ajay paper ijstm 021211

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ISSN: 2229-6646 IJSTM, Vol. 2 Issue 4, December 2011www.ijstm.com

International Journal of Science Technology & Management Page 8

Saturation of Fiber Tow and related issues in Vacuum Assisted Resin

Transfer Molding (VARTM) Process.

Ajay Kumar, Mechanical Engineering Department, University of Petroleum and Energy Studies,

Dehradun,[email protected]

Mukul Shukla, Mechanical Engineering Department, MNNIT, Allahabad; and Department of

Mechanical Engineering Technology, University of Johannesburg, Johannesburg, South Africa,

[email protected];[email protected]

Abstract

There has been substantial growth in the technology of composite manufacturing using the LCM method.

The RTM process was robust but was a costly affair for long composites parts due to the two sided mold

requirement and also due to the number of fixture required in a RTM process. VARTM or some time also

called as VI (Vacuum Infusion) is a cheap and a viable option for the big size composite parts .Vacuum

infusion has improved over the last decade due to the focus and ease in operation and its ability to

produce long composite parts. This has achieved a good attention of the scientist in the last decade andcontinues to receive the attention of the world. There are several variants of this process and most of

them operate at a compaction pressure of 1 bar. There are several research groups which are involved in

the advancement of this method of composite manufacturing. Some codes are now available for the

simulation of the process, and some amount of automation has also been applied in this method. As in VI

process one sided moulds are used and the other side covered with a plastic bag is always exposed to the

atmospheric pressure, there is no solid control on the face exposed, this increases the chances of

thickness variation along the length of the infusion. In the absence of proper infusion there is possibility

of improper saturation leading to the dry spot formation making the composite weak at the point of dry

spot. The strength of the composite manufactured by VI depends a lot on the proper design of the

injection point and vents, and online control so that the preform is completely saturated with the resin

before it cures. This paper investigates the evolution of this method of composite manufacturing, with the

focus on the key issue of saturation of fiber in the Vacuum infusion process.

Keywords: VARTM, Tow Saturation

____________________________________________________________________________

1. IntroductionComposites are fibrous materials infused

with a tough and durable plastic. Compositematerial is a technology that is being used to

make many items in today's world stronger

and lighter. These are starting to be

incorporated in armours of combat vehiclesand soldiers. When these panels are made in

the most economical way, they are inferior

to those that take much more time andmoney to construct. Developing a method

that is fast and reliable and is critical. A

controlled infusion setup must be designed

to get optimized infusion. The experimental

set and process which infusion isaccomplished is called Vacuum assisted

resin transfer molding (VARTM).In this

process a vacuum pulls resin in form of a

feed tube to distribute it evenly into the

preform. There are different steps that mustbe followed to in order to run a VARTM

process. A selection of material that will be

infused must be acquired.

Vacuum Assisted Resin Transfer Molding

(VARTM) has a potential advantage of

relatively low cost with sufficiently high
mailto:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]


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volume fractions of reinforcement and the

process can be readily applied to large-scale

structures like aircraft and marine structures.Essentially, VARTM is an infusion process

where vacuum draws the resin into a one-

sided mold. A flexible plastic bag material isplaced over the top to form a vacuum-tight

seal. However, for many aircraft

applications, VARTM does not currentlyprovide sufficient repeatability or control of

variability. This unpredictable variability is

commonly observed when processing with

the traditional VARTM process. In order toproduce VARTM parts of aircraft quality on

industrial basis, the variability must be

understood, which is possible through

modeling and computer simulation of theprocess.

2. Brief Details of the Process and the

important considerations in VARTM

In the VARTM process, the typical lay-up

sequence on the rigid mould (made of either

glass, metal or composite) comprises: (i) anon porous release film, (ii) a peel ply, (iii)

fabric (reinforcement) (iv) a peel ply, (v) aporous release film, (vi) flow distributionmedium (to enhance the flow on top), (vii)

non-porous release film, (viii) Caul plate

and (ix) breather cloth are placed in thatsequence. Finally, the edges are sealed using

modeling clay and the whole lay-up is

bagged using a vacuum bag film to a create

vacuum. The schematic of VARTM mouldset up is shown in Fig. 1. For purposes of

simulation however, the components to be

modeled would only be the fiberreinforcement, the flow distribution mediumand the resin. The other components do notaffect the process in any substantial way and

hence need not be modeled.

Fig.1. Schematic of VARTM mould set up.

3. Working Principle

In a typical wetting of fabric through

VARTM process, there are two macroscopicflow fronts. The top and bottom flow fronts.

