ROHIT as there is moisture absorption takes

 

ROHIT
SALVE1, R. S. DALU2

 

1P.G. Student, M.
Tech. (production Engineering), Government College of Engineering, Amravati.
(M.S.), India.

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2Assosiate
Professor, Department of Mechanical Engineering, Government College of
Engineering, Amravati. (M.S.), India.

 

Email: [email protected], [email protected]

 

 

Abstract:The use of composite materials is increasing day by day, especially in aircraft
structural parts and in different aerospace applications. There is wide scope
to study,to research the properties and performance of different composite
materials for proper selection of specific material for desired application.
Epoxy Composite Materials get affected by moisture as there is moisture
absorption takes place. This paper presents a review of FRC materials such as
CFRP, GFRP and Aramid Fiber reinforced polymer composite materials used in
aerospace applications and their performance evaluation. This study involves
water absorption test, hardness test and a Durometer to measure the depth of
the indentation in the material. Tests evaluation for the specimen is taken, before
and after absorption of moisture. From the result, the comparison of weight,
hardness, tensile strength, compressive strength of different composite
materials is evaluated.

 

Indexterms:Composite
Materials, CFRP, GFRP, FRC, Aerospace Applications, Performance Evaluation.

 

 

1.
INTRODUCTION

Composites were first used for military
aircraft during World War II. Application of composite materials was generally begun only at aerospace
industry in 1970s, but nowadays after only three decades, it is developed in
most industries. 8

Nowadays, composite
materials are used in large volume in various engineering structures including
spacecrafts, airplanes, automobiles, boats, sports’ equipments, bridges and
buildings. Widespread use of composite materials in industry is due to the good
characteristics of its strength to density and hardness to density.8

Composite structures
have been becoming increasingly popularespecially in the aerospace industry
because of their unique properties, such as excellent strength/weight ratio,
corrosion resistance and a possibility of manufacturing elements of complicated
shapes.7

 

Composite materials are used more and
more for primary structures in commercial, industrial, aerospace, marine and
recreational structures.

Weight reduction resulting in fuel
efficiency gained by an aircraft is becoming increasingly important with
today’s soaring fuel prices. This can be happened only because of use of
composite materials.

Every year the aerospace industry uses
a higher proportion of advanced composite materials in the construction of each
new generation of aircraft.Use of Composite is expected to grow significantly
in the next 20 years.

 

1I.
LITRATURE REVIEW

 

F.Di
Caprio2016 The
present work illustrates an experimental-numerical correlation on
the static and dynamic tests of structural subcomponent of a cargo subfloor of
a civil aircraft. The activities were developed in the frame of a national research
program finalized to the development of numerical procedures able to improve
the absorption energy capability of aero-structural components. A composite
stanchion represented the test case. The good correlation obtained between
numerical and experimental results demonstrates that the adopted methodologies
are able to provide reliable results. Therefore, these numerical procedures
could be a starting point in the definition of numerical models to be used in
the framework of optimization tools. The optimization tools aim to improve
further the absorption energy capability of aeronautical components.

 

Sonell
Shroff2017 The use of progressive damage prediction in a finite element based
analysis has led to the conclusion that the failure in the composite panel initiates
due to matrix cracking in the skin in the vicinity of the grid interfaces. When
these matrix cracks propagate and reach ply interfaces, they cause
delaminations in the skin. The delaminations then cause loss of stiffness in
the region, ultimately overloading the grid-skin interface. Here, the normal
and shear stresses exacerbated by the moment due to the eccentricity between
the grid and the skin, lead to ultimate failure by grid-skin separation. This
failure sequence predicted by the FE model was reproduced in the tests. The awareness
of the failure sequence can now be incorporated in to design practices to delay
or prevent early failure such that the ultimate failure is also delayed.

