-field theory is derived to describe the evolution of fibre concentration and orientation fields, and we explore the stability of the base state to perturbations of fibre concentration. We show that fibre flexibility affects suspension stability in two distinct and competing ways: the anisotropy of the base state renders the suspension more unstable to perturbations, while individual particle self-rotation acts to prevent clustering and stabilizes the suspension. In the presence of thermal noise, the dominant effect depends critically upon the relative scales of flexible fibre self-rotation compared to rotational Brownian motion.
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Feist, Markus, Hermann Nirschl, Jörg Wagner, Georg Hirsch, and Samuel Schabel. "Experimental Results for the Settling Behaviour of Particle-Fiber Mixtures." Physical Separation in Science and Engineering 2007 (February 11, 2007): 1–6. http://dx.doi.org/10.1155/2007/91740.

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Sedimentation of organic fibres and inorganic particles can be observed in several industrial applications. Fibres are involved not only in wastewater treatment but also in other separation applications. In the paper industry, the separation of inorganic filler and coating particles from short cellulose fibres is still a challenge in the recycling process. During that process, particles have to be removed to obtain a purified fibre suspension. These fibres can be used again to produce new paper. With the currently applied techniques, like screening and flotation, the efficiency of short fibre separation is very poor. Moreover, also separation by sedimentation fails due to similar settling velocities of heavy-small particles and the light and larger fibres. This paper concentrates on the sedimentation of organic fibres and inorganic particles in water. The investigated suspensions are made by resolving two different and specially produced papers a coated and an uncoated one, as well as the single components used for its production. We observe a different sedimentation behaviour according to the concentration of fibres and particles in the suspension and the pH-value of it. The main result is that, according to the fibre rate, the sedimentation behaviour is particle dominant or fibre dominant.
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Shankar, Vijay, Anton Lundberg, Taraka Pamidi, Lars-Olof Landström, and Örjan Johansson. "CFD Analysis of Turbulent Fibre Suspension Flow." Fluids 5, no. 4 (October 8, 2020): 175. http://dx.doi.org/10.3390/fluids5040175.

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A new model for turbulent fibre suspension flow is proposed by introducing a model for the fibre orientation distribution function (ODF). The coupling between suspended fibres and the fluid momentum is then introduced through the second and fourth order fibre orientation tensors, respectively. From the modelled ODF, a method to construct explicit expressions for the components of the orientation tensors as functions of the flow field is derived. The implementation of the method provides a fibre model that includes the anisotropic detail of the stresses introduced due to presence of the fibres, while being significantly cheaper than solving the transport of the ODF and computing the orientation tensors from numerical integration in each iteration. The model was validated and trimmed using experimental data from flow over a backwards facing step. The model was then further validated with experimental data from a turbulent fibre suspension channel flow. Simulations were also carried out using a Bingham viscoplastic fluid model for comparison. The ODF model and the Bingham model performed reasonably well for the turbulent flow areas, and the latter model showed to be slightly better given the parameter settings tested in the present study. The ODF model may have good potential, but more rigorous study is needed to fully evaluate the model.
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BUTLER, JASON E., and ERIC S. G. SHAQFEH. "Dynamic simulations of the inhomogeneous sedimentation of rigid fibres." Journal of Fluid Mechanics 468 (October 8, 2002): 205–37. http://dx.doi.org/10.1017/s0022112002001544.

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We have simulated the dynamics of suspensions of fibres sedimenting in the limit of zero Reynolds number. In these simulations, the dominant inter-particle force arises from hydrodynamic interactions between the rigid, non-Brownian fibres. The simulation algorithm uses slender-body theory to model the linear and rotational velocities of each fibre. To include far-field interactions between the fibres, the line distribution of force on each fibre is approximated by making a Legendre polynomial expansion of the disturbance velocity on the fibre, where only the first two terms of the expansion are retained in the calculation. Thus, the resulting linear force distribution can be specified completely by a centre-of-mass force, a couple, and a stresslet. Short-range interactions between particles are included using a lubrication approximation, and an infinite suspension is simulated by using periodic boundary conditions. Our numerical results confirm that the sedimentation of these non-spherical, orientable particles differs qualitatively from the sedimentation of spherical particles. The simulations demonstrate that an initially homogeneous, settling suspension develops clusters, or streamers, which are particle rich surrounded by clarified fluid. The instability which causes the heterogeneous structure arises solely from hydrodynamic interactions which couple the particle orientation and the sedimentation rate in particle clusters. Depending upon the concentration and aspect ratio, the formation of clusters of particles can enhance the sedimentation rate of the suspension to a value in excess of the maximum settling speed of an isolated particle. The suspension of fibres tends to orient with gravity during the sedimentation process. The average velocities and orientations, as well as their distributions, compare favourably with previous experimental measurements.
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HARLEN, OLIVER G., R. R. SUNDARARAJAKUMAR, and DONALD L. KOCH. "Numerical simulations of a sphere settling through a suspension of neutrally buoyant fibres." Journal of Fluid Mechanics 388 (June 10, 1999): 355–88. http://dx.doi.org/10.1017/s0022112099004929.

