Clases 1 y 2 Materiales II 2009 - CNEA

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Introduction

1

MATERIALES II

2012



Martes

8
:30
-

12:30

Horarios
*:




Viernes

8:30
-

12:30


Profesores

Visitantes
*:
horarios

a
definir

Visitantes
:

-

Alberto LUCAIOLI (UNS, Bahía Blanca)
Conformado

Plástico



-

Roberto HADDAD (CNEA, CAC)
Corrosión

Locales:


-

Dr. (
Ing
.
Nuc
.) Graciela BERTOLINO (JTP)


-

Ing
.
Mec
. Hugo SOUL (
Ayd
.
1ra)


-

Dr. Alejandro YAWNY (
Prof.
Asoc
.)

Docentes
:

Prácticas

/
Visitas
:

-
Talleres

/
Laboratorios

del CAB:
práctica

de
mecanizado
;
soldadura

(TIG, manual);
templabilidad

de
aceros
;
metalografía
;
fundición
.

-

IISA (INVAP
Ingeniería
)

-

INVAP
Satelital

Introduction

2

Contenidos

Curriculares

Ingeniería

Mecánica
:

1
°

CUATRIMESTRE


Mecánica

Racional

Matemática

Laboratorio

I

Introd
. al
Cómputo

2
°

CUATRIMESTRE


Termodinámica

Métodos

Numéricos

Mecánica

de los
Sólidos

Física

Moderna

3
°

CUATRIMESTRE


Mecánica

de
Fluidos

Materiales

I

Dinám
. de
Sists
. y Control

Mecanismos

4
°

CUATRIMESTRE


Transf
. de
Energía

y
Masa


Materiales

II

Sists
.
Electroméc
. y
Máq
.
Eléc

Electrónica

Electrotecnia

5
°

CUATRIMESTRE


Proyecto

Integrador

I

Laboratorio

II

Máquinas

Térmicas

e
Hidráulicas
.

Diseño

Mecánico

Seg
. e
Hig
. en
Plantas

y Labs.

Optativa

6
°

CUATRIMESTRE


Proyecto

Integrador

II

Econ. y
Gestión

de
Proyectos

Gestión

Ambiental

Optativa

Introduction

3

Objetivos

de la
Materia
:



Brindar

conocimientos

que

faciliten

el
proceso

de
Selección

de un Material
para

la
fabricación

de
un
componente

capaz

de
cumplir

con
una

determinada

Función



Introduction

4

MATERIAL

SHAPE

PROCESS

FUNCTION

transmit a load, heat, contain pressure,
store energy, etc. at minimum cost,
weight, or maximum efficiency, safety

interaction between
function, material, process
and shape


The central problem of
materials selection in
mechanical design:

Formability

Machinability

Weldability

Heat tretability

Precision

Tolerances

Surface quality

Defects (pores, cracks)

Cost

Introduction

5

* Role of materials in mechanical design

Types of Design

Original design:

(completely new idea) involves new working principles (the ballpoint
pen, the CD).

-

New
materials can offer new, unique combination of properties
wich

enable original
design
: high purity
Si


transistor; high purity
glass


optical
fibres
.

-

Sometimes
the new material suggest the product but often the product demands
development of new materials:

turbine technology


Hight

Temperature Alloys (
Superalloys
); nuclear technology


Zr

Alloys; space technology


Light Alloys


This
is the driving force behind the development of new materials.

Adaptive
or developmental design:

takes an existing concept and seeks an incremental
advance in performance
(the
evolution of a product)

often
possible by developments
in materials: polymers for metals in household appliances; carbon
fibre

for wood in
sports goods.

Variant design:

the
change of
scale or dimension
or shape without change
of function
.
Change of scale may require change of materials


scaling up of boilers (cooper to
steels), pressure vessels, planes (balsa wood models to Al full
-
scale planes)

Introduction

6

Design
Tools


Viability
Analysis


Approximate
Analysis


Optimization
Methods


Detailed
Analysis



Materials data
needs


Data for ALL
materials

low precision data


Data for a
SUBSET
of
materials

higher data
precision


Data for ONE
material

highest precision
and detail


THE DESIGN PROCESS

Generic properties
Materials
Selection Charts

ASM Handbooks
Smithells
: Metals
Reference Book

Supplier

Critical
components: run
your own test
!