 

WaqasAnwar2017 Structural dynamic characteristics are altered in
aero-elastically tailored design to achieve higher speed of aircraft without
flut-ter. This approach mostly compromises the stiffness of wing’s bending
mode. Decreased stiffness gives lower natural fre-quency and consequently
higher fatigue loading amplitudes during flight. Hence, the fatigue life and
damage tolerance of optimum tailored design becomes lower than the un-tailoreddesign.

b.In most of the test cases for aircraft/UAV wings or tails, dy-namic
instability is governed by the coupling of first torsional and the first
bending mode of vibration. Keeping in view the vulnerability of these modes,
the fibre direction in the plies may be equally aligned towards maximum
eigenvectors of both the modes. In this way, the stiffness of these modes may
be kept higher to prevent their flutter.

c.Fatigue
analysis of different aircraft parts is generally carried out using cycles count
from standard normal acceleration data of CG sensor. However, the vibration of
associated structures (wing or stores) must not be overlooked and the
additional stress reversals due to vibration of associated structures should
also be applied at higher CG load factors

d.Modal analysis simulations for fatigue load contributing struc-tures
may be carried out to estimate additional loading ampli-tudes for their
incorporation to combined cyclic loading spec-trum. Fatigue analysis is
generally performed to critical parts such as joints and spars near aircraft wing
root.

e.While performing the failure analysis simulations, Virtual Crack
Closure Technique may be adopted as the most conser-vative approach among other
fracture mechanics techniques.

f.While
incorporating final factor of safety, FE model calibration and correlation
factors may also be included for greater confi-dence in the design.

 

Andrzej Katunin2015 The analysis of
results was performed using the developed damage indices and has shown
comparatively good detectability of damage. This technique, however, cannot be
used as a NDT tool for precise damage characterization when using low number of
PZT transducers. The application of this technique is limited to rough
condition monitoring of composite structures and could be considered as an
initial step to the inspection of structures. The same structures were tested
using ultrasonic scanning and pulsed thermography. Both techniques have
revealed great effectiveness in detection and localization of introduced impact
damage. However, the thermographic technique was not able to detect the damage
of the lowest impact energy in the GFRP structure. Although ultrasonic technique
provides more detailed damage evaluation

 

 

 P Karthigeyan2017 The
results were that after dipping the composite material sample in the sea water
for seven days, its weight has been increased and its hardness was found to be
decreased from its previous hardness number. After heating process the sample
is subjected to acceleration. Sample is accelerated for nearly seventy two
hours, the weight has further increased and its hardness value found to further
decreased. Thus it shows that heating of this composite material causes
increase in weight and decrease in hardness. Also it has shown that this
composite material is 80% lesser weight than iron and it is 60% lesser weight
than aluminium. So, by employing this composite material in aircraft
industries, more than 800 kilogram of reduced for the construction of aero
planes.

 

LIU Wencheng2011The determination principles and methods
for material allowable value and design allowable value of the composite
Aircraft Structures, which referred to the design and certification process,
the methods for confirming material and design allowable values of composite
structures, the indication and application, test and statistical analysis methods
of material allowable value were clarified, and analyzing the method of
determining static strength, fatigue strength, damage tolerance and repair
design allowable value.

 

1.1
Composite Materials

One may define
a composite as material as a materials system which consists of a mixture or
combination of two or more micro constituents mutually insoluble and differing
in form and/or material composition.1

In modern
materials engineering, the term usually refers to a “matrix” material that is
reinforced with fibres. For instance, the term “FRP” (Fiber Reinforced
Plastic) usually indicates a thermosetting polyester matrix containing glass
fibres.8

In simple words
composite material is a combination of reinforcement and matrix.

 

1.2
Reinforcement

The
primary function of the reinforcement in composites reinforced with continuous
fibres is to provide strength and stiffness and to support the structural load.

 

1.3 Matrix

The
purpose of the matrix is to provide shape and form, to protect the fibres from
structural damage and adverse chemical attack, to distribute stress, and to
provide toughness. The matrix also stabilizes the composite against buckling in
compressive loading situations.8

 

2 Classifications of Composite
Materials

On
basis of matrix used in composite material it can be classified into three
types such as: Metal matrixcomposite, Ceramic matrix composite and Polymer
matrix composites.

Polymer,
Plastics matrix based composite materials constitute more than 95 per cent of
composite materials in use today. Both thermosets as well as thermoplastics are
used as matrix materials. As thermosets mostly exist in liquid state before
cross-linking, it is very convenient to combine reinforcements in the required
proportion, shape the product and cure it into solid. Thermoplastics, on the
other hand, have to be heated and liquefied for adding inserts.

