introduction to engineering design process

Topic Outline

1. Definition of Engineering Design

2. Importance and Challenges of Engineering Design

3. Introduction to Systematic Design

4. Design Process

5. Professionalism and Ethics

WHAT ISENGINEERINGDESIGN?

What is Engineering Design?

ABET definition:

• 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, mathematics, and engineering sciences are applied to optimally convert resources to meet a stated objective.

What is Engineering Design?

• Among the fundamental elements of the design process is the establishment of objectives and criteria, synthesis, analysis, construction, testing, and evaluation.

What is Engineering Design?

• Realistic constraints:• Economic factors

• Safety

• Reliability

• Aesthetics

• Ethics

• Social impact

DESIGNLEVELS

Adaptive Design

•

work will be concerned with the adaptation of existing designs.

• Design activity of this kind demands no special knowledge or skill, and the problems presented are easily solved by a designer with ordinary technical training.

Development Design

• Considerably more scientific training and design ability are needed.

• The designer starts from an existing design, but the final outcome may differ markedly from the initial product.

New Design

• Only a small number of designs are new designs.

• This is possibly the most difficult level in that generating a new concept involves mastering all the previous skills in addition to creativity and imagination, insight, and foresight.

IMPORTANCE AND

CHALLENGES OF

ENGINEERING DESIGN

Well-publicized disasters associated with engineering systems

• Chernobyl nuclear power plant

• The Challenger space shuttle

• Boeing 737

• Skywalk at the Kansas City Hyatt Regency Hotel

• Fuel tanks of Concorde airplanes

• Columbia Space Shuttle

The Chernobyl nuclear power plant disaster occurred in 1996.

According to the World Health Organization(WHO), this lead to the evacuation and resettlement of over 336,000 people, 56 direct deaths, 4000 thyroid cancer cases among children, and approximately 6.6 million people highly exposed to radiation.

The Challenger space shuttle exploded in 1986 after an O-ring seal in its right solid-rocket booster failed.

This caused a flame leak, which reached the external fuel tank. The space shuttle was destroyed in 73 seconds after takeoff, and all crew members died.

The loss of the cabin roof during the flight of a Boeing 737 in 1988 caused one crew member to be blown out of the airplane.

Age and the design of the aircraft, which relied on stress to be alleviated by control breakaway zones, were ultimately to blame.

A skywalk at the Kansas City Hyatt Regency Hotel collapsed just after the hotel was opened in 1981.

The skywalk rods were not designed to hold the combined weights of the walkways and the 2000 people that had gathered on them. 200 people were injured, and 114 were killed.

The design layout of the fuel tanks was the cause of the Concorde crash in 2000, killing 113 people.

When the aircraft struck the debris on the runway, the tire that subsequently exploded caused a tank to rupture.

certificate was revoked, and all Concorde airplanes remained grounded for 15 months. This eventually contributed to the demise of supersonic passenger planes.

The crash of Columbia Space Shuttle in 2003.

Attributed to the detachment of a piece of debris from the external tank bipod attach region and striking the underside or leading edge of the port wing of the Columbia.

Reason for failures in most engineering designs• Incorrect or overextended assumptions

• Poor understanding of the problem to be solved

• Incorrect design specifications

• Faulty manufacturing and assembly

Reason for failures in most engineering designs• Error in design calculations

• Incomplete experimentation and inadequate data collection

• Errors in drawings

• Faulty reasoning from good assumptions

INTRODUCTION TO SYSTEMATIC DESIGN

Systematic design process

• Requirements

• Product concept

• Solution concept

• Embodiment design

• Detailed design

Design Process1. Requirements

a) Identifying Customer Needs

b) Market Analysis

c) Defining Goals

2. Product Concepta) Establishing Functions

b) Task Specifications

3. Solution Concepta) Conceptualization (Solution

Concept)

b) Evaluating Alternatives (Solution Concept)

4. Embodiment Design

5. Analysis and Optimization

6. Experiment

7. Marketing

DESIGN PROCESS

Ways to design a device or system

• Evolutionary Change

• Innovation

• Invention

Process design map

Process design map

Process design map

Process design map

Design process

Design process

REQUIREMENTS

Identifying customer needs

• Sources of the need for new design• Client request

• Modification of an existing design

• Generation of a new product

Market analysis

• Sources to determine market availability• Technical and trade journals

• Abstracts

• Research reports

• Technical libraries

• Catalog of component suppliers

• U.S. Patent Office

• The Internet

Defining goals

• The designer defines what must be done to resolve the need(s).

• The definition is a general statement of the desired end product.

• Customer needs NOT EQUAL to product specifications

• clarifyrequirements.

PRODUCT CONCEPT

Establishing functions

• Recognize the generality of the need statement and where the problem/need stands in the whole system.

• Often the functions will be divided into subfunctions, and they will define the requirements of the artifact.

