Product Generation

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Product Generation

• (Ullman, Chapter 10)

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The Design Process
Identify needs
Plan for the design process
Develop engineering specifications
Develop concepts
Develop product/process
Release for production
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Elements of Product Design
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Product Generation

• form follows function
• (Bauhaus)
• form and function should be one, joined in
  spiritual union
• (Frank Lloyd Wright)

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Form

• Form is bound by geometric constraints and
  defined by the configuration of connected
  components.

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Elements of Product Design
Constraints
Configuration
Form
Connections
Components
Function
Production
Material
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Form Generation

• Collect spatial constraints
• Configure components
• Develop connections
• Develop components

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Form Generation Collect Spatial Constraints

• Spatial Constraints
• The envelope for the product
• Product development must begin with a knowledge
  of the spatial constraints
• Nature of spatial constraints
• from interfaces with other objects
• for functionally needed space
• for accessibility

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Form Generation - Configure Components

• Configuration
• the architecture , structure, or arrangement of
  components and assemblies in the product
• components vs assemblies
• relative location, orientation of components

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Form Generation Configure Components

• Should a product be decomposed into separate
  components? Yes, if
• They need to move relative to one another
• They need to be of different materials for
  functional reasons
• They need to be moved for accessibility
• They need to accommodate material/production
  limitations
• Standard components are available
• Separate components would minimize cost

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Form Generation Configure Components

• Other important factors in configuration design
• Location
• the measure of a components relative position in
  space
• Orientation
• the angular relationship of components

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Form Generation - Develop Connections

• Connections (interfaces) between components
• support their function
• determine their relative positions and locations

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Form Generation - Develop Connections

• Guidelines for interfaces between components
  (most design effort here)
• must reflect force equilibrium and flow of
  energy, material, and information
• focus particularly on interfaces which carry the
  most critical functions
• maintain functional independence in the design of
  components and assemblies
• avoid complexity

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Form Generation - Develop Connections

• Types of Connections
• fixed, nonadjustable
• rivets, bolts, welds
• adjustable
• bolts, screws, threaded rod
• separable
• locator
• hinged,or pivoting

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Form Generation - Develop Components

• Fewer than 20 of the dimensions of most
  components are critical to performance
• once the functional interfaces have been
  determined, designing the body of the component
  is often a sophisticated connect-the-dots problem

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Form Generation - Develop Components

• Less stress generally developed in components if
  direct force transmission paths are used
• use force flow visualization
• treat forces like a fluid that flows
• a fluid takes least path of resistance
• sketch multiple flow paths
• force at interfaces primarily compression shear
  only in welded, adhesive, friction surfaces

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Force Flow in a Tee Joint
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Form Generation - Develop Components

• Force flow helps in visualizing stresses in
  components or assemblies
• best if force paths are short and direct
• fewer potential failure points and stress
  concentrations
• In designing bodies of components, stiffness more
  frequently than stress determines the adequate
  size

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Elements of Product Design
Constraints
Configuration
Form
Connections
Components
Function
Manufacture
Production
Material
Assembly
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Materials/Process Selection

• Materials/process selection occurs concurrent
  with form generation
• Influencing factors
• design specifications
• quantity to be produced
• manufacturing/assembly methods
• prior-use knowledge for similar application
• when in doubt, make it stout, out of things you
  know about

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Vendor Development

• Use components, assemblies, systems from vendors,
  or design new hardware?
• Purchasing an already existing product meeting
  specifications is generally less expensive than
  designing/manufacturing
• Qualifying vendors to supply parts is an
  important activity
• Best vendors part of concurrent engrg team

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Product Generation - Summary

• Products are developed from concepts through
  concurrent development of form, material, and
  production methods.
• Form is bound by geometric constraints and
  defined by the configuration of connected
  components.
• Development usually starts at the interfaces
  (connections).
• An iterative process.

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Product Generation

• END