Engineering Fundamentals: An Introduction to Engineering, 4th ed.c

16.6 Civil, Electrical, and Electronic Drawings

In addition to the type of drawings that we have discussed so far, there are also discipline-specific

drawings. For example, civil engineers typically deal with land or boundary, topographic, con-

struction, connection and reinforcement details, and route survey drawings. Examples of draw-

ings used in civil engineering are shown in Figure 16.19. To produce these types of drawings,

a survey is first performed. A survey is a process by which something (such as a land) is mea-

sured. During a survey, information such as distance, direction, and elevation are measured

and recorded. Other examples of discipline-specific drawings include printed circuit-board

assembly drawings, printed circuit-board drill plans, and wiring diagrams; which are commonly

used by electrical and electronic engineers. Examples of the electrical and electronic drawings

are shown in Figure 16.20.

16.7 Solid Modeling

In recent years, the use of solid modeling software as a design tool has grown dramatically. Easy-

to-use packages, such as AutoCAD, IDEAS, and Pro-E, have become common tools in the

hands of engineers. With these software tools you can create models of objects with surfaces and

volumes that look almost indistinguishable from the actual objects. These solid models provide

great visual aids for what the parts that make up a product look like before they are manufac-

tured. The solid modeling software also allows for experimenting on a computer screen with

the assembly of parts to examine any unforeseen problems before the parts are actually made

and assembled. Moreover, changes to the shape and the size of a part can be made quickly with

such software. Once the final design is agreed upon, the computer-generated drawings can be

sent directly to computer numerically controlled (CNC) machines to make the parts.

Solid modeling software is also used by architects and engineers to present concepts. For

example, an architect uses such software to show a client a model of what the exterior or interior

of a proposed building would look like. Design engineers employ the solid modeling software

to show concepts for shapes of cars, boats, computers, and so on. The computer-generated

models save time and money. Moreover, there is additional software that makes use of these solid

models to perform additional engineering analysis, such as stress calculations or temperature dis-

tribution calculations for products subjected to loads and /or heat transfer. Examples of solid

models generated by commonly used software are shown in Figure 16.21.

Let us now briefly look at how solid modeling software generates solid models. There are

two ways to create a solid model of an object:bottom-up modelingandtop-down modeling. With

bottom-up modeling you start by defining keypoints first, then lines, areas, and volumes in

terms of the defined keypoints. Keypoints are used to define the vertices of an object. Lines, next

in the hierarchy of bottom-up modeling, are used to represent the edges of an object. You can

then use the created lines to generate a surface. For example, to create a rectangle, you first

define the corner points by four keypoints, next you connect the keypoints to define four lines,

and then you define the area of the rectangle by the four lines that enclose the area. There are

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