....

1. KOMPOSIT
E2034304-3 SKS
TEKNIK MESIN S1
FT-UNNES
Maret – Juni 2015
Dr. Rahmat Doni Widodo, ST., MT.
Email : rahmat.doni2015@gmail.com

2. PENDAHULUAN
Mata Kuliah : KOMPOSIT
Kode Mata Kuliah : E2034304
SKS : 3
Semester : Genap 2014/2015
Staf Pengajar : Rahmat Doni Widodo (RDW)
Tujuan Pengajaran :
Memahami jenis- jenis, sifat, proses pabrikasi
dan penggunaan dari material komposit
Sistem Evaluasi :
Kehadiran : 5 %
Tugas : 15 %
Ujian Tengah Semester (UTS) : 30 %
Presentasi : 15 %
Ujian Akhir Semester (UAS) : 35 %

3. SATUAN ACARA PENGAJARAN (SAP)
Pertemuan Tanggal Pokok Bahasan
1 5 Maret 2015
Maksud dan tujuan dibuatnya material komposit,
struktur, klasifikasi, konsep desain dan aplikasi material
komposit.
2 12 Maret 2015
Isotropy dan Anisotropy pada komposit, Karakteristik
Penguat dan Matrik, Unindirectional pada Lapisan (Ply),
Pabrikasi Woven, Mats dan Reinforce Matrix.
3 19 Maret 2015
Definisi struktur Sandwich, Sifat struktur Sandwich,
Pabrikasi dan desain struktur Sandwich.
4 26 Maret 2015
Konsep dasar desain, bentuk, kerusakan, dan sifat pada
struktur Laminate.
5, 6 dan 7
2, 9 dan 16 April
20015
Konsep dasar sifat mekanik, ketahanan pada: beban
dinamis, korosi, temperatur, lelah pada material
komposit.
8 23 April 20015 UJIAN TENGAH SEMESTER

4. SATUAN ACARA PENGAJARAN (SAP)
Pertemuan Tanggal Pokok Bahasan
9 30 April 2015
Sifat elektrik berupa konduktifitas, Volume tahanan
elektrik, Daya elektrik dan tahanan panas, Efek strain
terhadap sifat elektrik, Kuat sambungan mekanik
terhadap sifat elektrik pada material komposit.
10 7 Mei 2015
Konsep dasar Sifat thermal berupa: Expansi panas, Panas
jenis, dan konduktifitas panas pada material komposit.
11 21 Mei 20015
Proses pembuatan atau pabrikasi material komposit
melalui proses molding, dan proses selain molding.
12 dan 13
28 Mei dan 4 Juni
2015
Aplikasi material komposit untuk konstruksi transportasi
dan kepentingan lainnya.
14 dan 15 11 dan 18 Juni 2015
Prsentasi dari hasil review jurnal yang berhubungan
dengan Faktor-fakrot yang mempengaruhi sifat pada
material komposit melalui review journal penelitian.
25 Juni 2015 Minggu Tenang
16 2 Juli 2015 UJIAN AKHIR SEMESTER

5. References
Vincent K.S. Choo, Fundamentals of Composite
Materials, Knowen Academic Press Inc, 1990
Derek Hull, An Introduction to Composite Materials,
Cambridge University Press, 1981.
Deborah D.L. Chung, Composite Materials : Science and
Applications Ed.2, Springer-Verlag, 2010.
Suong V. Hoa, Principles of the Manufacturing of
Composite Materials, DEStech Publications Inc, 2009.
Sanjay K. Mazumdar, Composites Manufacturing :
Materials, Product and Process Engineering, CRC Press,
2002.

6. References
 Daniel Gay, Suong V. Hoa, Stephen W. Tsai, Composite
Materials: Design and Applications, CRC Press, 2003.
Campbell F.C., Structural Composite Materials, ASM
International, 2010.
Ajayan P.M., Schadler L.S., and Braun P.V.,
Nanocomposite Science and Technology, Wiley-VCH
Verlag, 2003.
Abdul Hamid Zureich and Alan T. Nettles, Composite
Materilas : Testing, Design and Acceptance Criteria,
ASTM International, 2002.
Jurnal-jurnal hasil penelitian yang relevan dengan
bahan kajian.

