Tai ngay!!! Ban co the xoa dong chu Engineering Design Process Second Edition This page intentionally left blank Engineering Design Process Second Edition Yousef Haik University of North Carolina—Greensboro Tamer Shahin Kings College London, UK Australia • Brazil • Japan • Korea • Mexico • Singapore • Spain • United Kingdom • United States Engineering Design Process, © 2011, 2003 Cengage Learning Second Edition Yousef Haik and Tamer Shahin ALL RIGHTS RESERVED. No part of this work covered by the copyright herein may be reproduced, transmitted, stored, Publisher, Global Engineering: or used in any form or by any means graphic, electronic, or Christopher M. Shortt mechanical, including but not limited to photocopying, Senior Acquisitions Editor: Randall Adams recording, scanning, digitizing, taping, web distribution, information networks, or information storage and retrieval Senior Developmental Editor: Hilda Gowans systems, except as permitted under Section 107 or 108 of the Editorial Assistant: Tanya Altieri 1976 United States Copyright Act, without the prior written Team Assistant: Carly Rizzo permission of the publisher. Marketing Manager: Lauren Betsos For product information and technology assistance, Media Editor: Chris Valentine contact us at Cengage Learning Customer & Content Project Manager: Kelly Hillerich Sales Support, 1-800-354-9706 Production Service: RPK Editorial Services, Inc.
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This page intentionally left blank Brief Table of Contents Chapter 1 Introduction 2 Lab 1: Ethics 27 Lab 2: Ethics and Moral Frameworks 33 Chapter 2 Essential Transferrable Skills 42 Lab 3: Ice Breaking—Forming Teams 45 Lab 4: Team Dynamics 54 Lab 5: Project Management (Microsoft Project) 61 Lab 6: Presentation Style 90 Chapter 3 Identifying Needs and Gathering Information (Market Research) 98 Chapter 4 Customer Requirements 114 Lab 7: Kano Model Customer Needs Assessment 126 Chapter 5 Establishing Functional Structure 132 Lab 8: Reverse Engineering 148 Chapter 6 Specifications 152 Chapter 7 Developing Concepts 172 Chapter 8 Concepts Evaluation 190 Chapter 9 Embodiment Design 212 Lab 9: Ergonomics 222 Chapter 10 Detailed Design 230 Lab 10: Material Selection Tutorial 239 Lab 11: Geometric Dimensioning and Tolerancing 243 Lab 12: Use of Pro/MECHANICA® for Structural Analysis 243 Chapter 11 Selection of Design Projects 270 vii This page intentionally left blank Contents Preface xv Chapter 1 Introduction 2 1.2 Definition of Engineering Design 3 1.3 Importance and Challenges of Engineering Design 4 1.4 Introduction to Systematic Design 6 1.1 Identifying Customer Needs (Requirements) 12 1.9 Analysis and Optimization 20 1.6 Professionalism and Ethics 22 1.1 NSPE Code of Ethics 22 LAB 1: Ethics 27 LAB 2: Ethics and Moral Frameworks 33 1.8 Selected Bibliography 40 Chapter 2 Essential Transferable Skills 42 2.2 Working In Teams 43 2.1 Forming a Team 44 LAB 3: Ice Breaking—Forming Teams 45 2.2 Dynamics of a Team 51 LAB 4: Team Dynamics 54 2.2 CPM/PERT 57 ix x Contents 2.3 CPM/PERT Definitions 57 2.4 CPM/PERT Network Development 58 LAB 5: Project Management (Microsoft Project) 61 2.5 Technical Writing and Presentation 83 2.1 Steps in Writing a Report 84 2.3 Mechanics of Writing 86 2.2 Oral Presentation Obstacles 88 2.3 Oral Presentation Dos and Don’ts 88 2.4 Oral Presentation Techniques 89 2.5 Question/Answer Session 89 LAB 6: Presentation Style 90 2.8 Selected Bibliography 97 Chapter 3 Identifying Needs and Gathering Information (Market Analysis) 98 3.2 Problem Definition: Need Statement 99 3.3 Gathering Information: Clarifying the Need 101 3.4 How To Conduct a Market Analysis 102 3.1 Define the Problem 102 3.3 Organize and Check the Information Gathered 105 3.5 Relevant Information Resources 106 3.7 Case Study: Automatic