The distribution flow medium which is

placed on top of the fabric will enhance the

resin flow and hence the top surface will getwet faster, whereas wetting of bottom

surface takes more time since the resin has

to flow through the thickness of the fabric,The through the thickness movement of the

resin is mainly governed by the through-

thickness permeability and the pressuregradient. The through-thickness

permeability is one or two orders of

magnitude higher than the in-plane

permeability. As there will be a large

difference in the top and bottom surfacewetting time, there is a flow front profile

across the thickness. That is, top flow frontwill always be ahead of the bottom flow

front. Thus one could make a conclusion

that if the bottom flow front reaches end ofthe mold, then the part is fully wet (although

this is not always true, especially for

complex geometries). In this way the bottom

flow front data is very important in order to

estimate the time to complete the infusion.

4.Issues in VARTM

Most variant process of VARTM has been

aimed at reducing the fill time of resin

infusion through the preform during this

process. SCRIMP is the most commonvariant of VARTM process being used in

the industrial composite production. In the

Vacuum bag

Resin

Distribution mediumFabric

Vacuum

pump

Mold surfaceBottom release film

Top release film

Sealant tape


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SCRIMP one key additional material is used

to the layup. Highly permeable netting

called as distribution media (DM) is placedon the top of the reinforcement layers to

allow an easy path for the resin to move and

cover the entire mould. Fig.2.Thepermeability of the DM is sometimes

hundred times the permeability of the

reinforcement, once the resin spreadsentirely along the distribution media the

resin needs to only infuse through the

thickness of the preform, thereby drastically

reducing the fill time

Fig.2. Schematic of a SCRIMP Process, it is same as VARTM ifDM is removed

Tow saturation and fill permeability are the

issues which need to be tackled in thedifferent variants of VARTM. Many models

are developed to predict the tow saturation

and the flow front of an infusion process but

they fail to exactly predict these due to some

inherent disadvantages of the VARTMprocess, the following need to be mentioned

in this context.

a) The infusion process used to forcethe resin into the mold is limited toatmospheric pressure.

b) The above aspect combined with thelow permeability of the typical fabricresults in an inability to completely

fill the part before the resin starts to

gel.c) The automation of a VARTM

process is difficult as its one side is a

solid mold cavity and the other side

is a flexible plastic bag, so theVARTM process which is used for

large size parts but for a low volume

production. And due to this fact the

infusion process is not repeatable

from one part to the next as the resin

may not completely wet the fabricdue to inherent variation in the

woven materials or due to the slight

misalignment in the fabric lay-upprocess.

d) If the saturation of the fiber is notcomplete the composite structureswhich have resin starved regions and

are discarded as the scrap, which

some time increases the production

cost.

Tow saturation being the last to beaccomplished in the VARTM process,

but the most important in deciding thestrength aspect of a composite as it is the

prominent reason for dry spot formationin the composites. The flow front of the

resin in most of the infusion process is

not the real indicator of the towsaturation behind it and it is found by

many researchers that the flow front

already reaching the vent and the region

behind that not was being completelysaturated. The permeability of the tow in

the comparison to the permeability of thefabric is too low some time of the orderof 13-14 times less and therefore the

time required for the saturation is more.

Some of the researchers give specialallowance for the permeability of the

tow and then simulate the results. And

with this new permeability the results

found for the tow saturation is in goodagreement of the actual fill time and

infusion process. LIMS developed by the

University of Delaware takes this feature

into account and the simulation resultsare found to be in good agreement of the

real infusion process. This feature of

defining the permeability of the tow i.e.locally in LIMS is a great help in

simulation but this cannot be done until

the permeability data for a particular


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fabric is available before the simulation,

so the tow permeability of a particular

fabric is a very important requirement

for any simulation to be realistic.

5. Phenomenon of tow saturation andthe issues.

Usually, Darcys law has been used todescribe the physics of flow through a

fabric considered as a porous medium

Where v is the volume-averaged

velocity, the pressure gradient, theviscosity and K the permeability tensor

of the porous medium. Although it is

valid when modeling flow in a singlescale porous medium, it is no longer

valid when applied to a dual scaleporous medium [1]. In a dual scale

porous medium, the difference in length

scale between micropores (pores inside afiber tow) and macro-pores (pores

between fiber tows) are usually 2 or 3orders of magnitude.

