Dr. Emmanuel Kwesi Arthur - Materials Quality Control ......Dr. Emmanuel Kwesi Arthur Email:...

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 Four

The chart-management tool bar

Box selection

tool

Cancel

selection

Add text

Zoom

Add

envelopes

Un-zoom

Black and white

chart

Hide failed

materials

Grey failed

materials

Line selection

tool

Exercise: selecting light, strong materials (1)

4.1 The material index for selecting

light strong materials is

M =

where is the yield strength and

the density.

Make a Graph stage with these

two properties as axes

Impose a selection line (slope 1)

to find materials with the highest

values of M.

Add a Limit stage to impose the

additional constraint:

Elongation > 10%

/y

y

Results: Age-hardening wrought Al-alloys

Nickel-based superalloys

Titanium alloys

Wrought magnesium alloys

Browse Select SearchBrowse Select Search

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

Density

Str

en

gth

y

1

yHigh

Density

Str

en

gth

y

1

yHigh

Density

Modulus

Strength

Elongation

etc

10

Density

Modulus

Strength

Elongation

etc

10

Min Max

Exercise: selecting light, strong materials (2)

4.2 Repeat the selection of 4.1, but use the

Advanced facility to make a bar-chart with

the index

M =

on the Y-axis.

Impose a Box selection to find materials

with the highest values of M.

Add a Limit stage to impose the additional

constraint:

Elongation > 10%

/y

Ind

ex

y /

yHigh


1. Selection data


2. Selection Stages

Graph Limit Tree

2. Selection Stages

Graph Limit Tree

Density

Modulus

Strength

Elongation

etc

10

Density

Modulus

Strength

Elongation

etc

10

Min Max

List of properties Density

Modulus

Yield strength

etc

+ - */ ^ ( )

Yield strength /

Density


Modulus

Yield strength

etc

+ - */ ^ ( )+ - */ ^ ( )

Yield strength /

Density

Exercise: selecting materials for springs (1)

4.3 A material is required for a spring that may be

exposed to shock loading, and must operate in

fresh and salt water.

Constraints:

Fracture toughness > 15 MPa.m1/2

Very good durability in fresh and salt water

Objective:

Maximise stored elastic energy

y

Strain

Str

es

s

E2

1

2

12y

yy

Elastic energy

The best materials for

springs are those with the

greatest value of

the index

E

2y

Make a graph with

Young’s modulus E on the X-axis

Yield strength on the Y-axis

Put on a line of slope 0.5 (corresponding to power 2)

Select materials above the line

Add the other constraints using a limit stage

y


1. Selection data


2. Selection Stages

Graph Limit Tree

2. Selection Stages

Graph Limit Tree

Modulus ES

tre

ng

th

y

0.5

E

2y

High

Modulus ES

tre

ng

th

y

0.5

E

2y

HighDensity

Fr. toughness

etc

Fresh water

Salt water

Min Max

15

v. good

v. good

Density

Fr. toughness

etc

Fresh water

Salt water

Min Max

15

v. goodv. good

v. goodv. good

Exercise: selecting materials for springs (2)

4.4 Repeat the selection of 4.3, but use the

Advanced facility to make a bar-chart with

the index

on the Y-axis.

.

E/2y

Ind

ex

y2

/E E

2y

High

Plot the bar chart

Use a box selection to select the materials

with high values of the index

Add the other constraints using a limit stage

Results: CFRP, epoxy matrix (isotropic)

Nickel-based superalloys

Titanium alloys


1. Selection data


2. Selection Stages

Graph Limit Tree

2. Selection Stages

Graph Limit Tree

Density

Fr. toughness

etc

Fresh water

Salt water

Min Max

15

v. good

v. good

Density

Fr. toughness

etc

Fresh water

Salt water

Min Max

15

v. goodv. good

v. goodv. goodList of properties Density

Modulus

Yield strength

etc

+ - */ ^ ( )

(Yield strength^2)/

Young’s modulus


Modulus

Yield strength

etc

+ - */ ^ ( )+ - */ ^ ( )

(Yield strength^2)/

Young’s modulus

Quiz 3

1. Use the modulus–density chart to find, from among the materials that appear on it:

(a) The material with the highest density.

(b) The metal with the lowest modulus.

(c) The polymer with the highest density.

(d) The approximate ratio of the modulus of woods measured parallel to the grain and perpendicular to the grain.

(e) The approximate range of modulus of elastomers.