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The sedimentation of a small dense sphere through a suspension of neutrally buoyant fibres is investigated via a numerical simulation technique that includes both fibre–fibre contact forces and long-range hydrodynamic interactions. In situations where the diameter of the sphere is smaller than the length of the fibres, calculations that exclude the effect of contacts between fibres severely underestimate the drag force on the sphere measured in experiments. By including fibre–fibre contacts in our simulations we are to able to account for this discrepancy, and also the strong dependence of the drag on the initial orientation of the fibres. At low and moderate values of nL3, where n is the number of fibres per unit volume and L the fibre length, hydrodynamic interactions are found to be important in moderating the effect of contacts between fibres.An asymptotic solution is presented for the limit when the sphere diameter is much smaller than both the fibre length and inter-fibre spacing, but large compared to the fibre thickness. This is found to be in good agreement with the simulations.Results of calculations on sedimentation through a monolayer of fibres are also presented, as a model of a semi-concentrated suspension. Collisions between fibres are much more frequent, due to the geometric confinement.
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Voinov, Nikolai, Anastasiya Bogatkova, Denis Zemtsov, Aleksandr Vititnev, and Roman Marchenko. "Sedimentation of refined cellulosic pulp fines in the suspension during physical agglomeration." BioResources 17, no. 3 (May 3, 2022): 3883–905. http://dx.doi.org/10.15376/biores.17.3.3883-3905.

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A physical coagulator of fines was employed to separate suspensions comprising refined sulphate cellulose and waste paper, where no reagents were required. The physical coagulator was a porous cylinder with a rotating disk placed in its cavity. Using the MorFi Neo fibre analyser and the Hitachi SU 3500 digital microscope, a dispersed size distribution of well-developed fines in a suspension derived from softwood and hardwood pulp was obtained. The kinetics of fine sedimentation in the suspension was studied. The sedimentation rate of both individual agglomerates and a mass of them, as well as the magnitude of mass concentration in a cleared liquid, was determined. A relationship between the concentration of fines in the suspension and the structure of the pulp during their sedimentation was established. To intensify the fines sedimentation process, it was proposed to return a part of the sediment to the suspension passing into the physical coagulator. Process parameters for the sedimentation process and the construction of the sedimentation tank were obtained. The unit designed for collecting fines from the suspension is shown schematically. Use of this unit reduced the fibre sedimentation time, decreased the loads in wastewaters, and retained the consumer value of the pulp fibres.
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Mackaplow, Michael B., and Eric S. G. Shaqfeh. "A numerical study of the rheological properties of suspensions of rigid, non-Brownian fibres." Journal of Fluid Mechanics 329 (December 25, 1996): 155–86. http://dx.doi.org/10.1017/s0022112096008889.

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Using techniques developed in our previous publication (Mackaplow et al. 1994), we complete a comprehensive set of numerical simulations of the volume-averaged stress tensor in a suspension of rigid, non-Brownian slender fibres at zero Reynolds number. In our problem formulation, we use slender-body theory to develop a set of integral equations to describe the interfibre hydrodynamic interactions at all orders. These integral equations are solved for a large number of interacting fibres in a periodically extended box. The simulations thus developed are an accurate representation of the suspensions at concentrations up to and including the semidilute regime. Thus, large changes in the suspensions properties can be obtained. The Theological properties of suspensions with concentrations ranging from the dilute regime, through the dilute/semi-dilute transition, and into the semi-dilute regime, are surprisingly well predicted by a dilute theory that takes into account two-body interactions. The accuracy of our simulations is verified by their ability to reproduce published suspension extensional and shear viscosity data for a variety of fibre aspect ratios and orientation distributions, as well as a wide range of suspension concentrations.
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Schiek, Richard L., and Eric S. G. Shaqfeh. "A nonlocal theory for stress in bound, Brownian suspensions of slender, rigid fibres." Journal of Fluid Mechanics 296 (August 10, 1995): 271–324. http://dx.doi.org/10.1017/s0022112095002138.

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A nonlocal theory for stress in bound suspensions of rigid, slender fibres is developed and used to predict the rheology of dilute, rigid polymer suspensions when confined to capillaries or fine porous media. Because the theory is nonlocal, we describe transport in a fibre suspension where the velocity and concentration fields change rapidly on the fibre's characteristic length. Such rapid changes occur in a rigidly bound domain because suspended particles are sterically excluded from configurations near the boundaries. A rigorous no-flux condition resulting from the presence of solid boundaries around the suspension is included in our nonlocal stress theory and naturally gives rise to concentration gradients that scale on the length of the particle. Brownian motion of the rigid fibres is included within the nonlocal stress through a Fokker–Planck description of the fibres’ probability density function where gradients of this function are proportional to Brownian forces and torques exerted on the suspended fibres. This governing Fokker–Planck probability density equation couples the fluid flow and the nonlocal stress resulting in a nonlinear set of integral-differential equations for fluid stress, fluid velocity and fibre probability density. Using the method of averaged equations (Hinch 1977) and slender-body theory (Batchelor 1970), the system of equations is solved for a dilute suspension of rigid fibres experiencing flow and strong Brownian motion while confined to a gap of the same order in size as the fibre's intrinsic length. The full solution of this problem, as the fluid in the gap undergoes either simple shear or pressure-driven flow, is solved self-consistently yielding average fluid velocity, shear and normal stress profiles within the gap as well as the probability density function for the fibres’ position and orientation. From these results we calculate concentration profiles, effective viscosities and slip velocities and compare them to experimental data.
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Dissertations / Theses on the topic "Fibre suspension"