8. BAHAN KOMPOSIT
(COMPOSITE MATERIALS)
Merupakan penggabungan dua macam
material atau lebih dengan fase yang
berbeda.
Untuk skala atomic - mikro , logam, polimer, dan
keramik dapat digolongkan KOMPOSIT.
Pd KOMPOSIT bisa terjadi reaksi antar komponen
penyusunnya shg akan muncul fase ketiga yg
memiliki sifat berbeda dari fase pertma maupun
fase ke dua

9. Composite
• Combination of two or more individual
materials
• Design goal: obtain a more desirable
combination of properties (principle of
combined action)
– e.g., low density and high strength

10. Advantages of Composite Materials
• Stronger and stiffer than metals on a density
basis
• Capable of high continuous operating
temperatures
• Highly corrosion resistant
• Tailorable thermal expansion properties
• Tunable energy management characteristics
• Outstanding durability
• Low Observable

11. Disadvantages
- complex production methods
- difficult processing (cutting, forming)
- difficult joining
- often impossible to repair
- sometimes brittle
- high cost

12. Composites can be found in:
-Boat hulls
-The aerospace industry (structural components as well as
engines and motors)
-Automotive parts (panels, frames, dashboards, body
repairs)
-Bathtubs, hot tubs, swimming pools
-Cement buildings, bridges
-Surfboards, snowboards, skis
-Golf clubs, fishing poles, hockey sticks
-Trees are technically composite materials, plywood
-Electrical boxes, circuit boards, contacts
-Everywhere

13. Pd Komposit dikenal istilah :
 MATRIK (fase Pertama)
 REINFORCEMENT (fase Kedua)
Fase Pertama (Matrik) berfungsi sbg PENGIKAT
Fase Kedua(Reinforcement) berfungsi sbg PENGUAT
KLASIFIKASI KOMPOSIT:
1. CMC (Ceramic Matrix Composites)
2. MMC (Metal Matrix Composites)
3. PMC (Polymer Matrix Composites)

14. Matrix
- continuous phase
- joins the reinforcement together
- transfers external loads onto the reinforcement
- determines external shape
- materials:
- metals (MMC): Al, Mg, Ti, Fe, Ni, Co
- ceramics (CMC): concrete, SiC, Al2O3,
- polymers: polyesters, polyamides, epoxy
resins, asphalt

15. Reinforcement
- embedded into matrix
- improvement of matrix properties: stiffness, hardness,
fracture toughness, thermal shock resistance, wear
resistance, friction coefficient, thermal conductivity
- different forms: powder, fibers (continuous-
discontinuous, aligned-random), laminates
- materials:
- metals: wires: Fe, powders: W, Mo
- ceramics: fiberes: glass, SiC and carbon; particles: SiC
and Al2O3, metal oxides
- polymers: Kevlar, Nylon

16. METALS
POLYMERS
CERAMICS
Metal-Polymer
Composites atau
Metallic Matrix
Composites (MMC)
Metal-Ceramic
Composites atau
Mineral Matrix
Composite/
Ceramic Matrix
Composites (CMC)
Ceramic-Polymer Composite atau
Organik Matrix Composite/
Polymer Matrix Composites (PMC)

18. Metal Matrix Composites (MMC)
• Metal matrix composites (MMCs), as the name
implies, have a metal matrix. Examples of matrices
in such composites include aluminum, magnesium,
and titanium.
• Typical fibers include carbon and silicon carbide.
• Metals are mainly reinforced to increase or decrease
their properties to suit the needs of design. For
example, the elastic stiffness and strength of metals
can be increased, and large coefficients of
thermal expansion and thermal and electric
conductivities of metals can be reduced, by the
addition of fibers such as silicon carbide.