CONCEPTUAL

explore working
principles

EMBODIMENT

define general layauot
and scale

DETAIL

optimize form,
manufacture and assembly

PRODUCT

SPECIFICATION

Market need

Design requirements

Introduction

7

Metals

Polymers

Ceramics

&

Glasses

HYBRIDS

(COMPOSITES)

MATERIALS
UNIVERSE

Introduction

8

METALS

Light alloys

Refractory metals

Heavy alloys

Precious metals

Plain carbon steels

Alloy steels

Cast irons


Low carbon (mild) steel


Medium carbon steels


High carbon steels


Low alloy steels


Tool steels


Stainless steels


Grey cast irons


White cast irons


Malleable alloys


Nodular cast irons


Aluminium alloys


Magnesium alloys


Titanium alloys


Copper alloys


Lead alloys


Nickel alloys (
incl.Superalloys
)


Molybdenum alloys


Tantalum alloys


Tungsten alloys


Gold alloys


Silver alloys


Platinum alloys

Ferrous Alloys

Nonferrous Alloys

Introduction

9

CARBON STEELS

The
most popular

structural material

based on the Fe
-

Fe
3
C

phase diagram

Introduction

10

Fe
-
C
-
Si !!

Phase diagram

Carbon Steels

*
to provide
solution strengthening:

alloying elements in low alloy steels in
substitutional solution give additional hardening and also W and Co in
tool steels

*
to allow
precipitation hardening:

carbide formers (Mo
2
C, W
2
C, VC) in
high
speed steels: 1%C, 0.4%Si, 0.4%Mn, 4%Cr, 5% Mo, 6%W, 2% V and 5% Co
(traditionally made from 1%C, 0.3%Si, Mn in the quenched plus tempered state to
cut mild steel but “run the temper” problem. Above 500
-
600 C: Fe
3
C dissolves but
Mo
2
C, W
2
C and VC form fine precipitates making steels even harder!!, allowing
high cutting speeds)

*
to improve
corrosion resistance
(Cr)
and stabilize austenite

(Ni)
:

stainless steels
(SS 18/8: 18Cr 8Ni wt.% )

*
to improve
hardenability:
up to
(in total)
7 % Mn, Cr, Ni, Mo in low alloy
steels: TTT diagrams “shift” to the right


Alloying:

what for?

Introduction

11

http://www.matter.org.uk/steelmatter/sitemap.htm

More on Steels:

SteelMATTER

Strength

Equilibrium Fe
-
C diagram

Toughness

Fe
-
C phase diagram: Lever rule

Hardenability

Transformation diagrams

U
nde
rlying Metallurgy

Introduction

12

Generic Aluminium Alloys: Matter Module

http://www.matter.org.uk

AluMatter

+

Phase Diagrams Modules

More on Al Alloys:

Introduction

13

Properties of the Generic Metals

SENSITIVE

to ….
MICROSTRUCTURE


周敲浯T散桡h楣慬a䍯C摩d楯渡

却牵捴畲攠䥎I䕎卉呉噅E
vs.
Structure SENSITIVE

PROPERTIES

Introduction

14

POLYMERS

Thermoplastics

Thermosets or
resins

Elastomers or
rubbers

Natural
polymers


Poyethylene
, PE
; partly crystalline; Tubing, films, bottles, cups, electrical
insulation, packaging


Polypropylene, PP
; partly crystalline; Same uses as PE, but lighter, stiffer, more
resistant to sunlight


Polytetrafluorethylene
, PTFE
; partly crystalline;
Teflon
; Good high
temperature polymer with very low friction and adhesion characteristics; Non
-
stick saucepans, bearings, seals


Polystyrene, PS
; amorphous; Cheap molded objects, toughened with butadiene
to make high impact polystyrene (HIPS), foamed with pentane to make common
packaging (“
Telgopor
”, Argentina)


Polyvinylchloride, PVC
; amorphous; Architectural uses, tubing, artificial
leather, hoses, clothes


Polymethylmethacrylate
, PMMA
; amorphous; Perspex,
lucite
, transparent
sheet and
mouldings
, aircraft windows


Nylon 66
; partly crystalline when drawn; Textiles, ropes, moldings


Epoxy
; amorphous; matrix in Fibreglass
composites, adhesives, expensive!