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Hyensjö, Marko. "On fibre suspension flow modelling : mechanical fibre flocculation and fibre orientation /." Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-344.

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Kvick, Mathias. "Transitional and turbulent fibre suspension flows." Doctoral thesis, KTH, Strömningsfysik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-153018.

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In this thesis the orientation of macro-sized fibres in turbulent flows is studied, as well as the effect of nano-sized fibrils on hydrodynamic stability. The focus lies on enabling processes for new materials where cellulose is the main constituent. When fibres (or any elongated particles) are added to a fluid, the complexity of the flow-problem increases. The fluid flow will influence the rotation of the fibres, and therefore also effect the overall fibre orientation. Exactly how the fibres rotate depends to a large extent on the mean velocity gradient in the flow. In addition, when fibres are added to a suspending fluid, the total stress in the suspension will increase, resulting in an increased apparent viscosity. The increase in stress is related to the direction of deformation in relation to the orientation of the particle, i.e. whether the deformation happens along the long or short axis of the fibre. The increase in stress, which in most cases is not constant neither in time nor space, will in turn influence the flow. This thesis starts off with the orientation and spatial distribution of fibres in the turbulent flow down an inclined plate. By varying fibre and flow parameters it is discovered that the main parameter controlling the orientation distribution is the aspect ratio of the fibres, with only minor influences from the other parameters. Moreover, the fibres are found to agglomerate into streamwise streaks. A new method to quantify this agglomeration is developed, taking care of the problems that arise due to the low concentration in the experiments. It is found that streakiness, i.e. the tendency to agglomerate in streaks, varies with Reynolds number. Going from fibre orientation to flow dynamics of fibre suspensions, the influence of cellulose nanofibrils (CNF) on laminar/turbulent transition is investigated in three different setups, namely plane channel flow, curved-rotating channel flow, and the flow in a flow focusing device. This last flow case is selected since it is can be used for assembly of CNF based materials. In the plane channel flow, the addition of CNF delays the transition more than predicted from measured viscosities while in the curved-rotating channel the opposite effect is discovered. This is qualitatively confirmed by linear stability analyses. Moreover, a transient growth analysis in the plane channel reveals an increase in streamwise wavenumber with increasing concentration of CNF. In the flow focusing device, i.e. at the intersection of three inlets and one outlet, the transition is found to mainly depend on the Reynolds number of the side flow. Recirculation zones forming downstream of two sharp corners are hypothesised to be the cause of the transition. With that in mind, the two corners are given a larger radius in an attempt to stabilise the flow. However, if anything, the flow seems to become unstable at a smaller Reynolds number, indicating that the separation bubble is not the sole cause of the transition. The choice of fluid in the core flow is found to have no effect on the stability, neither when using fluids with different viscosities nor when a non-Newtonian CNF dispersion was used. Thus, Newtonian model fluids can be used when studying the flow dynamics in this type of device. As a proof of concept, a flow focusing device is used to produce a continuous film from CNF. The fibrils are believed to be aligned due to the extensional flow created in the setup, resulting in a transparent film, with an estimated thickness of 1 um.

QC 20141003

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Yan, Huawei. "Fibre suspension flocculation under simulated forming conditions." Doctoral thesis, KTH, Fibre and Polymer Technology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3794.

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A flow loop system for study of fibre flocculation insuspensions has been developed. The system is designed tosimulate the flow conditions in a paper machine headbox. It isequipped with a radial distributor feeding a step diffuser pipepackage, after which the flow is contracted in a 2-D nozzle.The flow system is also equipped with a secondary flowcontraction with an area reduction ratio of 2:1 after theheadbox nozzle, mimicking accelerations that may take placeduring forming. The flow system is equipped with heating andcooling devices for the study of temperature effects on fibresuspension flocculation. An online dosage device for the studyof chemical effects on fibre suspension flocculation is alsoincluded. The maximum flow velocity in the system is 16m/s.

Flowing fibre suspensions were studied using a high speedCCD video camera and transmitted infra-red laser light pulseillumination. Images were taken either separately before andafter or along the secondary contraction. Images of fibreflocculation were evaluated by power spectrum analysis, and themean floc size and the flocculation index were calculated. Aconcept of mean floc area reduction, based on power spectrum,has been introduced to characterise the fibre network insuspensions. By comparingthe fibre flocculation before andafter the secondary contraction, or by following the fibreflocs along the secondary contraction, floc rheologyinformation can be obtained. The effects of chemical additivesand fibre surface modification can also be studied by comparingthe corresponding fibre flocculation.