It has been known that tows aremainly impregnated transversally [2]

owing to the sequence of layers in thefabric and the global flow front position

matches the macropores flow front. Thedirect result of this delayed impregnation

is the presence of air bubbles within the

fabric when resin starts exiting the mold.Different indirect experimental

observations proved the existence of the

unsaturation phenomenon. Themicrovoids formation processes has been

studied [35] and this is the most critical

consequence of unsaturation since voidscan dramatically reduce mechanicalproperties of composites. As bubbles

may be evacuated from the mold before

resin cures, microvoids content cannotbe directly linked to an unsaturation

degree. Hayward and Harris [6] gave the

evidence that applying a vacuum at the

vent reduces microvoids content, the

intensity of transmitted light decreasing

with microvoids content and as such,with unsaturation. Jillian et al. [7]

studied analytically and numerically the

formation of microvoids in multilayerwoven fabrics. The model predicts the

presence of voids in warp tows and size

of voids is found to be function of theratio between tow axial and transverse

permeability. Flow within a woven or

stitched fabric is driven both by viscous

forces on the macroscale and capillaryforces on the microscale and the

formation of micro- or macro-voids is

the result of the competition between

these two phenomena. Lee et al. [811]carried out some experimental work to

investigate the process of void

formation.Investigating the impregnation of

unidirectional stitched fiber mat, a

processing window corresponding to aminimal void content was obtained for

flow along fiber tows while it was not

for flow normal to fiber tows. According

to these results, at a given flow rate,

three different populations of voids maybe observed. (a) Only macrovoids.(b).No

voids (processing window).(c) Onlymicrovoids. B. Gourichon et.al.

Through these experiments for different

flow rates for automotive part compositemanufacturing found that there are three

zones in which the capillary and viscous

forces are acting simultaneously acting

with the dominance shifting from one tothe other in the different zones. The

nature of the void formation depends onthe typical dominating force.(a) capillary

force dominating region are witnessedwith the microvoid formation (b) viscous

force dominating region are witnessed

with the microvoids formation (c) theregion of completion between the

capillary and the viscous forces gives


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rise to an equivalent force which gives

rise to minimum void content region .it

also highlighted that the flow rate ofinjection does not have any influential

bearing on the saturation of the preform

and the saturation is more closely relatedto the void formation and void

mobilization. Although all the above

varies from one preform fabric to theother and the exact prediction of void

formation and tow saturation is not

possible but a general important

observation is that the wholeunsaturation grows linearly with time for

1D flow.

6. Threshold pressure of infiltrationinto fibrous preforms normal to the

fibers axes

Interfacial phenomena at the

fiber/liquid/gas interface play a key role

in the infiltration process. The interplaybetween the surface tension of the

infiltrating liquid, the wetability of the

fibers by this liquid and the

morphological details of the preform

influence the value of the thresholdpressure of infiltration. The value of the

threshold pressure is generally higherand therefore, it is more important for

producing (metal matrix composites)

compared to PMCs, (Polymer matrixcomposites) due to higher surface

tension of liquid metals and their higher

contact angle compared to molten

polymers. Nevertheless, theimprovement of the microstructure and

physical properties of both types ofcomposites is possible only through the

better understanding of all the processesand their governing equations during the

production of fiber reinforced composite

materials. The importance of thisquestion for PMCs is demonstrated by

the need of surface treatment of fibers

[29, 30] and by the necessity to measure

the adhesion between the fibers and the

matrix [3133].The threshold pressure needed to

infiltrate the liquid through the small

space between parallel fibers in normaldirection to their axes is given by Kaptay

[13].

6.1 Existing equations for capillary

pressure

According to the classical Young

Laplace equation, the capillary pressurein a straight, cylindrical capillary of

radius r can be written as

Pc =

(1)Where is the surface tension of

the infiltrating liquid (J/m2 = N/m), the contact angle of the infiltrating liquid

on the inner wall of the capillaries, or

generally on the solid surface of thepreform.

The capillary pressure is a

spontaneous pressure, arisingperpendicular to the solid/liquid/gas

three-phase line and pulling the liquid

into the capillary (Pc > 0) or pushing itout of the capillary (Pc < 0). To thecontrary, the threshold pressure is the

minimum pressure required to start

infiltration, provided that venting of thegas from the preform takes place without

problems (no trapped bubbles) and

friction losses and also gravity effectsare neglected. By definition, the

threshold pressure equals the negative of

the capillary pressure: Pth = - Pc.

