CK-12 Engineering: An Introduction for High School
Page 11
Testing and evaluation of the prototype may reveal weaknesses in the design or may provide information that can be used to improve the design. In this case, the design will often be refined, particularly if it does poorly with respect to some of the criteria or constraints. Sometimes, the chosen design concepts do not meet the criteria or constraints, and the design team must go back and perform more concept generation and then select another concept. This is an integral part of a spiral design process.
Communication and Implementation
As the design team has gone through the design process, they have kept records of the different processes that they used and results of these processes. Often, this information is used to create user manuals and maintenance manuals for the product. This information is important for team members who will be required to update or modify the design in the future. Lessons are learned in the design process that should be conveyed to other teams in the company or perhaps to external stakeholders in government or academia. An important part of the design process is to document these issues and communicate the results to the appropriate stakeholders.
As the design is completed, the effort to implement the design increases. If the design is of a product that is manufactured, a manufacturing system must be developed. For example, in the alternate commuter vehicle design, suppliers for components such as motors and solar cells must be located; facilities for manufacturing the frame are created; and a sales and marketing staff are identified.
Review Questions
Multiple Choice
The following questions will help you assess your understanding of the Discovering Engineering section. There may be one, two, three, or even four correct answers to each question. To demonstrate your understanding, you should find all of the correct answers.
Design problems are broken down into subproblems because each design team member needs a specific problem to solve
the customer or stakeholders do not understand the overall problem
smaller problems must be solved in order to solve the overall problem
engineering companies make more money solving many smaller problems
When a design team searches externally for ideas they interview customers
look at existing products
look at technical databases
talk to experts in the problem area
A concept combination table helps you to explore design ideas systematically
see the complete design concept
identify the overall design problem
keep track of rejected designs
A concept screening matrix is used to select a design
eliminate constraints
develop a design
eliminate criteria
A prototype can be a physical representation
a scale model
a virtual representation
a final product
Implementation means that a physical model is built
virtual model is built
prototype is built
product is manufactured
A design is refined because it has met the constraints and criteria
testing has found weaknesses in the design
a product must go through the spiral design process
there are no further improvements to make
Communicating processes and results is done by posting designs on a website
creating a users manual
text messaging team members
emailing manufacturers
A detailed design includes a market analysis
shapes and dimensions of all physical components
computer code
assembly process
The step in the design process called Explore Possibilities is used to make additional designs
improve the design
understand the design characteristics
test the prototype
Searching internally for ideas is called mind searches
design sessions
idea dumps
brainstorming
When engineers generate ideas in the design process they use an unstructured approach
use a step by step approach
use a mathematical approach
use a structured approach
Which techniques are used to define the design problem? Find expert information
Try to identify the real problem
Gather information from customers
None of the above
Free Response Questions
How can you tell the difference between a good design and a bad design?
What is the difference between engineering design and other types of design (architectural, fashion, etc.)?
How do you know that your design team has considered enough ideas to ensure that they develop a good design?
What are the characteristics of a good problem definition statement?
What are the steps of the design process? Why are they not always completed in order?
How do you use team decision-making tools in the design process?
How do you create a detailed design from a design concept?
Review Answers
The Design Process in Action
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a,b,c,d
a
a
a,b,c
d
b
b
b,c,d
b,c
d
d
a,b,c
Vocabulary
Artifact
An object made by a human being for a particular purpose.
CADD
CADD stands for computer-aided design and drafting. It is the practice of using computer software to represent the geometry of designed objects.
Carbon dioxide emissions
Carbon dioxide is a gas that results from burning fuels that contain carbon (e.g., coal and gasoline). Because carbon dioxide is a greenhouse gas that traps solar radiation, release of large amounts of carbon dioxide into the atmosphere by burning fossil fuels is believed to contribute to global warming.
Characterize
Something is characterized by discovering its distinctive features.
Concept generation
The process of developing ideas that may be used to create a design.
Configuration
An arrangement of the elements of a design in a particular form.
Constraint
A constraint is a limitation or condition that must be satisfied by a design. Constraints are either satisfied or they are not.
