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Accepted Manuscript
The engineering aspects of automated prepreg layup: History, present and future
D.H.-J.A. Lukaszewicz, C. Ward, K.D. Potter
PII: S1359-8368(11)00545-2
DOI: 10.1016/j.compositesb.2011.12.003
Reference: JCOMB 1624
To appear in: Composites: Part B
Received Date: 8 July 2011
Revised Date: 30 November 2011
Accepted Date: 10 December 2011
Please cite this article as: Lukaszewicz, D.H.-J.A., Ward, C., Potter, K.D., The engineering aspects of automated
prepreg layup: History, present and future, Composites: Part B (2011), doi: 10.1016/j.compositesb.2011.12.003
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers
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The engineering aspects of automated
prepreg layup: History, present and future
D.H.-J.A. Lukaszewicz (1)
, C. Ward (2)
, K.D. Potter (3,*)
(1) Research Assistant, ACCIS, University of Bristol, Queen’s Building, University
Walk, BS8 1TR, UK; Email: [email protected] Phone: +44 (0)
117 33 15331; Fax: +44 (0) 117 927 2771
(2) Research Assistant, ACCIS, University of Bristol, Queen’s Building, University
Walk, BS8 1TR, UK; Email: [email protected] Phone: +44 (0) 117 33
15503; Fax: +44 (0) 117 927 2771
(3) Professor in Composites Manufacture, ACCIS, University of Bristol, Queen’s
Building, University Walk, BS8 1TR, UK; Email: [email protected]
Phone: +44 (0) 117 33 15277; Fax: +44 (0) 117 927 2771
(*): Corresponding author
Abstract
Highly consistent quality and cost-effective manufacture of advanced composites
can be achieved through automation. It may therefore open up new markets and
applications for composite products in aerospace, automotive, renewable energy, and
consumer goods. Automated Tape Laying (ATL) and Automated Fibre Placement
(AFP) are the two main technologies used to automate the layup of prepreg. The
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historical development and past research of both technologies is reviewed; with an
emphasis on past issues in application and capability as well as their solution, including
both thermoset and thermoplastic material layup. It is shown that past developments
have moved away from simply emulating manual layup into the now unique layup
procedures for ATL, and into the current AFP technology base. The state of the art for
both technologies is discussed and current gaps in the understanding of both processes
highlighted. From this, future research needs and developments are derived and
discussed.
Keywords: E. Lay-up; E. Automation; A. Laminates; A. Prepreg
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1 Introduction
Future aircraft programs, such as the Boeing 787 and Airbus A350XWB, contain
more than 50% by weight of advanced composite components. Consequently the rate
and economy of composite manufacture needs to improve to meet the requirements of
these and future build programs. Additional areas where advanced composites are of
increasing interest are renewable energy and automotive, where advanced composites
need to be cost effective in manufacture when compared to their metallic counter-parts.
To achieve this automation is one way forward.
Automated Tape Laying (ATL) and Automated Fibre Placement (AFP) are the
two main technologies that are employed today to manufacture advanced composite
laminates from unidirectional prepregs. ATL is employed to deliver wide prepreg tape
onto a surface whilst automatically removing the ply backing. Layup speed, tape
temperature, speed and tape tension can be controlled during layup. AFP is similar to
ATL but utilises a band of narrow prepreg slices, which are collimated on the head and
then delivered together.
A review of ATL layup was published by Grimshaw [1], however this source
covers only a single industrially relevant equipment supplier. Similarly, Evans [2]
published a review of AFP systems only pertaining to a single industrial system. Short
introductions to different aspects ATL and AFP are also given by Åstrøm [3], Campbell
[4] and Gutowski [5]. Recently, Sloan [6] has published an industrially focused
overview of ATL and AFP.
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Despite this, the authors are not aware of any other independent review of this
important area of composite manufacture; indeed even the above reviews were never
peer-reviewed publications. Further, while most components are manufactured from
thermoset prepreg, most research in the field was directed at thermoplastic layup.
Currently, an increasing amount of research is being conducted to improve existing
thermoset layup processes, see Figure 1. It shows the result of a literature search on
Google Scholar for the number of archivable publications for AFP and ATL. The results
were summed over a five-year period to provide meaningful trends. Filament winding
with respect to composite manufacture (excluding process relevant to electrical
components) is shown in an insert graph as a reference to illustrate the relative
shortcomings in terms of scientific publications, and consequently understanding, for
ATL and AFP.
With this in mind, this paper will review the historic development of ATL and
AFP to highlight the development, and also present the current State-of-the-Art (SOA)
for both processes. Lastly, current and future research opportunities are discussed. This
work will mostly aim to identify the engineering aspects of thermoset prepreg layup, but
thermoplastic prepreg is also discussed, where analogies are appropriate. Special
emphasis is placed on the impact of current trends in areas such as structural tailoring
and out-of-autoclave curing with respect to automated layup.
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2 Automated Tape Laying (ATL)
2.1 Historical developments of ATL
2.1.1 Early developments
Carbon fibres became commercially available from 1966 [7] onwards, and very
early on it was realised that prepreg layup could be automated to improve the
productivity and consistency of manual layup. ATL systems were conceived from the
end of the 1960’s onwards [8] and by the middle of the 1970’s research systems were
developed and in application use. The earliest known reference to an ATL is a patent
assigned to Chitwood and Howeth [9] in 1971, describing a method of laminating
composite tape onto a rotatable base-plate using Computer Numeric Control (CNC). In
1974 Goldsworthy et al. [10], see Figure 2, described an automated system delivering
76mm wide tape over a curved surface where the head was able to rotate and withhold
material to improve the part complexity that could be manufactured using ATL layup.
Huber [11] noted that aerospace manufacturers and research institutions built most ATL
systems as early as 1975 in-house, and as a result they were normally part of a
component centred production system for a given aircraft program, see Figure 3. Layup
speeds were given to be 10-20 m/min, however it was argued that this did not affect
overall productivity.
More importantly, ATL could reduce layup errors and material wastage, which
resulted in improved material utilisation. For example, Grimshaw [1] in 2001 calculated
the material wastage generation of an ATL layup as a function of part size to be up to
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30% for small parts and decreasing exponentially to 2-4% for larger parts; with similar
results having been reported elsewhere [12]. Productivity of manual forming at the
beginning of 1980 was stated as ~1kg/h [13,14] and materials wastage rates were 50-
100 %, due to both the lack of automated ply cutters and optimised consumables and
prepregs. Postier [15] reported a comparison between manual and ATL layup, with
ATL capable of achieving a 65% reduction in layup time and an additional reduction in
material wastage rates for certain components.
2.1.2 ATL development from the 1980’s
To enable ATL to become more widespread the technology was converted into a
more generic process. The early 1980’s were as such a time of rapid development with
multiple competing concepts. To address the issue of higher layup speeds, Eaton [16]
and Saveriano [17] introduced a layup system with a lightweight head that dispensed
tape over a rotatable surface, similar to the first patent of Chitwood and Howeth [9], at
up to 60m/min. At that time most ATL systems were Flat Tape Laminating Machines
(FTLM), which could only deliver tape onto a flat tool. Coad, Werner and Dharan [18]
by contrast discussed a robotic pick-and-place system to overcome ATL’s limitations
regarding geometric complexity.
To finally address this limitation, Stone [19] introduced a commercial ATL
system in 1984 from Cincinnati Milacron (now MagCincinnati) who had acquired a
license for a UD-tape layup head from Vought Corp, Dallas, TX. The system was
capable of delivering tape over geometries with curvature up to 15° using an ultrasonic
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tracking system, to follow the contour of the mould, making it the first example of a
Contour Tape Laminating Machine (CTLM). However, several technical issues still
remained, including layup speeds, accurate layup onto complex moulds, and improved
reliability and quality. Albus [20] pointed out the limitations that robotic arms had
during the middle of the 1980’s, which were limited to speeds < 60m/min for layup
applications, and that accuracy was key to enabling off-line programming. To alleviate
this issue most ATL systems became high-rail gantries resulting in heavy and stiff
structures that were associated with very poor machine dynamics [21]. Furthermore,
layup systems were still not capable of delivering tape with defined compaction
pressure and regular debulking cycles were still necessary. Reliability was likely to be
low, for example due to breakage of the ply backing. While layup dexterity had been
increased by modifications and additions to the layup head, layup speeds remained
fairly low.