In geometries other than cylindricalcapillaries Eq. (1) can be used, if r is

treated as the effective radius.Although the effective radius is quite ill-

defined in porous solids of randommorphologies, sometimes it is used for

simplicity [34, 35]. For absolutely non-

wetting liquids ( = 180), infiltrating


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normal to the axes of the fibers, Clyne et

al. [21] used Eq. (1) with r, taken as the

half of inter-fibre spacing.Considering the infiltration of a

perfectly wetting liquid ( = 0) into a

porous solid, the following expressionfor the capillary pressure was obtained

by Carman [36]:

Pc,o = S. (2)Where, S is the specific surface area

of the initial preform (1/m), i.e. the ratio

of the solid/gas interface to the volume

of the pores within the preform, before

infiltration.Independently of Eq. (2), Eq. (3) was

obtained on pure thermodynamic basis,supposing that the original solid/gasinterface is fully replaced by the

solid/liquid interface during infiltration,

independent of the contact angle [37,38]:

Pc = S. (3)It can seen that in the case of perfect

wetability ( = 0) Eq. (3) simplifies backto Eq. (2), and thus Eq. (3) can be

considered as an extension of Eq. (2).

One can also see that Eq. (3) becomesidentical to Eq. (1), if the effective

radius of the pores is taken equal to: r =S-1. Nevertheless, it should be mentioned

that the basic assumption behind Eq. (3)

is not valid. In fact the original solid/gasinterface is not fully replaced by the

solid/liquid interface during infiltration,

especially for non-wetting liquids and

difficult inner morphologies of poroussolid preforms [39]

If the preform is made of cylindricalfibers of equal diameters D (m) and with

a fiber volume fraction of Vf (Vf is adimensionless number, 0 < Vf < 1), its

specific surface area can be easily

expressed as (if the ends of the fibers areneglected): S = 4Vf /D(1 -Vf).

Substituting this equation into Eq. (3)

and taking into account Pth = - Pc, the

following final equation is obtained:

Pth = -

(4)

The threshold pressure in accordance toEq. (4) is independent of fiber

orientation and distribution [38]. It is

found that an infinitely high pressurewould be needed to achieve full

infiltration in this case [38]. Actually

this conclusion also follows from Eq.

(4), as locally Vf 1 is taking place,and hence Pth .

Eq. (4) is widespread in PMC[17,18,4446] literature However, there

are at least two problems with its usage.1. The first problem is connected withthe value of the threshold contact angle

(th), defined as the contact angle, below

which spontaneous infiltration starts.According to Eq. (4), th = 90, as at any

< 90: Pth < 0, i.e. the infiltration takesplace spontaneously, without any outsidepressure. This is indeed the case, when

the preform is infiltrated parallel with

the fibers. However, when the

infiltration takes place in normaldirection to the axes of the fibers, the

threshold contact angle is usually lower

than 90. As was shown independently

by Bayramli and Powell [47] and laterby Yang and Xi [48], the threshold

contact angle in this case depends on

fiber arrangement and on the volumefraction of the fibers and is generally

lower than 45, what is in contradiction

to Eq. (4). It was also shown [39]

recently that in most cases the thresholdcontact angle is below 90, and thus Eq.

(4) should be modified. Unsuccessful

infiltration of a liquid into a fibrouspreform with a contact angle ranging

between 60 and 80 was experimentally

demonstrated in [49], serving as an


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experimental confirmation of the ideas,

developed in [39,47,48]

2. The second problem with Eq. (4) isthat it is derived from the average value

of the specific surface area (S). It means

that infiltration is ensured only into thepores with average openings, and thus

into the largest volume segments inside

the preform. At the first sight it issufficient, as it ensures a high filling

ratio of the free space in the composite.

However, this will not ensure the

infiltration into smaller spaces betweenthe fibers see appropriate photographs

in papers [38, 5052] and measured

values [53]. It is, however, not entirely

clear, whether the empty spaces recordedbetween the fibers are due to non-

infiltration, or to the appearance of the

solidification shrinkage. Whatever is thereason these small empty spaces appear

to be the weakest points of the

composites.A more advanced equation for the

capillary pressure was derived by

Bayramli and Powell [47] (see also [54,

55]). The capillary pressure was

described as function of the directionalbody angle (gradually changing while

the liquid infiltrates between the fibers ina normal direction to their axes).

However, the final equation for the

threshold pressure was not given in [47]A more detailed analysis was carried out

by G. Kaptay [13] for the threshold

pressure for the case when the direction

of infiltration is normal to fibers axeswhich in most of the infiltration case the

common direction of infiltration. At thispoint it should be noted that Eq. (4) is

valid for the case when the direction of

infiltration is parallel to fibers axes.