Polyester
; amophous; matrix in Fibreglass
composites, laminates, cheaper than epoxy!


Phenol
-
formaldehyde
; amoprphous;
Bakelite, Formica; rather brittle


Urea
-
formaldehyde;
amoprphous; replace
Bakelite, Electrical fittings


Melamine
-
formaldehyde
;

amorphous;
replace Bakelite, Tableware


Cellulose
; crytalline


Lignin
; amophous


Protein
; partly crystallines


Polyisoprene
; amorphous;
Natural rubber


Polybutadiene
; amophous;
Synthetic rubber


Polychloroprene
;
amoprphous; Neoprene, oil
resistant rubber used for
seals

Introduction

15

Introduction

16

CERAMICS

and

GLASSES

Glasses

Vitreous
ceramics

High performance
engineering
ceramics

Cement
and
concrete

Rock
and
minerals

Electronic
materials


Portland cement;
CaO

+
SiO
2

+
Al
2
O
3


Limestone (Marble)
; CaCO
3


Sandstone
; SiO
2



Granite
; Aluminium silicates

(building, foundations)



Ice
; H
2
O


Ferrites


Ferroelectrics


Semiconductors



Superconductors



Dense alumina
;

Al
2
O
3


Silicon carbide, nitride
;

SiC, Si
3
N
4
;


Sialons
; Si
2
AlON
3


Zirconia (PSZ)
; ZrO
2

+ 5 wt.% MgO


Porcelain;
electrical insulators


China Pottery
;

artware and tableware tiles


Brick
; construction and refractory use

Made form
clays
: hydrous aluminosilicates such as
Al(Si
2
O
5
)(OH)
4

mixed with other inert minerals.
Final State:
crystalline

phases (sislicates) in a
glassy

matrix based on SiO
2



Soda
-
lime glass
; 70
SiO
2
, 10 CaO, 15 Na
2
O; windows, bottles, easily formed and shaped


Borosilicate glass
; 80
SiO
2
, 15 B
2
O, 5 Na
2
O; pyrex; cooking and chemical glassware; high
temperature strength, low coefficient of thermal expansion, good thermal shock resistance

Introduction

17

COMPOSITES

Natural
(biological)

composites

Engineering
composites

Fibrous
composites

Particulate
composites

Lamellar
composites


Concrete
: cement + aggregates


Macadam
: gravel in bitumen


Cemented carbide
: Tungsten carbide
particles in cobalt matrix (WC +Co)


fillers
: usually added to lower costs
and increase wear resistance


GFRP
: glass fibre reinforced
polymers


CFRP
: carbon fibre reinforced
polymers


MMC
: metal matrix composites


Plywood
: uniform properties in the
plane of the sheet (contrary to
anisotropic wood!)


NEW:
Fibre

Metal laminates


Arall


Glare (used in the Airbus 380
fuselage)


wood
: fibrous chain of cellulose in a matrix of lignin


bone / teeth
: hard inorganic crystals (hydroxyapatite)
in a tough organic constituent (collagen)

Introduction

18

difficult to grip in TENSION !:
Strength measured in BENDING
(MOR: modulus of rupture)

Typical Mechanical Behaviours

Introduction

19

How to
compare

Materials at the Conceptual Design Stage?:

Materials Properties Charts

Introduction

20

Materials Selection Charts

Selection of materials:

-

usually dictated by a
combination, or several
combinations, of properties
(E
1/n
/
r
,
s
f
/
r,
E /
s
f
).