Aluminum Can Crusher 110 3.9 Selected Bibliography 113 Chapter 4 Customer Requirements 114 4.1 Objectives 115 Contents xi 4.2 Identifying Customer Requirements 115 4.3 Prioritizing Customer Requirements 116 4.4 Case Study: Automatic Aluminum Can Crusher—Requirements 118 4.5 Organizing Customer Requirements—Objective Tree 120 4.6 Case Study: Automatic Aluminum Can Crusher—Objective Tree 123 LAB 7: Kano Model Customer Needs Assessment 126 4.8 Selected Bibliography 131 Chapter 5 Establishing Functional Structure 132 5.3Function Decomposition and Structure 134 5.1 Bounding Box and Overall Function Diagram 134 5.4 Detailed Procedure to Establish Functional Structures 139 5.5 Function Structure Examples 140 5.1 Reverse Engineering Example—Dishwasher 145 5.7 Reverse Engineering Example—Paper Stapler 147 LAB 8: Reverse Engineering 148 5.9 Selected Bibliography 150 Chapter 6 Specifications 152 6.2 Performance-Specification Method 156 6.3 Case Study Specification Table: Automatic Can Crusher 158 6.4 Quality-Function-Deployment Method 159 6.5 House of Quality: Automatic Can Crusher 165 6.7 Selected Bibliography 171 Chapter 7 Developing Concepts 172 7.2 Developing Working Structures 174 7.3 Steps to Develop Concepts From Functions 176 7.1 Mechanism of Brainstorming Session 177 7.1 How to Increase Your Level of Creativity 180 xii Contents 7.6 Developing Concepts—Samples 182 7.2 Wheelchair Retrieval Unit 182 7.3 Automatic Can Crusher 185 7.8 Selected Bibliography 188 Chapter 8 Concepts Evaluation 190 8.2 Sketch Assembly of Alternatives 192 8.3 Evaluating Conceptual Alternatives 192 8.1 Pugh’s Evaluation Matrix 194 8.4 Concepts Evaluation: Machine Shop Kit 197 8.5 Concepts Evaluation: Automatic Can Crusher 202 8.7 Selected Bibliography 210 Chapter 9 Embodiment Design 212 9.1 Design for Manufacturing 217 9.2 Design for Assembly 218 9.3 Design for Environment 218 9.1 Safety Analysis Techniques 218 9.1 Human Sensory Capabilities 220 9.2 Anthropometric Data 221 LAB 9: Ergonomics 222 9.8 Selected Bibliography 229 Chapter 10 Detailed Design 230 10.1 Material Classifications and Properties 233 10.2 Material Selection Process 233 10.3 Primary Manufacturing Methods 235 Contents xiii 10.4 Material Selection Theory–An Introduction 235 10.3 Coefficient of Linear Thermal Expansion 236 10.5 Strength of Material 236 10.5 Bill of Material 238 LAB 10: Material Selection Tutorial 239 10.6 Geometric Dimensioning and Tolerancing 241 LAB 11: Geometric Dimensioning and Tolerancing 243 LAB 12: Use of Pro/MECHANICA® for Structural Analysis 243 10.7 Analysis Example: Mechanical Vegetable Harvesting Machine 250 10.10 Cost Estimate Methods 259 10.1 Break-Even Chart 261 10.14 Selected Bibliography 269 Chapter 11 Selection of Design Projects 270 11.1 Design Project Rules 271 11.2 Aluminum Can Crusher 273 11.3 Coin Sorting Contest 273 11.4 Model (Toy) Solar Car 274 11.5 Workshop Training Kit 275 11.8 All Terrain Vehicle 276 11.9 Pocket-Sized Umbrella 277 xiv Contents 11.10 Model of Therapeutic Wheelchair 277 11.11 Disposable Blood Pump 277 11.12 Newspaper Vending Machine 278 11.13 Peace Corps Group Projects 278 11.4 Deliverables 279 Index 280 Preface Design remains the focal point of engineering disciplines; it is what distinguishes engi- neering from other scientific disciplines. Engineers throughout history have wrestled with problems of water not being where it is needed, of minerals not being close at hand, of building materials having to be moved. Ancient engineers were often called on to devise the means for erecting great monuments, for designing defenses against enemies, and for moving people and goods across rough terrain and even rougher water. The word engineer originated in the eleventh century and is derived from the Latin origin “ingeniator” meaning one with “ingenium” or the clever one.