7. Influence of dynamic capillary on

the permeability of the preform

In the LCM process, resin impregnation

is highly dependent on the permeability

of fibrous reinforcement. As animportant material parameter,

permeability represents the degree of

difficulty for a fluid to penetrate aporous medium, determined by the

geometry of the fibrous preform, which

can be predicted according to empiricalequations, such as CarmanKozeny

equation [57], Gebart model [58] and

Westhuizen model [59]. However,

discrepancies are always observedbetween data from models and typical

experiments [60], which are believed to

be caused by neglecting the effect of

microscopic flow on the interpretation ofthe macroscopic impregnation. It has

been known that complicated preform

structure induces a dual-scale flowbehavior: microscopic flow and

macroscopic flow [61-65]. A direct

result from this flow competition isentrapment of voids within the fabric

[66], especially micro voids formed due

to the microscopic capillary effects and

low permeability of the fiber tows [67].

Because of the importance of capillaryflow in LCM process, a number of

studies have paid close attention to theevaluation of capillary pressuresMin li et al. carried out the test on the

influence of the dynamic capillarity onthe fiber preform in the vacuum infusion

and found that

i. Dynamic capillary pressures varydepending on the velocity ofpenetration, totally different from

the thermodynamic capillarypressure estimated by Young

equation. As infiltration goingon, the interfacial effect

gradually becomes stronger in

competition with the viscouseffect, and the dynamic capillary


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pressure closely related to the

capillary number.

ii. Negative capillary pressuresdefinitely present the dynamic

synergistic effect of interfacial

force on velocity of vacuumdriving penetration in

unidirectional fiber bundles,

where viscous and interfacialforces are the dominant flow

regime.

iii. The new equations obtained bythe different researchers aretheoretical hexagonal models and

there are certain assumptions in

those models. In reality, the

following modifications shouldbe taken into account apart from

the considerations of the

orientation of the fiber in thepreform and the (parallel or

normal to the flow of the resin in

the mould):iv. (a) The fibers are not straight, (b)

The fibers are not perfectly

cylindrical, (c) The fibers have

not identical diameters, (d) The

fibers have some roughness, (e)The fibers are not packed

regularly, (f)it is not a particularvalue, rather a distribution of

fiber distances.

8. Conclusion1. Number of variable to be controlled

for having a thoroughly saturated

infusion is many due to the presence

of bagging and the rigid mould ononly one side of the preform.

2. The complete saturation of thepreform before gelation time is not asimple issue, and to tackle the issueof improper saturation the science of

the flow has to be better understood.

3. The capillary pressure initiallyneglected in the modeling of the

infusion is an important

consideration and especially in

vacuum infusion.

4. As per the Min li et.al. In the 70%fiber fraction experiment of vacuum

driving penetration, the data of -1.7

kPa indicates almost negligibleinfluence of capillary pressure. This

phenomenon gives a hint on the

consideration of critical factorswhich determines the drag or

promotive effect of capillary force

acting on the velocity of penetration

flow in liquid composite moldingunder the assistance of vacuum.

5. It can be concluded that negativecapillary pressures definitely present

the dynamic synergistic effect ofinterfacial force on velocity of

vacuum driving penetration in

unidirectional fiber bundles, whereviscous and interfacial forces are the

dominant flow regime.

6. The calculated Kozeny constant theEq. (4) of compressed air driving

penetration was calculated as k0 =

1.1 and for the vacuum driving

penetration, the Kozeny constant was

reported to be 0.37. The resultdisplayed a much lower k0 (Kozeny

constant.) in comparison with thecase for compressed air driving

experiment, which further

demonstrated the influence of type ofapplied external pressure on the

geometry of fiber bundle.

7. It has been shown that the widelyaccepted Eq. (4) for the thresholdpressure of infiltration describes

correctly the condition of infiltrationonly along the fibers axes and it

seriously underestimates thecondition of infiltration in direction

normal to fibers axes.8. The threshold pressure of infiltration

normal to fibers axes was described

as function of the contact angle and


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smallest separation of the fibers

divided by the fiber diameter.

9. The earlier researchers have focusedon the applied external pressure and

the synergistic effect of the dynamic

capillary pressure in the vacuumdriven infusion process, there is a

better understanding of the void

formation and void mobilization induring the infusion process which

help in accurate location of the flow

front during infusion which further

help in knowing correct pressureprofile during infusion and strategic

injection port and vent locations,

some of the researchers are also

including the effect of phasetransition at the voids to better the

models to the real flow behavior in

their modeling and betterunderstanding of the flow physics.

