4-materials selection basics (1)
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New approaches to Materials Education- a course authored byMike Ashby and David Cebon, Cambridge, UK, 2005
The CESEduPackThe CESEduPackUniversity ofCambridge
Unit 1. Materials Selection:
exploring the world of materials
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Outline
Resources:
Materials Selection in Mechanical Design, 3rd edition (The Text) by M.F. Ashby,
Butterworth Heinemann, Oxford, 2005, Chapters 1 - 4.
CESEduPack 2009 software (www.grantadesign.com).
Background: the motivation
History -- the evolution of materials
Materials and their attributes
The nature of materials data
Exploring relationships: material property charts
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Teaching materials to engineering students
Engineers make things. They make them out of materials.
The philosophy
The CES EduPack provides the resources to achieve this. It introduces
students to a resource they can use in their later profession (like CAD or FEtools)
What do they need to know to do this successfully?
A perspective of the world of materials and processes (understanding)
An ability to select those that best meet requirements of a design (methods)
Access to information and tools to facilitate selection
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History the evolution of materials
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The world of materials
CompositesSandwiches
HybridsLattices
Segmented
PE, PP, PCPS, PET, PVC
PA (Nylon)
PolymersPolyesterPhenolic
Epoxy
Soda glass
Borosilicate
GlassesSilica glass
Glass ceramic
IsopreneButyl rubber
ElastomersNatural rubber
SiliconesEVA
Alumina
Si-carbide
CeramicsSi-nitrideZiconia
Steels
Cast ironsAl-alloys
Metals, alloysCu-alloysNi-alloys
Ti-alloys
100,000 -150,000 commercial materials!
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Organising information: the MATERIALS TREE
Kingdom
Materials
Family
Ceramics& glasses
Metals& alloys
Polymers& elastomers
Hybrids
Class
Steels
Cu-alloys
Al-alloys
Ti-alloys
Ni-alloys
Zn-alloys
Member
1000
2000
3000
4000
50006000
7000
8000
A material record
Attributes
Density
Mechanical props.
Thermal props.
Electrical props.
Optical props.
Corrosion props.
Supporting information
-- specific
-- general
Structured
information
Unstructured
information
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Structured information for ABS*
General PropertiesDensity 1.05 - 1.07 Mg/m^3
Price 2.1 - 2.3 US $/kg
Mechanical PropertiesYoung's Modulus 1.1 - 2.9 GPa
Elastic Limit 18 - 50 MPa
Tensile Strength 27 - 55 MPa
Elongation 6 - 8 %
Hardness - Vickers 6 - 15 HV
Endurance Limit 11 - 22 MPa
Fracture Toughness 1.2 - 4.2 MPa.m1/2
Thermal Properties
Max Service Temp 350 - 370 KThermal Expansion 70 - 75 10-6/K
Specific Heat 1500 - 1510 J/kg.K
Thermal Conductivity 0.17 - 0.24 W/m.K
Acrylonitrile-butadiene-styrene (ABS) - (CH2-CH-C6H4)nElectrical PropertiesConductor or insulator? Good insulator
Optical PropertiesTransparent or opaque? Opaque
Corrosion and Wear ResistanceFlammability AverageFresh Water Good
Organic Solvents Average
Oxidation at 500C Very Poor
Sea Water Good
Strong Acid Good
Strong Alkalis Good
UV Good
Wear Poor
*Using the CESLevel 2 DB
+ links to processes
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Unstructured information for ABS*
What is it? ABS (Acrylonitrile-butadiene-styrene ) is tough, resilient, and easily molded. Itis usually opaque, although some grades can now be transparent, and it can be given vividcolors. ABS-PVC alloys are tougher than standard ABS and, in self-extinguishing grades, are
used for the casings of power tools.Design guidelines. ABS has the highest impact resistance of all polymers. It takes colorwell. Integral metallics are possible (as in GE Plastics' Magix.) ABS is UV resistant foroutdoor application if stabilizers are added. It is hygroscopic (may need to be oven driedbefore thermoforming) and can be damaged by petroleum-based machining oils.
ABS can be extruded, compression moulded or formed to sheet that is then vacuum thermo-formed. It can be joined by ultrasonic or hot-plate welding, or bonded with polyester, epoxy,isocyanate or nitrile-phenolic adhesives.
Technical notes. ABS is a terpolymer - one made by copolymerising 3 monomers: acrylonitrile, butadiene and syrene. Theacrylonitrile gives thermal and chemical resistance, rubber-like butadiene gives ductility and strength, the styrene gives a glossy surface,ease of machining and a lower cost. In ASA, the butadiene component (which gives poor UV resistance) is replaced by an acrylic ester.Without the addition of butyl, ABS becomes, SAN - a similar material with lower impact resistance or toughness. It is the stiffest of thethermoplastics and has excellent resistance to acids, alkalis, salts and many solvents.
Typical Uses. Safety helmets; camper tops; automotive instrument panels and other interior components; pipe fittings; home-securitydevices and housings for small appliances; communications equipment; business machines; plumbing hardware; automobile grilles;
wheel covers; mirror housings; refrigerator liners; luggage shells; tote trays; mower shrouds; boat hulls; large components for recreationalvehicles; weather seals; glass beading; refrigerator breaker strips; conduit; pipe for drain-waste-vent (DWV) systems.