Criterion
A criterion is a measurable standard or attribute of a design; for example, weight and size are both criteria. Criteria are used to compare different possible designs and determine which better solve the design problem.
Customer
A person or organization that pays for the design either directly or through the purchase of a product.
Decompose
Decompose means to break down into simpler parts.
Design architecture
The design architecture is the assignment of the functions that the design performs to the physical building blocks of the design.
Dimension
A specification of height, width, depth, or length.
Greenhouse gas
A greenhouse gas is a gas in the atmosphere that traps solar radiation and re-radiates it as heat, leading to warming of the environment.
Incremental design
The incremental design process begins with an existing design that is modified.
Infrastructure
Infrastructure is the basic structures and organization needed for the operation of a society. For example, the automotive transportation infrastructure is the roads, bridges, traffic signals, traffic signs, etc. necessary to drive cars.
Iterative
An iterative process is one that may be repeated.
Model
A model
is a purposeful abstract representation of some aspect of a design. Types of models include equations, physical representations, computer representations, and other representations.
Photovoltaic
Photovoltaic means that light energy is converted into electrical energy (see also solar cell).
Problem statement
A problem statement is a concise description of the problem or need a design will address.
Prototype
A prototype is a first or a preliminary model of the design or some aspect of the design. Prototypes are often physical models, but increasingly computer models are used as prototypes. Prototypes are used to evaluate designs and discover flaws and weaknesses.
Regenerative brakes
Brakes that slow a vehicle by converting its energy of motion into electrical energy that can be stored in a battery.
Renewable energy
Renewable energy is energy that comes from sources that are not permanently depleted by use. For example, solar and wind energy are renewable, while coal and oil are nonrenewable.
Root cause analysis
An analysis of a problem or situation to find the real cause (root cause) of the problem and deal with it; in the absence of a root cause analysis, people often deal only with the symptoms of the problem.
Solar cell
A solar cell is a device typically made of metal and semiconductors that converts light energy into electrical energy.
Stakeholder
A stakeholder is a person or organization who has a stake in (e.g. an interest in or one who may be affected by) a design project. Stakeholders often include users and customers, the design team, and the company that employs the design team.
Sustainability
A sustainable solution is one that can be continued without using up non-renewable resources.
Unfeasible
A design is unfeasible if it does not meet the constraints.
Viable
Viable means able to work successfully.
References
ABET, Inc. “Criteria for Accrediting Engineering Programs 2007–2008.” Downloaded March 17, 2007. Available on the web at
http://www.abet.org/Linked%20Documents-UPDATE/Criteria%20and%20PP/E001%2007-08%20EAC%20Criteria%2011-15-06.pdf.
H. Scott Fogler and Steven E. LeBlanc. Strategies for Creative Problem Solving. Prentice-Hall, Upper Saddle River, NJ, 1995.
Yousef Haik. Engineering Design Process. Thomson-Engineering, 2002.
Gerhard Pahl and Wolfgang Beitz. Engineering Design: A Systematic Approach. Springer, 1999.
Karl Ulrich and Steven Eppinger. Product Design and Development. McGraw-Hill/Irwin, 3rd edition, 2003.
US Department of Transportation. “BCW: About the Program—Facts and Figures.” Downloaded October 2006. Available on the web at
http://www.bwc.gov/about/facts.htm
Joseph W. Walton. Engineering Design: From Art to Practice. West Publishing, St. Paul, MN, 1991.
Instructor Supplemental Resources
Standards
ASEE Draft Engineering Standards. This chapter is focused on “Dimension 1: Engineering Design” of the ASEE Corporate Members Council Draft Engineering Standards; these draft standards will serve as input to the National Academy of Engineering process of considering engineering standards for K-12 education. This dimension includes the following outcomes:
Students will develop an understanding of engineering design.
Students will apply the engineering design process, troubleshooting, research and development, invention and innovation, and experimentation in problem solving and engineering design.