10.The effect of the permeabilityvariation due to compaction andsticking of the plastic bags to the top

surface of the preform during

infusion in a VARTM process is

been reduced through the concepts of

FFC and VIPR attachment in theconventional VARTM process.

11.The VIPR is automation in VARTMand the mechanical properties of the

composites obtained through the

VIPR method show the improvementover the conventional VARTM

technique.12.The Automation in VARTM should

be judicious and careful as this mayto some extent is adding cost to the

VARTM process and may jeopardizethe flexibility of the VARTM

process.The VARTM is a much understood

technology then just a cheap method of

producing long composite parts, which itwas earlier the simulation tools like

LIMS, RTM -Worx and attachment like

the FFC and VIPR are going to take this

methods to the next level in the coming

decade. The compressibility of thepreform is the basic difference between

the RTM and VARTM process and the

modeling the VARTM process looks tobe the needing some time to be robust

and repeatable as the RTM process.

9. References

[1] Parnas RS, Salem AJ, Sadiq TAK, Wang

HP, Advani SG. The interaction between micro-

and macroscopic flow in resin transfer moldingpreforms. Compos Struct 1994;27:93107.[2] Chan AW, Morgan RJ. Tow impregnation

during resin transfer molding of bi-directionnal

nonwoven fabrics. Polym Compos

1993;14(4):33540.

[3] Binetruy C, Hilaire B, Pabiot J. Tow

impregnation model and void formation

mechanisms during resin transfer molding. J

Compos Mater 1998;32(3):22345.[4] Peterson RC, Robertson RE. Flow

characteristics of polymer resin through glass

fiber preforms in resin transfer molding. In:

Advanced composite materials: new

developments and applications conference

proceedings, Detroit, MI, USA; 1991. p. 2038.

[5] Chen Y, Davis HT, Macosko C. Wetting of

fiber mats for composites manufacturing: I.

visualization experiments. AIChE J

1995;41(10):226173.[6] Hayward JS, Harris B. The effect of vacuum

assistance in resin transfer molding. Compos

Manuf 1990;1(3):1616.

[7] Jinlian H, Yi L, Xueming S. Study on void

formation in multi-layer woven fabrics.

Composites A 2004;35:595603.[8] Patel N, Rohatgi V, Lee LJ. Microscale flow

behavior and void formation mechanism during

impregnation through a unidirectional stitched

fiberglass mat. Polym Eng Sci 1995;35(10):83751.

[9] Patel N, Lee LJ. Effect of fibermat

architecture on void formation and removal in


10/12



liquid composite molding. Polym Compo

1995;16(5):38699.[10] Patel N, Rohatgi V, Lee LJ. Macro- and

microvoid formation in liquid composite

molding. In: 9th ASM/ESD advanced

composites conference, Dearborn, MI, USA;

1993. p. 8198.[11] Rohatgi V, Patel N, Lee LJ. Experimental

investigation of flowinduced microvoids during

impregnation of unidirectionnal stitched

fibermat. Polym Compos 1996;17(2):16170.[12] B. Gourichon, C. Binetruy , P.Krawczak.

Experimental investigation of high fiber tow

count fabricunsaturation during RTM

Composites Science and Technology 66 (2006)

976982[13] Kaptay G The threshold pressure of

infiltration into fibrous preforms normalto the

fibers axes. Composites Science andTechnology 68 (2008) 228237[14] Bakis CE, Bank LC, Brown VL, et al.

Fiber-reinforced polymer composites for

constructionstate-of-the-art review. J ComposConstr 2002;6:7387.[15] Arib RMN, Sapuan SM, Hamdan MAMM,

et al. A literature review of pineapple fibre

reinforced polymer composites. Polym Polym

Compos 2004;12:3418.[16] Clyne TW, Markaki AE, Tan JC.

Mechanical and magnetic properties of metalfibre networks, with and without a polymeric

matrix. Compos Sci Technol 2005;65:24929.[17] Ehleben M, Schurmann H. Manufacturing

of centrifuged continuous fibre-reinforced

precision pipes with thermoplastic matrix.Compos Sci Technol 2006;66:26019.

[18] Verrey J, Michaud V, Manson J-AE.