In 1986, Meier [22] introduced a system that has formed the basis for all modern
commercial single-phase ATL systems. Direct layup force control and head normality
over curved surfaces was enabled by replacing the previous ultrasonic tracking system
with force-controlled Z- and A-axes [23]. However, no mention of tape heating
facilities was made and remaining issues were mostly related to layup reliability as a
function of out-time of the prepreg and initiation of the first ply, which usually had to
adhere to a coated mould or release cloth.
Grone, Schnell and Vearil [24] then patented a method to finalise the end of a tape
course cut under an oblique angle using a second flexible layup element. This method
has since been modified by Torres [25] not only to finalise a tape course, but also to
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start a ply, and in particular to overcome the technical difficulties of first-ply
attachment. However, prepreg layup was still limited to fairly simple components and
reliabilty was still affected by tack levels and their degradation with out-life due to
limited heating. To address the first, Lewis and Romero [26] introduced a layup system
combined with significant software capability, to enable layup over a curved surfaces
along a natural (the path a tape will take over a surface without friction) or geodesic
path.
As layup capability had increased to more and more complex geometries at the
end of the 1980s, ply alignment increasingly became an issue. The soft rollers employed
for layup over complex geometries lead to uneven layup pressure and tape tension on
the head. Both of which could result in compressive forces acting on the tape between
the layup roller and the tape supply and allowed transverse movement of the ply prior to
delivery. To prevent such movement tape was delivered with controlled tension and
combined with tightly controlled layup pressure to enable correct alignment of a ply.
One such system is shown by Torres [27] which combined means for ply tensioning
with layup pressure control. Grimshaw [28] further demonstrated an ATL system
having a segmented layup shoe connected to a pressure chamber, enabling accurate
layup pressure and improved ply alignment over contoured surfaces. In 1995 this
approach was extended to multiple layup elements operating independently from the
layup head [29]. The other aim in using layup pressure control was to reduce debulking
operations, as it detrimentally affected productivity, but it is unclear whether ATL layup
systems at the time were sufficiently capable to achieve this. For example, Olsen and
Craig [30] argued that the effective pressure transferred from the head onto the laminate
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was a function of layup speed, and had to be much higher than during vacuum
debulking, due to the fact that it is applied over a much shorter time frame. The pressure
on the laminate depends on the machine capability, the roller geometry, roller material,
and the shape of the mould the material is applied onto.
All of the works explored so far were aimed at increasing the manufacturing
capability of ATL equipment but the issue of material outlife and changing tack levels
remained unresolved. Further, whilst layup systems enabled accurate pressure control
during layup it was unclear what the desirable pressure level was, or what it depended
on. Disappointingly, actual layup speeds were generally unchanged from the 10-20
m/min previously achieved.
A particular issue that remained in this period was the cost of an ATL system,
which was given by Goel [31] as ~ US$3.5 M for most basic systems. This meant that
ATL had to be highly productive to offset the initial capital expenditure, making its
adoption into the commercial aircraft industry a slow process. Krolewski and Gutowski
[13,14] and Foley [32] published economic assessments of various manufacturing
methods available at the end of the 1980’s in terms of productivity and part cost. They
showed that automated layup offered no appreciable increase in productivity over
manual forming. Considering the additional capital investment for layup systems, the
recurring part cost increased for automated layup, however the authors concluded that
automation was still desirable due to effects that were not accounted for in their study,
including improved reliability, consistency, and reduction of material wastage.
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2.1.3 Development in the 1990s until today
Tape heating was introduced in the 1990’s to overcome issues during layup of
complex laminates, and also enable tack control for layup of large parts. It is unclear
from the literature when heating was first used for thermoset layup, but irradiation
heating for thermoplastic layup was in use by 1991 [33]. Benda and Stump [34]
discussed the joint development of a component and layup system, where a hot-air
heating system was added to an ATL to enable tape attachment onto complex contours.
Further changes included the layup roller diameter, which was reduced from 150mm to
50mm to improve dexterity when delivering tape onto contours with > 30° curvature.
To enable layup onto such complex geometries some tape tension was required to keep
the plies aligned. Lastly, it was mentioned that the effective layup rate was 13m/min,
again unchanged from the earliest discussion dating back to 1981.
Sarrazin and Springer [35] addressed the question of optimal processing
conditions for thermoset tape, in the context of a cure-on-the fly system, to effectively
reduce post-curing. Their work proposed a layup system where thermoset tape was
heated to 150°C and used at speeds ~0.06m/min. It was observed that the thermoset
material only reached a limited degree of cure and that post-curing was still a necessity;
that layup pressure was independent of the number of plies, and scaled weakly with the
roller diameter and ply orientation. Finally the authors concluded that a high layup
pressure could result in delamination during layup, as the material is pushed and pulled
apart in front of and behind the layup roller compressing the material onto the tool,
however their study did not include tack, which could prevent such separation.
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Grove [36] (in 1988) proposed a model for the laser assisted heating of
thermoplastic tape to enable direct layup and consolidation of thermoplastic materials,
however, the focus of thermoplastic layup shifted quickly to AFP. Since the middle of
the 1990’s to the present day, further developments to ATL have thus been rather
limited and were starting to be dominated by productivity requirements.
Torres [37] introduced a system that combined at least two rolls of either 75, 150
or 300mm wide material on one ATL head to potentially improve both productivity and
layup dexterity, though this can also be considered an AFP layup system. Forest-Liné
[38,39] developed a nesting technology for ATL layup, to improve productivity for
large parts with small features. Ply patches are pre-cut in a separate operation, stored on
a ply-backing, and wound back onto a roll. Forest-Liné’s system employ two separate
head sides to deliver either the continuous ply course or small pre-cut prepreg patches,
often referred to a twin (or dual) -phase layup, with conventional layup being single-
phase layup.
Today, ATL layup has further diversified by returning to the earliest ATL systems
using a part centred layup approach, and machines are currently being developed that
can address specific layup issues while also yielding very high productivity rates.
ATL can be considered a highly productive process for prepreg layup, which is in
widespread use in the aerospace and renewable energy industries in particular.
Advantages are high layup rates, high mechanical properties due to the use of prepreg,
capability to manufacture large parts, capability to handle high areal weight materials,
and simplified offline machine programming. Disadvantages are high initial capital
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expenditure, limited geometric complexity capability, and higher material wastage rates
than AFP (see 3.1). Despite the potential complexity limitations of ATL manufacture, it
has recently received renewed interest due to the high productivity achievable for flat
laminates [40]. After layup, flat laminates can be formed into the desired shape by hot
drape forming [41], offering a cost competitive manufacturing route for large composite
components and material with high prepreg areal weight, however forming may
detrimentally affect the mechanical performance of the structure, e.g. due to fibre
wrinkling.
ATL systems are used for manufacture of a variety of parts, such as tail planes,
wing skins [42,43] and the centre wing box of the A380 [43,44]. The main
manufacturers of aerospace ATL equipment are MAGCincinnati (USA), MTorres
(Spain), and Forest Liné (France), although the latter was recently acquired by
MAGCincinnati. GFM (Germany), Mikrosam (Macedonia), Entec (USA) and ATK
(USA) supply ATL systems, but do not have a comparable number of installed systems.
Ingersoll (USA) currently only supplies AFP systems, but has delivered ATL systems in
the past.
2.2 ATL Process description
ATL (and AFP) can be interpreted as a form of additive manufacturing or inverse
machining, since the part is built up by adding material, as opposed to material removal
during machining [5]. The ATL head handles the prepreg tape, which is typically 75,
150, or 300mm wide and supplied on a cardboard core [12] similar to the prepreg used
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for manual layup. However, the prepreg can be modified for automated layup by
changing the backing paper or degree of impregnation. Most commercially available
systems store the prepreg material directly in the layup head, and a schematic according
to Ästrøm [3] is shown in Figure 4, and a picture of ATL head is shown in Figure 5.
Due to the mass of both the head and material, as well as the size of the parts typically
manufactured, ATL systems are normally mounted on horizontal gantries, Figure 6
[45], or a vertical column system, Figure 7.