 

3. ADVANTAGES OF COMPOSITE MATERIALS

1. Weight reduction – savings in the range 20% –
50% are often quoted

2.
Fatigue resistance and corrosion resistance.

3.
Capability of high degree of optimization tailoring the directional strength
and stiffness.

4.
Capability mould large complex shapes in small cycle time reducing part count
and assembly times: good for thin walled or generously curved construction.

5.
Capability to maintain dimensional and alignment stability in space
environment.

6. Mechanical properties can be tailored
by ‘lay-up’ design, with tapering thicknesses of reinforcing cloth and cloth
orientation.

7. High impact resistance – Kevlar
(aramid) armour shields
planes, too – for example, reducing accidental damage to the engine pylons
which carry engine controls and fuel lines.

8. High damage tolerance improves accident survivability.

9.
Possibility of low dielectric loss in radar transparency.

10.
Possibility of achieving low radar cross-section.

 

4.
DISADVANTAGES OF COMPOSITE MATERIALS

1. Some higher recurring costs,

2. Higher nonrecurring costs,

3. Higher material costs,

4. Non-visible impact damage,

5. Repairs are different than those to metal
structure,

6. Isolation needed to prevent adjacent
aluminium part galvanic corrosion.

7.Laminated
structure with weak interfaces: poor resistance to out-of-plane tensile loads.

8. Susceptibility
to impact-damage and strong possibility of internal damage going unnoticed.

9.
Moisture absorption and consequent degradation of high temperature performance.

10. Multiplicity of possible manufacturing defects and variability in
material properties.

 

5. THE USE OF COMPOSITE MATERIALS IN
AEROSPACE INDUSRTY

It is important to note that the three
most common existing types of composites are reinforced with fiberglass, carbon fibre and aramid fibre. It is also interesting that each of these types has
subtypes which provides for a wide variety of composites.

 

Table 1. Reinforcing fibers commonly use in
aerospace applications.

Several types of composites are commonly used in the aerospace
industry. For example,

. Fiberglass
is a fibre reinforced polymer made of a plastic matrix reinforced by fine
fibres of glass. It is a lightweight, extremely strong and robust material.
Although strength properties are somewhat lower than carbon fibre and it is
less stiff, the material is typically far less brittle, and the raw materials
are much less expensive.

Carbon-fiber-reinforced polymer is an extremely strong and light
fiber-reinforced polymer which contains carbon fibers.

The composite may contain other fibers, such as aramid, e.g. kevlar,
twaron, aluminium or glass fibres, as well as carbon fibres. Aramid fiber is a
class of heart-resistant and strong synthetic fibres. They are used in
aerospace and military applications, for ballistic rated body armour fabric and
ballistic composites, in bicycle tires, and as an asbestos substitute.

 

 

Table 3. Polymeric matrices commonly used in
aerospace sector.

 

 

Composite materials maximise weight
reduction – as they typically are 20% lighter than aluminium and are known to
be more reliable than other traditional metallic materials, leading to reduced
aircraft maintenance costs, and a lower number of inspections during service.

 

Most aerospace composites use prepregs as
raw materials with autoclave moulding as a popular fabrication process.
Filament winding is popular with shell like components such as rocket motor
casings for launch vehicles and missiles. Oven curing or room temperature
curing is used mostly with glass fibre composites used in low speed small
aircraft. It is common to use composite tooling where production rates are
small or moderate; however, where large numbers of components are required, metallic
conventional tooling is preferred. Resin injection moulding also finds use in
special components such as radomes

 

Advanced composites do not corrode like
metals – the combination of corrosion and fatigue cracking is a significant
problem for aluminium commercial fuselage structure.

Other positive attributes include
excellent fatigue and corrosion resistance and good impact resistance.

Composite materials can provide a much
better strength-to-weight ratio than metals: sometimes by as much as 20% better.

The lower weight results in lower fuel
consumption and emissions and, because plastic structures need fewer riveted
joints, enhanced aerodynamic efficiencies and lower manufacturing costs. The
aviation industry was, naturally, attracted by such benefits when composites
first made an appearance, but it was the manufacturers of military aircraft who
initially seized the opportunity to exploit their use to improve the speed and
maneuverability of their products.

Weight is everything when it comes to
heavier-than-air machines, and designers have striven continuously to improve
lift to weight ratios since man first took to the air.

Composites materials played a major
part in weight reduction, and today there are 3 main types in use: carbon
fibre, glass and aramid – reinforced epoxy.