Dynamic capillary effects in liquid composite

moulding with non-crimp fabrics. Composites A

2006;37:92102.[19] Czigany T. Special manufacturing and

characteristics of basalt fiber reinforced hybrid

polypropylene composites: mechanicalproperties and acoustic emission study. Compos

Sci Technol 2006;66:321020.[20] Clyne TW, Bader MG, Cappleman GR,

Hubert PA. The use of \delta-alumina fiber for

metal matrix composites. J Mater Sci

1985;20:8596.

[21] Clyne TW, Mason JF. The squeeze

infiltration process for fabrication of metalmatrix compostes. Metall Trans A

987;18A:151930.

[22] Andrews RM, Mortensen A. Lorentz force

infiltration of fibrous preforms. Metall Trans A

1991;22A:290315. [10] Nakanishi H,Tsunekawa Y, Okumiya M, Mohri N. Ultrasonic

infiltration in alumina fiber/molten aluminum

system. Mater Trans JIM 1993;34:628.[23] Korner C, Schaff W, Ottmu ller M, Singer

RF. Carbon long fiber reinforced magnesium

alloys. Adv Eng Mater 2000;2:32737.[24] Blucher JT, Katsumata M, Narusawa U,

Nemeth A. Continuous manufacturing of fibre-

reinforced metal matrix composite wires technology and product characteristics.

Composites A 2001;32: 175966.[25] Xu HY, Geng L, Meng QC. Effect of Cu

content on microstructure and properties of

Al2O3SiO2 fiber reinforced aluminum matrixcomposites. Mater Sci Forum 2005;475

479:8736.[26] Rohatgi PK, Towari V, Gupta N. Squeeze

infiltration processing of nickel coated carbon

fiber reinforced Al-2014 composite. J Mater Sci

2006;41:72329.

[27] Kientzl I, Dobranszky J. Production and

examination of double composites. Mater Sci

Forum 2007;537538:1917.[28] Tang LG, Kardos JL. A review of methods

for improving the interfacial adhesion between

carbon fiber and polymer matrix. Polym

Compos 1997;18:10013.

[29] Szabo JS, Karger-Kocsis J, Gryshchuk A,Czigany T. Effect of fibre surface treatment on

the mechanical response of ceramic fibre

matreinforced interpenetrating vinylester/epoxy

resins. Compos Sci Technol 2004;64:171723.

[30] DiFrancia C, Ward TC, Claus RO. The

single-fibre pull-out test. Review and

interpretation. Composites A 1996;27:597612.

[31] Chandra N, Ghonem H. Interfacialmechanics of push-out tests: theory and

experiments. Composites A 2001;32:57584.[32] Vas LM, Czigany T. Strength modeling of

two-component hybrid fiber composites in case

of simultaneous fiber failure. J Compos Mater

2006;40:173562.


11/12



[33] Delannay F, Froyen L, Deruyttere A. The

wetting of solids by molten metals and its

relation to the preparation of metalmatrixcomposites. J Mater Sci 1987;22:116.

[34] Asthana R, Rohatgi PK, Tewari SN.

Infiltration processing of metal matrixcomposites: a review. Process Adv Compos

1992;2:117.[35] Carman PC. Capillary rise and capillary

movement of moisture in fin sands. Soil Sci

1941;52:114.[36] White LR. Capillary rise in powders. J

Colloid Interface Sci 1982;90:5368.[37] Mortensen A, Cornie JA. On the infiltration

of metal matrix composites. Metall Trans A

1987;18A:11603.[38] Kaptay G, Barczy T. On the asymmetrical

dependence of the threshold pressure of

infiltration on the wettability of the porous solid

by the infiltrating liquid. J Mater Sci

2005;40:25315.[39] Xia Z, Zhou Y, Mao Z, Shang B.

Fabrication of fiber-reinforced metalmatrixcomposites by variable pressure infiltration.

Metall

Trans B 1992;23B:295302.[40] Long S, Zhang Z, Flower HM.

Hydrodynamic analysis of liquid infiltration of

unidirectional fibre arrays by squeeze casting.

ActaMetall Mater 1994;42:138997.

[41] Yamauchi T, Nishida Y. Infiltration

kinetics of fibrous preforms y aluminum with

solidification. Acta Metall Mater 1995;43:1313

21.[42] Nishida Y, Ohira G. Modeling of

infiltration of molten metal in fibrous preform

by centrifugal force. Acta Mater 1999;47:84152.

[43] Connor M, Toll S, Manson JA. On surface

energy effects in composite impregnation and

consolidation. Compos Manuf 1995;6:28995.

