FP given by an autoclave which can

FP

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

INTRO

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Overview of some manufacturing processes available for composites

 

1)    PREPREG MOULDING

Textures and filaments are pre-impregnated by the
materials maker, under warmth and weight or with dissolvable, with a
pre-catalysed resin. The impetus is generally inert at encompassing
temperatures giving the materials a little while, or here and there months, of
valuable life when defrosted. However, to elongate the life of the materials
are put away frozen, the resin is typically close to encompassing temperatures,
thus the prepregs have a gooey feel to them. Unidirectional materials are held
together by the resin alone. The prepregs are laid up by hand or machine onto a
form surface, vacuum bagged away and after that warmed to commonly 120-180°C.
This enables the resin to at first reflow and in the end to cure. Extra weight
for the shaping is typically given by an autoclave which can apply up to 5
atmospheres to the laminate.

Typical Applications: Aircraft structural components, F1 racing cars,
sporting goods such as tennis racquets and skis. (Gurit, c2018)

 

2)    AUTOMATIC
TAPE LAYING

Over the time
Airbus has industrialized from manual tape laying to computerized processes for
optimization and assurance of processes. Automated Tape Laying (ATL) that involves placing a single end of fibre tape or fabric
either binder infused or resin impregnated, onto a flat to slightly bended
surface. It is regularly utilized for parts with exceedingly complex structures
or angles. The framework is primarily used for prepreg carbon fibre layup. This
innovation became out of the machine apparatus industry and have seen broad use
in the make of the fuselage, wingskin boards, wingbox, tail and different
structures on the imminent Boeing 787 Dreamliner and the Airbus A350 XWB. In
the assembling of aeronautical parts, the work cost and the piece rate can be
fundamentally decreased by utilizing ATL although extensive venture is required
for these. There are a lot of most recent outlines of Automatic Tape Layer
Machines created by producers that gives the best compacting outcomes, keeping
away from any debulking operation while manufacturing a section for ideal
result. (Staff,
2016)

Typical Applications: aerospace
industry

3)    HAND LAYUP

hand layup which ordinarily comprises of putting layers,
called plies of either dry textures, or fabric pre-impregnated with resin
(prepreg), by hand onto an instrument to shape a component stack. Resin is
connected to the dry plies after layup is finished (e.g., by methods for resin
implantation). In a variety known as wet layup, each ply is covered with resin
and is compacted after it is fixed.

Typical Applications: Standard wind-turbine blades, production boats,
architectural mouldings. (Gurit,
c2018)

 

4)    VACUUM
BAGGING

This procedure is done for improving the solidification
of the laminate via fixing a plastic film over the entire wet laid-up overlay
and the instrument, followed by the extraction of the sum air exhibiting under
the bag by a vacuum pump which can supply up to one atmosphere of pressure in
order to cement the part

Typical
Applications: Large, one-off cruising boats, racecar components,
core-bonding in production boats. (Staff, 2016)

5)    CURING

Curing includes warming the
epoxy until the point when a compound response starts.

A few curing techniques are accessible. The
most fundamental is just to permit cure to happen at room temperature. This
response gives extra warmth and proselytes the epoxy into its final vulnerable
phase. The epoxy holds the carbon fibre’s set up with respect to each other and
gives some compressive quality while the fibres give tensile strength. One of
the other vital focal points of composites is that they can be amassed into
vast structures by bonding which is easier as opposed to riveting. (Dave Dickson, 2007)

The
concurring technique: preformed uncured parts are set surface to surface on a mould,
compressed with a plastic vacuum bag, and set in an extensive weight vessel called
an autoclave. Where they are exposed to high pressure and temperature while the
epoxy cures. The co-bonding method: preformed and pre-cured parts are stuck
together with epoxy, and the epoxy joints are cured utilising the vacuum bag
and autoclave technique. (Dr
guillaume kister, no date)

6)    PULTRUSION

Pultrusion
is a nonstop procedure utilised principally to deliver long, straight states of
consistent cross-area. Pultrusion is like extrusion aside from that the
composite material is pulled, instead of pushed, through a die. Pultrusions are
delivered utilising constant reinforcing fibres called ‘roving’ that give
longitudinal fortification, and transverse support as fabric materials. These
reinforcements are resin impregnated by going through a resin wet-out station;
and for the most part formed inside a controlling, or preforming, framework.
They are then in this way moulded and cured through preheated dies.

