Selecting Materials

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Selecting Materials

• Product function interdependence
• Mechanical properties
• Physical properties
• Families of materials
• Materials first screening

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When do we select specific materials?
arrangement of parts/features (i.e. shaping
materials)
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Therefore, lets examine
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Interdependence - compatibility
Material Properties
Manufacturing Processes
compatible materials processes
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Interdependence - capability
capable processes for the geometry
Manufacturing Processes
Product Geometry
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Product function is interdependent
Material Properties
Product Function
Manufacturing Processes
Product Geometry
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Example
Design a support for the electric motor
Tekniker-ILL neutron monochromator
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Example
Tekniker-ILL neutron monochromator
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Example
Tekniker-ILL neutron monochromator
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Example
Tekniker-ILL neutron monochromator
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Material properties

• Mechanical properties

quantities that characterize the behavior of a
material in response to external, or applied
forces

• Physical properties

quantities that characterize the behavior of a
material in response to physical phenomena
other than mechanical forces (e.g. such as heat,
electricity, radiation)
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Mechanical properties
stiffness ?
Strength stress at failure ?(failure)
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Mechanical properties
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Fundamental properties
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Fundamental properties
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Material families / sub-families
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Material sub-families / classes
Materials
Metals
Ferrous
Cast iron Carbon steel Alloy steel Stainless
steel
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Metals
Metals
Non-ferrous
Ferrous
aluminum brass bronze copper
lead magnesium nickel tin titanium
tungsten zinc
cast iron carbon steel alloy steel stainless steel
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Polymers
Natural and synthetic rubbers
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Polymers
No chemical reaction
Cross-linking
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Ceramics
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Composites
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Composites
Manufacturing process
Carbon fiber Style 282 bidirectional. Araldit
e epoxy resin with HY956 additive.
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Composites
College Park Foot
Otto Bock Advantage
Ossur Flexwalk
Pie protésico dinámico2004
Pie protésico dinámico2005
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Composites
Marlon Shirley Ossur Cheeta Flex-Foot
Cameron Clapp Otto Bock C-Leg
Date of birth April 21, 1978 Hometown
Thatcher, Utah Current HomeSan Diego, CA
Date of birth Sep 15, 1986
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Property profiles by family
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Materials selection
prospective materials and processes
rejected materials and processes
functional? manufacturable?
screening
feasible materials and processes
relative performance?
rating
best material(s) and processes
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Screening How do we choose a material?

• Product function depends upon
• material, manufacturing process, geometry
• We have to consider all three
• Do we select a few feasible materials first
• then select the specific mfg process?
• or
• Do we select a few feasible mfg processes
• then select the specific material?

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Screening Materials first approach

• Application Information
• Applied loads
• magnitude
• cyclic nature (steady, fatigue)
• rate (slow, impact)
• duration (creep)
• Ambient conditions
• temperature
• moisture
• sunlight
• chemical liquids/vapors
• Safety
• Cost

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Screening Manufact process first approach

• Part Information
• Production volume
• Part size (overall)
• Shape capability (features)
• boss/depression 1D
• boss/depression gt1D
• holes
• undercuts (internal/external)
• uniform walls
• cross sections (uniform /regular)
• rotational symmetry
• captured cavities

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Materials selection
prospective materials and processes
rejected materials and processes
functional? manufacturable?
screening
feasible materials and processes
relative performance?
rating
best material(s) and processes
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Rating Material indices

• Given the same cost/volume which is stronger?
• index Strength/cost
• Given the same cost/volume which is stiffer?
• index Youngs modulus/cost

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AshbyChart
How can we use it?
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Summary

• Product function interdependence
• Mechanical properties
• Physical properties
• Families, sub, classes of materials
• Ashby charts
• Materials first approach
• Process first approach