1. Chapter Three Engineering Design Process

3. What is Design ?

4. WHAT IS DESIGN: 'Design is the decision making process by which an idea is transformed into an outcome” ( product or service)

5. Engineering Design Process

13. 3.3 Engineering Economics
Economic factor always play important role in engineering design decision making.
If you design a product that is too expensive to manufacture, then it can not be sold at a price that consumers can afford and still be profitable to your company.
The fact is that companies design products and provide services not only to make our lives better but also to make money. 13 13

14. 3.4 Material Selection
As design engineers, whether you are designing a machine part, a toy, or frame for car or a structure, the selection of materials is an important design decision.
There are a number of factors that engineers consider when selecting a material for a specific application. For example, they consider the properties of materials such as density, ultimate strength, flexibility, machinability, durability, thermal expansion, electrical and thermal conductivity, and resistance to corrosion.
They also consider the cost of the material and how easily it can be repaired.
Engineers are always searching for ways to use advanced materials to make products lighter and stronger for different applications. 14 14

15. Density—Density is defined as mass per unit volume; it is a measure of how compact the material is for a given volume. For example, the average density of aluminum alloys is 2700 kg/m3; when compared to steel density of 7850 kg/m3, aluminum has a density that is approximately one third of the density of steel.
Compression Strength—Some materials are stronger in compression than they are in tension; concrete is a good example. The compression strength of a piece of material is determined by measuring the maximum compressive load a material specimen in the shape of rectangular bar, cylinder, or cube can carry without failure.
Thermal Conductivity—Thermal conductivity is a property of materials that shows how good the material is in transferring thermal energy (heat) from a high-temperature region to a low-temperature region within the material.

16. 3.5 Teamwork
A design team may be defined as a group of individuals with complementary expertise, problem solver skills, and talent who are working together to solve a problem or achieve a common goal.
The goal might be providing a service; designing, developing, and manufacturing a product; or improving an existing services or product.
A good team is one that gets the best out of each other. Communication is an essential part of successful teamwork.

17. 3.6 Common Traits of Good Teams
Successful teams have the following components:
The project that is assigned to a team must have clear and realistic goals. These goals must be understood and accepted by all members of the team.
The team should be made up of individuals with complementary expertise, problem solving skills, background, and talent.
The team must have a good leader.
The team leadership and the environment in which discussion take place should promote openness, respect, and honesty.
Team needs and goals should come before individual needs and goals.

18. 3.7 Conflict Resolution
When group of people work together conflict sometimes arise.
Conflicts could be the result of miscommunication, personality differences, or the way events and actions are interpreted by a member of a team.
Accommodating team members are highly cooperative, but their low assertiveness could result in poor team decision.
Compromising team members demonstrate a moderate level of assertiveness and cooperation.

19. 3.7 Conflict Resolution
A better approach is the collaborative “conflict resolution” approach, which demonstrates a high level of assertiveness and cooperation by the team. With this approach, the conflict is treated as a problem to be solved by the team.
Good communication is an integral part of any conflict resolution.
Team member must listen to each other. Good listeners do not interrupt; they allow the speaker to feel at ease and do not get angry or criticize.

20. 3.8 Project Scheduling and Task Chart
Project scheduling is a process that engineering managers use to ensure that a project is completed on time and within the allocated budget.
A good schedule will assign an adequate amount of time for various project activities. It will also make use of personnel and the available resources for planning, organizing, and controlling the completion of the project.
A well planned schedule could also improve the efficiency of the operation and eliminate redundancy in task assignments.
See Example Next Page

21. 3.8 Project Scheduling and Task Chart

22. 3.9 Evaluating Alternatives
Once you have narrowed down your design to a few workable concepts, it is customary to use an evaluation table similar to the one shown in the next page.
You start by assigning a level of importance (I) to each design criterion. For example, you may use a scale of 1 to 5., with I=1 indicating little importance, and I=5 extremely important .
Next you will rate ® each workable concept in terms of how well it meets each design criterion. You may a scale of R=3 for high, R=2 and R=1 for medium and low, respectively.
The design criteria vary depending on a project.
(See Table 3.4 page 56)