Typical Applications: Beams used in roofs and
bridges, framework. (Jeff jose, 2015)

7)    ADDITIVE
MANUFACTURING

Otherwise called 3D
printing, this later type of composite part creation came out of endeavours to
decrease the expenses in the plan to-model period of item advancement, focusing
especially at the material-, work and time-taken for toolmaking. Additive
manufacturing is a stage change in the advancement of quick prototyping ideas
that were presented over 20 years back, a gathering of comparable, yet
independently created additive creation innovations — that is, computerised
forms that collect a three-dimensional (3D) component from a progression of
two-dimensional (2D), cross-sectional layers of specific materials.

All additive
creation systems start with a CAD drawing. Strong model CAD information is
changed over, utilising exceptional programming, into a well organised 3D data
as a get together of planar triangles. Ordinarily restrictive, programming at
that point is utilised to “slice” this virtual picture into thin 2D
cross-sectional examples. This layer information is utilised to train additive
manufacture apparatus as it fabricates a 3D physical model by
“stacking” the 2D slices. (Staff, 2016)

Typical Applications: architecture, medical, dental, aerospace,
automotive, furniture and jewellery (J F Isaza and & C Aumund-Kopp, 2014)

 

8)   
FILAMENT
WINDING

Filament
winding is a procedure for manufacturing composite materials in which nonstop
strands, either already impregnated with a matrix material or impregnated while
winding, are twisted by a long, round and hollow device called a
“mandrel” which is suspended on a level plane between end supports,
while a fibre application instrument called a “head” moves forward
and backward along the length of a pivoting mandrel, putting fibre onto the
device in a foreordained design. Simultaneously, the filaments are
“inter-woven” to frame a standard sheet, which gets a better quality
from the fibre than from any other composite manufacturing methods. High-speed,
accurate setting of the reinforcement in pre-determinate design is the premise
of the filament winding procedure. It is a persistent manufacture technique
that can be profoundly mechanised and repeatable, with generally low material
expenses. These days computer-controlled filament-winding machines are easily
accessible. (Jeff
jose, 2015)

Typical
Applications: Chemical
storage tanks and pipelines, gas cylinders, fire-fighters’ breathing tanks
(Gurit,
c2018)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CASE STUDY OF AIRBUS A350-XWB CENTRE FUSELAGE

Ø 
INTRODUCTION

A fuselage
forms the main body of an aircraft for the making which composites are taking over
metals. The Airbus A350 XWB consists of three long sections: forward, aft and
centre fuselage all made up of four large composite
panels. In any case, the centre fuselage is the longest of the three, which
joins the fuselage to the wings through lateral intersections. It is developed
from six sizeable composite boards made by Spirit AeroSystems (Wichita, Kan.).
Fabricated at Spirit’s office in the U.S. (Kinston, N.C.)

Spirit’s
plan uses “smart manufacturing” practices a physical format that
enhances work process and the most recent automated fibre placement (AFP)
technology to expand profitability. Substantial segments are developed from
more straightforward, all the more effortlessly fabricated subcomponents that
are additionally less demanding to repair and keep up.

Ø 
MATERIALS

The Airbus
A350 XWB utilises Carbon Fibre Reinforced Plastic (CFRP) to make the composite
fuselage. It has properties like high strength to weight ratio, high tensile
strength and high elastic modulus similar to steel. Carbon fibres are produced
using polymeric resins, carbon fibres, rayon or petroleum pitch. These
materials are natural polymers. The correct structure shifts from one
organisation to another. During the assembling procedure, an assortment of
gases and fluids are utilised. Some of these materials are intended to react
with the fibre to accomplish a particular impact.

The carbon
fibre raw material Polyacrylonitrile (PAN) normally costs around $21.5/kg, with
a conversion efficiency of just 50%. The raw materials have a great availability
but the manufacturing and designing processes are very expensive. Advancement in
manufacturing processes are done like developing highly reactive resins to
reduce cycle time for cost reduction.

