An engineer needs to be able to communicate his or ideas in a clear concise manner'

1
Introduction

• An engineer needs to be able to communicate his
  or ideas in a clear concise manner.
• In order to accomplish this, a standard graphical
  method using various techniques has been
  developed to illustrate 3-D objects and features
  on a 2-D media (paper or the computer screen).

Traditional Method versus Non-Traditional Method

• In the traditional method (Drafting), pencil
  (pen) and paper are used. Layouts containing
  views or projections of the object are
  constructed on standard size paper using
  established methods and common practice.
• CAD-Computer Aided Design (Geometric Modeling).
  The computer is used to produce the images
  normally produced by mechanical means. Because
  the images can be easily stored and retrieved,
  changes can be made easily and quickly.

2
Introduction
Design intent is communicated through production
drawings that have been standardized. This
allows all involved to understand what is being
designed and how one component influences another.
3
Introduction
Detailed drawings of each part in the assembly
are created and used in the manufacture of the
component.
4
Introduction
Geometric Modeling

• Geometric modeling is a process of creating
  graphic images on the computer (CAD).
• Documentation is minimized and the model is
  constantly changed and updated in the computer.
• The product is constructed directly from the
  computer model often using computer driven
  manufacturing processes (CNC).

Graphic Visualization

• In order to be able to do CAD, the user must
  understand what the computer is doing.
• That is, the designer must understand the
  geometric and projection techniques employed in
  the industry.

5
Introduction
Design and Graphic Visualization

• The design process is an interactive one. In the
  past, the design of a product proceeded along a
  succession of steps. For example

Establish goals
Ergonomics
Idea new A/C
Conceptual Design
Refinement
Propulsion
Aerodynamics
Structure

• Example A new aircraft design
• RFP
• Internal
• Specific customer

Financing
Meet Goals?
Prototype Test
Deliver Service
6
Concurrent Engineering

• Modern approach to design.
• This is a team oriented design approach involving
  all areas of the company.
• The individual team members (groups) communicate
  via computer and computer aided graphics.
• Customer involved in the design process

Deliver Service
Idea
Concept sketch
Refinement
CAD, Analysis
7
Concurrent Engineering

• Since the customer is involved in the design
  process, the design teams are immediately aware
  of what the customer wants.
• Furthermore, the customer is aware of how the
  design is progressing.
• Because the design is carried on concurrently
  among various groups, changes are updated
  automatically.
• Design groups can be located at great distances
  from each other. The computer is used to allow
  the groups to communicate with each other.
• The emphasis of the process is to design the
  final product rather than the prototype.
• During the design process, the prototype is
  created in the computer and changed thousands of
  times.
• The overall process translates to low cost.

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Design Ideation and Refinement
Use sketching to develop a proof of concept.
Model is refined with CAD using input information
from analysis and finance.
CAD model of final design
9
Parametric Modeling

• Also known as CONSTRAINT BASED MODELING.
• Parametric modeling allows the user to represent
  the dimensions of the object with parameters.
• Then numbers are assigned to the parameters.
• If the dimensions of the object are changed, the
  model can be easily modified since only the
  numerical values of the parameters need to be
  changed.

Consider the following block.
10
Parametric Modeling
Block with dimensions
sd110.00 sd25.00 sd32.00
Block drawn with respect to parameters sd1, sd2
sd3
11
Feature Based Modeling

• Method of combining the commands needed to
  produce a common manufactured feature.

The two circles and lines used to model the hole
in the block are created and treated by the
software as a single feature. Update one part of
the feature, say, the diameter of the hole and
the rest of the feature is automatically updated.
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Primitive Modelers

• Primitive Modelers use basic solid shapes in
  order to create a solid model.

• Constraint based solid modelers mimic
  manufacturing processes.

13
Projection Theory

• Trimetric-most pleasing to the eye but the most
  difficult to create. Trimetric is the default in
  Pro/E.
• Isometric-least pleasing to the eye but the
  easiest to draw. When sketching, we will use
  Isometric.

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Multi-View Projections

• A Multi-View projection is an Orthographic
  projection where only two dimensions are shown.
• Unlike a pictorial, a Multi-View does not distort
  an image. Thus, the true dimension or shape of
  the objected is shown.
• However, in order to convey the entire model
  several projections or views are required.

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Multi-View Projections

• At most, six multi-view projections may be
  obtained.
• In general, only three are used. These views are
  the Front, Top and Right.
• Note the positions of each view. The placement
  of multi-views has been standardized.