Upload
trinhanh
View
219
Download
0
Embed Size (px)
Citation preview
1
Materials: engineering, science, processing and design, 2nd edition Copyright (c)2010 Michael Ashby, Hugh Shercliff, David Cebon
• A successful product – one that performs well, is good value for money and gives pleasure to the user – uses the best materials for the job, and fully exploits its potential and characteristics
• Materials selection is not about choosing a material, but a profile of properties that best meets the needs of the design
• Material and process are interdependent
• Materials and processes are grouped into families; each family has a characteristic profile, the “family likeness,” which is useful to know when selecting which family to use for a design
Introduction to Materials and Processes
Materials: engineering, science, processing and design, 2nd edition Copyright (c)2010 Michael Ashby, Hugh Shercliff, David Cebon
2
Figure 2.1
Families of Materials
Members of a family have common features:
• Similar properties
• Similar processing routes
• Similar applications
Hybrids are a combination of materials from other families
Materials: engineering, science, processing and design, 2nd edition Copyright (c)2010 Michael Ashby, Hugh Shercliff, David Cebon
Polymers (Macromolecules)Ceramics
Families of Materials
Materials: engineering, science, processing and design, 2nd edition Copyright (c)2010 Michael Ashby, Hugh Shercliff, David Cebon
3
Figure 2.2
Examples of Each Material Family
Materials: engineering, science, processing and design, 2nd edition Copyright (c)2010 Michael Ashby, Hugh Shercliff, David Cebon
Figure 2.3
These attributes in addition to processing characteristics, environmental impact and typical applications make-up thematerial’s property profile
Materials: engineering, science, processing and design, 2nd edition Copyright (c)2010 Michael Ashby, Hugh Shercliff, David Cebon
4
• Stiff – high E (Young’s modulus)
• Hard – High Y (Strength)
• Abrasion resistant
• Good high temperature strength
• Good corrosion resistance
• Brittle – low KIC
Materials: engineering, science, processing and design, 2nd edition Copyright (c)2010 Michael Ashby, Hugh Shercliff, David Cebon
Ceramics
• Hard
• Corrosion resistant
• Electrically insulating
• Transparent
• Brittle – low KIC
Glasses
• Light – low ρ
• Easily shaped
• High strength per unit weight (σ/ρ)
• Lack stiffness – low E (50X less than metals)
• Properties highly sensitive to temperature
Materials: engineering, science, processing and design, 2nd edition Copyright (c)2010 Michael Ashby, Hugh Shercliff, David Cebon
Polymers (Engineering Plastics)
• Lack stiffness – low E (500 – 5000X less than metals)
• Able to retain initial shape after being stretched
• Relatively strong and tough
Elastomers
5
• Lightweight & Cost efficient
• Can be engineered
• Properties dependent on combination of materials
• Tough – high KIC
• Stiff – high E
• Ductile
• Wide range of strengths depending on composition and processing
• Thermally and electrically conductive
• Reactive – low corrosion resistance
Materials: engineering, science, processing and design, 2nd edition Copyright (c)2010 Michael Ashby, Hugh Shercliff, David Cebon
Metals / Alloys
Hybrids (Composites)
• Material
• Shape, dimensions, and precision
• Number to be made
Materials: engineering, science, processing and design, 2nd edition Copyright (c)2010 Michael Ashby, Hugh Shercliff, David Cebon
Choice of process is based on design requirements:
Process Families
Shaping -Primary
Shaping -Secondary Joining Surface
Treatment
Primary process creates shapes
Secondary process modifies shapes or properties
Classifying Processes
6
Materials: engineering, science, processing and design, 2nd edition Copyright (c)2010 Michael Ashby, Hugh Shercliff, David Cebon
Figure 2.4
Classes of Processes
Materials: engineering, science, processing and design, 2nd edition Copyright (c)2010 Michael Ashby, Hugh Shercliff, David Cebon
Primary ShapingHot Isostatic Pressing
7
Materials: engineering, science, processing and design, 2nd edition Copyright (c)2010 Michael Ashby, Hugh Shercliff, David Cebon
Secondary Processes
Materials: engineering, science, processing and design, 2nd edition Copyright (c)2010 Michael Ashby, Hugh Shercliff, David Cebon
Joining
8
Materials: engineering, science, processing and design, 2nd edition Copyright (c)2010 Michael Ashby, Hugh Shercliff, David Cebon
Surface Treatment
Materials: engineering, science, processing and design, 2nd edition Copyright (c)2010 Michael Ashby, Hugh Shercliff, David Cebon
Figure 2.7
Process selection involves matching attributes of a process to design requirements
9
Process-property Interaction
Materials: engineering, science, processing and design, 2nd edition Copyright (c)2010 Michael Ashby, Hugh Shercliff, David Cebon
• Soft, stretchy rubber becomes hard and brittle when vulcanized
• Annealing a metal increases its ductility• Glass becomes bullet-proof through a
specific heat treatment• Electroplating improves corrosion resistance
Effects processing can have on material properties:
• Gives an overview of physical, mechanical, and functional properties
• Reveal aspects of the physical origins of properties
• Tool for optimized selection of materialsMaterials: engineering, science, processing and design, 2nd edition Copyright (c)2010 Michael Ashby, Hugh Shercliff, David Cebon
• Plot of one property for all materialsBar Chart
• Plot of two properties for all materialsBubble Chart
Material Property Charts
10
Materials: engineering, science, processing and design, 2nd edition Copyright (c)2010 Michael Ashby, Hugh Shercliff, David Cebon
Figure 2.8
Bar chart comparing stiffness (modulus) between different material families
Materials: engineering, science, processing and design, 2nd edition Copyright (c)2010 Michael Ashby, Hugh Shercliff, David Cebon
Bubble chart comparing stiffness (modulus) and weight (density) of different material families
Figure 2.9
Figure 2.9
11
Materials: engineering, science, processing and design, 2nd edition Copyright (c)2010 Michael Ashby, Hugh Shercliff, David Cebon
Material and process records in CES contain two types of data:
Structured
• Numeric• Boolean (yes/no)• Discrete
(low/medium/high)
Unstructured
• Text• Images• Graphs• Schematics
Computer-aided Information Management
Materials: engineering, science, processing and design, 2nd edition Copyright (c)2010 Michael Ashby, Hugh Shercliff, David Cebon
Figure 2.10
Part of a record for a material, ABS; it contains numeric data, text, and image-based information
12
Materials: engineering, science, processing and design, 2nd edition Copyright (c)2010 Michael Ashby, Hugh Shercliff, David Cebon
Figure 2.10
Part of a record for a process, injection molding; the image shows how it works, and the numeric and Boolean data and text document its attributes