For a bleached softwood kraft pulp suspension at a fibreconcentration of 5 g/l, the fibre flocs along the secondarycontraction have been manually evaluated, and the resultsconfirm that the power spectrum analysis is applicable. Ca 1/5of the flocs were broken into two by the contraction. The meanfloc size increases in MD while in CD it decreases during theflow contraction. Both the floc aspect ratio and the flocorientation in MD increase during the flow contraction. The netfibre floc area is decreased and the fibre flocs areconcentrated by the flow contraction, which is confirmed by anincrease of gray value of the flocs in the light transmissionimages. The dewatering of fibre flocs may thus have alreadybeen started in the suspension before reaching the wires in theforming zone.

Some physical influences on fibre suspension flocculationhave been investigated. The results confirm that fibreconcentration and fibre length are the dominating factorsaffecting fibre suspension flocculation. Increasing absoluteflow velocity has an insignificant effect on fibre flocs in theflow contraction. Suppressing turbulence, by increasingsuspension viscosity via a decrease of medium temperature,shows a clear effect on reducing fibre suspensionflocculation.

Some chemical influences on fibre suspension flocculationhave also been investigated. A retention aid, flocculant,cationic polyacrylamide, C-PAM, increases fibre suspensionflocculation by a bridging mechanism, and a formation aid,class II, anionic polyacrylamide, A-PAM, decreases fibresuspension flocculation by suppressing turbulence. Fibresuspension flocculation can also be reduced by surfacemodification with carboxymethyl cellulose, due to a reductionof the friction between fibres. The amount of fibre dispersiondepends on the ionic form of the grafted CMC, due to theelectrostatic repulsion between negatively charged groups onthe grafted CMC moieties. Xyloglucan, a non-ionic polymer,which is strongly adsorbed on cellulosic fibre surfaces, showsa similar influence on reduction of fibre suspensionflocculation by decreasing the friction between fibres.

The fibre flocculation data in the flow loop system werealso compared with the corresponding paper formation data inthe sheets produced on a pilot paper machine, both with andwithout chemical additives. The results show that the fibresuspension flocculation is well correlated with the paper sheetformation: when the fibre suspension flocculation is increased,the corresponding paper sheet formation deteriorates,especially in the large scale range.

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Diatezua, Jacquie Kiangebeni. "Some theoretical aspects of fibre suspension flows." Master's thesis, University of Cape Town, 1999. http://hdl.handle.net/11427/9707.

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Bibliography: leaves 77-82.
This thesis is concerned with properties of equations governing fibre suspensions. Of particular interest is the extent to which solutions, and their properties, depend on the type of closure used. For this purpose two closure rules are investigated: the linear and the quadratic closures. We show that the equations are consistent with the second law of thermodynamics, or dissipation inequality, when the quadratic closure is used. When the linear closure is used, a sufficient condition for consistency is that the particle number Np satisfies Np ≤ 35/2. Likewise, flows are found to be monotonically stable for the quadratic closure, and for the linear closure with Np ≤ 35/2. The second part of the thesis is concerned with one-dimensional problems, and their solution by finite element. The hyperbolic nature of the evolution equation for the orientation tensor necessitates a modification of the standard Galerkin-based approach. We investigate the conditions under which convergence is obtained, for unidirectional flows, with the use of the Streamline Upwind (SU) method, and the Streamline upwind Petrov/Galerkin (SUPG) method.
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Joung, Clint Gwarngsoo. "Direct simulation studies of suspended particles and fibre-filled suspensions." Thesis, The University of Sydney, 2003. http://hdl.handle.net/2123/554.

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A new Direct Simulation fibre model was developed which allowed flexibility in the fibre during the simulation of fibre suspension flow.This new model was called the 'Chain-of-Spheres' model.It was hypothesised that particle shape and deformation could significantly affect particle dynamics,and also suspension bulk properties such as viscosity.Data collected from the simulation showed that flexible fibres in shear flow resulted in an order of 7 −10% bulk relative viscosity increase over the 'rigid' fibre result.Results also established the existence of a relationship between bulk viscosity and particle stiffness. In comparison with experimental results,other more conventional rigid fibre based methods appeared to underpredict relative viscosity.The flexible fibre method thus markedly improved the ability to estimate relative viscosity.The curved rigid fibre suspension also exhibited increased viscosity of the order twice that of the equivalent straight rigid fibre suspension.With such sensitivity to fibre shape,this result has some important implications for the quality of fibre inclusions used.For consistent viscosity,the shape quality of the fibres was shown to be important. The 'Chain of Spheres' simulation was substantially extended to create a new simulation method with the ability to model the dynamics of arbitrarily shaped particles in the Newtonian flow field.This new '3D Particle' simulation method accounted for the inertial force on the particles,and also allowed particles to be embedded in complex flow fields.This method was used to reproduce known dynamics for common particle shapes,and then to predict the unknown dynamics of various other particle shapes in shear flow. In later sections, the simulation demonstrated inertia-induced particle migration in the non-linear shear gradient Couette cylinder flow,and was used to predict the fibre orientation within a diverging channel flow.The performance of the method was verified against known experimental measurements,observations and theoretical and numerical results where available.The comparisons revealed that the current method reproduced single particle dynamics with great fidelity. The broad aim of this research was to better understand the microstructural dynamics within the fibre-filled suspension and from it,derive useful engineering information on the bulk flow of these fluids.This thesis represents a move forward to meet this broad aim.It is hoped that future researchers may benefit from the new approaches and algorithms developed here.
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Joung, Clint Gwarngsoo. "Direct simulation studies of suspended particles and fibre-filled suspensions." University of Sydney. Chemical Engineering, 2003. http://hdl.handle.net/2123/554.

