buat mahasiswa yang mencari material teknik

1. ENGINEERING
MATERIALS AND TEIR
PROPERTIES
DISUSUN OLEH:
FITRI HANDAYANI (0804102010003)
ANDRIANSYAH (0804102010025)
JURUSAN TEKNIK MESIN
FAKULTAS TEKNIK
UNIVERSITAS SYIAH KUALA
2010

2. INTRODUCTION
a) Material boleh dikatakan sebagai makanan dari
design.
b) Suksesnya produk dilihat dari:
 tampilan yang baik yaitu memiliki nilai uang dan
memberikan kepuasan kepada si pengguna
 menggunakan material terbaik untuk pekerjaan
tersebut dengan memanfaatkan sepenuhnya
potensi dan karakterstik yang ada.
a) Material yang kita cari adalah material yang ciri
dan sifat tertentu.
b) Material yang bagus adalah material yang telah
kita ketahui moduli, strength , damping
capacities, konduktivitas listrik dan thermal.

3. The Families of Engineering Material
composites,
sandwichses
Hybrids
segmented
structures,
lattices weaves
Steels, Cast
Irons, Al-
alloys
Metals
Cu-alloys,
Zn-alloys, Ti-
alloys
PP, PE, PC,
PS, PA,
PMMK
Plastics
Phenolics,
Expoxies
Isoprene, Neo
prene, Butyl
rubber
Elastomers
Natural rubber
Silicons EVA
Soda glass,
borosillicate
glass.
Glasses
Silica glasses,
Glass-
ceramics
Aluminas,
Silicon
Ceramic
carbidas
Zirconia

4. The Material Properties
 General properties :
1) Densitas
2) Harga
 Mechanical properties :
1) ultimate strength
2) Compressive strength
2) Failure strength
3) Hardness
4) Fatique endurance limit
5) Thoughness
6) Damping capacity
Stress
ζ
=
F/A
o
Metals
ζu
ζy
Ao F
L
Slope E = ζ/ε
0.2% offset
Strain ε = δL/L
Stress
ζ
=
F/A
o
X Brittle: T << Tg
Polymers
Limited plasticity: T = 0.8 Tg
Ao F
ζy Cold drawing: T = Tg
L
Viscous flow: T >> Tg
1% strain
Strai ε = δL/L
Polymers

5.  Thermal properties:
1) melting point
2) Glass temperatur
3) Maximum service
4) Minimum service
5) Specific heat
6) Thermal conduktivity
7) Thermal expansion coefficient
8) Thermal shock resistance
 Electrical properties:
1) Electrical resistivity
2) Diaelectric constant
3) Breakdownpotential
4) Power factor
 Optical properties:
optical, transfarent, translucent, opaq
ue, Referactive index.
 E-co properties: energy/kg to
extract material, CO2 /kg to extract
material.
 Environmental resistance
properties: Corrotion
rates, Oxidation rates, wear rate
constant.

6. Mechanical Properties
Ao
Tension
Strain ε = δL/L
ζf (compression)
Ceramics
Stress
ζ
=
F/A
o
Compression
Slope E = σ/ε
L
ζt (tension)
Kekuatan pada keramik dan glass
bergantung dengan kekuatan
pada bentuk pembebanan.
Intension, ‘‘strength’’ berarti
kekuatan sebelum patah, tIn
compression itu maksudnya the
crushing strength c, yang
memiliki daerah yang lebih luas
dengan tipe tersendiri.

7. Stress
amplitude
∆ζ
Endurance limit
ζu
Ao ∆F
L
Endurance limit
∆ζe
107
cycles
The endurance limit, e, is the
cyclic stress that causes failure in Nf
¼ 107 cycles.
Hardness is measured as the load P
divided by the projected area of
contact, A, when a diamond-shaped
indenter is forced into the surface.

8. Stress
ζ
=
F/A
o
Fracture toughness
ζc
2c
K1C = ζc(πa)
1/2
The fracture toughness, KIC,
measures the resistance to the
propagation of a crack.
The failure strength of a brittle solid
containing a crack of length 2c is KIC
¼ Y ð ,where Y is a constant near
unity.