Task specifications

• Requires the designer to list all pertinent data and parameters that tend to control the design and guide it towards the desired goal

• It also sets limits on the acceptable solutions

• It should not be defined too narrowly and it cannot be too broad or vague

SOLUTIONCONCEPT

Conceptualization

• The process of generating alternative solutions to the stated goal in the form of concepts requires creative ability

• In this stage, the designer must review the market analysis and the task specifications as he or she engages in the process of innovation and creativity

• This activity usually requires free-hand sketches for producing a series of alternative solutions

Evaluating alternatives

• Once a number of concepts have been generated in sufficient detail, a decision must be made:• about which one or ones will enter the next

• most expensive

• stages of the design process

• Scoring Matrix, an excellent technique to guide the designer in making the best decision regarding these alternatives

• Chapter 8 covers this stage of the design process in more detail

Embodiment design

• This where the product that is being designed begins to take shape

• This stage does not include any details yet (no dimensions or tolerances, etc.) but will begin to illustrate:• a clear definition of a part

• how it will look

• how it interfaces with the rest of the parts in the product assembly

Analysis and Optimization

• Once a possible solution for the stated goal has been chosen, the synthesis phase of the design has been completed and the analysis phase begins

• Detailed Designmost of the engineering courses in an undergraduate degree program cover

Experiment• The experiment stage in engineering design requires that

a piece of hardware is constructed and tested to verify the concept and analysis of the design as to its work ability, durability, and performance characteristics

• Here the design on paper is transformed into a physical reality

• Three techniques of construction are available to the designer:• Mock-up

• Model

• Prototype

Experiment• Mock-up:

• The mock-up is generally constructed to scale from plastics, wood, cardboard, and so forth

• The mock-up is often used to check clearance, assembly technique, manufacturing considerations, and appearance

• It is the least expensive technique, provides the least amount of information, and is quick and relatively easy to build

• Model:• This is a representation of the physical system through a

mathematical similitude

Experiment• Four types of models are used to predict behavior of the

real system:a) A true model is an exact geometric reproduction of the real

system, built to scale, and satisfying all restrictions imposed in the design parameters.

b) An adequate model is so constructed to test specific characteristics of the design.

c) A distorted model purposely violates one or more design conditions. This violation is often required when it is difficult to satisfy the specified conditions.

d) Dissimilar models bear no apparent resemblance to the real system, but through appropriate analogies, they give accurate information on behavioral characteristics.

Experiment• Prototype:

• This is the most expensive experimental technique and the one producing the greatest amount of useful information

• The prototype is the constructed, full-scale working physical system

• Here the designer sees:• his or her idea come to life

• learns about such things as appropriate construction techniques, assembly procedures, work ability, durability

• performance under actual environmental conditions

Marketing

• This stage requires specific information that defines thedevice, system, or process

• Communication is involved in selling the idea tomanagement or the client, directing the shop on how toconstruct the design, and serving management in theinitial stages of commercialization

• The description should take the form of one of thefollowing:• A report

• A flyer

PROFESSIONALISM AND ETHICS

Professional engineers

• Engages in an activity that requires a specialized and comprehensive education

• Motivated by a strong desire to serve humanity

• Provides services with honesty, integrity, and morality

NSPE Code of Ethics

• National Society of Professional Engineers

• Engineers must uphold and advance the integrity, honor, and dignity of the engineering profession by• Using their knowledge and skill for the enhancement of human

welfare

• Being honest and impartial, and serving with fidelity the public, their employers and clients

• Striving to increase the competence and prestige of the engineering profession

NSPE Code of Ethics: Main Sections• The Fundamental Canons

1. Hold paramount the safety, health, and welfare of the public.

2. Perform services only in areas of their competence.

3. Issue public statements only in an objective and truthful manner.

4. Act for each employer or client as faithful agents or trustees.

5. Avoid deceptive acts.

6. Conduct themselves honorably, responsibly, ethically, and lawfully so as to

7. Enhance the honor, reputation, and usefulness of the profession.

NSPE Code of Ethics: Main Sections• Rules of Practice

1. Engineers shall hold paramount the safety, health, and welfare of the public.

2. Engineers shall perform services only in the areas of their competence.

3. Engineers shall issue public statements only in an objective and truthful manner.

4. Engineers shall act for each employer or client as faithful agents or trustees.

5. Engineers shall avoid deceptive acts.

NSPE Code of Ethics: Main Sections• Professional Obligations

1. Engineers shall be guided in all their relations by the highest standards of honesty and integrity.

2. Engineers shall at all times strive to serve the public interest.

3. Engineers shall avoid all conduct or practice that deceives the public.

4. Engineers shall not disclose, without consent, confidential information concerning the business affairs or technical processes of any present or former client, employer, or public body on which they serve.

NSPE Code of Ethics: Main Sections• Professional Obligations

5. Engineers shall not be influenced in their professional duties by conflicting interests.

6. Engineers shall not attempt to obtain employment or advancement or professional engagements by untruthfully criticizing other engineers, or by other improper or questionable methods.

7. Engineers shall not attempt to injure, maliciously or falsely, directly or indirectly, the professional reputation, prospects, practice, or employment of other engineers. Engineers who believe others are guilty of unethical or illegal practice shall present such information to the proper authority for action.

NSPE Code of Ethics: Main Sections• Professional Obligations

8. Engineers shall accept personal responsibility for their professional activities, provided, however, that engineers may seek indemnification for services arising out of their practice for other

interests cannot otherwise be protected.

9. Engineers shall give credit for engineering work to those to whom credit is due and will recognize the proprietary interests of others.

Final thoughts

• Engineers, perhaps, more than any other single occupation, are responsible for the artifacts of the modern world in which many of us live.

• In order to be good engineers, we not only must be technically competent, but we must also understand how to evaluate the moral implications of our designs.

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Source

• Haik, Y. and T. Shahin. (2011). "Engineering Design Process." Stamford: Cengage Learning.