[44] Batch GL, Chen YT, Macosko CW.Capillary impregnation of aligned fibrous beds:

experiments and model. J Reinf Plast Compos

1996;15:102751.[45] Amico A, Lekakou C. An experimental

study of the permeability and capillary pressure

in resin-transfer moulding. Compos Sci Technol

2001;61:194559.

[46] Bayramli E, Powell RL. The normal

(transverse) impregnation of liquids into axially

oriented fiber-bundles. J Colloid Interface Sci

1990;138:34653.

[47] Yang XF, Xi XM. Critical wetting angle for

spontaneous liquid infiltration into orderly

packed fibres or spheres. J Mater Sci

1995;30:5099102.[48] Shi W, Kobashi M, Choh T. Effect of

wettability and power premixing on the

spontaneous infiltration of molten Mg into

alumina fiber preform. Z Metallkd 1999;90:2948.

[49] Pippel E, Wolersdorf J, Doktor M, Blucher

J, Degischer HP. Interlayer structure of carbon

fibre reinforced aluminium wires. J Mater Sci

2000;35:227989.

[50] Dopler T, Modaressi A, Michaud V.

Simulation of metalmatrix compositeisothermal infiltration. Metall Mater Trans B

2000;31B: 22534.[51] Blucher JT, Dobranszky J, Narusawa U.

Aluminium double composite structures

reinforced with composite wires. Mater Sci Eng

A 2004;387389:86772.[52] Kurnaz SC. Production of saffil fibre

reinforced ZnAl (ZA 12) based metal matrix

composites using infiltration technique and

study of their properties. Mater Sci Eng A

2003;A346:10815. [41] Carnali JO, KotkinCA. Determination of the capillary nature of

simple woven textiles. J Colloid Interface Sci

1993;159: 31923.[53] Foley ME, Gillespie Jr JW. Modeling of the

effect of fiber diameter and fiber bundle counton tow impregnation during liquid molding

process. J Compos Mater 2005;39:104565.[54] Kaptay G. Classification and general

derivation of interfacial forces, acting on phases,

situated in the bulk, or at the interface of other

phases. J Mater Sci 2005;40:212531[55] Min Li a, Shaokai Wanga, Yizhuo Gu a,

Zuoguang Zhang a, Yanxia Li a, Kevin Potter.Dynamic capillary impact on longitudinal micro-

flow in vacuum assisted impregnation and the

unsaturated permeability of inner fiber tows.

Composites Science and Technology 70 (2010)

16281636[56] Kang MK. A dual-scale analysis of

macroscopic resin flow in vacuum assisted resin


12/12



transfer molding. Polym Compos

2004;25(5):51020.[57] Gutowski TG, Cai Z, Bauer S, Boucher D.

Consolidation experiment for laminate

composites. J Compos Mater 1987;21:65069.[58] Gebart BR. Permeablity of unidirectional

reinforcement for RTM. J Compos Mater

1992;26(8):110033.[59] Vd Westhuizen J, Du Plessis P.

Quantification of unidirectional fiber bed

permeability. J Compos Mater 1994;28(7):61937.

[60] Pillai KM, Advani SG. Wicking across a

fiber-bank. J Colloid Interface Sci

1996;183:10010.[61] Zhou F, Kuentzer N, Simacek P, Advani

SG, Walsh S. Analytic characterization of the

permeability of dual-scale fibrous porous media.

Compos Sci Technol 2006;66(15):2795803.[62] Zhou F, Alms J, Advani SG. A closed form

solution for flow in dual scale fibrous porous

media under constant injection pressure

conditions. Compos Sci Technol 2008;68(34):699708.

[63] Acheson JA, Simacek P, Advani SG. The

implications of fiber compaction and saturation

on fully coupled VARTM simulation. Compos

Part AAppl Sci Manuf 2004;35:15969.

[64] Simacek P, Advani SG. A numerical model

to predict fiber tow saturationduring liquid

composite molding. Compos Sci Technol

2003;63:172536.[65] Luo Y, Verpoest I, Hoes K, Vanheule M,

Sol H, Cardon A. Permeability measurement of

textile reinforcements with several test fluids.

Compos Part A Appl Sci Manuf2001;32:1497504.[66] Kuentzer N, Simacek P, Advani SG, Walsh

S. Correlation of void distribution to VARTM

manufacturing techniques. Compos Part A Appl Sci Manuf 2007;38:80213.

[67] Patel N, Rohatgi V, Lee LJ. Micro scale

flow behavior and void formation mechanism

during impregnation through a unidirectional

stitched fiberglass mat. Polym Eng Sci

1995;35(10):83751.

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