Before the scientific revolution, ingenuity was demonstrated in many devices. These devices were built by using a simple principle of what works and why it works in this way. Adaptation from nature was prominent in this era. For example, Leonardo da Vinci earned the title Ingenere General for his flying device and his bridge design to connect Istanbul to Europe, amongst his many other inventions.
Galileo’s use of systematic explanation and scientific approach to tackle problems is regarded by historians as the landmark of structured engineering design that is based on scientific merits and mathematical presentation. Following the first Industrial Revolution, beginning in the eighteenth century, the French developed a univer- sity engineering education with emphasis on civil engineering, while the British pioneered mechanical engineering. The Industrial Revolution brought a proliferation of new machines and manufacturing techniques and provided an impetus for the growth of science and commerce on an international scale. During the second Industrial Revolution in the middle of nineteenth century, mass production and automation prevailed and were driven by many branches of engineering.
Our modern lifestyle is deeply influenced by our ability to employ scientific discov- eries in a wide variety of devices. The continued pursuit of design excellence is empow- ered by engineers’ ability to produce products that meets consumer needs. In the early 1900s, it was common in American industry for master mechanics to invent and, subsequently, for draftsmen to copy on paper what had been synthesized experimen- tally in the shop. Since it was less costly and more efficient to erase rather than to remake parts in the shop, the value of synthesizing on paper was soon realized.
Recent trends have been to apply theory where appropriate in the process of mechanical design. But overall, it is emphasized that all of the useful ingredients—such as various aspects of art, science, engineering, practical experience, and ingenuity—must be properly blended in the design process. A successful design is achieved when a logical procedure is followed to meet a spe- cific need. This procedure, called the design process, is similar to the scientific method with respect to its step-by-step routine.
Often, designs are not accomplished by an engineer sim- ply completing the design steps in the given order. The design process holds within its struc- ture an iterative procedure. As the engineer proceeds through the steps, new information may be discovered and new objectives may be specified, at which time the steps may xv xvi Preface require revisiting. The more time and effort an engineer spends on articulating the problem definition and understanding the needs statement, the less frequent the need for iteration.
This book is written as an introductory course in design. Students’ technical capabilities are assumed to be at the level of college physics and calculus. For students with advanced technical capabilities the analysis part in the design sequence could be emphasized. This book consists of eleven chapters.
Chapter 1 is an overview of the design steps and serves as an introduction to the book. Chapter 2 presents a few design tools that designers must master prior to the design process. Some of these tools serve as an intro- duction to courses that students will encounter in future course work. Chapters 3 through 9 present the steps of the design process.
The author is aware that the sequence of these steps can be changed according to instructor preference. Instructors can alter the presenta- tion sequence without having to change the presentation material. Chapter 10 discusses issues relating to the design cost. Chapter 11 presents a list of project descriptions that can serve as an entry point to instructors’ assignments.
In this second edition we have inte- grated design labs with the chapters. The purpose of these labs is to create design activi- ties that help students, especially freshmen and sophomores, to adjust to working in teams. The first few of these labs are geared toward team building. It is anticipated that instruc- tors may want to include other activities in their design classes.