Common Preconceptions
The following are preconceptions and tendencies that novice designers may exhibit:
The novice designer tends to believe that design is primarily developing creative or novel ideas (e.g., brainstorming), and does not understand the role or importance of iteration, evaluation, and planning.
Novice designers show an inability to evaluate and recognize quality ideas and to discriminate between effective and ineffective design processes.
Novice designers often have difficulty clearly defining the problem in the context of the user’s environment and constraints.
Novice designers often focus on a single idea without considering alternatives (often the first idea that comes to mind).
Novice designers are often unaware of the difference between an abstract concept and a detailed design, and do not use appropriate tools and processes to go from the abstract concept to the detailed design.
Novice designers often see design as a strictly serial process and do not recognize the need for iteration, revisiting past decisions, and evaluating alternatives.
Novice design teams often exhibit poor team decision making.
The idea that a design is a decorative pattern may be a preconception. Students may not understand that another meaning of design is a representation of the appearance and function of an object before it is made.
Students may also have preconceptions about models. The most important are that models are always physical and that models have a one to one correspondence with reality. Students do not understand that models often leave out important aspects found in the real object or system.
Bibliography and References
Clive L. Dym and Patrick Little. Engineering Design: A Project-Based Introduction. Wiley, 1999.
Michael McCracken, Wendy Newstetter, and Jeff Chastine. “Misconceptions of Designing: A Descriptive Study.” Proceedings of the 4th annual SIGCSE/SIGCUE ITiCSE Conference on Innovation and Technology in Computer Science Education, Cracow, Poland, 1999.
Project—Design a Solar Cooker
Goal: students will engage in the engineering design process. To the extent possible, the emphasis in the activity should be on the process, and not on the designed artifact; students tend to focus on the object being designed and not see that the quality of the process determines the quality of the design. Novice designers should demonstrate awareness of their design process and see where they have or have not used elements of the design process. Experienced designers should follow a design process and be able to identify the strengths and weaknesses of their process.
This project activity is structured using the 5E Learning Cycle.
Objectives
Students will recognize that design is a process and understand that the quality of the process affects the quality of the resulting design. Students will be able to apply each step of the engineering design process to design a solar cooker.
Materials
The activity requires materials to build a simple solar cooker. Since the emphasis of the activity is on the design project, it would be helpful if there is a wide range of available materials. Possible materials could include
Cardboard boxes (shoe box or larger size).
Cardboard.
White and black paint.
Transparent materials such as plastic wrap, clear hard plastic, and glass.
Reflective materials such as aluminum foil or unbreakable mirrors.
Packing tape or duct tape.
Stiff wires or skewers.
The following tools will be needed:
Scissors
A thermometer capable of measuring up to 250 degrees Fahrenheit.
Engage
The teacher engages the students in a discussion of how much of their environment has been designed by humans. For example, if the class is in a building, it is a building that people designed, engineered, and constructed. The teacher points out that almost every aspect of modern life depends on and is affected by technological artifacts such as bridges, buildings, vehicles, cell phones, computers, and so on. These technological artifacts are designed and created by engineers using the engineering design process.
Students complete the first two columns of the KWL chart (What I know, What I Want to Know) in Table 2, indicating what they know about the design process and what they want to
learn.
KWL Chart for engage activity. What I Know What I Want to Know What I Learned
The teacher then explains that the engineering design process is used to solve problems, and shows examples of deforestation caused by people collecting wood to be used in cooking fires. For example, Figure 18 shows a man carrying firewood in Mozambique. (Haiti is another source that provides a dramatic example of the problem.) The teacher engages the students in a discussion about alternative methods of cooking food in developing nations. Solar energy is one potential alternate energy source; Figures 19 and 20 show two devices that use solar energy to cook food.
Figure 4.18
A man carrying firewood in Mozambique. Firewood is the primary source of energy for cooking food; collection of firewood in many developing countries has led to severe deforestation.
Figure 4.19
A simple solar oven made out of a cardboard box, foil, and clear plastic.
Figure 4.20
A solar cooker and a solar water heater in India. The solar water heater is on the roof of the building. The solar cooker is the silver dish in front of the building.