materials quality control, assurance and selectionthe decision-making strategy design requirements...

Materials Quality Control,Assurance and Selection

Dr. Emmanuel Kwesi Arthur

Email: [email protected]

Phone #: +233541710532

Department of Materials Engineering,

Kwame Nkrumah University of Science and Technology, Kumasi, Ghana

©2019

Course Code: MSE 456

1

Lecture Two

Materials Selection

Materials Selection in Engineering Design

MATERIALS SELECTION

MATERIALS SELECTION IN DESIGN-

BASICS

Methods of Material Selection

The common methods of material selection are as follows:

1. Performance indices (including the use of Ashby charts)

2. Decision matrices

– Pugh selection method Pugh selection method

– Weighted property index

3. Selection with Artificial Intelligence tools (i.e. Expert Systems)

4. Selection with Computer-Aided Databases

5. Value analysis

6. Failure analysis

7. Benefit-cost analysis

We will be focusing on computer-Aided Databases, performance indices and weighted property index.

Intro Lecture. Design Stage:

the first steps of optimised

selection

The design process and material search space

Product specification

Concept

Embodiment

Detail

Market need

Problem statement

Final choice

Material search space

Screen

Screen

Rank

All materials

Increasing

constraints

Material & process needs

Choice of material family

(metals, ceramics, polymers..)

Choice of material class

(Steel, Al-alloy, Ni-alloy…..)

Choice of single material

(Al-2040, Al-6061, Al-7075…..)

Need – Concept -- Embodiment

ConceptsNeed

Embodiments

Direct pull Levered pull Spring assisted pullGeared pull

Embodiment -- Detail

The decision-making strategy

Design requirements

expressed as

Constraints and

Objectives

Normative information

Material attributes

Process attributes

including prompts for

Intuitive estimation

Factual information

Final selection

Comparison engine

Screening

Ranking

Documentation

Methodic information

Translation to create Normative information

Translation: “express design requirements as constraints”

Constraints What essential conditions must it meet ?

Free variables Which design variables are free ?

Design requirements

ObjectivesWhat measure of performance is to

be maximized or minimized ?

Choice of

material

Be strong enough

Conduct electricity

Tolerate 250 C

Be able to be cast

Cost

Weight

Volume

Eco-impact

Function What does the component do ?

A label

QUESTIONS

Translation: a heat sink for power electronics

Power micro-chips get hot.

They have to be cooled to

prevent damage.

Free variable Choice of material

Constraints 1. Max service temp > 200 C

2. “Good electrical insulator”

3. “Good thermal conductor”

(or T-conduction > 25 W/m.K)

Translation

Function Heat sinkKeep chips below 200 C

without any electrical

coupling.

Design requirements

A Limit stage

Thermal properties Min. Max

Mechanical properties

Maximum service temperature C

Thermal conductivity W/m.K

Specific heat J/kg.K

Electrical properties

Electrical conductor

or insulator?

Good conductor

Poor conductor

Semiconductor

Poor insulator

Good insulator

Thermal properties Min. Max


Maximum service temperature C

Thermal conductivity W/m.K

Specific heat J/kg.K


Electrical conductor

or insulator?

Good conductor

Poor conductor

Semiconductor

Poor insulator

Good insulator

Screening using a LIMIT STAGE

Browse Select Search Print Search web

Screening: “Eliminate materials that can’t do the job”

2. Selection Stages

Graph Limit Tree

1. Selection data

Edu Level 2: Materials

Results X out of 95 pass

Material 1 2230 113

Material 2 2100 300

Material 3 1950 5.6

Material 4 1876 47

etc...

RankingProp 1 Prop 2

200

25

2000C

Screening using a GRAPH STAGE


File Edit View Select Tools

Don’t need

numbers!

1. Selection data



Material 1 2230 113

Material 2 2100 300

Material 3 1950 5.6

Material 4 1876 47

etc...