For most aerospace structures, courses consist of ramps and valleys as well as ply
terminations, resulting in complex surface topologies. ATL’s are CNC systems that
follow predefined paths accurately and reproducibly, allowing the elimination of layup
errors that could occur in manual layup. During the layup of each ply, a tape course is
placed next to one other with a gap of 0.5-1mm, which is required to accommodate
variations in placement due to layup control and tape tolerances. Material tolerances are
normally sufficiently small to minimise the impact of gaps on mechanical performance.
At the start of a layup sequence, the ATL system attaches a pre-determined length
of tape onto the tool using a soft silicone roller. Once the course has been applied, the
system accelerates to the layup speed and delivers the remaining material [23-25,28,29].
During layup the material is attached to the tooling using controlled additional force that
is transferred through the end-effector. This can be a flexible silicone roller, but more
sophisticated methods have also been developed to control the pressure distribution over
complex surfaces, such as segmented laying shoes [24,29]. Most ATL systems achieve
a maximum linear layup speed of 0.83-1ms-1
and accelerate at 0.5ms-2
and typically
deliver a compaction of F = 445N (for 75mm wide thermoset tape [46]) - 1000N (for
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300mm wide thermoset tape), which would translate to a pressure of ~0.1 MPa. By
contrast, for thermoplastic material layup, Colton [47] quoted a necessary pressure of
1.4 MPa for APC-2 at 316°C, whilst layup pressures up to < 3.6 MPa have been
reported elsewhere [48]. The head controls the input tension on the plies and ply
backing between the material supply and the layup point during layup. Tension is
imparted to avoid tearing of the backing paper, improving the alignment of the plies,
and enabling layup into curved geometries. To control the temperature during layup the
material can be heated either in front of the layup head or on the layup system in
delivery.
At the end of the ply course the head decelerates just prior to finishing and cuts
the tape automatically, using rotating or pinching blades. The distance between the
blade position and the roller contact point is termed the “minimal course length”, and it
is used as a lower bound on the part sizes that can be manufactured - around 100mm for
most systems. After severing the tape, the remaining or minimal course length, is
delivered to finish the ply course. This entire process is repeated course by course until
the ply is finished, the system is stopped by the program, user intervention, or if an
automated fault detection system has identified a layup error.
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3 Automated Fibre Placement (AFP)
3.1 Historical developments of AFP
3.1.1 Early developments
Quite possibly the first published AFP system has already been introduced in
Figure 2. The 1974 Goldsworthy [10] patent described an ATL system but also
highlighted the challenge of conforming a tape to a curved surface. To address this the
layup head had the ability to slit down the wide tape into 3.2mm slices and then deliver
those at individual speeds by keeping the additional material on the head, Figure 8. In
reality this would have resulted in technical limitations during material layup and it is
unclear whether these issues were resolved, but further developments in this process
could not be identified.
3.1.2 Development from the 1990
AFP systems were commercially introduced towards the end of the 1980’s, and
were described as a logical combination of ATL and Filament winding (FW) [49]; by
combining the differential payout capability of FW and the compaction and cut-restart
capability of ATL. Several of the lessons learnt during the development of ATL, such as
roller design and material guiding were incorporated into these AFP systems and as
such they were immediately available from commercial suppliers.
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Evans [50] initially overcame the limitations of Goldsworthy’s approach by
keeping slit tape on separate bobbins, which were also individually driven. Bullock,
Kowalski, and Young [51] demonstrated another type of AFP machine together with an
offline programming system, and argued that offline programming was essential to AFP
productivity as it directly affected machine production time. The AFP system controlled
layup speed, pressure, temperature, and tape tension. They also showed that a layup
speed of 7m/min would result in a productivity of 5kg/h, which was given to be
comparable to ATL. Barth [52] showed an AFP system that made use of cooled creel
houses to reduce prepreg tack, thus enabling reliable despooling and improved layup
reliability. Additionally, the compression-after impact strength of laminates
manufactured by AFP and manual forming was evaluated, showing that mechanical
properties of both were comparable.
Technical issues that remained unresolved in this period were the tension in the
tows, reliability, productivity, and layup accuracy. The tows were typically delivered in
a very complex path to the head prior to collimating, which could increase tension in the
material and affect layup reliability. Layup accuracy is highly important for AFP
because the narrow tape will result in gaps between the material, which are a function of
the placement accuracy, and may affect mechanical performance. This had not however
been studied in any detail, though later studies showed a significant impact on
mechanical performance [53,54].
To enhance productivity, Enders [55] for example introduced an AFP system that
could deliver up to 24 tows in a sequence. The system was uniquely tightly integrated
into the Computer-Aided-Design (CAD) system to address the earlier note [51]
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regarding AFP productivity. In use on a demonstrator component, a layup rate of up to
30m/min was reported - yielding a productivity of 1.9kg/h – and this was compared to a
manual layup productivity of 0.7kg/h for the same component. Rather differently, Evans
[56] improved productivity by focussing on reliability, such as material changes, tape
tolerances and intermittent debulking. More reliable layup over complex geometries
was achieved by delivering the tows along a curvilinear path; this is often referred to as
steering. Quickly, it was realised that the ability to deliver material in curved fibre
orientations added additional design freedom and enabled potential improvements in
mechanical performance. Due to the smaller individual tape widths that were used for
AFP, smaller steering radii could be achieved than for ATL.
Some very interesting results for an industrial application were shown by Measom
[57], who reported on the development process of a part with a complex layup. The
component had initially been manufactured by FW and manual layup but manufacture
with AFP reduced material wastage rates from 62% to 6% and productivity improved
by 450% for layup of a single 12.7mm wide tape. However, to improve material
delivery the areal weight was doubled, resulting in reduced downtime and further
improved productivity. This result was supported by Pasanen [58] who reported a 43%
cost reduction for AFP over manual layup.
A schematic of an AFP layup head for layup of multiple tows was given by Evans
[2], see Figure 9. Whilst the benefits of AFP for complex layups had been successfully
demonstrated, the process was still not productive enough to quickly offset the initial
capital expenditure with systems costing up to US$6 M [31]. The limitations were now
affordability, process reliability, and productivity. Furthermore, the development of
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AFP in this period coincided with the advent of thermoplastic composites for aerospace
structural applications, and significant research effort was devoted at developing AFP
for thermoplastic layup. As Gruber [59] noted, this was driven by the need to
manufacture large spacecraft and submarine structures, that exceeded most autoclaves
diameters and required in-situ processing and reduced thermal residual stresses.
The earliest approaches for developing thermoplastic layup were reported by
Grove [36], Mantell and Springer [60,61], and Sarrazin and Springer [35]. These works
identified a trade-off between layup pressure, temperature, and speed. Layup quality,
mainly measured by interfacial healing and voidage, was detrimentally affected by
layup speed; and as discussed by Bourban [62] the main limiting factor for
thermoplastic layup was the amount of time required to heat the material above its
melting point. Thus, the maximum layup speed was limited, with works reporting
speeds of 3.6mmin-1
[63] to 5mmin-1
[64], resulting in considerably lower layup
productivity than thermoset materials. This was further explored by Ranganathan [65],
Pitchumani [66,67], and Tierney [68] to predict the optimal processing conditions for
reduced void growth, as well as maximising speed and interfacial bonding. Most works
used hot gas torches for material heating, but a laser heating was also successfully
developed by Funck and Neitzel [69], Rosselli [70], and Pistor [71]. Goodman [72], and
Burgess [73], similarly reported a method for curing photoactivated thermoset prepregs
on the fly using an electron beam or ultra-violet-light(UV) as a radiation source for
faster processing and reduction of residual thermal stresses. Overall however, both
thermoplastic and thermoset in-situ processing approaches achieved limited layup
speeds, whilst also exhibiting reduced mechanical properties.
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3.1.3 Development from the 2000 until today
Grant [8,74,75] described the change in focus for AFP layup from novel processes
to addressing issues regarding affordability, process reliability, and productivity, and
showed that AFP had mainly been employed in military and space programs until 2000,
Table 1. Process reliability was detrimentally affected by splicing (welding of the tape
ends) errors at the end of a bobbin, dropped tows, and material changes, which would
result in unscheduled downtime and decrease productivity. Torres [76] introduced an
automated system for splicing the tows together, and this could improve productivity by
reducing down-time for material refilling. Oldani [77] also introduced an automated
system to detect layup errors, improving productivity by reducing the time for quality
inspection after ply layup. To increase tack levels and further minimise layup errors
infrared heating of thermoset tape was introduced by Calawa and Nancarrow [78] to
allow faster heating and higher layup temperatures. Furthermore, Hamlyn [79]
introduced a system for rapidly exchanging layup heads and tools by keeping a second
layup head ready for immediate layup, and this led reduced system downtime. Material
delivery was also improved by using systems that either reduced the feed length, or by
minimising the amount of redirects and twists in the tow using appropriate guide
systems [80].