 

·        
CFRP (Carbon Fiber
reinforced Polymer)

·        
GFRP (Glass Fiber
reinforced Polymer)

·        
Aramid
Fiber Reinforced Polymers

 

The use of
composite-based components in place of metal as part of maintenance cycles is
growing rapidly in commercial and leisure aviation. Overall, carbon fibre is
the most widely used composite fibre in aerospace applications.

 

 

6. METHODOLOGY

Methodology
consists of creation of sample, experimental tests, and result analysis and
evaluation.

1. creation of Sample.

2. Experimental Tests.

3. tabulation of the
experimental data.

4. ReslutAnyalisis.

 

6.1 CREATION OF SAMPLE

During the
experiment, the surface of clean plate flat surface was waxed to facilitate
easy removal of the laminate before apply mix of resin on the waxed surface.
Then, cut the first fiber layer into required dimension and placed on the top
of that and apply the resin again. Make even the resin using serrated roller
and brush and removed all trapped air in resin and fiber. Repeat this step for
the next layer until 6 layers. Finally, cover the layers with waxed flat
surface and put load on the top of it to produce a better surface. Specimen was
cured at room temperature for 24h in ambient condition.

Then, it was
cut into the specimen dimension which is 25 mm x 250 mm. 1

 

6.2 EXPERIMENTAL TESTS

The work consists of
tensile test, water absorption test, hardness test and a durometerto measure
the depth of the indentation in the materail.3

 

TENSILE TEST: The tensile
test was undertaken using Material Test System (MTS) machine. 1

 

MOISTURE ABSORPTION

The percent increase in weight of a
material after exposure to water under specified conditions. Water absorption
can influence mechanical and electrical properties.

 

Apparatus: Balance: An analytical balance
capable of reading 0.01 g.

Calculations: Calculation of moisture
absorption can be done at atmospheric temperature for 7 days. 3

 

 

HARDNESS TEST

Hardness is the property of a material
that enables it to resist plastic deformation, usually by penetration. However,
the term hardness may also refer to resistance to bending, scratching, abrasion
or cutting. 3

 

DUROMETER SCALES

The two most commonly used durometer
scales for measurement are ASTM D2240, type A and type D scales. 3

 

COMPRESSION TEST

UNIVERSAL
TESTING MACHINE

Universal testing machine (UTM) is
called so because of the versatility of its application. The following tests
can be performed with it:

1. Tension Test 2.Compression Test

3. Bending Test 4. Hardness Test 3

 

6.4 RESULT EVALUATION

Experimental data tabulation and its
analysis is taken for the evaluation of the performance of different types of
composite materials.

 

10. CONCLUSION

Performance
of CFRP, GFRP and Aramid Fiber Reinforced Polymers composite material can be
evaluated On the basis of different types of tests and analysis.Comparative
performance evaluation leads to the selection of best material the specific
aerospace application.

 

REFERENCES

 

1 Nikhil V Nayak, “Composite
Materials in Aerospace Applications.” International Journal of
Scientific and Research Publications, Volume 4, Issue 9, September 2014 1 ISSN
2250-3153

2 Valeriy A. Komarov,”Reinforcement of aerospace
structural elements made of layered compositeMaterials”. 6th Russian German
Conference on Electric Propulsion and Their Application.

3 P. Karthigeyan, “Performance
evaluation of composite material for aircraft industries,” 5th International
Conference of Materials Processing and Characterization (ICMPC 2016)

4 SukritiYadav,”Micro/Nano
Reinforced Filled Metal Alloy Composites: A Review Over Current Development in
Aerospace and Automobile Applications,”ICMDA 2016.

 

5 F.C. Campbell, “Introduction to Composite Materials,” Structural
Composite Materials, (#05287G)

 

6 S. Moustakidis, “Non-destructive
inspection of aircraft composite materials using triple IR imaging,”IFAC-PapersOnLine 49-28 (2016) 291–296

 

 7
AndrzejKatunin, “Damage identification in aircraft composite structures: A case
study using various non-destructive testing techniques,” Composite Structures
127 (2015) 1–9

 

  8
G.V.Mahajan, “Composite Material: A Review over Current Development and
Automotive Application.” International Journal of Scientific and Research
Publications, Volume 2, Issue 11, November 2012 ISSN 2250-3153

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