Progettazione di Materiali e Processi Università degli Studi di Trieste Facoltà di Ingegneria Corso di Laurea in Ingegneria Chimica e dei Materiali A.A. 2016-2017

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)

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

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.

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

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

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

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.

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

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

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

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

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: /