Despite improvements in raw productivity and reliability, several technical issues
remained. Foremost, capital expenditure was still high compared to other manufacturing
methods, and offline programming was still un-optimised although layup of curved
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tapes onto a mould and AFP layup control are currently an area of ongoing research
[81,82]. The capability to automatically manufacture unsymmetrical laminates that can
have locally changing fibre orientations makes AFP a lead technology for future
developments in the areas of smart and tailored structures, and their application.
The main manufacturers of AFP systems are Automated Dynamics (USA),
Accudyne (USA), MAGCincinatti (USA), Coriolis (France), Electroimpact (USA),
Foster Miller/ATK (USA), Ingersoll (USA), Mikrosam (Macedonia) and MTorres
(Spain). Automated Dynamics, Accudyne, Coriolis and Electroimpact supply their
systems on industrial robots and gantries. Cincinnati, Foster Miller, Ingersoll, Mikrosam
and MTorres use either column type or horizontal gantries. Robotic layup systems tend
to have a lower initial capital expenditure and can be better tailored for specific
applications. Gantry layup systems offer improved general productivity and reliability
by handling more tows in the head.
3.2 AFP Process description
AFP systems differ from ATL in the width of the material that is laid down with
typical material widths of 3.2mm, 6.4mm, and 12.7mm, however AFP will normally
deliver several [83] tows in a single sequence, termed bands. A band then forms a
course, while a sequence of courses is termed ply. Presently, AFP can deliver up to 32
tows in parallel at linear speeds of up to 1ms-1
[83]. The systems also tend to have
higher acceleration in the linear axes with typical values around 2ms-2
. Rotational
speeds and accelerations are more varied by company and therefore not quoted.
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However, it is important to note that rotational speed and acceleration can have great
impact on layup productivity for complex components, and are therefore more relevant
to AFP than ATL. The width and number of tows delivered depends strongly on the
complexity and local geometry of the part that the course is to be laid over, thus
material width and tow count will affect productivity.
Each tow is normally driven individually and can be clamped, cut, and restarted,
during manufacture [83,84]. This makes it possible to deliver each tow at individual
speeds, enabling layup over complex geometries and some tow steering, as Figure 10
shows, and is beneficial for example in structures such as fuselage sections with
window cut-outs, or wing skins with numerous pad-ups and valleys. Whilst steering was
initially conceived to improve layup over surfaces with double-curvature [10], the
individual tow payout may improve productivity and reduced materials wastage rates
[13]. An important consideration is the amount of gap between the tows, which is much
larger than for ATL and typically scales with the amount steering. This may affect
mechanical performance detrimentally and is often countered by transversely offsetting
subsequent plies by half a tow-widths.
The quality of the “on-the-fly” cut normally decreases with increasing speed
during cutting and secondary operations are therefore still necessary to remove
crenulations around a geometric feature. For this reason AFP systems tend to have a
lower “minimal course length’” than ATL, typically around 50mm.
AFP productivity is typically lower than ATL because it is generally employed
for more complex parts. For example, productivity for layup of a complex fuselage
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section is ~8.6kg/h [85], which is about half of current ATL rates. During AFP layup
tow tension on the head is negligible or controlled to be very low to enable layup into
the convex geometries and features. The composite material for AFP layup can either be
impregnated tows or slit prepreg tape. Slit tape is more expensive than impregnated
tows but potentially offers advantages with respect to productivity, reliability, and
product quality [12]. The slit tape or impregnated tows are normally wound onto
cardboard bobbins and supplied with an interleaf film to reduce tack and friction in the
material supply. The small diameter of the bobbin can additionally enable accurate
tension control during unwinding.
Despite the differences in material form and material supply to the layup head, the
layup operation during AFP is similar to that of ATL. The prepreg tape or tows are
either delivered to the head from a creel cabinet, or stored directly on the head [86]. The
first allows the use of simple industrial robots due to the reduced head weight; the latter
requires column or gantry type systems, see Figure 11. The material is delivered from
the spools to a compaction roller, where additional heat and force are again applied to
compact the material in an attempt to eliminate vacuum void removal. AFP systems
tend to use flexible rollers to compress the material and reduce voidage, but as
previously mentioned for ATL the short contact times may be ineffective to achieve
sufficient compaction. To heat the tapes hot torches, Laser, and infrared irradiation
techniques are used. Robotic systems improve the affordability of AFP since industrial
robots are significantly cheaper than gantry units, and as a result robotic AFP systems
are presently cheaper than comparable gantry AFP or ATL systems.
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4 Research Opportunities
4.1 Productivity
Currently, increases in productivity are the overriding goal for both ATL and
AFP. Consequently, all potential improvements that are discussed in the following are
governed by, or linked to potential productivity increases. Potential improvements are
possible through improved software, machine layouts, materials and enhanced layup.
The first two are discussed in this section, while the latter two are discussed in
following sections.
Examples of software improvements can be found in Debout, Chanal and Duc
[87], where AFP layup paths were optimised to reduce unnecessary acceleration with
reported possible reductions in layup time of 33%. Theoretical productivity drivers have
been studied using simple models based on the machine capability. Lukaszewicz,
Weaver and Potter [88] and Lukaszewicz [89] have published productivity estimates for
a simple flat component for both technologies based on the raw productivity values of
the layup systems, see Figure 12 and Figure 13. It is interesting to note that AFP was
found to be more productive for all part sizes studied but particularly for small parts. To
translate this model into real productivity estimated it needed to be considered that a
typical ply course of a primary structural aerospace laminate is 2m long [90]. For
typical machine data productivity was thus expected to be around 29.2kg/h for ATL and
41.3kg/h for AFP [89]. This correlated well with laydown-rate estimates for APF from
Boeing given to be 45.4kg/h [85], however, actual productivity quoted was given to be
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8.6kg/h, a knockdown of 80%. This shows that theoretical productivity can be well
estimated, but the translation into real productivity is still unresolved. More recently,
Ward, Lukaszewicz and Potter [91] have studied the AFP layup of a small complex
component with symmetric layup on a flat bottom side and contoured topside. By
comparing the relative layup time between the two sides the productivity reduction due
to part complexity was estimated to be 29% to 51% for this component due to
acceleration and deceleration during layup.
This large productivity reduction can further be explained by the fact that layup
machines only spend a fraction of the time on actual layup. For the speed and
acceleration data given in Section 2.2 for ATL, and 3.2 for AFP, the layup time for an
8m long course is 4s and 2.5s respectively including time for acceleration and
deceleration. However, time for starting a new ply, including ply cutting, turning and
repositioning is ~9s for ATL and ~7s for AFP due to the lack of cutting operations [89].
This shows that that even during layup of simple components the ratio between
productive time and secondary operations is unfavourable. In addition, quality
inspection and layup errors will result in further productivity reductions.
This downtime of layup machines, due to material refilling, error correction or
cleaning is significant, up to 50% for AFP [77]. Further increases in layup speed are
thus unlikely to yield any further productivity increases [88,89] since current
productivity is already largely constrained by part design, secondary operations and
down-time. Addressing any of these productivity constraints should easily yield
increases in productivity. To enhance the predictive capability of existing software
approaches, a better understanding of the part complexity is required. It is likely that
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small geometric features heavily impact layup time. This can only be resolved during
the design phase to achieve higher productivity.
Lastly, AFP is currently limited to low areal weight prepregs, which restricts its
use to aerospace applications. Since prepregs in renewable energy industries and others
tend to have higher areal weights, up to 1600gsm and more, future AFP systems need to
be able to deliver these materials. To address this novel cutting methods are required,
possibly laser cutting.
4.2 Steering and Control
Shirinzadeh and co-workers [81,82,91-93] give an excellent overview of the
relevant work relevant to path planning for AFP and ATL. To match the material to a
mould a point-cloud is typically generated that the control system will aim to follow.
