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PREFACE:

Preface

Rationale

Engineering Design Communication is a new approach to the traditional foundation course in engineering graphics. We believe that the role of the CAD database as the hub of the concurrent engineering environment has implications for the way engineering graphics is taught. In the concurrent environment, engineers are expected to communicate effectively with customers as well as other technical personnel and to prepare the CAD database so it will be useful for analysis, manufacturing, and presentation purposes.

New software tools, especially solid and parametric modeling software, have changed the way engineers create drawings. These packages automate much of the work of creating drawing views and offer functions that make it easier to modify and refine a solid model. They also offer many options for viewing the model and exporting it for use in other applications. These software developments have shifted the rationale for CAD modeling from the creation of documentation drawings to the creation of multipurpose models for design visualization and communication. At the same time, the ability of parametric models to capture the design intent for the part or assembly in its geometric relationships puts an added burden on the beginning student to grasp the bigger picture of the design process in order to use these tools effectively.

Approach

Engineering Design Communication addresses this shift in two ways. First, it presents the CAD file as a database of design information that is developed over time. The use of solid and parametric modeling software makes it possible to follow the design processthrough the course— students first learn to sketch their ideas, to transform 2D sketches into 3D models, to refine the models and use them for analysis, and finally to use the models to document the design. This organization more closely reflects industry practice and gives students a strong framework for understanding why they should learn to sketch, when it is appropriate to use different kinds of models, and what they need to discover in order to prepare a model for manufacture.

Second, it introduces topics that will help students learn to reflect design intent in their models. Building effective models that will update correctly requires some consideration of design goals. For beginning students unfamiliar with design issues, Engineering Design Communication anchors modeling techniques in the context of design to help them build an understanding of design intent as they learn to model. Case histories in the text show how design goals influence the way models are made. The text encourages students to think about the broader context for their models so they are more receptive to rules of thumb being taught in the CAD lab. By presenting the big picture of the many uses of the CAD database— and the power of automatic model updates—the text motivates students to practice building design intent into their models.

Engineering Design Communication is designed to be a true foundation course in graphic communication. From sketching to modeling to documentation drawings, the text emphasizes the nature of visual information. Because the concurrent engineering environment expects engineers who can present ideas and work with nontechnical personnel, EDC presents the wide variety of software and presentation tools that an engineer will use to visualize design. Students will learn what a technique communicates well and when it might be useful. Each technique is illustrated with real examples. Understanding when to sketch and when to model— and when to use a different medium&3151; will help students use these tools effectively in future courses and the workplace. It will also prepare them to evaluate and adopt new graphics tools as they are developed.

Organization

Engineering Design Communication is designed to be used with a tutorial guide for a specific computer-aided design package. Step-by-step tutorial guides that follow the organization of the text are being prepared for popular parametric modeling packages. As students learn the specifics of CAD modeling in the lab, the text presents the sketching and modeling techniques as they are used in the design process.

Design Framework

Engineering Design Communication introduces students to the process of design in Chapter 1, then uses the design process as an organizing framework for the rest of the book. Each chapter opens with an introduction that explains how the graphic skills presented in the chapter relate to and are used in engineering practice. Numerous examples and illustrations from industry motivate students with real examples of engineering practice and reinforce the connection between the technique and its application.

Industry Cases Case histories at the end of each chapter reinforce key topics by showing students how a practicing engineer applies them. These case histories present specific instances of general principles presented in the text, giving students a clear idea of the contemporary software tools and techniques used to create design. Although focused on the chapter content, most industry cases detail the use of specific graphics tools to solve a design problem.

Sketching

Sketching is the focus of the early chapters (2 through 4) of the text, which correspond to the ideation and visualization stages of the design process. Many topics traditionally taught in the context of documentation drawings are presented in these chapters so that students learn to use a full range of drawing views and projections in their sketches. Actual sketches are used to illustrate these early chapters so that students may compare their efforts with other sketches, not instrument or CAD drawings.

Designer's Notebook

The role of sketches in planning and visualization is reinforced in each chapter through the Designer's Notebook. Each chapter opens with sketches and notes from a practicing engineer's notebook. The excerpt previews the information to be conveyed through graphics in that chapter and gives students real examples of how they might use their own design notebook. (Chapter 1 encourages them to begin and use such a notebook throughout the course.)

Modeling

Modeling— and creating the design database— is the focus of the middle chapters of the book (5 through 10), where it is linked to the process of design refinement and analysis. These chapters begin with an introduction to geometry that takes students from the 2D sketching environment to the 3D environment that they will work with on screen. After a survey of different modeling methods, separate chapters on parametric modeling and assembly modeling introduce modeling considerations unique to 3D solid models. Each general modeling principle is illustrated with real models and examples showing the application of key ideas. A chapter (10) on exporting and using the model data with downstream applications, including rapid prototyping, presents additional considerations for creating a useful design database.