-

Condense a large body of
information in a compact form!

-

Allows comparison /selection
of materials at the conceptual
design level:
guide lines
(log
-
log
plot).

Example:


Velocity of sound:
v

= (E/
r
)
1/2

-

range: 50 to 10
4

m/s

-

Al and Glass: high
v
(low E)

-

Wood vs. Steel

Introduction

21

Example:

The combination of properties which maximise stiffness
-
to
-
weight ratio and the
strength
-
to
-
weight ratio for various loading geometries

Combination of Properties
(
Merit Index
)

depends on
the mode of loading

Loading geometry affects
material selection
!

Introduction

22

-

s
f
different meanings !

-

Strength not so well defined as E
(
metals!
): vertical extensions of the
“bubbles”
(strength is a structure
sensitive property!!!,
compare with E
)

-

Metals:

dislocations, Peierls stress,
metallic bonding;
Ceramics:

ionic or
covalent bonding;
Polymers:

relative
slippage of polymer chains or
segments;
Glasses:

breakage of strong
bonds.

Use of the Strenght
-

Density Chart:

-

lightweight plastic design

(minimum weight design of ties,
beams, plates and yield
-

limited
design of moving components where
low inertial forces are important )

Introduction

23

The Merit Index is E
1/2

/
r

for Optimun Stiffness
design of beams

The same for plates (E
1/3

/
r),

etc
.

Introduction

24

Optimum stiffness

case:

For Ties
(E/
r
):

Steels
: (27)

Al
: (25)


GFRP

50 % uniaxial in polyester: (24)

KFRP

60% uniaxial: (54)

CFRP

58 % uniaxial C in epoxy: (126)

For Beams
(E
1/2
/
r
):

Steels
: (1.8)

Al
: (3) (
principal airframe material!!
)


GFRP

50 % uniaxial in polyester: (3.5)

KFRP

60% uniaxial: (6.2)

CFRP

58 % uniaxial C in epoxy: (9)
(
increasingly being used in aircraft structures
)

For Plates
(E
1/3
/
r
):

Steels
: (0.76)

Al
: (1.5) (
principal airframe material!!
)


GFRP

50 % uniaxial in polyester: (1.8)

KFRP

60% uniaxial: (3)

CFRP

58 % uniaxial C in epoxy: (3.8) (
floor
panels, flaps, tail planes
)

Introduction

25

Optimum strenght

case:

composites are always better than metals (even for ties)

composites are always better
than metals, even for ties !

For Ties
(
s
Y

/
r
):

Steels
: (128)

Al
: (179)


GFRP

50 % uniaxial in polyester: (620)

KFRP

60% uniaxial: (886)

CFRP

58 % uniaxial C in epoxy: (700)

For Beams
:

……


For Plates
:

……

Introduction

26

The combination of properties which maximise stiffness
-
to
-
weight ratio and the strength
-
to
-
weight ratio for various loading geometries

Combination of Properties
(
Merit Index
)

depends on
the mode of loading

Loading geometry affects
material selection
!

But we were considering
only the material (shape
was pre
-
defined)



SHAPE ?

!

Introduction

27

MATERIAL

SHAPE

PROCESS

FUNCTION

transmit a load, heat, contain pressure,
store energy, etc. at minimum cost,
weight, or maximum efficiency, safety

interaction between
function, material, process
and shape


The central problem of
materials selection in
mechanical design:

Formability

Machinability

Weldability

Heat tretability

Precision:

Tolerances

Surface quality

Defects (pores, cracks)

Cost

Manufacturing Processes
Cards

We were discussing MATERIAL, then SHAPE, now …. PROCESS

Introduction

28

Selection of Material and Shape

Ways to
increase
mechanical
efficiency

combining material with macroscopic shape

combining material with microscopic shape

combining material, microscopic and macroscopic shape

Introduction

29

Macroscopic
Shape

A
: cross section area

I
xx
: second moment of area
about the axis of bending

K
: torsional moment of area
(K = polar moment of area
J

for circular cross section):

G
K
l
T
*
*


y
m
: distance from neutral
axis of bending to the outer
surface

Q
: equivalent to I
xx
/y
m

for
Torsion

Q
T


Introduction

30

Examples of definitions of SHAPE FACTORS

Material: can be thought of as having properties but no shape.