The placement accuracy depends on the density of this cloud with a higher density
leading to more accurate layup. However, as discussed by Debout, Chanal and Duc [87]
this will also lead to unnecessary acceleration and deceleration as the control system
follows the defined layup path. Optimising the layup program or identifying suitable
starting points can alleviate this problem.
The available degree of steering in AFP and ATL layup is often reported to be the
smallest possible radius fibres can be laid into without significant defect development,
such as detachment from the tool and ply wrinkling. There are, in principle three main
tow steering defects, tow buckling, tow pull-up and tow misalignment, see Figure 14.
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Twisted tows can also occur but are less common. Tow buckling occurs on the inside
radius of a tow if compressive forces are too high, similarly tow pull-up occurs on the
outside of a tow due to excessive tensile forces. Lastly, tow misalignment is the result of
variability in the layup system, layup control or prepreg material.
Wiehn and Hale [94] reported the successful layup of AFP tows into radii as small
as 50.8cm compared to 610cm for ATL layup of 150 mm wide tape. Moon, Johnson,
and Hale [95] reported that the number of defects is a function of the smallest steering
radius. Recently, a model for the defect development during layup of a curved tape was
reported by Beakou et. al. [96], however their model was not directly validated by the
experimental results. A possible explanation could be the effect of viscoelastic material
behaviour, which was not included in the model. This, and the importance of material
tack are discussed in section 4.4. The interaction between material properties and
processing conditions needs to be studied further to gain a more detailed understanding
of limitations of steering during layup. A combination of experimental and modelling
approaches is required to explain the changes in the tow or tape during steering. Further,
current steering approaches aim to incrementally form a radius by forcing the tape to
follow the head rotation whilst being attached to the substrate and different steering
approaches, such as shearing of the tape [97] need to be explored.
Other steering defects include tow gaps, steering overlaps, and gaps, see Figure
15, but the impact of these defects on the mechanical performance of laminates has not
been extensively studied. Wang and Gutowksi [21] presented a theoretical approach to
reduce laps and gaps during thermoplastic layup by allowing the plies to flow
transversely during layup, to simplify layup accuracy requirements for thermoplastic
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layup. There is continued interest in this topic due to the higher number of gaps during
AFP layup and the relative difficulty of placing tows with the required tolerances. Blom
et. al. [53] explored the mechanical performance of AFP laminates using numerical
modelling, and results showed significant strength reductions, up to 32%, and stiffness
reductions arising from tow drop areas, see Figure 16 and Figure 17. By contrast, Croft
et. al. [54] conducted a number of mechanical tests on AFP laminates containing all the
aforementioned defects and found significantly lower (3-15%) strength reductions than
previously predicted, see Table 2. This may be explained with defect reduction and fibre
rearrangement during autoclave curing and is as such not a demonstration of the
robustness of AFP but rather autoclave curing. The impact of AFP layup on mechanical
performance as well as its reduction thus warrants further research. In particular,
approaches are required that aim to capture the translation of initial layup defects, laps
and gaps into the final cured component.
4.3 Processing conditions during layup
The exact conditions during layup may have a significant impact on the
mechanical performance of the final laminate. To this end Lukaszewicz, Weaver and
Potter [98], and Lukaszewicz et.al. [99], conducted layup trials on industrial equipment
to correlate the voidage in an uncured laminate to the processing conditions, such as
layup speed, temperature or pressure. In an additional study Lukaszewicz and Potter
[100] showed that the variability in the prepreg material was too high to allow simple
development of strong analytical models. It has been shown that this was aggravated by
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the additional variability in the layup control [89], which had an additional impact on
analytical layup quality models. Mechanical testing on laminates manufactured using a
wide range of layup conditions and subsequent oven cure showed a change in
mechanical performance of up 50% for the ILSS and compressive strength due to layup
conditions alone [101], see Figure 18 and Figure 19. Further work in this area will be
required to establish the impact of different layup conditions on the microstructural
features of laminates, such as the fibre volume fraction and the void content. To
overcome the limitations due to inaccurate layup control, Lukaszewicz and Potter [88]
have introduced a small research layup system, that can be used to manufacture small
test coupons using automated layup. Experimental results from such a system could
then be used to evaluate models that link the deformation of plies during layup to
microstructural features, such as voidage.
4.4 Material research
Prepreg materials have historically been developed with mechanical performance
in mind and were then simply adapted for automated layup by developing specific ply
backing films, or slitting prepreg tape for AFP layup. Despite this, research on the use
of thermoplastic tape has illustrated the importance of tape uniformity, porosity and
interface properties on the quality of the final product in in-situ layup [102,103] and this
can be applied to thermoset layup. An improved understanding of the translation of the
initial prepreg microstructure into the final part is thus required. Material variability
needs to be reduced to achieve uniform properties at the slit-tape level, which is
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typically only 3.2 or 6.4mm wide. In most cases the dimensional and physical
tolerances between manual and automated layup are the same and only the backing and
tack specification are changed [24,50,56], which consequently leads to unreliable layup.
For example, Figure 20 shows an image of slit tape for AFP layup with fuzzy edges.
This would lead to unscheduled downtime for AFP layup and could result in excessive
voidage in the dry fuzzy areas. To avoid this, slit tape needs to be prepared in the future
with high degrees of impregnation. Figure 21 shows a defect in a roll of ATL tape. This
area would need to be removed and laid outside of the part. Removing materials
wastage during layup is very time consuming and naturally has an excessively
detrimental effect on productivity. The most promising method of improving the
uniformity of the final prepreg is an improvement of the uniformity of the resin film that
is used during hot-melt processing. Further, computerised optical fault detection is
required to ensure that prepregging defects are detected during manufacture.
Another aspect of the prepreg layup process is the material tack. Ahn et.al [104]
used a compression-tension test on a stack of prepregs to measure the energy of
separation, which was linked to tack. They observed that prepreg tack was a bulk
property as well as surface-sensitive with viscoelastic behaviour that depended on
material as well as operating conditions. Later, this approach was extended to material
aging as well. It was observed that prepreg tack correlated with the glass transition
temperature and instantaneous temperature which was linked to both the increase in
wetting area as well as the change in resin viscosity [105]. More recently, this topic has
found new attention due to the impact tack can have on productivity, process reliability
and tow steering. Dubois, Le Cam and Béakou [106] used a probe tack test to measure
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various parameters influencing on a modern, high toughness prepreg. They observed an
increase in tack force with increasing hold-time, contact force, deformation rate and
humidity, while tack decreased with increasing temperature and outlife.
However, all the works previously explored use low deformation rates during
testing, which differ by one or two orders of magnitude from the deformation rates
found during high-speed layup. Crossley, Schubel and Warrior [107] thus introduced a
novel tack test which enabled testing at higher deformation rates. Their work
demonstrated a non-linear behaviour of prepreg tack as a function of layup temperature
and speed of deformation which should help to understand the development of defects
during layup further.
4.5 Layup modelling and simulation
This section will not address existing Computer Aided Manufacturing (CAM)
software, but rather discuss a more fundamental understanding of the effects of layup on
thermoset prepreg. This is important as currently, models for the layup of thermoset
prepreg that enable modelling of defects and their development do not exist.
Depending on the pressure, temperature, and contact time of the roller, some flow
can occur between the plies during layup, which may reduce interply-voidage and
improve laminate quality prior to cure [102]. Currently this interaction is not well
understood and further improvements in this area should be made. Lukaszewicz and
Potter [108] recently proposed a model for the compaction of thermoset prepreg during
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layup, which can be used to describe this interaction and to enable direct layup at high
quality, effectively reducing debulking instances [34]. Again, it has been demonstrated,
that an understanding of this interaction can improve ILSS and compressive strength by
50% [101].
Other aspects of the layup process that could be captured by modelling are the
development of wrinkles and bridging at geometric features, however it is likely that
these issues are not only related to the material and the processing conditions, but also
to the choice of system. As an example, flexible rollers are commonly used to conform
difficult ramps, but by using flexible rollers some chatter during layup inevitably occurs
which may then lead to wrinkling or bridging. Potential solutions to this would either
use a layup roller with tailored stiffnesses or uncouple the necessary flexibility of the
layup system from the layup element. Further, bridging over concave features or
crowning over convex features is often observed. Both may lead to wrinkling in the
final part, which can severely affect mechanical properties. If machine control is
inaccurate both types of defects can be linked to the amount of material that is available
on the head. However, even if it is assumed that material delivery is accurately
controlled these defects can occur due to the interpolation of geometric features in the
CNC program. Approaches are therefore necessary to ensure that the interpolation and
axis control result in the correct amount of material being available at any point during
layup.
