selecting materials product function interdependence mechanical properties physical properties...
TRANSCRIPT
Selecting Materials
Product function interdependence
Mechanical properties Physical properties Families of materials Materials first screening
When do we select specific materials?
?
FormulationFormulation
Customer Needs
Customer requirementsImportance weightsEng. characteristicsHouse of QualityEng. Design Spec’s
Concept DesignConcept Design
Abstract embodiment Physical principlesMaterialGeometry Configuration
DesignConfiguration
Design
arrangement of parts/features(i.e. shaping materials)
Therefore, let’s examine…
Formulation
Detail Design
Parametric Design
Configuration Design
Concept Designmaterials manufacturing
processes
Interdependence - compatibility
Material Properties
ManufacturingProcesses
compatiblematerials & processes
Interdependence - capability
ManufacturingProcesses
ProductGeometry
capable processesfor the geometry
Product function is interdependent
Material Properties
ManufacturingProcesses
ProductGeometry
ProductFunction
Tekniker-ILL neutron monochromator
Example
Design a support for the electric motor
Example
Tekniker-ILL neutron monochromator
Example
Tekniker-ILL neutron monochromator
Example
Tekniker-ILL neutron monochromator
Material properties
Mechanical properties
quantities that characterize the behavior of a material in response to external, or applied forces
quantities that characterize the behavior of a material in response to physical phenomena other than mechanical
forces …(e.g. such as heat, electricity, radiation)
Physical properties
Mechanical properties
stiffness ?
E
F
F
LL L
A
brittle
Strength = stress at failure = (failure)
A/F
stress
L
LLstrain
yS
utS
elastic plastic
y f
ductile ?
Mechanical properties
Fundamental properties
Characteristic Behavior Property Units
Strength strong, weak ultimate strength MPa (ksi)
Elastic strength elastic then plastic yield strength MPa (ksi)
Stiffness flexible, rigid modulus of elasticity MPa (Mpsi)
Ductility draws, forms easily % elongation, % area reduction
dimensionless
Hardness resists surface indentation
Brinell No. MPa (ksi)
Corrosion resistance
resists chemicals, oxidation
galvanic series activity number
Fundamental properties
Characteristic Behavior Property Units
Fatigue resistance endures many load cycles endurance limit MPa (Mpsi)
Conductivity (heat, electric)
conducts, insulates
thermal conductivity electrical conductivity
(Btu/hr) / (F-ft), Mhos
Creep resistance time dependent stretching
creep strength MPa (ksi)
Impact resistance shock, impact loads Charpy energy N-m, (ft-lbs)
Density (mass) Density (weight)
heavy, light mass density weight density
kg/m3, (slugs/ft3) N/m3, (lbs/ft3)
Temperature tolerance softens, or melts easily melting point degrees C, F
Material families / sub-families
CeramicsMetals Plastics Composites
Materials
Elastomers
Thermosets
Thermoplastics
Non-ferrous
Ferrous
Sub-family
Family(Ashby)
Material sub-families / classes
Metals
Materials
FerrousSub-family
Family
Classes
Cast ironCarbon steelAlloy steelStainless steel
Metals
Non-ferrousFerrous
Metals
aluminum brass bronze copper lead magnesium nickeltin titanium tungstenzinc
cast ironcarbon steelalloy steelstainless steel
ElastomersThermosetsThermoplastics
Polymers
butylfluorocarbonneoprenenitrilepolysulfiderubbersilicone
alkydepoxymelaminephenolicpolyesterurethane
ABSacetalacrylicnylonpolycarbonatepolyethylenepolypropylenepolystyrenevinyl
Natural and synthetic rubbersPolymers
Polymers
Cross-linking
No chemical reaction
Ceramics
Ceramics
aluminaberylliadiamondmagnesiasilicon carbidesilicon nitridezirconia
Composites
carbon fiberceramic matrixglass fiberKevlarmetal matrix
Composites
Composites
Carbon fiber Style 282 bidirectional.
Araldite epoxy resin with HY956 additive.
Manufacturing process
Composites
Ossur Flexwalk
College Park Foot
Otto Bock Advantage
Pie protésico dinámico2004
Pie protésico dinámico2005
Composites
MarlonShirley
OssurCheetaFlex-Foot
Cameron Clapp
Otto Bock C-Leg
Date of birth: April 21, 1978 Hometown: Thatcher, Utah Current Home:San Diego, CA
Date of birth: Sep 15, 1986
Property profiles by family
Materials selection
prospective materials and processes
screening
rating
rejected materials and processes
best material(s) and processes
functional?manufacturable?
relativeperformance?
feasiblematerials and
processes
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?
Screening: Materials first approach
Application Information
1. Applied loadsmagnitudecyclic nature (steady, fatigue)rate (slow, impact)duration (creep)
2. Ambient conditionstemperaturemoisturesunlightchemical liquids/vapors
3. Safety4. Cost
Screening: Manufact process first approach
Part Information
1. Production volume2. Part size (overall)3. Shape capability (features)
boss/depression 1Dboss/depression >1Dholesundercuts (internal/external)uniform wallscross sections (uniform
/regular)rotational symmetrycaptured cavities
Materials selection
prospective materials and processes
screening
rating
rejected materials and processes
best material(s) and processes
functional?manufacturable?
relativeperformance?
feasiblematerials and
processes
Rating: Material indices
Given the same cost/volume… which is stronger?
index = Strength/cost
Given the same cost/volume… which is stiffer?
index = Young’s modulus/cost
AshbyChart
How can we use it?
Summary
Product function interdependence
Mechanical properties Physical properties Families, sub, classes of
materials Ashby charts Materials first approach Process first approach