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A new Direct Simulation fibre model was developed which allowed flexibility in the fibre during the simulation of fibre suspension flow.This new model was called the �Chain-of-Spheres �model.It was hypothesised that particle shape and deformation could signi ficantly a ffect partic e dynamics,and also suspension bulk properties such as viscosity.Data collected from the simulation showed that flexible fibres in shear flow resulted in an order of 7 −10% bulk relative viscosity increase over the �rigid �fibre result.Results also es- tablished the existence of a relationship between bulk viscosity and particle sti ffness.In comparison with experimental results,other more conventional rigid fibre based methods appeared to underpredict relative viscosity.The flexible fibre method thus markedly improved the ability to estimate relative viscosity.The curved rigid fibre suspension also exhibited increased viscosity of the order twice that of the equivalent straight rigid fibre suspension.With such sensitivity to fibre shape,this result has some important implications for the quality of fibre inclusions used.For consistent viscosity,the shape quality of the fibres was shown to be important. The �Chain of Spheres �simulation was substantially extended to create a new simulation method with the ability to model the dynamics of arbitrarily shaped particles in the Newtonian flow field.This new �3D Particle �simulation method accounted for the inertial force on the particles,and also allowed particles to be embedded in complex flow fields.This method was used to reproduce known dynamics for common particle shapes,and then to predict the unknown dynamics of various other particle shapes in shear flow. In later sections, the simulation demonstrated inertia-induced particle migration inthe non-linear shear gradient Couette cylinder flow,and was used to predict the fibre orientation within a diverging channel flow.The performance of the method was verified against known experimental measurements,observations and theoretical and numerical results where available.The comparisons revealed that the current method reproduced single particle dynamics with great fidelity. The broad aim of this research was to better understand the microstruc- tural dynamics within the fibre-filled suspension and from it,derive useful engineering information on the bulk flow of these fluids.This thesis represents a move forward to meet this broad aim.It is hoped that future researchers may bene fit from the new approaches and algorithms developed here.
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Lindström, Stefan B. "Simulations of the Dynamics of Fibre Suspension Flows." Licentiate thesis, Mid Sweden University, Department of Natural Sciences, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-53.

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A new model for simulating non-Brownian flexible fibres suspended in a Newtonian fluid has been developed. Special attention has been given to include realistic flow conditions found in the industrial papermaking process in the key features of the model; it is the intention of the author to employ the model in simulations of the forming section of the paper machine in future studies.

The model considers inert fibres of various shapes and finite stiffness, interacting with each other through normal, frictional and lubrication forces, and with the surrounding fluid medium through hydrodynamic forces. Fibre-fluid interactions in the non-creeping flow regime are taken into account, and the two-way coupling between the solids and the fluid phase is included by enforcing momentum conservation between phases. The incompressible three-dimensional Navier-Stokes equations are employed to model the motion of the fluid medium.

The validity of the model has been tested by comparing simulation results with experimental data from the literature. It was demonstrated that the model predicts the motion of isolated fibres in shear flow over a wide range of fibre flexibilities. It was also shown that the model predicts details of the orientation distribution of multiple straight, rigid fibres in a sheared suspension. Model predictions of the viscosity and first normal stress difference were in good agreement with experimental data found in the literature. Since the model is based solely on first-principles physics, quantitative predictions could be made without any parameter fitting.


En ny modell för simulering av rörelserna hos icke-Brownska böjliga fibrer dispergerade i en Newtonsk vätska har utvecklats. Eftersom det är författarens avsikt att modellen skall kunna tillämpas vid simulering av arkformning under de förhållanden som råder i en modern pappersmaskin, har särskilt omsorg givits till att inkludera motsvarande flödesvillkor i modellens giltighetsområde.

Modellen hanterar fibrer av varierande form, massa och styvhet, som växelverkar sinsemellan via normal-, friktions- och smörjkrafter. Deras växelverkan med den omgivande vätskan sker via hydrodynamiska krafter vid finita Reynolds-tal. Den så kallade tvåvägskopplingen mellan fibrerna och vätskefasen har tagits i beaktande genom att kräva att rörelsemängden bevaras vid interaktionen mellan faserna. Vidare har Navier-Stokes ekvationer för inkompressibla vätskor använts för att beskriva mediets rörelser.

