www.grantadesign.com

„Software-based systematic approaches to material

selection and lightweighting‟

Sirris Materials Day

4th October 2011 - Ghent

Dr Charles Bream

Granta Design - Introduction

Granta Design – history

• Founded in 1994 from the University of Cambridge

Professors Mike Ashby & David Cebon

Owners: Cambridge Univ, ASM International, Founders, Employees

• Technology firsts include:

Materials selection (Ashby charts, performance indices…)

Integrated materials data management

Software-based teaching of materials engineering

The materials information technology experts

• Software – manage materials information, selection…

• Data products – specialist materials data libraries

• Services – implement, configure, apply…

Customers

• Airbus, Arcelor, Aubert & Duval, Boeing, Dow, Emerson, EADS Astrium, Ferrari, GE, Honeywell, IHI, J&J, Moen, NASA…

• 800+ universities worldwide

Design brief / requirements

CADPreliminary design concept

CAD, CAE

Optimisation packages Detailed design

Final design

Prototype & testing

LCA

Selection of Materials

Increasing:

Time

Effort

Cost

When?

Use previous or familiar material

Ask material supplier

Ask colleague or consultant

Development trials

How?

Implication of using wrong material:

Suboptimal design

Non-competitive

Extended development cycle

Product recall

Systematic Material Selection

All materials

Breakdown design requirements into:

Function – What does the component do?

Constraints – What essential conditions must be met?

Objectives – What is to be maximized or minimized?

Free variable – What am I free to change?

Screen on constraints - ‘Go’ / ‘no-go’ criteria (usually many)

Rank on objectives - Ordering of materials that ‘go’

Top candidate materials

Supporting information – Specialist databases, contact suppliers

Local conditions – Preferred suppliers, process capability, location

Final Selection

Train Floor Example

Function:

Self-supporting „Intermediate‟ floor for train carriage

Screen on Constraints:

• Temperature resistance (-40°C to +85°C)

• Adequate toughness & strength

• Durable to rain and salt water

• Manufacture from flat sheet/profile

Rank on Objectives:

• Minimize mass

• Minimize cost

Design Requirements:

Panel loaded in bending

Stiffness-limited design

Length, width specified

Thickness free

Ranking on Objectives

• Minimize mass, cost… Minimize mass, cost…

per unit of performance

Function &

Loading

Tie in tension

Panel in bending

Shaft in torsion

Column in compression

……….

Mechanical,

Thermal,

Electrical...

Limiting

Constraint

Stiffness specified

Strength specified

Fatigue limit

Geometry

……….

Objective

Minimum cost

Minimum weight

Max energy storage

Minimum

environmental impact

……….

Each combination of:

Function

Constraint

Objective

has a characteristic index

E1M

312E

M

• Maximise performance

Low weight

Tensile Strut

E(m) Index

Low alloy steel = 1

Influence of Application on Material Choice

COMPOSITES METALS PLASTICS

Low weight

Panel in Bending

Low alloy steel = 1

31E(m) Index

Influence of Application on Material Choice

COMPOSITES METALS PLASTICS

Low weight

Panel in Bending

Low alloy steel = 1

31E(m) Index

Mass vs Cost trade-off

31

m

E

C.(c) Index

Hybrid Materials & Structures?

“A hybrid material is a combination of two or more materials in a pre-determined

configuration and scale, optimally serving a specific engineering purpose”

Kromm et al, 2002

Design variables:

Choice of materials

Volume fractions

Configuration

Connectivity

Scale

Optimization of Hybrid Materials

Influence of adding different reinforcement types and loading levels to a magnesium alloy

Application = Lightweight stiff panel loaded in bending

All materials along line exhibit same

value of the index:

Materials with the highest value are optimal for the

application

31

E

quasi-isotropic

composite

Optimization of Hybrid Structures

Orange: Sandwich panel, Mg-50% carbon fibre skins & 50kg/m3Mg octet lattice core

(Core thickness = 20mm, face sheet thickness = 0.05 – 5mm)

Yellow: Predicted performance of core & skin materials

All materials along line exhibit same

value of the index:

Materials with the highest value are optimal for the

application

31

E

Summary

Integration of material selection tools into typical design workflow

Design brief / requirements

CADPreliminary design concept

CAD, CAE

Optimisation packages Detailed design

Final design

Prototype & testing

LCA

Increasing:

Time

Effort

Cost

CES Selector

Material

Selection

Eco Audit

Tool

Hybrid

Synthesizer

• Evaluate different materials and

design concepts before committing

expenditure

• Avoid problems associated with

incorrect material choice

• Reduce development time

Thank You!