Quiz 3

Exercise 2

1) Make an E–ρ chart using the CES software. Use a box selection to find three materials with densities between 1000 and 3000 kg/m3 and the highest possible modulus.

2) Data estimation. The modulus E is approximately proportional to the melting point Tm in Kelvin (because strong inter-atomic bonds give both stiffness and resistance to thermal disruption). Use CES to make an E–Tm chart for metals and estimate a line of slope 1 through the data for materials. Use this line to estimate the modulus of cobalt, given that it has a melting point of 1760 K.

3) Sanity checks for data. A text reports that nickel, with a melting point of 1720 K, has a modulus of 5500 GPa. Use the E–Tm correlation of the previous question to check the sanity of this claim. What would you expect it to be?

Exercise 3

1) Explore the potential of PP–SiC (polypropylene–silicon carbide) fiber composites in the following way. Make a modulus–density (E–ρ) chart and change the axis ranges so that they span the range 1 < E <1000 GPa and 500 < ρ < 5000 kg/m3 . Find and label PP and SiC, then print it. Retrieve values for the modulus and density of PP and of SiC from the records for these materials (use the means of the ranges).

2) Use a ‘Limit’ stage to find materials with modulus E > 180 GPa and price Cm < 3 $/kg.

3) Use a ‘Limit’ stage to find materials with modulus E > 2 GPa, density ρ < 1000 kg/m3 and Price < 3/kg.

Exercise 4

1) Make a bar chart of modulus, E. Add a tree stage to limit the selection to polymers alone. Which three polymers have the highest modulus?

2) Make a chart showing modulus E and density ρ. Apply a selection line of slope 1, corresponding to the index E/ρ positioning the line such that six materials are left above it. Which are they and what families do they belong to?

3) A material is required for a tensile tie to link the front and back walls of a barn to stabilize both. It must meet a constraint on stiffness and be as cheap as possible. To be safe the material of the tie must have a fracture toughness K1c > 18 MPa.m1/2. The relevant index is

Assignment 2

1) Construct a chart of E plotted against Cm ρ. Add the constraint of adequate fracture toughness, meaning K1c > 18 MPa.m1/2, using a ‘Limit’ stage. Then plot an appropriate selection line on the chart and report the three materials that are the best choices for the tie.

Example 2: Stiff & Light Tension Members

Assignment 3

1) List the six main classes of engineering materials. Use your own experience to rank them approximately:`

(a) By stiffness (modulus, E).

(b) By thermal conductivity (λ).

1) What are the steps in developing an original design?

2) Describe and illustrate the ‘translation’ step of the material selection strategy.

3) What is meant by an objective and what by a constraint in the requirements for a design? How do they differ?

4) You are asked to design a fuel-saving cooking pan with the goal of wasting as little heat as possible while cooking. What objective would you choose, and what constraints would you think must be met?

Assignment 4

a) Sprint bikes.

b) Touring bikes.

c) Mountain bikes.

d) Shopping bikes.

e) Children’s bikes.

f) Folding bikes.

Use your judgement to identify the primary objective and the constraints that must be met for each of these.

Bikes come in many forms, each aimed at a particular sector of the market:

Quiz 4

Examine the material property chart of modulus versus density. By what factor are polymers less stiff than metals? Is wood denser or less dense than polyethylene (PE)?

Example 3: Cheap Stiff Column

A column supports compressive

loads e.g. legs of a table or pillars

The goal is to identify the cheapest

materials that will support the load

without failing

19

Cheap Stiff Column

The objective function is cost

The buckling constraint is given by (safe design)

Noting that I = r4/4 = A2/4 and eliminating the

variable A gives

The material index for a low cost column that resists

buckling is

Performance of Stiff but Cost Effective Column

Slope=2

Quiz 5

1) Use the modulus–relative cost chart to find, from among the materials that appear on it:

(a) The cheapest material with a modulus greater than

1 GPa.

(b) The cheapest metal.

(c) The cheapest polymer.

(d) Whether magnesium alloys are more or less expensive than aluminum alloys.

(e) Whether PEEK (a high-performance engineering polymer) is more or less expensive than PTFE.

Quiz 5

Assignment 5

Pick any three engineering applications and answer thefollowing:

1. Determine required properties: ex: mechanical,electrical, thermal,

magnetic, optical, deteriorative.

2. Express the design requirements into functions andobjectives.

3. Properties: identify candidate materials

4. Material: identify required ProcessingProcessing: changes structure and overall shapeex: casting, sintering, vapor deposition, dopingforming, joining, annealing.

QUESTIONS

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