Modellens giltighet har undersökts genom att jämföra resultat från simuleringar med experimentella data från litteraturen. Det har påvisats att modellen förutsäger rörelsen hos ensamma fibrer i ett skjuvflöde, för vitt skilda fiberflexibiliteter. Det visades också att modellen förutsäger detaljer hos fiberorienteringsdistributionen i suspensioner utsatta för skjuvflöde. Det kunde också konstateras att modellens förutsägelser av fibersuspensioners viskositet och första normalspänningsdifferens under skjuvning väl överensstämde med experimentella data i litteraturen. Kvantitativa förutsägelser har kunnat göras utan någon parameteranpassning, då modellen bygger uteslutande på väletablerade fysikaliska samband inom klassisk mekanik och strömningslära.

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Kvick, Mathias. "Hydrodynamic stability and turbulence in fibre suspension flows." Licentiate thesis, KTH, Mekanik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-95279.

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Raghem-Moayed, Amir. "Characterization of fibre suspension flows at papermaking consistencies." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq41040.pdf.

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Holm, Richard. "Fluid mechanics of fibre suspension related to paper making." Doctoral thesis, KTH, Mechanics, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-100.

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This thesis deals with fluid dynamic mechanisms related to papermaking, specif- ically: the initial dewatering mechanisms during roll-forming and fibre motion in sedimentation and in shear flow.

Pressure and wire position measurements have been conducted in a model resembling the forming zone and the measured pressure distributions are shown to have more complex patterns than the simple model p / T/R (where T is the wire tension and R is the roll radius). It is shown that an increase in wire tension has a similar effect as a decrease in flow-rate on the shape of the pressure distribution. In addition, it is shown that the drainage has a stabilizing effect on the dewatering pressure.

The flow around the forming roll has also been modelled with the assump- tion that the wire is impermeable. A non-linear equation for the position of the wire is derived that clearly shows that the Weber number, We, is an im- portant parameter. The equation is linearized around the trivial solution and has a standing wave solution with a specific wavelength that scales with the We-number.

Motion of non-Brownian fibre settling in a Newtonian fluid at a small but finite Reynolds number has been studied experimentally. Two different regimes of sedimentation were identified. For dilute suspensions, fibres gener- ally fall without flipping and may travel at velocities larger than that of an isolated particle. In the semi-dilute regime we found the settling process to be dominated by large-scale fluctuations. The velocity fluctuations scale with the suspension volume concentrationφ according toφ1/3, which is similar to the findings for settling spheres.

The influence of shear on fibre orientation in the near wall region was studied in cellulose acetate fibre suspensions. At low concentration and low aspect ratio fibres were observed to orient perpendicular to the streamwise direction (named rollers) in the near wall region whereas the orientation further into the suspension was unchanged. As the concentration and aspect ratio increased the fraction of rollers decreased.

Finally, an evaluation of a commercial Ultra Velocity Profiler unit in fibre suspensions are presented. The idea was to determine the velocity and characterise the turbulence from ultra sound echoes from particles in the fluid. However, the spatial and/or temporal resolution of the measurements did not permit turbulence characterisation. These limitations might be possible to overcome and some procedures are proposed and evaluated.

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Books on the topic "Fibre suspension"

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Luo, Chitao. The investigation of turbulent statistics of a fibre suspension undergoing mixing. Ottawa: National Library of Canada, 1999.

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Plikas, Atanasis. Numerical modeling of fibre suspensions in grid-generated turbulent flow. Ottawa: National Library of Canada, 2000.

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Hartley, James Joseph. The effects of electrical strength training on the contractile function and fiber morphometry of skeletal muscle during hindlimb suspension. Ottawa: National Library of Canada = Bibliothèque nationale du Canada, 1993.

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Raghem-Moayed, Amir. Characterization of fibre suspension flows at papermaking consistencies. 1999.

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Segal, Jane. Rheological properties of fibre suspensions. 2005.

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Book chapters on the topic "Fibre suspension"

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Boger, D. V., D. U. Hur, and C. J. S. Petrie. "The Rheology of Fibre Suspensions." In Third European Rheology Conference and Golden Jubilee Meeting of the British Society of Rheology, 4–5. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-0781-2_4.

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Lohmann, Christoph. "Simulation of fiber suspensions." In Physics-Compatible Finite Element Methods for Scalar and Tensorial Advection Problems, 211–61. Wiesbaden: Springer Fachmedien Wiesbaden, 2019. http://dx.doi.org/10.1007/978-3-658-27737-6_6.

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Tucker III, Charles L. "Suspension Rheology and Flow-Orientation Coupling." In Fundamentals of Fiber Orientation, 173–204. München: Carl Hanser Verlag GmbH & Co. KG, 2022. http://dx.doi.org/10.3139/9781569908761.006.

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Zhao, L. H., H. I. Andersson, J. J. J. Gillissen, and B. J. Boersma. "Simulating Fibre Suspensions: Lagrangian versus Statistical Approach." In Springer Proceedings in Physics, 347–50. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-03085-7_84.