Ø 
DESIGN

Airbus
selected vast fuselage boards, rather than unitising fuselage barrel segments,
since they can be custom fitted according to their laminate arrangement,
thickness and the load each piece of the airframe has to take. This empowers a
fuselage upgraded for better performance and weight. The utilisation of less,
longer areas additionally implies less joints that are said to be better put
for load and weight streamlining. The Boeing 787’s fuselage utilised four
shorter, one-piece composite barrels. The Airbus selected outline is required
to maintain a strategic distance from the fit issues Boeing had when it joined
the initial 787 barrels made with very different tooling approaches. The A350’s
composite boards join an external copper work to deal with the immediate
impacts of lightning, passing the electrical current around the fuselage
innocuously. This versatility keeps away from added structure related with
electrical structure network (ESN) components which would include more weight
that would balance the light weighting pro of a CFRP fuselage. Subsequently,
the six gathered segments of the centre fuselage, at 19.7m long and 6.7m in
diameter, will measure a approx. 4,082 kg.

Ø 
MANUFACTURING

The centre fuselage is the largest and the most complex
component of the aircraft. As the centre fuselage is to be connected with the
wing there are two lateral
junction panels with both convex and concave curvatures, which provide an
aerodynamic fairing and structural connection to the all-composite wingbox. The
manufacturing method used for making this component is automated
fibre placement (AFP) which is a common process for manufacturing large
components. This technique
enables complex geometries to be produced. The manufacture of section begins
with an Electroimpact
Inc. (Mukilteo,
Wash.) S-15 dual-head AFP machine that was designed for these large structures.
The machine lays up Hexply M-21E
carbon fibre/toughened epoxy prepreg from Hexcel(Stamford, Conn.) onto a male Invar tool.

·      AUTOMATED
FIBRE PLACEMENT (AFP)

The process optimises the reinforcement lay-up, close
control of process parameters and minimize the number of defects. An
automated fibre placement machine applies tows (of 3.175 mm to 12.7 mm width), in the
form of a ribbon of unidirectional prepreg with fibres in either thermosetting
or thermoplastic matrix onto the surface of a mould through a placement head.
 In order to obtain the required dimensions, the tape placement is
optimized, controlling the orientations and lengths of the tapes to limit
defects (gaps and overlaps). The AFP process requires pre-impregnated
tapes, as the material is heated locally. The lack of tack and drape of most
thermoplastic prepregs is a drawback. In general, after tape lay-up by
AFP components are consolidated in an autoclave to minimize defects.

MTorres supplied Spirit’s two 5m/16.4-ft tall columnar ultrasonic (UT)
inspection machines

to achieve simultaneous inspection of inner and outer skins for each
fuselage panel. Most of the frames are composite, but a few are aluminium
to support the electrical structure network.

Ø 
ISSUES IN DESIGNING
AND MANUFACTURING COMPOSITE FUSELAGE

Metal-to-composites interfaces

Damage tolerance of crown, keel, and side panel

Basic detail and assembling cost

The high temperature thermoplastic polymers used in
aeronautical structures are not suited to AFP with natural fibres.

Development of joints for major panel splices

Ø 
PROPOSED
SOLUTIONS

Adhesive bonding method shows potential to join the
panels with other components.

Hybrid laminates could be used in order to achieve a
better fatigue resistance.

Biocomposite components can be put into manufacturing
according to aerospace industry’s specifications.

 

 

   

 

 

 

 

 

 

 

 

 

 

 

Ø 
CONCLUSION

the
sensitivity of these polymers to the temperature, both structural and
biochemical degradation

Airbus
has opted to clothe a pre-fabricated fuselage skeleton with large carbon fibre
composite panels. This less radical solution reduces risk, says Airbus, while
also having the advantage that panel properties can be optimised to their
locations in the fuselage (whether crown, belly or sides) with resultant weight
saving. Other benefits include easier handling, less expensive autoclaves and
the fact that having a panel fail at post-manufacture inspection for any reason
is less of a setback than losing a complete barrel.

CASE STUDY OF EUROFIGHTER TYPHOON RADOME

“If you lost the radome, you’d lose
the aircraft” -unknown

Ø 
INTRODUCTION

Eurofighter Typhoon is the world’s most
advanced swing-role combat aircraft. An aircraft radome is a dome or a structure shielding radar
hardware and produced using material transparent to radio waves, particularly
one on the external surface of an aircraft. Eurofighter’s radome is a complex
structure manufactured to close tolerances. Eurofighter’s radome is a complex
structure manufactured to close tolerances. It includes layers of frequency-selective
surface (FSS) materials, comprising metallic micro-arrays that absorb all
frequencies outside the band of the aircraft’s own radar. The radome must
remain transparent to the radar to reduce the Typhoon’s frontal radar
cross-sectional area and hence its detectability. Jenoptik is a leading
manufacturer for making civil and defence aircraft radomes who have
manufactured Eurofighter Typhoon’s Radome for Airbus Group and BAE Systems.