1000

0.1

Metals

Polymers &

elastomersComposites

Foams

10301 1010 1020

Ceramics

10

1

100

0.01

Electrical resistivity (.cm)

T-c

on

du

cti

vit

y (

W/m

.s)

PEEK

PP

PTFE

PEEK

PP

PTFE

WC

Alumina

Glass

WC

Alumina

Glass

CFRP

GFRP

Fibreboard

CFRP

GFRP

Fibreboard

Steel

Copper

Lead

Zinc

Aluminum

Steel

Copper

Lead

Steel

Copper

Lead

Zinc

Aluminum

Metals Polymers Ceramics Composites

2. Selection Stages

Graph Limit Tree

Translation: a CD case, an example of redesign

Free variable Choice of material

CD cases are made of polystyrene

(PS). They crack and scratch the

disks. Find a better material.

Injection-moldable

Contain and protect CD

better than the PS case.

As transparent as PS

Recylable

Design requirements

Function CD enclosure

Translation

Constraints

1. Can be injection molded

2. Toughness K1c > that of PS

3. Optically clear

4. Can be recycled

Screening using a TREE STAGE

Tree stage for material

Material

Ceramics Steels

Hybrids Al alloys

Metals Cu alloys

Polymers Ni alloys...

2. Selection Stages

Graph Limit Tree


1. Selection data


Process

Join

Shape

Surface

Cast

Deform

Mold

Composite

Powder

Prototype

Tree stage for processResults X out of 95 pass

Material 1

Material 2

Material 3

Material 4

etc...

Stacking selection stages

Pro

pert

y

Stacked stages


1. Selection data


Density

Modulus

Strength

T-conduction

2

100

10

200

Min Max

Process

Join

Shape

Surface

Cast

Deform

Mold

Composite

Powder

Prototype

2. Selection Stages

Graph Limit Tree


Material 1 2230 113

Material 2 2100 300

Material 3 1950 5.6

Material 4 1876 47

etc...


Optical properties

Transparency

Eco properties

Recycle

Optical quality

Transparent

Translucent

Opaque

3

Tree stage: injection mold1

Fra

ctu

re t

oughness

Polystyrene

Keep these!

2

The CD case: the whole story

Select Level 2: Materials

Free variable Material

Function CD enclosure

Translation

Constraints

1. Can be injection molded

2. Toughness K1c > that of PS

3. Optically clear

4. Can be recycled

Documentation: the pedigree

Granta’s Web Portal (http://matdata.net) gives

indexed access to information providers’ web sites.

Documentation: “now that the number of candidates is small, explore their

character in depth”

Suppliers’

data sheetsHandbooksMaterial

portals

Trade

associations

Documentation:the “pedigree” of surviving candidates

Quiz 1

1) The cases in which most CDs are sold have an irritating way of cracking and breaking. Which design-limiting property has been neglected in selecting the material of which they are made?

2) State two reasons why proper materials selection procedure should be used in choosing suitable material for a given application

Documentation with CES

Browse Select Search Print

ResultsX out of 94 pass

Material 1

Material 2

Material 3

Material 4

Material 5

………..

Search web

Matdata.netSearches information sources

for selected record

1. Selection data


2. Selection Stages

Graph Limit Tree

Open the record

Age hardening ALUMINUM ALLOYS The material The high-strength aluminum alloys rely on age-hardening: a sequence of heat treatment steps that causes the precipitation of a nano-scale dispersion of intermetallics that impede dislocation motion and impart strength.

General properties Density 2500 - 2900 kg/m^3 Price 1.423 - 2.305 USD/kg

Mechanical properties Young's modulus 68 - 80 GPa Elastic limit 95 - 610 MPa Tensile strength 180 - 620 MPa Elongation 1 - 20 % Hardness - Vickers 60 - 160 HV Fatigue strength at 10

7 cycles 57 - 210 MPa

Fracture toughness 21 - 35 MPa.m^1/2

Thermal properties Thermal conductor or insulator? Good conductor Thermal conductivity 118 - 174 W/m.K

Age hardening ALUMINUM ALLOYS The material The high-strength aluminum alloys rely on age-hardening: a sequence of heat treatment steps that causes the precipitation of a nano-scale dispersion of intermetallics that impede dislocation motion and impart strength.

General properties Density 2500 - 2900 kg/m^3 Price 1.423 - 2.305 USD/kg

Mechanical properties Young's modulus 68 - 80 GPa Elastic limit 95 - 610 MPa Tensile strength 180 - 620 MPa Elongation 1 - 20 % Hardness - Vickers 60 - 160 HV Fatigue strength at 10

7 cycles 57 - 210 MPa

Fracture toughness 21 - 35 MPa.m^1/2

Thermal properties Thermal conductor or insulator? Good conductor Thermal conductivity 118 - 174 W/m.K

These are

often enough !