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Laigaard-Jensen, J., Harikrishna Narasimhan, and Jakob Mouritsen. "Fire protection of suspension bridge cables." In Bridge Safety, Maintenance, Management, Life-Cycle, Resilience and Sustainability, 1939–46. London: CRC Press, 2022. http://dx.doi.org/10.1201/9781003322641-240.

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Eberle, Aaron P. R., Kevin Ortman, and Donald G. Baird. "Structure and Rheology of Fiber Suspensions." In Applied Polymer Rheology, 113–51. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2011. http://dx.doi.org/10.1002/9781118140611.ch4.

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Blanc, R. "Order and Disorder in Fiber Suspensions." In Mobile Particulate Systems, 105–28. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-015-8518-7_9.

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Strautins, Uldis. "Fiber Suspension Flows: Simulations and Existence Results." In Mathematics in Industry, 1081–85. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-23413-7_150.

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Gyr, A., and H. W. Bewersdorff. "Drag Reduction in Fibre- and Non-Fibrous Suspensions." In Drag Reduction of Turbulent Flows by Additives, 175–90. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-017-1295-8_7.

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Strautins, Uldis. "On Stability of a Concentrated Fiber Suspension Flow." In Mathematics in Industry, 127–33. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-05365-3_17.

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Conference papers on the topic "Fibre suspension"

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AbuYousef, Imad A., James A. Olson, D. Mark Martinez, and Sheldon Green. "Pumping Performance Increase Through the Addition of Turbulent Drag-Reducing Polymers to Pulp Fibre Suspensions." In ASME 2010 International Mechanical Engineering Congress and Exposition. ASMEDC, 2010. http://dx.doi.org/10.1115/imece2010-37697.

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The addition of a small amount of long chain polymers to a turbulent fluid is known to reduce the wall shear stress and drag. Similarly, the addition of pulp fibres to a turbulent suspension is also turbulent-drag reducing despite pulp fibres having a length scale that is 1000 times larger than polymer molecules. The mechanism of drag reduction and its impact on centrifugal pump performance is poorly understood, especially when there is a combination of polymer and fibres in suspension. Centrifugal (slurry) pump performance was measured as a function of pulp fibre and PAM polymer concentration. Both the pump best efficiency and maximum head rise were greater when pumping modest concentrations of polymer solutions and low consistency pulp fibre than pure water. We measured an efficiency increase of 22 percent and a maximum head increase of 4.3 percent with the addition of 150 ppm PAM polymer relative to pure water. We measured an increase of 8 percent and 2.3 percent in pump efficiency and maximum head coefficient, respectively, with 2 percent pulp fibres over that of water alone. With both 1 percent consistency pulp fibres and 100 ppm of PAM polymers, we measured a 12 percent increase in efficiency over that of pulp suspension alone. With both 2 percent consistency pulp fibres and 100 ppm of PAM polymers, we measured an 8 percent increase in efficiency over that of pulp fibre suspension alone. The reasons for the increased pump efficiency with addition of additives is not known but are thought to be due to the turbulent-drag-reducing properties associated with flow of these suspensions.
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Gillissen, Jurriaan J. J., Bendiks Jan Boersma, Geert Brethouwer, Pal H. Mortensen, and Helge I. Andersson. "DIRECT NUMERICAL SIMULATION OF TURBULENT FIBRE SUSPENSION SHEAR FLOW." In Fifth International Symposium on Turbulence and Shear Flow Phenomena. Connecticut: Begellhouse, 2007. http://dx.doi.org/10.1615/tsfp5.2070.

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Carlsson, A., F. Lundell, and L. D. So¨derberg. "Fibre Orientation Control Related to Papermaking." In ASME 2006 2nd Joint U.S.-European Fluids Engineering Summer Meeting Collocated With the 14th International Conference on Nuclear Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/fedsm2006-98408.

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The wall effect on the orientation of fibres suspended in a shear flow has been studied experimentally. A fibre suspension, driven by gravity down an inclined glass plate, constitutes the shear flow field. A CCD-camera was mounted underneath the flow in order to visualize the flow. The orientation of fibres in the plane perpendicular to the plate was determined, by using the concept of steerable filters. In a region close to the smooth plate surface the fibres oriented themselves perpendicular to the flow direction. This did not occur when the surface structure was modified with ridges.
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Wu Hao, Yu Zhong Chen, and Wang Song. "Acrylic fibre wastewater treatment in a nested biofilm airlift suspension reactor." In 2011 International Symposium on Water Resource and Environmental Protection (ISWREP). IEEE, 2011. http://dx.doi.org/10.1109/iswrep.2011.5893226.

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Messana, Alessandro, Lorenzo Sisca, Alessandro Ferraris, Andrea Giancarlo Airale, and Massimiliana Carello. "Lightweight Design of a Multi-Material Suspension Lower Control Arm." In ASME 2020 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/detc2020-22323.