19. Advantages of MMC’s
• Metal matrix composites are mainly used
to provide advantages over monolithic
metals such as steel and aluminum.
These advantages include higher specific
strength and modulus by reinforcing low-
density metals, such as aluminum and
titanium; lower coefficients of thermal
expansion by reinforcing with fibers with
low coefficients of thermal expansion, such
as graphite; and maintaining properties
such as strength at high temperatures.

20. Advantages of MMC’s
• Advantages over polymer matrix
composites. These include higher elastic
properties; higher service temperature;
insensitivity to moisture; higher electric
and thermal conductivities; and better
wear, fatigue, and flaw resistances.
• The drawbacks of MMCs over PMCs
include higher processing temperatures
and higher densities.

22. Fabrication Method
Fabrication methods for MMCs are varied. One
method of manufacturing them is diffusion bonding
which is used in manufacturing boron/aluminum
composite parts. A fiber mat of boron is placed
between two thin aluminum foils about 0.05 mm
thick. A polymer binder or an acrylic adhesive holds
the fibers together in the mat. Layers of these metal
foils are stacked at angles as required by the design.
The laminate is first heated in a vacuum bag to
remove the binder. The laminate is then hot pressed
with a temperature of about 500°C and pressure of
about 35 MPa in a die to form the required machine
element.

24. Applications of MMC’s
• Space: The space shuttle uses
boron/aluminum tubes to support its
fuselage frame. In addition to
decreasing the mass of the space
shuttle by more than 145 kg,
boron/aluminum also reduced the
thermal insulation requirements because
of its low thermal conductivity. The mast
of the Hubble Telescope uses carbon-
reinforced aluminum.

25. • Military: Precision components of missile
guidance systems demand dimensional
stability — that is, the geometries of the
components cannot change during use.
Metal matrix composites such as
SiC/aluminum composites satisfy this
requirement because they have high
microyield strength. In addition, the
volume fraction of SiC can be varied to
have a coefficient of thermal expansion
compatible with other parts of the system
assembly.

26. • Transportation: Metal matrix
composites are finding use now in
automotive engines that are lighter than
their metal counterparts. Also, because
of their high strength and low weight,
metal matrix composites are the
material of choice for gas turbine
engines.

27. Ceramic Matrix Composites
(CMC)
Ceramic matrix composites (CMCs) have a
ceramic matrix such as alumina calcium
alumino silicate reinforced by fibers such
as carbon or silicon carbide.

28. Advantages of CMC’s
• High strength,
• Hardness,
• High service temperature limits for
ceramics,
• Chemical inertness, and
• Low density.
However, ceramics by themselves have low
fracture toughness. Under tensile or impact
loading.

29. Reinforcing ceramics with fibers, such as
silicon carbide or carbon, increases their
fracture toughness because it causes
gradual failure of the composite. This
combination of a fiber and ceramic matrix
makes CMCs more attractive for
applications in which high mechanical
properties and extreme service
temperatures are desired.
Advantages of CMC’s

31. Manufacturing Method of CMC
One of the most common methods to
manufacture ceramic matrix composites is called
the hot pressing method. Glass fibers in
continuous tow are passed through slurry
consisting of powdered matrix material, solvent
such as alcohol, and an organic binder (Figure
1.31). The tow is then wound on a drum and dried
to form prepreg tapes. The prepreg tapes can now
be stacked to make a required laminate. Heating
at about 500°C burns out the binder. Hot pressing
at high temperatures in excess of 1000°C and
pressures of 7 to 14 MPa follows this.

33. Carbon Carbon Composites
Carbon–carbon composites use carbon
fibers in a carbon matrix. These
composites are used in very high-
temperature environments of up to
3315°C, and are 20 times stronger and 30%
lighter than graphite fibers.

34. Carbon Carbon Composites
Carbon–carbon composites use carbon
fibers in a carbon matrix. These
composites are used in very high-
temperature environments of up to
3315°C, and are 20 times stronger and
30% lighter than graphite fibers.