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4.6 Functional integration
Returning to Figure 1, it is important to note that automated layup derives its
possible increases in productivity not only from automation of the manual operations,
but also from combining several serial tasks into a single or parallel operation. Future
layup systems will thus likely target automation and integration of more functions onto
the head, as well as higher productivity by controlling more tows, having less
downtime, or allowing the layup of high prepreg areal weight materials.
Additional functions feasible for integration on the manufacturing process are
tooling preparation and online inspection systems [109]. Systems that allow inline
quality control by optical means are already in use or in development, for example by
Ingersoll. Multiple robot interaction and synchronisation, improved layup kinematics,
and optimised CNC post-processing can deliver further gains in productivity for both
ATL and AFP. Synchronisation of multiple robots can greatly improve the layup of
large parts as several robots can work on different part areas and different stages of a
ply sequence. Adding more and more features to a single layup system will inevitably
result in reduced per task performance. The most promising approach is therefore the
combination of multiple robots into a single work-cell, where the robots either
cooperate to achieve tasks quicker, for example through reducing unproductive travel of
the individual units, or by equipping each robot for a specific task which can be carried
out more efficiently.
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5 Summary
ATL and AFP are finding more wide-spread adoption in a number of industries
due to potential reliability and economic improvements. ATL has been developed since
the 1970’s as an automated version of manual tape laying and offers high productivity
and reliability for simple or low complexity components. It is in particular highly
productive for large simple flat components, and able to handle high areal weight
materials with few modifications. Future developments in renewable energy, for
example rotor blade manufacture, will likely rely on ATL layup of low-cost, high-areal-
weight prepreg. Overall, potential productivity gains for ATL are limited, due to the
robust nature and long history of the technique.
AFP improves on ATL layup by allowing direct layup of more complex
components. In addition, material wastage rates are reduced and productivity for
aerospace components may be higher due to the unique cut, clamp, and restart
capability per tow. Since the 1980’s AFP has become a relatively mature process, which
also has greater potential for future improvements. Productivity improvements can be
expected from improved programming, reduction of secondary operations, reduction of
down-time and multiple robot interaction. Currently, AFP seems more suitable for
typical aerospace components and materials and modifications are necessary to enable
layup of wider and higher areal weight materials.
The automated layup systems we see today were developed by industrial machine
companies with either none or limited background in the composite industry. Currently
these companies are developing their composite expertise and tend to look for material
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solutions to address constraints in the manufacturing system. Material suppliers have
historically worked with composite users employing manual layup and have limited or
no expertise in the industrial machine industry and tend to look for machine
modifications to address current constraints. The design approaches and software
packages used by end-users to design components are often derived from manual layup
and/or are insufficiently integrated with the layup machines. This results in unnecessary
constraints on the machine and its capability.
By addressing the topics and future targets outlined within this paper, the
academic community will have an important role in the future of composites and
automated composite layup.
Acknowledgements
Studentship funding for D.H.-J.A. Lukaszewicz from Airbus Operations Ltd. is
gratefully acknowledged. The authors would like to thank Dr. K. Hazra, Dr. J. Etches
(University of Bristol) and M. Buckley (Airbus Operations Ltd.) for helpful discussions.
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References
[1] Grimshaw MN. Automated Tape Laying. Cincinnati: Cincinnati Machine, 2001.
[2] Evans DO. Fiber placement. Cincinnati: Cininnati Machine, 1997.
[3] Åström. Manufacturing of Polymer Composites. London, UK: Chapman& Hall;
1997.
[4] Campbell FC. Manufacturing processes for advanced composites. Oxford, UK:
Elsevier Advanced Technology; 2004.
[5] Gutowski TG (ed). Advanced composites manufacturing. New York: John
Wiley & Sons, Inc.; 1997.
[6] Sloan J. ATL and AFP: Defining the megatrends in composite aerostructures.
High Performance Composites: Gardner Publications, 2008.
[7] Dorey. Carbon fibres and their applications. J Phys D: Appl Phys. 1987;20:245-
56.
[8] Grant C. Automated processes for composite aircraft structure. Ind Robot.
2006;33(2):117-21.
[9] Chitwood; Composite tape laying machine with pivoting presser member, Patent
4627886, 6th April 1971.
[10] Goldsworthy WB; Geodesic path length compensator for composite-tape
placement method, Patent US 3,810,805, 14th May 1974.
[11] Huber J. Automated lamination of production advanced composite aircraft
structures. SAE International Congress and Exposition. Detroit, Michigan, USA,
1981.
[12] Anon. MIL-HDBK-17-3F-Composite materials handbook.In: Volume 3F:
Departement of Defense; 2002.
[13] Krolweski S, Gutowski T. Effect of the automation of advanced composite
fabrication processes on part cost. Sampe J. 1987;23(3):21-6.
[14] Krolewski S, Gutowsi T. Economic comparison of advanced composite
fabrication technologies. 34th International SAMPE Symposium. Volume 34.
Covina, California, USA: SAMPE, 1989:329-40.
[15] Postier RA. Factory automation for composite structures manufacturing. Sampe
Quart. 1985;April:45-8.
[16] Eaton HL. Cost effective tape laying. 29th National SAMPE Symposium. Reno,
Nevada, USA, 1984.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
[17] Saveriano JW. Automated contour tape laying of composite materials. 16th
National SAMPE Technical Conference. Albuquerque, New Mexico, USA,
1984.
[18] Coad CL, Werner SM, Dharan CKH. Design of a composite four-axis robot for
prepreg layup. 29th National SAMPE Symposium. Reno, Nevada, USA, 1984.
[19] Stone KL. Automation in composite processing. 29th National SAMPE
Symposium. Reno, Nevada, USA, 1984.
[20] Albus JS. Research issues in robotics. 16th National SAMPE Technical
Conference. Albuquerque, New Mexico, USA, 1984.
[21] Wang EL, Gutowsi T. Laps and gaps in thermoplastic composites processing.
Compos Manuf. 1991;2(2):69-78.
[22] Meier RA. An advanced control system for composite material placement. 31st
International SAMPE Symposium. Covina, California, USA, 1986.
[23] Grone RJ, Grimshaw MN; Composite tape laying machine with pivoting presser
member, Patent US 4627886, 30 May 1985.
[24] Grone RJ, Schnell LR, Vearil L; Composite tape laying machine and method,
Patent US 4557783, 5 December 1983.
[25] Torres Martinez M; Torres Martinez, M., Tete enrubanneuse pour l'application
de bande en materiau composite, Patent EP 1097 799 A1, 9 May 2001.
[26] Lewis HW, Romero JE; Composite tape placement apparatus with natural path
generaton means, Patent US 4,696,707, 29.9.1987.
[27] Torres Martinez M; Tete pour l'application de bande de composite, Patent FR
2713213-A1, 30 November 1994.
[28] Grimshaw MN; Machine for applying composite and presser assembly therefor,
Patent EP 0371289-A1, 8 November 1989.
[29] Grimshaw MN, Hecht JR; Method and apparatus for laying composite material,
Patent EP 0644040-A1, 8 November 1994.
[30] Olsen HB, Craig JJ. Automated composite tape layup using robotic devices. In:
IEEE International Conference on robotics and automation. Atlanta, Georgia,
USA: 1993.
[31] Goel A. Economics of composite material manufacturing equipment [BSc
Thesis]. Cambridge, MA: Massachusetts Institute of Technology, 2000.
[32] Foley MF. Techno-economic analysis of automated composite manufacturing
techniques. 22nd International Sampe Technical Conference. Boston,
Massachusetts, USA, 1990.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
[33] Zaffiro JA; Cincinnati Milacron Inc., Control of radiation heating system for
thermoplastic composite tape, Patent 5177340, 5 January.
[34] Benda BJ, Stump KH. A case study of contoured tape laying. American
Helicopter Society 52nd Annual Forum. Washington D.C., USA, 1996.
