1. Progettazione di Materiali e Processi
Università degli Studi di Trieste
Facoltà di Ingegneria
Corso di Laurea in Ingegneria Chimica e dei Materiali
A.A

2. PRODUCT (MATERIALS) AND PROCESS DESIGN
Intro
Design, Product, Process
Product Design; Process Design; Product and Process Design
Material, process, shape, properties, function
Example
Fundamentals
Identification of needs (market; coevolution; true need)
Types of design
Design tools
Databases
Analytical tools
Simulation tools
Design process
Selection and design of materials and processes (Lughi)
Tools for optimal systematic selection
Design of materials: case studies (nano, meso, microstructures; hybrid materials; composites)
Design and optimization of chemical processes (Fermeglia)
Advanced tools and methods (ad-hoc lectures and seminars: FEM, product/process economics, Life Cycle Assessment, …)
Special topic seminars (Intellectual Property, product evaluation, materials in industrial design, theory of scenarios, rapid plant assessment, material selection in engines, design for recycle, refurbish, reuse)

3. Progettazione di Materiali e Processi
Modulo 1
Selezione sistematica di materiali e processi
Lecture 2
Selection process
Materials indexes

4. The selection process
This decision-making strategy is developed here. For simplicity, it is first applied to the selection of a car.
The requirements (upper left) are the features that the purchaser wishes to have: a mid-sized car with 4 doors and at least 200 horsepower. These are constraints – cars that do not meet them are not acceptable. In addition there is an objective: that of minimizing the cost of ownership.
The data (upper right) are the attributes of available models of car – size, number of doors, power, fuel consumption, CO2 rating and so on.
The comparison engine imposes constraints and objectives to isolate a subset of cars that meet the requirements. Documentation of these provides details: available colors, delivery time, warranty details, service intervals and such like on which a final choice is based.

5. The selection process All materials Screening: apply property limits
Innovative choices
Ranking: apply material performance indices
Subset of materials
Shortlisting: apply supporting information
Prime candidates
Final selection: apply local conditions
Final material choice

6. Properties FUNCTIONS: Carry load Transmit load Transmit heat
Transmit current
Store energy …
Function
Shape
Material
OBJECTIVES:
Minimize mass
Minimize cost
Minimize impact …
Iterative process
Process

7. Function – Objectives - Constraints
What does the component do?
e.g.: support load, seal, transmit heat, bycicle fork, etc.
Objective
What do we want to maximize (minimize)?
e.g.: minimize cost, maximize energy storage, minimize weight, etc.
Constraints
What conditions must be met? (non-negotiable or negotiable)
e.g. geometry, resist a certain load, resist a certain environment, etc.
Implicit functions (e.g. tie, beam, shaft, column)
Constraints often translate to property limits (temperature, conductivity, cost, …)
Some constraints are more complex (e.g. stiffness, strength, etc.) as they are coupled with geometry -> need of a specific objective
Material indices help unravel such complexity

8. The material index
This decision-making strategy is developed here. For simplicity, it is first applied to the selection of a car.
The requirements (upper left) are the features that the purchaser wishes to have: a mid-sized car with 4 doors and at least 200 horsepower. These are constraints – cars that do not meet them are not acceptable. In addition there is an objective: that of minimizing the cost of ownership.
The data (upper right) are the attributes of available models of car – size, number of doors, power, fuel consumption, CO2 rating and so on.
The comparison engine imposes constraints and objectives to isolate a subset of cars that meet the requirements. Documentation of these provides details: available colors, delivery time, warranty details, service intervals and such like on which a final choice is based.

9. Functional requirements
Material index
Performance = f (F, G, M)
Functional requirements
Material properties
Geometry
If separable:
Performance = f1(F) f2(G) f3(M)
Material index

10. Index for a stiff, light tie-rod
Stiff tie of length L and minimum mass L F
Area A
Tie-rod
Function
Length L is specified
Must have axial stiffness > S*
Constraints
m = mass
A = area
L = length
 = density
= yield strength
Equation for constraint on A:
This and the next frame work through examples illustrating how to derive material indices when there is a free variable in addition to the choice of material; more appear in later frames. Here we have the simplest of components – a tie rod. Its length L is defined. It must carry a prescribed tensile load F without failure (a constraint) and at the same time be as light a possible (an objective). The frame shows the steps. Materials satisfying all the other constraints (such as operating temperature, corrosion resistance and so forth) and that have a large value of the index σy/ρ (or, equivalently, a small value of ρ/σy ) are the best choice.
If the constraint had been on stiffness rather than strength, the index becomes E/ρ (E is Young’s modulus).
Minimize mass m:
m = A L 
Objective
Performance metric m
Chose materials
with largest

11. Index for a stiff, light beam
Stiff beam of length L and minimum mass L
Square
section,
area
A = b2 b F δ
Beam
Function b
Length L is specified
Must have bending stiffness > S*
Constraints
Equation for constraint on A:
m = mass
A = area
L = length
 = density
E = Young’s modulus
I = second moment of area
(I = b4/12 = A2/12)
C = constant (here, 48)
S = stiffness (F/δ)
Minimize mass m:
m = A L 
Objective
The most usual mode of loading of engineering structures is bending: wing-spars of aircraft, ceiling and floor joists of buildings, golf club shafts, oars, skis, ….all these structures carry bending moments; they are beams. The requirement here is for a beam of specified stiffness and minimum mass. The frame lays out the steps, leading to the index ρ/E1/2 ; it differs from the index for a light stiff tie-rod because the mode of loading is bending, not tension. Later frames show how these indices are used to rank materials.
A panel is a flat sheet of given length and width: a table top, for instance. It differs from a beam in that the width of the beam is a free variable, whereas the width of the panel is prescribed. Otherwise the method, given in this frame, is the same. It leads to the index ρ/E1/3.
Performance metric m
Chose materials
with largest

12. Index for a strong, light tie-rod
Strong tie of length L and minimum mass L F
Area A
Tie-rod
Function
Length L is specified
Must not fail under load F
Constraints
m = mass
A = area
L = length
 = density
= yield strength
Equation for constraint on A:
F/A < y
Minimize mass m:
m = A L 
Objective
This and the next frame work through examples illustrating how to derive material indices when there is a free variable in addition to the choice of material; more appear in later frames. Here we have the simplest of components – a tie rod. Its length L is defined. It must carry a prescribed tensile load F without failure (a constraint) and at the same time be as light a possible (an objective). The frame shows the steps. Materials satisfying all the other constraints (such as operating temperature, corrosion resistance and so forth) and that have a large value of the index σy/ρ (or, equivalently, a small value of ρ/σy ) are the best choice.
If the constraint had been on stiffness rather than strength, the index becomes E/ρ (E is Young’s modulus).
Performance metric m
Chose materials
with largest

13. Min. environmental impact
Material indices
Material index:
E/
Material index:
E0.5/
Function
Objective
Constraint
Tie
Beam
Shaft
Column
…..
Minimum cost
Max energy storage
Minimum weight
Min. environmental impact ……
Stiffness
Strength
Fatigue resistance
Geometry
…..
Material index:
/