Component or structure: is a SHAPED MATERIAL

A SHAPE FACTOR is defined as a dimensionless number which characterises
the efficiency of a section shape, regardless of scale, in a given mode of loading

Elastic extension:

no shape factor is needed!

Elastic bending and torsion:

shape enters through the second moment of area:

2
)

(
.
4
A
I
I
I
area
same
e
B





2
.
2
A
K
e
T



Introduction

31

Definitions:

Stiffness:

Strength:

Bending:

Torsion:

Bending:

Torsion:

2
.
2
A
K
e
T



2
.
4
A
I
e
B



2
3
16









m
f
B
y
I
A


3
2
.
4
A
Q
f
T



Introduction

32

Performance Index
including Shape

Introduction

33

Metal Matrix Composites:
MMCs

=

metallic matrix + ceramic reinforcement

strong and stiff constituent

embedded in

softer constituent

reinforcement


matrix

Example of Material Development

Introduction

34

MMCs design:

Composite material: Al + ceramic
additions to reduce thermal
distortion

Candidates:
BN and SiC

(fibres,
particles); both have lower
a

than
Al !

Aim:

reduce thermal distortion
of an Al alloy component

However, the correct
Merit
Index
is the ratio:

K /
a

Conclusion:

SiC good but BN not

Introduction

35

Monofilaments

Whiskers /
Fibres

Particulate

continuously
reinforced

discontinuously reinforced

Usual types of MMCs microstructures

Introduction

36

Reinforcement:

Saffil fibres (Al
2
O
3
(
d
) + 3
-
4 wt.
-
% SiO
2
)

100
m
m

Al alloy + Saffil short fibres

“Saffil” short fibre reinforced MMCs

Saffil:
Saf
e
fil
ament

Introduction

37

Squeeze Casting Process

Eidgenössische


Materialprüfungs


und


Forschungsanstalt


(CH)


Introduction

38

208
210
212
214
216
218
220
10
100
B (1.2 MPa)
A (0.8 MPa)
Load (kN)
d
x (mm)
1750 kN

(100 MPa)

Infiltration and pressurization

Squeeze Casting

Dim.: 150 x 115 x 35 mm

Weight: approx. 1700 g

MMC Casting

Introduction

39

Applications of Saffil reinforced

Al
-
alloys

SFR in automobiles

15 vol.%

Time to fracture [h]

Stress

[MPa]

Creep: Stress vs. Life

Introduction

40

USEFUL APPROXIMATE SOLUTIONS TO STANDARD DESIGN
PROBLEMS

Modelling is a key part of design. In the early stage (conceptual design), approximate
modelling establishes whether the concept will work at all, and identifies the combination of
material properties which maximise performance. At the embodiment stage, more accurate
models brackets the forces, the displacements, the velocities and the dimensions of the
components. And in the final stage, modelling gives precise values for the stresses, strains
and failure probability in key components.

Many simple components have been modelled already and many more
-
complex components
can be modelled approximately by idealising them as one of these. THERE IS NO NEED
TO REINVENT THE BEAM OR THE COLUMN OR THE PRESSURE VESSEL; THEIR
BEHAVIOUR UNDER ALL COMMON TYPES OF LOADING HAS ALREADY BEEN
MODELLED:

Many problems of conceptual design can be analysed, with adequate precision, by patching
together solutions like those given here; and even the final detailed analysis of non
-
critical
components can be tackled in the same way.

Examples of results of modelling of some standard problems:



additional comments ….

Introduction

41

Elastic
Deflection
of Beams

Introduction

42

Failure of
Beams

Introduction

43

Torsion of
Shafts

Introduction

44

Buckling of
Columns