Introduction to Engineering Design

1
Introduction to Engineering Design

• Definition of Design
• Principle of Design
• Design Process
• Product Design
• Process Design
• Factors Involved in Design

2
Characteristics of an Engineering Science Problem

• Problem statement is compact and well-posed
• Problem has a readily identifiable closure
• Solution is unique and compact
• Problem uses specialized knowledge

3
Typical Engineering Science Problem Statement

• A simply supported steel beam with a 3 diameter
  circular cross-section is loaded as shown.
  Determine the maximum stress and deflection.

Fig. 1.1
4
Another Typical Engineering Science Problem
Statement

• How much current is flowing through the circuit
  0.1 sec after the switch is closed?

Fig. 1.2
5
Characteristics of an Engineering Design Problem

• Problem statement is incomplete, ambiguous, and
  self-contradictory
• Problem does not have a readily identifiable
  closure
• Solutions are neither unique nor compact
• Problem requires integration of knowledge from
  many fields

6
Typical Engineering Design Problem Statement

• Design a system for lifting and moving loads of
  up to 5000 lb in a manufacturing facility . The
  facility has an unobstructed span of 50 ft. The
  lifting system should be inexpensive and satisfy
  all relevant safety standards.

7
Topography of Engineering Science and Engineering
Design
Solid Ground of Engineering Science
Design Swamp
8
Contemplating Engineering Design
Typical Engineering Student with Science and
Mathematics Background
Solid Ground of Engineering Science
Design Swamp
Fig. 1.3
9
Guidance Provided by Design Professor
Design Professor
This Way
Solid Ground of Engineering Science
Design Swamp
Fig. 1.4
10
Benefits of Understanding Engineering Design
Design Professor
Solid Ground of Engineering Science
Design Swamp
Fig. 1.5
11
ABET Definition of Design

• Engineering design is the process of devising a
  system, component, or process to meet desired
  needs.
• It is a decision-making process (often
  iterative), in which the basic sciences and
  mathematics, and engineering sciences are applied
  to convert resources optimally to meet a stated
  objective.
• Among the fundamental elements of the design
  process are the establishment of objectives and
  criteria, synthesis, analysis, construction,
  testing, and evaluation.

12
ABET Definition of Design (cont.)

• The engineering design component of a curriculum
  must include most of the following features
• development of student creativity,
• use of open-ended problems,
• development and use of modern design theory and
  methodology,
• formulation of design problem statements and
  specifications,
• consideration of alternative solutions,
• feasibility considerations,
• production processes,
• concurrent engineering design, and
• detailed system descriptions.
• Further, it is essential to include a variety of
  realistic constraints, such as economic factors,
  safety, reliability, aesthetics, ethics, and
  social impact.

13
Nine Step Model of Design Process

• 1. Recognizing the need
• 2. Defining the problem
• 3. Planning the project
• 4. Gathering information
• 5. Conceptualizing alternative approaches
• 6. Evaluating the alternatives
• 7. Selecting the preferred alternative
• 8. Communicating the design
• 9. Implementing the preferred design

14
Relation Between Design Process Model and
Organization of this Book
Table 1.1
15
A Map of The Design Swamp
Fig. 1.6
16
Comparison of Two Models of the Design Process
17
Step 1 Recognizing the Need

• Sandra Jane, we need you to design a stronger
  bumper for our new passenger car.
• Jane Why do we need a stronger bumper?
• Sandra Well, our current bumper gets easily
  damaged in low-speed collisions, such as those
  that occur in parking lots.
• Jane Well, a stronger bumper may be the way to
  go, but there may be better approaches. For
  example, what about a more flexible bumper that
  absorbs the impact but then returns to its
  original shape?
• Sandra I never thought of that. I guess I was
  jumping to conclusions. Lets restate the need
  as there is too much damage to bumpers in
  low-speed collisions. That should give you more
  flexibility in exploring alternative design
  approaches.

18
Step 3 Planning the Project
Table 1.2
19
Step 7 Selecting the Best Alternative
Fig. 1.7
20
Step 8 Communicating the Design
Fig. 1.8
21
Three-level Diagram of Automobile Bumper/Bracket
System
Fig. 1.9
22
Five-level Diagram Including Bumper/Bracket
Subsystem
Fig. 1.11
23
System Concepts

• System collection of elements that interact to
  fulfill a function
• Boundaries separate system from environment
• Components smallest identifiable element of
  system
• Subsystems collection of components

24
Six-level Diagram Including Bumper/bracket
Subsystem
Fig. 1.12
25
Paint-by-Numbers Puzzle Illustrating Systems
Concepts

• Fig. 1.13

26
International Signage Symbol - System Design

• Fig 1.14

27
Solution to the Paint-by Numbers System Puzzle
Fig 1A.1
28
Paint-by-Numbers Coarse Grid Design of Signage
Symbol
Fig 1A.2
29
Paint-by-Numbers Fine Grid Design of Signage
Symbol
Fig 1A.3
30
Life Cycle of Engineering Designs

• Needs analysis
• Feasibility study
• Preliminary design
• Detailed design
• Production
• Distribution
• Consumption
• Retirement

31
Detailed Design

• Models and Prototypes
• Rapid Prototyping
• Production Prototypes
• Testing

32
Cost of Making Changes During Different Phases of
the Design Life Cycle
Fig 1.15
33
Preliminary Design Ideas
Fig 1.16
34
Controlled Convergence During Preliminary Design
Fig 1.17
35
Exploded Assembly Model

• See Textbook page 27

Fig 1.19
36
Production

• Design for Manufacturing and Assembly
• Taguchi Method

37
Overview of System Life Cycle
Fig 1.22
38
Inputs and Outputs at Typical Stage of Life Cycle
Fig 1.23