35. Advantages of C-C Composites
• Carbon is brittle and flaw sensitive like
ceramics. Reinforcement of a carbon matrix
allows the composite to fail gradually and also
gives advantages such as ability to withstand
high temperatures, low creep at high
temperatures, low density, good tensile and
compressive strengths, high fatigue resistance,
high thermal conductivity, and high coefficient of
friction.
• Drawbacks include high cost, low shear strength,
and susceptibility to oxidations at high
temperatures.

37. Processing a c–c composite
Low-pressure carbonization
A graphite cloth is taken, impregnated by resin
(such as phenolic, pitch, and furfuryl ester), and laid
up in layers. It is laid in a mold, cured, and trimmed.
The part is then pyrolized, converting the phenolic
resin to graphite. The composite is then
impregnated by furfuryl alcohol. The process drives
off the resin and any volatiles. The process is
repeated three or four times until the level of
porosity is reduced to an acceptable level. Each
time, this process increases its modulus and
strength. Because carbon–carbon composites
oxidize at temperatures as low as 450°C, an outer
layer of silicon carbide may be deposited.

38. • Mechanical fasteners: Fasteners needed for
high temperature applications are made of
carbon–carbon composites because they lose
little strength at high temperatures.

39. NATURAL FIBERS
• abaca, coconut, flax, hemp, jute, kenaf and sisal
are the most common — are derived from the
bast or outer stem of certain plants.
• They have the lowest density of any structural
fiber but possess sufficient stiffness and strength
for some applications.
• The automotive industry, in particular, is using
these fibers in traditionally unreinforced plastic
parts and even employs them as an alternative to
glass fibers. European fabricators hold the lead in
use of these materials, in part because regulations
require automobile components to be recyclable.

40. Types of Natural Fiber
Banana Fiber
Hemp Fiber
Jute Fiber
Kenaf Fiber
Sugarcane-
Bagasse
Fiber

41. Applications1. Car parts
Door
panels
Exterior body
parts
Car
Hood
Front bumpers
and fenders
Various interior
parts

42. Natural fiber composites vs. synthetic fiber
composites
Study Materials Application Performance
Schmidt & Meyer
(1998)
Hemp-EPDM-PP
vs. GF-EPDM-
PP
Auto Insulation
component (Ford
car)
Hemp fibers are
able to replace
glass fibers
Diener & Siehler
(1999)
GF-PP vs. Flax-
PP
Auto car panel
(Mercedes A car)
Successfully
passed all test
Wotzel et al.
(1999)
Hemp – Epoxy
vs. ABS
Auto side panel Do not discuss
the performance
Corbiere-Nicollier
et al. (2001)
China reed-PP
vs. Glass-PP
Transport pallet Satisfying
service
requirement
Source : Joshi et al. (2003)

43. Weight Reduction
Component Study NFRP
component
Base
component
Auto side panel Wotzel et al. 820 g (hemp-
epoxy)
1125 g (ABS)
Auto insulation Schmidt &
Meyer (1998)
2.6 kg (hemp-
PP)
3.5 kg (GF-PP)
Transport-Pallet Corbiere-
Nicollier et al.
(2001)
11.77 kg (China
reed – PP)
15 kg (GF – PP)
Source : Joshi et al. (2003)

44. 2. Recreation and Leisure
Decking product
Railing
Patio furniture

45. 3. Insulated Roofing
Roof
sandwich
with foam
core
Roof
sandwich
structure
with
bamboo
core

46. Applications4. Door panel

47. Mechanics Terminology
The approach to analyze the mechanical behavior
of composite structures is:
1. Find the average properties of a composite ply
from the individual properties of the
constituents. Properties include stiffness,
strength, thermal, and moisture expansion
coefficients. Note that average properties are
derived by considering the ply to be
homogeneous. This is called the micromechanics
of a lamina.

48. 2. Develop the stress–strain relationships for a
unidirectional/bidirectional lamina. Loads may
be applied along the principal directions of
symmetry of the lamina or off-axis. Also, one
develops relationships for stiffness, thermal and
moisture expansion coefficients, and strengths
of angle plies. Failure theories of a lamina
are based on stresses in the lamina and
strength properties of a lamina. This is called
the macromechanics of a lamina.