25. 3.11 Engineering Standards and Codes
Standards and codes have been developed over the years by various organizations to ensure:
a)product safety and reliability in services, such as:
1-safe food supplies,
2-safe structures,
3-safe water systems,
4-safe and reliable electrical systems,
5-safe and reliable transportation systems,
b) uniformity in the size of parts and components that are
made by various manufacturers around the world to ensure
that parts manufactured in one place can easily be combined
with parts made in other places

26. Examples of Standards and Codes Organizations in the United States
1-The American National Standards Institute (ANSI)
The American National Standards Institute (ANSI) was founded in 1918 by five engineering societies and three government agencies to administer and coordinate standards in the United States.
The ANSI is supported by various public and private organizations.
The institute itself does not develop the standards, but instead it assists qualified groups, such as various engineering organizations, with the development of the standards and sets the procedures to be followed.

27. 2-The American Society for Testing and Materials-ASTM
Founded in 1898
The ASTM publishes standards and test procedures that are considered
authoritative technical guidelines for product safety, reliability, and uniformity.
Testing is performed by its national and international member laboratories.
The ASTM collects and publishes the work of over 100 standards-writing
committees dealing with material test methods. For example,
1-ASTM sets the standard procedures for tests and practices to determine elastic properties of materials, (Mechanical properties) such as: impact testing, shear and torsion properties, bend and flexure testing, compression, ductility, and thermal expansion.
2-ASTM also sets the standards for medical devices and equipment,
including bone cements, screws, bolts, pins, prostheses, and plates, and
specifications for alloys used in surgical implants. Electrical insulation etc

28. 3-Additional examples of ASTM work include the following:
Test guidelines for evaluating mechanical properties of silicon or other
procedures for testing semiconductors, such as germanium dioxide.
• Testing methods for trace metallic impurities in electronic-grade aluminum-
copper and aluminum-silicon.
• Standards related to the chemical analysis of paints along with tests to
measure the physical properties of applied paint films, such as film
thickness, physical strength, and resistance to environmental
• Standard procedures for evaluating properties of motor, diesel, and aviation
fuels, crude petroleum, hydraulic fluids, and electric insulating oils.
• Test procedures for measurements of insulation properties of materials.
• Standard procedures for soil testing, such as density characteristics, soil
texture, and moisture content.
• Building-construction-related tests and procedures, such as measuring the
structural performance of sheet metal roofs.
• Tests for evaluating the properties of textile fibers, including cotton & wool
• Standards for steel piping, tubing, and fittings.

29. Examples of International Standards and Codes:
1-The International Organization for Standardization (ISO)
Established in 1947, consists of a federation of national standards from various countries.
The International Organization for Standardization promotes and develops standards that can be used by all countries in the world, with the objective of facilitating standards that allow for free, safe exchange of goods, products, and services among countries.
2-CЄ Standards
All products sold in Europe must now comply with C Є standards.
C Є provides a single set of safety and environmental standards that is used
throughout Europe.
The C Є marking on a product ensures conformity to European standards.

30. Other Internationally Recognized Standardization Organizations
1-The British Standards Institute (BSI) is another internationally known organization that deals with standardization. In fact, BSI, founded in 1901, is one of the oldest standardization bodies that organizes and distributes British, European, and International standards.
2- the German Deutsches Institut für Normung (DIN),
3-the French Association Française denormalisation (AFNOR),
4-The Swedish Standardiserigen I Sverige (SIS),
5-the China State Bureau of Quality and Technical Supervision (CSBTS).
Visit the Web sites of these organizations to obtain more information about them. Searching for information about organizations dealing with engineering standards and codes as example: American Institute of Chemical Engineers
( The American Society of Agricultural and Biological Engineers ( American Society of Civil Engineers (