The four steps of selection:

1. Translation, giving constraints and objectives

2. Screening , using constraints

3. Ranking, using objectives

4. Documentation in CES, and http://matdata.net

The main points

CES allows Screening using

• Limit stages,

• Graph stages

• Tree stages and

• All three in any number and sequence

Pause for demo

Exercise: Stage 1, a tree stage

3.1 A material is required for a molded electrical

enclosure that may be used outdoors. There are

requirements on

Processing (this Stage)

Properties (Stage 2)

Price (Stage 3)

Apply Stage 1 – a Tree Stage Tree stage

ProcessUniverse

Shaping

Molding -- Insert

OK

Now add Stage 2 – next page

Browse Select SearchBrowse Select Search

Select from

materials or

process tree

1. Selection data

Edu Level 2: MaterialsEdu Level 2: MaterialsEdu Level 2: MaterialsEdu Level 2: Materials

2. Selection Stages

Graph Limit Tree

2. Selection Stages

Graph Limit Tree

Exercise: Stage 2, a limit stage

3.2 The material of the enclosure must have Hardness - Vickers > 8 HV

Be a good electrical insulator

Have dielectric strength > 10 MV/m

Be able to be recycled



Eco properties

Recycle

Good conductor

Poor conductor

Poor insulator

Good insulator

Hardness - Vickers 8 HV

Conductor or insulator?

Dielectric strength 10 MV/m



Eco properties

Recycle

Good conductor

Poor conductor

Poor insulator

Good insulator

Good conductor

Poor conductor

Poor insulator

Good insulator

Hardness - Vickers 8 HV

Conductor or insulator?

Dielectric strength 10 MV/m

Now add Stage 3 – next page


1. Selection data


2. Selection Stages

Graph Limit Tree

2. Selection Stages

Graph Limit Tree

Enter

limits

Exercise: Stage 3, a graph stage

3.3 The material of the enclosure should be as cheap

as possible. Find the four materials meeting all the

previous constraints that have the lowest price per kg.

Graph stage – Y-axis – Price

Hide all materials failing previous stages

Rank the final Results list by Price


1. Selection data


2. Selection Stages

Graph Limit Tree

2. Selection Stages

Graph Limit Tree

Choose

Y-axis3. Results: 15 of 95 pass

Name Price (USD/kg)Polypropylene (PP) 1.41 - 1.62

Soda-lime glass 1.41 - 1.659

Polystyrene (PS) 1.476 - 1.574

Polyvinylchloride (tpPVC) 1.6 - 2.2

Polyethylene terephthalate (PET) 1.608 - 1.769

Polyethylene (PE) 1.718 - 1.89

Polyoxymethylene (Acetal, POM) 2.203 - 2.732

Polymethyl methacrylate 2.335 - 2.569

Acrylonitrile butadiene styrene (ABS) 2.511 - 2.952

Polyamides (Nylons, PA) 3.194 - 3.569

Polycarbonate (PC) 3.6 - 4.47

Polylactide (PLA) 3.667 - 4.584

Polyurethane (tpPUR) 3.723 - 4.45

Cellulose polymers (CA) 3.921 - 4.313

Polyetheretherketone (PEEK) 99.14 - 109

Assignment 1

1) What is meant by the design-limiting properties of a material in a given application?

2) There have been many attempts to manufacture and market plastic bicycles. All have been too flexible. Which design-limiting property is insufficiently large?

3) What, in your judgement, are the design-limiting properties for the material for the blade of a knife that will be used to gut fish?

4) What, in your judgement, are the design-limiting properties for the material of an oven glove?

5) What, in your judgement, are the design-limiting properties for the material of an electric lamp filament?

6) A material is needed for a tube to carry fuel from the fuel tank to the carburetor of a motor mower. The design requires that the tube can bend and that the fuel be visible. List what you would think to be the design-limiting properties.

Assignment 1

7) A material is required as the magnet for a magnetic soap holder. Soap is mildly alkaline. List what you would judge to be the design-limiting properties.

8) List three applications that, in your judgement, need high stiffness and low weight.

10) List three applications that, in your judgement, need optical quality glass.

Pause for demo

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