[35] Sarazin H, Springer GS. Thermochemical and mechanical aspects of composite
tape laying. J Compos Mater. 1995;29:1908-43.
[36] Grove SM. Thermal modelling of tape laying with continous carbon fibre-
reinforced thermoplastic. Composites. 1988;19(5):367-75.
[37] Torres Martinez M; Head for application of carbon-fibre strips and application
method, Patent WO 2008/020094 A1, 21 February 2008.
[38] Tillement PAH, Charra SRE; Device for separating and discharging trimmings
cut in a pre-impregnated strip, Patent Wo 2008/135645 A1, 13 November 2008.
[39] Tillement PAH, Charra SRE; Composite lay-up head with a retractable device
for separating a prepreg from its support tape, Patent WO 2008/142273 A2, 27
November 2008.
[40] Larberg YR, Åkermo M. On the interply friction of different generations of
carbon/ epoxy prepreg systems. Compos Part A-Appl S. 2011;42(9):1067-74.
[41] Gutowski TG, Dillon G, Chey S, Li H. Laminate wrinkling scaling laws for
ideal composites. Composite Manufacturing. 1995;6(3-4):123-34.
[42] Kau. Automated fabrication of grpahite-epoxy composites. 32nd International
SAMPE Symposium. Anaheim, California, USA, 1987.
[43] Thomas J. The A380 Programme - The big task for Europe's aerospace industry.
Air & Space Europe. 2001;3(3/4):35-9.
[44] Hinrichsen J, Bautista C. The challenge of reducing both airframe weight and
manufacturing cost. Air & Space Europe. 2001;3(3/4):119-21.
[45] . Torreslayup - Tape Layer Machine. Volume
2010, http://www.mtorres.es/pdf/torreslayup.pdf, 2010.
[46] Land IB. Design and manufacture of advanced composite aircraft structures
using automated tow placement [Master Thesis]. Cambridge, MA, USA:
Massachusetts Institute of Technology, 1996. 91 p.
[47] Colton JS, Baxter J, Behlendorf J, et al. The automation of the lay-up and
consolidation of PEEK/Graphite fiber composites. 32nd International SAMPE
Symposium. Anaheim, California, USA, 1987.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
[48] Lamontia MA, Gruber MB, Waibel BJ. Conformable Compaction System used
in Automated Fiber Placement of Large Composite Aerospace Structures.
Proceedings of the 23rd Sampe Conference. Paris, France, 2002.
[49] Knight BW. The technique of filament winding. Composites. 1970;June:228-33.
[50] Evans DO, Vaniglia MM, Hopkins PC. Fiber placement process study. 34th
International SAMPE Symposium. Covina, California, USA, 1989:1822-33.
[51] Bullock DE. Automated prepreg tow placement for composite structures. 35th
International SAMPE Symposium. Anaheim, California, USA, 1990.
[52] Barth JR. Fabrication of complex composite structures using advanced fiber
placement technology. 35th International SAMPE Symposium. Anaheim,
California, USA, 1990:710-20.
[53] Blom AW, Lopes CS, Kromwijk PJ, Gurdal Z, Camanho PP. A Theoretical
Model to Study the Influence of Tow-drop Areas on the Stiffness and Strength
of Variable-stiffness Laminates. J Compos Mater. 2009;43:403-25.
[54] Croft K, Lessard L, Pasini D, Hojjati M, Chen J, Yousefpour A. Experimental
study of the effect of automated fiber placement induced defects on performance
of composite laminates. Compos Part A-Appl S. 2011;42:484-91.
[55] Enders ML, Hopkins PC. Developments in the fiber placement process. 36th
International SAMPE Symposium. San Diego, California, USA, 1991:778-90.
[56] Evans DO. Design considerations for fiber placement. 38th International
SAMPE Symposium. Anaheim, California, USA, 1993:170-81.
[57] Measom R, Sewell K. Fiber placement low-cost production for complex
composite structures. American Helicopter Society 52nd Annual Forum.
Washington D.C., USA, 1996.
[58] Pasanen MJ, Martin JP, Langone RJ, Mondo JA. Advanced composite fiber
placement: process to application. Schenectady, NY: Automated Dynamics
Corporation, 1997.
[59] Gruber MB, Lamontia MA. Automated fabrication processes for large
composite aerospace structures: a trade study. 46th International SAMPE
Symposium. Volume 46. Long Beach, California, USA, 2001:1986-97.
[60] Mantell SC, Wang QL, Springer GS. Processing thermoplastic composites in a
press and by tape laying - experimental results. J Compos Mater.
1992;26(16):2378-401.
[61] Mantell SC, Springer GS. Manufacturing process models for thermoplastic
composites. J Compos Mater. 1992;26(16):2348-77.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
[62] Bourban P, Bernet N, Zanetto J, Manson J. Material phenomena controlling
rapid processing of thermoplastic composites. Compos Part A - Appl S.
2001;32(8):1045-57.
[63] Hulcher AB. Processing and testing of thermoplastic composite cylindrical
shells fabricated by automated fiber placement. 47th International SAMPE
Symposium. Long Beach, California, USA, 2002.
[64] Lamontia MA, Gruber MB. Limitations on mechanical properties in
thermoplastic laminates fabricated by two processes: Automated Thermoplastic
Tape Placement And Filament Winding. 26th SAMPE Europe Conference.
Paris, 2005.
[65] Ranganathan S, Advani SG, Lamontia MA. A nonisothermal process model for
consolidation and void reduction during in-situ tow placement of thermoplastic
composites. J Compos Mater. 1995;29(8):1040-62.
[66] Pitchumani R, Ranganathan S, Don R, Gillespie J, Lamontia M. Analysis of
transport phenomena governing interfacial bonding and void dynamics during
thermoplastic tow-placement. Int J Heat Mass Tran. 1996;39(9):1883-97.
[67] Pitchumani R, Gillespie J, Lamontia M. Design and optimization of a
thermoplastic tow-placement process with in-situ consolidation. J Compos
Mater. 1997;31(3):244-75.
[68] Tierney J, Gillespie J. Modeling of heat transfer and void dynamics for the
thermoplastic composite tow-placement process. J Compos Mater.
2003;37(19):1745-68.
[69] Funck R, Neitzel M. Improved thermoplastic tape winding using laser od direct-
flame heating. Composite Manufacturing. 1995;6(3-4):189-92.
[70] Rosselli F, Santare M, Guceri S. Effects of processing on laser assisted
thermoplastic tape consolidation. Compos Part A - Appl S. 1997;28(12):1023-
33.
[71] Pistor C, Yardimci M, Guceri S. On-line consolidation of thermoplastic
composites using laser scanning. Compos Part A - Appl S. 1999;30(10):1149-
57.
[72] Goodmann DL, Weidman DJ, Bryne CA, et al. Automated tape placement with
in-situ electron beam cure: a viable process. 46th International SAMPE
Symposium. Long Beach, California, USA, 2001:2127-39.
[73] Burgess JW, Wilenski MS, Belvin HL, Cano RJ, Johnston NJ. Development of a
cure-on-the-fly automated tape placement machine for electron curable prepregs.
46th International SAMPE Symposium. Long Beach, California, USA,
2001:2024-36.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
[74] Grant C, Martin J. Automated processing technology for composites: Current
status and vision for the future. 48th International SAMPE Symposium. Long
Beach, California, USA, 2003.
[75] Grant CG. Fiber placement process utilization within the worldwide aerospace
industry. 45th International SAMPE Symposium. Long Beach, California, USA,
2000:709-20.
[76] Torres Martinez M; Faserstreifenverbinder fuer Bandwickler, Patent DE 10
2008 010 424 A1, 2nd October 2008.
[77] Oldani T. Increasing Productivity in Fiber Placement Processes. SAE
Aerospace Manufacturing and Automated Fastening Conference & Exhibition.
North Charleston, South Carolina, USA, 2008.
[78] Calawa R, Nancarrow J. Medium wave infrared heater for high-speed fiber
placement. SAE Aerofast. Los Angeles, California, USA, 2007.
[79] Hamlyn A, Hardy Y; Fibre application machine with tool changing system,
Patent WO 2008/149004 A1, 11th December 2008.
[80] Hamlyn A, Hardy Y; Fibre application machine with fibre supply flexible tubes,
Patent WO 2008/122709-A1, 28 February 2007.
