INTRODUCTION TO DESIGN

13

1

 

FIGURE 1-2

 

A CAD Solid Model of the Ball Bracket from the Trailer Hitch Assembly of Figure 1-1

 

Figure 1-5 shows a fully dimensioned, orthographic, multiview drawing of the ball bracket that was generated in the CAD software package. Another major advantage of creating a solid model of a part is that the dimensional and tool-path information needed for its manufacture can be generated in the CAD system and sent over a network to a computer-controlled machine on the manufacturing floor. This feature allows the production of parts without the need for paper drawings such as Figure 1-5. Figure 1-6

shows the same part after a finite element mesh was applied to it by the CAD software before sending it to the FEA software for stress analysis.

 

 

FIGURE 1-3

 

Mass Properties of the Ball Bracket Calculated Within the CAD System from Its Solid Model

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14

MACHINE DESIGN -

An Integrated Approach

1

 

 

 

 

 

 

 

 

 

 

 

 

 

FIGURE 1-4

 

A Wireframe Representation of the Ball Bracket Generated from Its Solid Model in a CAD System Computer-Aided Engineering (CAE)

The techniques generally referred to above as CAD are a subset of the more general topic of computer-aided engineering (CAE), which term implies that more than just the geometry of the parts is being dealt with. However, the distinctions between CAD and CAE continue to blur as more sophisticated software packages become available. In fact, the description of the use of a solid modeling CAD system and an FEA package together as described in the previous section is an example of CAE. When some analysis of forces, stresses, deflections, or other aspects of the physical behavior of the design 26.0

 

 

 

 

38.0

 

 

10.0

 

TYP. 2 PL.

 

 

90  2

 

Widgets Perfected Inc.

Title: BALL BRACKET

AS-MILLED FINISH

Mat'l: AISI 1020 Hot-Rolled Steel

All dims in: mm By: RLN 4/12/04

 

F I G U R E 1 - 5

 

A Dimensioned, 3-View Orthographic Drawing Done in a 2-D CAD Drawing Package

 

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Chapter 1