materials for energy [phy563] material design & engineering

Materials for Energy[PHY563]

Material Design & Engineering

13/01/2021

Jean-François Guillemoles,

Nathanaëlle Schneider

PART II: MATERIAL SELECTION AND ENGINEERING

Recommended reading M.F. Ashby (e.g. Engineering materials) and Y. Brechet

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Learning curves and Progress ratio

Improved technologies (materials)

Better production processes

Scaling up & constraints

PHY563 – JF Guillemoles 3

J.R. Lovering et al. / Energy Policy 91 (2016) 371–382

Nuclear

Wind

Solar

Fuel cells

Wind turbine – Mechanical material selection

Outline

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• Mechanical properties and structure

• Ashby’s method

• Example

PHY563 – JF Guillemoles

Mechanical properties of materials: definitions

Poisson’s ratio 1/3

= 0.5 (no volume change)

• Elastic modulus:

o Hooke’s law : linear regime at small deformations

o Ball and spring model of solids

o Young’s modulus (E), Shear modulus (G=E/[2(1+)]) and Bulk modulus (K=E/[3(1-2)])

A Quick Review of some Major Materials Properties

nE .

.G

.Kp

RelationshipsKE G3/8 E

0.33

Elastic vs plastic

• Elastic energy is stored

• Plastic energy is dissipated


Young’s Modulus


Yield strength

Onset of plastic flow

(usually stress yielding 0.2% permanent strain)


• Cohesion:

o Lower energy at r°, weak attraction at 2r°, max force/bond at ~1.25 r°

o Beyond 1.25 r°, F> max attractive force : bond breaks

o Melting for average dist. ~1.1 r°

Strength of crystals

15. EE bmb

Ideal strength

Point defects


Vacancies, interstitials, impurities (interstitial ou substitutional)

Vacancies interstitials impurities

X

X

(interstitial ou substitutional)

Planar and linear defects


A

B

A

B

A

B

C

A

C

A

C

A

Fault I2

vide

vide

plan de glissement

vecteur de faute

Grain Boundary

Stacking fault

Edge dislocation and plastic (tensile) deformation

Screw dislocation and shear strain

Strengthening methods


Microprecipitates hardening

Dislcocation pinning and escape

Other mechanical properties

• Yieldy and Hardness

• Gc (toughness) is energy /unit area of Crack t.da

Also: creep, fatigue, …


H 3 y

• How defect propagate : fixed displacement

• Existence of critical load in presence of defects

• Elastic energy is converted into surface energy

Modulus of RuptureSurface stress at failure

• Fracture Toughness (Kc)

cYK CC

1

2

E

KG C

C

Termal effects


• Linear thermal-expansion coefficient,

• Creep o Creep exponent, n; Activation energy, Q; reference stress, 0; kinetic factor, A

RT

QA

n

exp0

• Thermal conductivity,

• Thermal diffusivity, for transient heat flux

• Melting temperature, Tm and Glass transition temperature, Tg

Thermal properties

dx

dTQ

pCa

• Wear resistance

• Corrosion rate

Loss of material

Elastic bending: second moment of area

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METHOD


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References

Material selection

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1- Material properties limit performance.More than one property: may need to minimize cost

2- Performance can be maximized by comparing and selecting the appropriate material

- Find design criteria- Consider a wide range of materials.

Références

The Ashby method: material selection charts

Materials Selection Charts

• Usually the performance of a component depends on more than one property

• For most load-bearing components, performance are quantified by a combination of properties (The Performance Indices)

• Plotting charts of one property vs. the other reveals the correlations between properties and facilitates optimization

• The materials property charts provide convenient tool for applying design constraints and optimizing performance indices

• Assemble data database• Formulate list of constraints• Decide on the criterion to rank the candidates objectives• Research the top-ranked candidates seek documentation

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Material selection strategies

Ashby, Materials and the Environment: Eco-informed Material Choice, 2012, 2nd edition

Simple example: choosing a car

If 2 or more objectives, a compromise is neededtrade-off methods

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Simple example: selecting a material for a portable bike shed

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• Translation= Convert design requirement into contraints and objectives that canbe applied to material databases

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• Screening = constraints on material property charts

Material property charts : bar and bubble charts

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• Ranking = indices on material property charts(indices are necessary as often more than one property is required)

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• Ranking = indices on material property charts(indices are necessary as often more than one property is required)

Possibility to use these indices for scaling and evaluating material substitution

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Ratios

• Often must consider more that one property, i.e.

o Pressure vessel should resist creep and fracture

o mechanical structures must be light, stiff, and tough

• Indices appear as product of power laws of properties that should be optimized :

o specific modulus E / = …

o specific strength failure / = …

o

Relative importance depends on design criteria

Examples of Performance Indices are (E1/2/) for light and stiff beam, (f

2/E) for spring(f/E) for thermal shock resistance.

Material selection charts

Light and rigid design: log-log scales makes optimal indices readily apparent


Same line => same mass => cost evaluation

Pressure vessel

39Références

Stress on wall

Mass

materials for energy [phy563] material design & engineering

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