9. =
F/A
o
Loss coefficient
Area
∆U
A ∆F
Area
U
The loss-coefficient, (a
dimensionless quantity),
measures the degree to which a
material dissipates vibrational
energy (Figure 3.9). If a
material is loaded elastically to a
stress, max, it stores an elastic
energy per unit volume. If it is
loaded and then unloaded, it
dissipates an energy
I
U ¼ d"

10. Heat
flux
q
Thermal conductivity
T T2
X
Heat
input
q W/m2
Heat
sink
q W/m2
nsulation Sample
Slope λ
q =− λ
∆T
∆X
Thermal Properties
Two temperatures, the melting
temperature, Tm, and the glass
temperature, Tg (units for both: K
or C) are fundamental because they
relate directly to the strength of the
bonds in the solid. Crystalline
solids have a sharp melting point,
Tm. Non-crystalline solids do not; the
temperature Tg characterizes the
transition from true solid to very
viscous liquid. It is helpful, in
engineering
design, to define two further
temperatures: the maximum and
minimum service temperatures Tmax
and Tmin (both: K or C).
Temperature gradient (T1 T2)/X

11. Thermal
strain
ε
=
δL/L
Thermal expansion
Slope α
α = 1 ∆L
L ∆T
L
∆L
α
Insulation Heater Sample
Thermal Expansion
The thermal strain per
degree of temperature change is
measured by the linear thermal-
expansion coefficient, (units: K
1 or, more conveniently, as
‘‘microstrain/C’’ or 10 6 C 1). If
the material is thermally isotropic,
the volume expansion, per degree, is
3 . If it is anisotropic, two or more
coefficients are required, and the
volume expansion becomes the sum
of the principal thermal strains.
The thermal shock
resistance Ts (units: K or C) is
the maximum tem- perature
difference through which a
material can be quenched
suddenly without damage. It,
and the creep resistance, are
important in high- temperature
design.
Temperature change
∆T

12. Electrical Properties
The electrical conductivity is simply
the reciprocal of the resisitivity.
When an insulator is placed in an
electric field, it becomes polarized
and charges appear on its surfaces
that tend to screen the interior
from the electric field. The
tendency to polarize is measured
by the dielectric constant, Ed (a
dimensionless quantity). Its value
for free space and, for practical
purposes, for most gasses, is 1.
Most insulators have values
between 2 and 30, though low-
density foams approach the value 1
because they are largely air.
Potential
difference
∆V
Electrical resistivity
∆V
ι ι
Resistance
X
Resistivity
Area A
R = ∆V/ι ∆V A
ρe =
X ι
Current ι

13. Optical Properties
All materials allow some passage of
light, although for metals it is exceed-
ingly small. The speed of light when in
the material, v, is always less than
that in vacuum, c. A consequence is that
a beam of light striking the surface of
such a material at an angle , the
angle of incidence, enters the material at
an angle , the angle of refraction.

14. Eco - Properties
 The contained or production energy (units
MJ/kg) is the energy required to extract 1
kg of a material from its ores and
feedstocks. The associated CO2 production
(units: kg/kg) is the mass of carbon dioxide
released into the atmosphere during the
production of 1 kg of material.

15. Environmental Properties
3.4 Summ
Wear
volume
V
Wear rate
P3 P2 P1
Load P
W = V/S
Sliding
velocity v
Environmental resistance is
conventionally characterized on a
discrete
5-point scale: very good, good,
average, poor, very poor. ‘‘Very good’’
means
that the material is highly resistant
to the environment, ‘‘very poor’’ that
it is completely non-resistant or
unstable. The categorization is
designed to help with initial
screening; supporting information
should always be sought if
environmental attack is a concern.
Ways of doing this are described
later.

16. Summary
 There are six important families of materials for
mechanical design: metals, ceramics, glasses, polymers,
elastomers, and hybrids that combine the properties of
two or more of the others.
 Within a family there is certain common ground:
ceramics as a family are hard, brittle, and corrosion
resistant; metals are ductile, tough, and good thermal
and electrical conductors; polymers are light, easily
shaped, and electrical insulators, and so on — that is
what makes the classification useful.
 In design we wish to escape from the constraints of family,
and think, instead, of the material name as an identifier
for a certain property-profile

17. THANK YOU