Ø 
MATERIALS

The 2.30-meter-long
radome is made from fibre-glass-reinforced plastic and forms the tip of the
aircraft. It acts as a cover for the sensitive radar system behind it and undergoes
radar-electrical optimisation so that the radar signals can be received and
transmitted without distortion. fibre-glass-reinforced plastic is made from extremely fine fibres of glass,
resins and fillers. It costs approx. $10 per square metre. It has properties like good heat resistance,
high insulating properties, high tensile strength and elastic modulus.

Ø 
DESIGN

Radome design very requires
special knowledge and techniques and the use of proper tools and materials as
due to the essential properties that a radome needs to bare such as Transmissivity
(he ability of a radome to pass radar energy through it), Reflection (the
return or reflection of the outgoing radar energy from the radome back into the
antenna and waveguide system), Diffraction (the bending of the radar energy as
it passes through the radome).Radomes suffer ultra-high temperature (1500-2000 °C)
which is also a huge challenge for radome material.

Ø  The design

Ø  considerations for the radome are

Ø  The design

Ø  considerations for the radome are

Ø  The design

Ø  considerations for the radome are

Ø  The design

Ø  considerations for the radome ar

High performance radar radomes are very
precisely constructed and sometimes the slightest change in their physical
characteristics, such as excessive layers of paint, can adversely affect radar
system performance. All repairs to radomes, no matter how minor, should return
the radome to its original or properly altered condition, both electrically and
structurally. An improper minor repair can eventually lead to an expensive
major repair.

Ø 
MANUFACTURING

The Eurofighter Typhoon’s Radome is
made of GRP (Glass Reinforced Plastic) which helps to have overall economy and
weight reduction. It weighs approx. 65 kgs. The
most common process used to manufacture fibreglass radome is Pultrusion. The process
is great for producing components that need to be light weight, excellent
performing through the waves (wave transmitting rate is as high as 98%), shape
and size diversity, smoothly adapting to a variety of harsh environment and
other characteristics, and this process have been widely used in aerospace.
The glass fibre rovings, stitch continuous polyester as reinforcing material,
and unsaturated polyester resin (or vinyl resin) thermosetting plastic products
matrix materials by pultrusion compounded high temperature moulding equipment,
can be carried out according to the requirements of the surface of the paint
coating.

To achieve repeatability between production units, manufacturers employ
an automated fine-tuning system. This corrects the radome electrical thickness
at 4000 points across the entire surface before it goes onto electrical
acceptance. These parts
can also be oven-cured at temperature up to 400°F or in autoclaves, which
require high pressure cures at high temperatures.

Ø 
ISSUES IN DESIGNING
AND MANUFACTURING RADOMES

Poor
fabrication techniques

Patches
formed of different thickness

Abrupt
changes in cross-sectional areas

Poor
bonding of skin to core

Color
Difference in Pultrusion process: Heating points will lead to uneven shrinkage
and the color difference (also known as color transfer) 

For performance purposes, it is critical to
maintain these radomes in their original condition.

The materials are not nearly as critical to
the radome’s transparency to radar as the thickness of the wall and the
orientation of the materials used. 

one of the biggest problems with radomes is
moisture ingression

 

 

 

 

Ø 
PROPOSED
SOLUTIONS

Instead of constant manual inspections during
the manufacturing like checking the symmetry to avoid component bending that
could lead to future failure of the product or, automated testing methods can
be developed that can be placed between the manufacturing belts to check
factors like symmetry, temperature, resin mixture ratio, colour of the component.
Especially a very continuous process like Pultrusion can be intervened by a set
of automated testing equipment between the production stages in order to
improve the quality of the overall process and to as many unqualified products
at the end of the process.

maintenance personnel have perceived the
radome as simply an aerodynamic housing that goes on the front of the aircraft.
As a result, they often wrongly perceive that all repairs that qualify from a
structural aspect are acceptable. Technicians need to realize that the radome
needs special attention and that industry needs and requirements are changing.

Advancement in moisture detectors can
be made to avoid moisture ingression problems/moisture absorbing elements can
be added to the resin while manufacturing.

 

Ø 
CONCLUSION