[81] Shirinzadeh B, Alici G, Foong CW, Cassidy G. Fabrication process of open
surfaces by robotic fibre placement. Robot Com-Int Manuf. 2004;20(1):17-28.
[82] Shirinzadeh B, Cassidy G, Oetomo D, Alici G, Ang MH. Trajectory generation
for open-contoured structures in robotic fibre placement. Robot Com-Int Manuf.
2007;23(4):380-94.
[83] Izco L, Isturiz J, Motilva M. High speed tow placement system for complex
surfaces with cut / clamp / & restart capabilites at 85m/min (3350IPM). SAE
Aerospace manufacturing and automated fastening conference and exhibition.
Toulouse, France, 2006.
[84] DeVlieg R, Jeffries K, Vogeli P. High-speed fiber placement on large complex
structures. SAE Aerofast. Los Angeles, California, USA, 2007.
[85] Airbus SAS. Boeing 787 - Lessons learnt.
http://www.slideshare.net/aergenium/b787-lessons-learnt-presentation, 2008.
[86] Kisch RA, Vogeli P, Jeffries K, DeVlieg R; End effector and methods for
contructing composite membranes, Patent US 2008/0295954 A1, 4th December
2008.
[87] Debout P, Chanal H, Duc E. Tool path smoothing of a redundant machine:
Application to Automated Fiber Placement. Computer-Aided Design.
2011;43(2):122-32.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
[88] Lukaszewicz DH-JA, Weaver PM, Potter K. An automated ply collation system
for material and process development. SAMPE Seico. Paris, France, 2010.
[89] Lukaszewicz DH-JA. Optimisation of high-speed automated layup of thermoset
carbon-fibre preimpregnates [Ph.D. Thesis]. Bristol: University of Bristol, 2011.
[90] Morey B. Automating composites fabrication. Manufacturing Engineering.
2008;140(4): http://www.sme.org/cgi-bin/find-
articles.pl?&ME08ART28&ME&20080415&&SME&.
[91] Alici G, Shirinzadeh B. Enhanced stiffness modeling, identification and
characterization for robot manipulators. IEEE Transactions on Robotics.
2005;21:554-64.
[92] Shirinzadeh B. Robotic fibre placement process planning and control. Assembly
Automation. 2000;20:313-20.
[93] Alici G, Shirinzadeh B, McConville A, Foong CW, Ang M. A mathematical
model for a pneumatically actuated robotic fibre placement system. Robotica.
2002;20:545-51.
[94] Wiehn MP, Hale RD. Low cost robotic fabrication methods for tow placement.
47th International SAMPE Symposium. Long Beach, California, USA, 2002.
[95] Moon RS, Johnson CC, Hale RD. Nondestrcutive evaluation and mechancial
testing of steered fiber composites. 47th International SAMPE Symposium.
Long Beach, California, USA, 2002.
[96] Beakou A, Cano M, Le Cam J-B, Verney V. Modelling slit tape buckling during
automated prepreg manufacturing: a local approach. Compos Struct.
2011;93(10):2628-35.
[97] Potter K. In-plane and out-of-plane deformation properties of unidirectional
preimpregnated reinforcement. Compos Pt A - Appl Sci Manuf.
2002;33(11):1469-77.
[98] Lukaszewicz DH-JA, Weaver PM, Potter K. The impact of processing
conditions on the final part quality in automated tape deposition technologies.
Sampe Seico. Paris, France, 2009.
[99] Lukaszewicz DH-JA, Weaver PM, Potter K. An empirical model for the
automated deposition of thermoset composite. ACS - 24th Technical Conference
Newark, Delaware, USA, 2009.
[100] Lukaszewicz DH-JA, Potter KD. The internal structure and conformation of
prepreg with respect to reliable automated processing. Compos Part A-Appl S.
2011;42:283-92.
[101] Eales J, personal communication. 2011.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
[102] Lamontia MA, Gruber MB, Tierney JJ, Gillespie Jr. JW, Jensen BJ, Cano RJ. In
situ thermoplastic ATP needs flat tapes and tows with few voids. 30th
International SAMPE Europe Conference. Paris, France, 2009.
[103] Khan MA, Mitschang P, Schledjewski R. Identification of Some Optimal
Parameters to Achieve Higher Laminate Quality through Tape Placement
Process. Adv Polym Tech. 2010;29(2):98-111.
[104] Ahn KJ, Seferis JC, Pelton T, Wilhelm M. Analysis and characterization of
prepreg tack. Polym Comp. 1992;13(3):197-206.
[105] Ahn KJ, Peterson L, Seferis JC, Nowacki D, Zachmann HG. Prepreg aging in
relation to tack. J Appl Polym Sci. 1992;45(3):399-406.
[106] Dubois O, Le Cam JB, Béakou A. Experimental analysis of prepreg tack. Exp
Mech. 2009.
[107] Crossley RJ, Schubel PJ, Warrior NA. The experimental characterisation and
investigation of prepreg tack. Proceedings of ICCM-18. Edinburgh, 2009.
[108] Lukaszewicz DH-JA, Potter KD. Through-thickness compression response of
uncured prepreg during manufacture by automated layup. Proc IMechE, Part B:
J Engineering Manufacture. 2011; DOI: 10.1177/0954405411411817.
[109] Bannister M. Challenges for composites into the next millennium - a
reinforcement perspective. Compos Part A - Appl S. 2001;32(7):901-10.
[110] Lukaszewicz DH-JA, Potter K. Modelling of automated layup processes for
improved efficiency and sustainability. In: Sampe Setec. Leiden, Netherlands:
2011.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
Figure 1: Overview of annual publications on ATL and AFP, with Filament winding
added in an insert graph as reference.
Figure 2: Drawing of an ATL delivering slit tape over a curved surface [10].
Figure 3: Drawing of an early composite components manufacturing system from [11].
The material is moved from left to right and material is applied to a mould using a
bespoke tape layup head.
Figure 4: Schematic of an ATL layup head, according to Ästrøm [3].
Figure 5: Picture of an ATL layup head with relevant functional groups labelled. The
prepreg material supply is not shown.
Figure 6: Example of a gantry type ATL laying onto a female tool [45].
Figure 7: Column Type ATL laying 300mm wide tape onto a vertical tool.
Figure 8: Integrated slitting unit with individual tow pay-out from [10]. This can be
interpreted as the first AFP concept.
Figure 9: Schematic of an AFP head [2].
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
Figure 10: AFP layup of steered tows on a flat mould [53].
Figure 11: Ingersoll gantry-type AFP laying into a female mould [77].
Figure 12: Theoretical productivity comparison for ATL and AFP layup of a flat
laminate as a function of part size, from [89].
Figure 13: Theoretical productivity comparison for ATL and AFP layup of a flat
laminate as a function of maximum layup speed, from [89].
Figure 14: Overview of the most common tow steering defect.
Figure 15: Illustration of Laps and Gaps during AFP layup.
Figure 16: Effect of tow drop angle T0 and to drop area on the stiffness reduction of a
panel with steered tows, from [53].
Figure 17: Effect of tow drop angle T0 and to drop area on the strength reduction of a
panel with steered tows, from [53].
Figure 18: ILSS for a laminate manufactured at different layup temperatures and
subsequently oven-cured [110].
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
Figure 19: Void content, measured by light microscopy, for the ILSS samples from
Figure 18, from [110].
Figure 20: Example of fuzzy edges at the edge of a roll of slit tape.
Figure 21: Example of a common defect in ATL grade prepreg.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
Table 1: Overview of AFP applications in 2000, from [75]. AFP was mostly used for
military applications.
Table 2: Overview of the effect of various layup defects on the tensile, compressive, in-
plane shear, open-hole tension (OHT) and open-hole compression (OHC) strength of
AFP laminates, according to [54].
Aircraft program Components made by AFP
F-18 E/F Inlet Duct, Aft Center Side Skins, Stabilator Skins
C-17 Globemaster Fan Cowl Doors, Landing Gear Pods
Bell Agusta 609 Fuselage Panels
V-22 Osprey Aft fuselage, Side Skins, Drag Angle, Sponsons, Grips
Premier I Fuselage Sections
Hawker Horizon Fuselage Sections
F22 Raptor Stabilator Pivot Shaft
Sea Launch Payload Fairing