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Abstract This paper is focused on the design, analysis and testing of a multi-material (carbon fibre and steel) Lower Control Arm (LCA) of a McPherson suspension for a C segment vehicle. Therefore, starting from the existing component (made of steel), the LCA mass has been reduced by using a hybrid technology, diminishing the steel thickness and adding a carbon fiber tailored cover without compromising the mechanical performance in terms of stiffness and stress distribution. In so doing, it has been possible to evaluate the potential and the capabilities of the hybridization without re-designing the component totally. In particular, it has been developed a specific methodology that combines both virtual and experimental procedures to face the hybridization challenges of mechanical coupling, safety and lightweight. For these reasons, the multi-material lower control arm represents a noticeable case study in which this methodology has been applied, correlated and validated.
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Wang, Xiang, Rinze Benedictus, and Roger M. Groves. "Light scattering and rheological effects in an optical fibre coupled nanoparticle suspension." In Optical Sensing and Detection VI, edited by Francis Berghmans and Anna G. Mignani. SPIE, 2020. http://dx.doi.org/10.1117/12.2556799.

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Zhang, F. H., P. J. Scully, and E. Lewis. "An optical fibre yeast concentration sensor based on inter-fibre distributed coupling." In The European Conference on Lasers and Electro-Optics. Washington, D.C.: Optica Publishing Group, 1994. http://dx.doi.org/10.1364/cleo_europe.1994.cthi42.

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A novel fibre optic sensor has been developed, which is capable of accurately measuring yeast concentrations in suspension over a range of 0 to 16 g/1. To date a solution for on-line measurement of suspended particulate masses such as yeast has proved difficult and expensive for many industrial users. The sensor reported in this paper relies upon light being radiated through the cladding of one fibre and detected at the end of an adjacent receiving fibre (Fig. 1). Some light is coupled with no yeast present, but the received intensity grows as yeast concentration increases and more light is scattered into the receiving fibre (Fig. 1). The process of scattering is well understood for controlled laboratory conditions where small spherical particles of predetermined diameters have been employed.1,2
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Esan, Ayomikun, Trulani Van Der Heyde, Cushla McGoverin, Simon Swift, and Frédérique Vanholsbeeck. "A single channel microfluidic device with integrated optical fibre for large volume detection and enumeration of bacterial cells." In Frontiers in Optics. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/fio.2022.jtu4a.50.

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We present a novel microfluidic and optical system for the rapid detection and enumeration of bacteria cells. Our system uses a single microchannel with an integrated optical fibre to achieve large volume excitation and detection of bacteria cells in low concentration suspension.
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Wagner, David, Daniel Mainz, Thomas Gerhards, and Xiaoming Chen. "Carbon Fiber Composite Chassis Components, Opportunities and Challenges." In FISITA World Congress 2021. FISITA, 2021. http://dx.doi.org/10.46720/f2020-mml-059.

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Using lightweight components to reduce vehicle mass is one of the tactics available to vehicle manufacturers to reduce CO2 emissions. Carbon fibre reinforced polymer composite with its high strength to density ratio is one of the potential materials to reduce component mass. The lessons learned from three research and development projects on automotive chassis structural components designed, manufactured and tested using carbon fibre composites provides insights into the opportunities for mass reduction and the cost, manufacturing and analysis challenges that combine to limit the applicability of carbon fibre composites in high volume automotive use. Projects investigated three structural cassis components, the Focus rear suspension tie blade knuckle, the F-150 front suspension lower control arm, and the Fusion (Mondeo) front subframe. All the projects developed, analysed, manufactured and tested carbon fibre composite replacement components that fit the package and met equivalent performance requirements to the production parts. Then the designs and manufacturing plans informed the cost estimates for these components at high automotive volumes. The tie blade knuckle chose thermoplastic resin while the front lower control arm and subframe investigated thermoset resin carbon fibre composites. Carbon fibre reinforced polymer composites offer the opportunity of approximately a 30% mass reduction compared to a steel component. This mass savings is less than anticipated. Due to the high constituent material costs of both the carbon fibre and the high performance resin, the complex manufacturing processes, and the final assembly processes the resultant "weight buy" exceeds an additional $35 USD of variable cost per kilogram of mass saved compared to the production steel component. All three of the components investigated require multi material solutions that include both random chopped and oriented continuous carbon fibre composites plus steel reinforcements at high point load areas such as the bolted connections. Also, the predictive CAE tools are not yet fully mature for carbon fibre composites leading to lower confidence initial designs.
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CASSIN, G., I. APPELQVIST, and I. T. NORTON. "THE RHEOLOGY OF FIBRE SUSPENSION — A POTENTIAL MECHANISM OF MICROSTRUCTURE CHANGES INDUCED BY STRESS CONTROLLED EXPERIMENTS." In Proceedings of the Fifth Royal Society–Unilever Indo-UK Forum in Materials Science and Engineering. A CO-PUBLICATION OF IMPERIAL COLLEGE PRESS AND THE ROYAL SOCIETY, 2000. http://dx.doi.org/10.1142/9781848160163_0016.

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