Documentation

Implementation and documentation are the focus of the latter chapters of the book (11 through 13). Because many students lack an understanding of basic manufacturing processes, an overview of these processes presents key questions to be asked and answered before a design is ready for manufacture. As in the modeling chapters, documentation and presentation techniques are presented in the context of the 3D model that students will use to generate drawings, rendered views, animations, and files for numerically controlled machinery.

Flexibility

Engineering Design Communication is designed to be used in a one- or two-semester sequence in engineering graphics. An instructor teaching a one-semester sequence may choose material from or omit chapters 2, 9,10, 11, or 13 to match the emphasis in the course.

Each chapter opener signals to the student which stage of the design process corresponds to the chapter content. This device makes it possible to cover chapters earlier in the text without losing the link to the design process. A comprehensive glossary is included as an aid to students who choose to read chapters out of order.

The implementation chapter (11) is a stand-alone chapter that may be covered at any point before the documentation chapter. Because manufacturing issues are addressed in the context of modeling in Chapter 8, some instructors may want to assign 11 before 8.

For instructors who wish to ask students to start making drawings from their solid models earlier, the documentation chapter (12) may be covered any time after Chapter 4.

The drawing control chapter (9) may be covered at any point in the text. For courses with more emphasis on rendering and animation, the presentation graphics chapter (13) may be covered any time after Chapter 6.

Annotated Overview

Chapter 1

This introductory chapter presents the many ways that graphics are used in the engineering design process and introduces key themes of the text, such as concurrent engineering, design teams, and the CAD model as a design database. It uses a comprehensive case study to illustrate the role of graphics in the design process from start to finish.

Chapter 2

This chapter introduces sketching as a tool in the ideation process. Needs assessment and design constraints provide a context for sketching as a means to refining the problem definition. Students begin to develop their sketching ability with contour sketches and schematic drawings methods and with exercises that help them "see" objects as they truly appear. For courses with less emphasis on design, the latter half of this chapter may be assigned.

Chapter 3

In this chapter, students learn to create freehand pictorial sketches in the context of design visualization. The chapter introduces 2D projections of 3D objects and the kinds of 3D sketches that can be used to convey design information.

Chapter 4

Techniques of multiview sketching and orthographic projection are presented in the context of design communication and visualization. The first half of the chapter illustrates the techniques of creating multiview sketches, while the latter half helps students interpret multiview drawings and their conventions.

Chapter 5

The geometry of modeling presents key geometric entities, relationships (such as symmetry), and transformations as they apply to both sketching and modeling. The chapter links the entities in a sketch to those used by the CAD modeling software and introduces topics such as coordinate systems, extrusion, revolution, and Boolean operations, which are common in working with geometry in most 3D modeling packages.

Chapter 6

This broad introduction to modeling defines, illustrates, and compares the many kinds of models that may be used to represent and test a design. The chapter presents strengths and weaknesses of each kind of model, including 2D and 3D CAD modeling systems, and builds a context for understanding parametric modeling.

Chapter 7

This chapter defines and explains the terms and techniques used in creating parametric models. It shows the steps in planning and adding features to create a model, explains how the information is stored, and demonstrates the role of parameters in updating the model.

Chapter 8

Bringing individual parts together into a complete assembly and adding details required by the manufacturing process are the focus of this chapter. Students are introduced to dynamic assemblies, how the model can be used to check for fit and interference, and ways to augment the 3D database with standard and static parts. They also learn about model modifications related to key manufacturing processes (such as draft) that are added after issues of functionality have been resolved.

Chapter 9

This chapter discusses the engineer's responsibility for managing the design database and introduces students to drawing control and file-sharing issues in a networked engineering environment.

Chapter 10

Chapter 10 familiarizes students with exporting data from the model to be used for testing and analysis. Common analysis applications as well as rapid prototyping systems are introduced.

Chapter 11

This overview of common manufacturing processes gives students an appreciation for issues addressed in the implementation phase. They also learn about the use of the 3D model to generate NC machine code and how this may affect the way design information is transmitted.

Chapter 12

This chapter shows students how drawings are generated from the 3D model and the role of the engineer in applying dimensioning and tolerancing to the model, then documenting it in the drawing.

Chapter 13

The final chapter introduces good presentation practice and media-from charts and graphs to rendered views to animated sequences-that are commonly used to present engineering information. The pages of the textbook are a "flip book" that previews the animation coverage in Chapter 13; see page 55 of the text for a description of this feature.

Associated Materials

Web Resources

Many of the examples and case histories in the text can be explored further through World Wide Web sites that include additional images, animations, and details about the design. These links and additional course materials are available on the EDC Web site at www.pre-nhall.com/lockhart.

We would like to thank Todd Amundson of Lower Columbia College for developing and providing the content for the EDC Web site.

Presentation Slides

A series of PowerPoint slides prepared by the authors are available for adopter use. Visit the EDC Web site for more information.