The environment. The acrylonitrile monomer is nasty stuff, almost as poisonous as cyanide. Once polymerized with styrene it
becomes harmless. ABS is FDA compliant, can be recycled, and can be incinerated to recover the energy it contains.
*Using the CESLevel 2 DB
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Organising information: the PROCESS TREE
Kingdom
Processes
Family
Joining
Shaping
Surfacing
Class
Casting
Deformation
Moulding
Composite
Powder
Rapid prototyping
Member
Compression
Rotation
Injection
RTM
Blow
Attributes
A process record
Material
Shape
Size Range
Min. section
Tolerance
Roughness
Economic batch
Supporting information
-- specific
-- general
Structured
information
Unstructured
information
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The EduPack
Engineering textSoftware Industrial design text
Resource books, exercisesand worked solutions
PowerPoint lectures
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The CES Software
Level 1
1st year students:Engineering,Materials Science,Design
64 materials
75 processes
Level 2
2nd - 4th year studentsof Engineering andMaterials Science andDesign.
91 materials
107 processes
Level 3
4th year, masters andresearch students ofEngineering Materialsand Design.
2916 materials
233 processes
Specialist DBs
Eco design
Mil handbook 5 and 17
Campus and IDES.
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Finding information with CES
Choose what you want to explore(materials, processes..)
Find what?
Which table?
Processes
Casting
Moulding
Powder
etc
Data
tableMaterials
Metals
Polymers
Ceramics
etc
Data
table
Browse Select SearchToolbar Print Search web
Links
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Property
Demo -- creating charts
New
Graph stage
Limit stage
Tree stage
Browse Select Search Print Search webToolbar
Prop
erty
2
Property 1
Select what? Materials, Level 1
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Relationships, perspective and comparisons
Metals Polymers Ceramics Hybrids
PEEK
PP
PTFE
WC
Alumina
Glass
CFRP
GFRP
Fibreboard
Steel
Copper
Lead
Zinc
Aluminum
Material bar-charts
Material property charts
Data sheets do not allow comparison,
perspective. For these we need
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Material property- charts: modulus - density
0.1
10
1
100
Metals
Polymers
Elastomers
Ceramics
Woods
Composites
Foams
0.01
1000
1000.1 1 10
Density (Mg/m3)
Youngsmodu
lusE,
(GPa)
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Mechanical properties
Why the differences?
Atom size and weight
Bonds as (linear) springs
Spring constant for variousbond types.
Manipulating properties
Making composites
Making foams
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Thermal properties
Why the differences?
Bonds as non-linear springs
10% expansion at meltingpoint, so expansion goesinversely as Tm
Thermal energy as atomvibration, propagates aswaves, scattered by obstacles
Manipulating properties
High conductivity: purity
Low conductivity, obstaclesand foams
P idi h d d l
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Materials that are light and stiff?
Providing methods and tools
At this stage students have a tool.
Materials with low expansion?
Develops a perspective
with high conductivity?
D R t iti
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Demo -- Report writing
Open project
Save project
Print .
File
Copy
Paste.
Edit
What is it? ABS (Acrylonitrile-butadiene-styrene ) is tough, resilient, and easilymolded. It is usually opaque, although some grades can now be transparent, and itcan be given vivid colors. ABS-PVC alloys are tougher than standard ABS and, inself-extinguishing grades, are used for the casings of power tools.
Design guidelines. ABS has the highest impact resistance of all polymers. Ittakes color well. Integral metallics are possible (as in GE Plastics' Magix.) ABS is UVresistant for outdoor application if stabilizers are added. It is hygroscopic (may needto be oven dried before thermoforming) and can be damaged by petroleum-basedmachining oils.
ABS can be extruded, compression moulded or formed to sheet that is then vacuumthermo-formed. It can be joined by ultrasonic or hot-plate welding, or bonded withpolyester, epoxy, isocyanate or nitrile-phenolic adhesives.
Technical notes. ABS is a terpolymer - one made by copolymerising 3 monomers: acrylonitrile, butadiene and syrene. Theacrylonitrile gives thermal and chemical resistance, rubber-like butadiene gives ductility and strength, the styrene gives aglossy surface , ease of machining and a lower cost. In ASA, the butadiene component (which gives poor UV resistance) isreplaced by an acrylic ester. Without the addition of butyl, ABS becomes, SAN - a similar material with lower impactresistance or toughness. It is the stiffest of the thermoplastics and has excellent resistance to acids, alkalis, salts and many
solvents.Typical Uses. Safety helmets; camper tops; automotive instrument panels and other interior components; pipe fittings;home-security devices and housings for small appliances; communications equipment; business machines; plumbinghardware; automobile grilles; wheel covers; mirror housings; refrigerator liners; luggage shells; tote trays; mower shrouds; boathulls; large components for recreational vehicles; weather seals; glass beading; refrigerator breaker strips; conduit; pipe fordrain-waste-vent (DWV) systems.
The environment. The acrylonitrile monomer is nasty stuff, almost as poisonous as cyanide. Once polymerized withstyrene it becomes harmless. ABS is FDA compliant, can be recycled, and can be incinerated to recover the energy itcontains.
Th i i t
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The main points
The data take two broad forms:
(a) numeric, non-numeric data that can be structured in a uniformway for all materials
(b) supporting information, best stored as text and images
Classification allows materials data to be organized and retrieved
Visual presentation of data as bar-charts and property (bubble) chartsreveals relationships and allows comparisons
The CES EduPack allows rapid access to information, and ability tomake charts
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