Lect 12P. 1

1
Solid Modeling

• Lecture 12

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Getting Started with 3-D CAD by Solid Modeling

• Goals
• 3-D CAD models developed from primitive solids
• Reference
• Chap 11 3-D Geometry Concepts BTG
• CADKEY 99 Chapter 6
• AutoCAD 2002 Tutorial 3-D Modeling Chapter 6

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Agenda

• Understand basic ways to generate 3-D solid
  models
• Create solid models from primitive shapes
  usage of Solids99 or AutoCAD functions and
  features
• Derive shapes using Boolean functions
• Modify solids using fillets and chamfer
• Use Drawing Layout Mode

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Review of important concepts in CAD

• CAD model is a virtual part
• A 3-D CAD model stores the entire 3-D shape of
  the object
• 3-D models can be generated from 2-D profiles by
  using CAD programs

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Approaches to developing a solid model

• Constructive solid or primitive modeling
• Constraint-based modeling
• Feature-based modeling

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Primitive Modeling - combine simple shapes
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Constraint-based solids modeling

• Part roughed in
• Constrained or detailed by adding dimensions
• 3-D Objects created by revolving or extruding

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Constraint-based solids modeling by revolving
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Constraint-based solids modeling by extruding
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Feature-based Modeling

• Creating and modifying geometric features of a
  solid model like a manufacturing process.

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Example of Feature-based process
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How Solids Models Can Be Used

• Improve efficiency in design by visualization and
  virtual assembly
• Link to Numerical Analysis
• Stress
• Heat Transfer Analysis
• Fluid Flow
• Link to Computer-aided Manufacturing

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Using CADKEY 99 and AutoCAD 2002 as 3-D Programs

• Chapter 6 introduces some of the basic techniques
  for creating 3-D geometry
• Basic models are initially built from primitive
  shapes modified to create more complex objects
• A CADKEY 3-D blank seed drawing or AutoCAD
  4-viewport template would serve as the basis for
  3-D solids modeling

14
Creating Layout Mode drawings

• Even if the model is built with a 3D construction
  approach, conventional orthographic views with
  dimensioning and in some cases sectioning will be
  needed.
• CADKEY Chapter 6 demonstrates how to create
  layout mode drawings, starting with a 3D model.
• AutoCAD Chapters 6 and 7 show modeling, Chapter 8
  shows the layout.
• Procedures and conventions for dimensioning will
  be covered later

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Creating Layout Mode drawings

• CADKEY and AutoCAD have two system modes - Model
  mode and Layout mode.
• CADKEY and AutoCAD distinguish between the two so
  that you can create part files in Model mode,
  then switch to Layout mode to create different
  layouts of the part file and detail them for
  drafting purposes.
• In Model mode you can take advantage of all the
  CADKEY and AutoCAD functions to create and edit
  part files. Model mode is the default system
  mode that you enter when you start CADKEY and
  AutoCAD.
• Layout mode is a drafting tool that you use to
  create, dimension and then print or plot

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Example Problem from CADKEY
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Review Questions

• What are the views listed in the four view port
  option?
• What is the difference between View and WLD
  coordinates?