Objectives:
Apply mathematical principles and analysis in design; Apply scientific
principles and analysis in design; Design within constraints; Apply the
engineering design process
PD Activities:
This portion of professional development will include an in-depth presentation
by an engineering partner, and it will include a discussion that will help
teachers be able to relate engineering design to what they may or may not
have experienced in the bridge design icebreaker activity. Another activity
that we have completed is the Food for the World Challenge. We had to design
a irrigation system that will meet certain specifications. Some of what
follows requires you to try to relate to such an activity and to the bridge
design icebreaker.
• The NCETE engineering design process will next be taught
to teachers through direct instruction but also with reference back to the
Bridge Design Simulation activity so that what was experienced by teachers
will have more meaning. Teachers will learn how to improve on the engineering
design process and can reflect on what was learned. Starting with an icebreaker
activity instead of starting with a lecture on the engineering design process
is more motivating than starting with the lecture and moving to the activity.
Enabling Objective:
Explain and describe the engineering design process.
Resources
Holtzapple, M. T., & Reese, W. D. (2005). Concepts in engineering.
Boston: McGraw-Hill. [ISBN 0-07-282199-X] This book will be mailed to you if it was not provided
in professional development on campus. Even though there are references to
it in the text below, you can still benefit from the text here without the
book until you get it. If you have not yet been issued a book, it will be
mailed to you soon.
Frye, E. (1997). Engineering problem solving for mathematics, science,
and technology education. Hanover, NH: Trustees of Dartmouth College. Retrieved
November 12, 2007 from: http://thayer.dartmouth.edu/teps/book.html
Professional Developer Input
In order to provide a brief overview of what engineering is, the following
information is presented in the first or second session of professional
development.
The following reiterates what Holtzapple and Reese (2005) stress about
engineering design. These ideas are immediately important to you because
by the time that we reassemble in person, each participant will need to have
with him or her, an Engineering Notebook and it should eventually reflect
what was learned under the engineering partner and the authors. It will specifically
reflect what was developed in the first two Engineering Design Challenges.
The Challenge documents will be available to you on your CDs that you receive
in future professional development sessions. Click here also
to get the resource. The username is "ncetepd,"
and the password is "materials08." You will
discover later that you will need to make schematic and technical drawings
of your designs. You may also, in your spare time between now and the next
time that we meet after a full challenge, prepare your finished drawings
using CAD.
In the following, notice that keywords
are colored in blue.
Engineering Design
Notice that Holtzapple and Reese emphasize that the steps in the engineering
design are not only iterative but parts of
it can be repeated in the feasibility study, the preliminary design, and
the detailed design. The arrows in the figure here symbolize that various
steps and sub-steps can be repeated as needed as the overall engineering
design process proceeds. The NCETE Engineering Design Process was adapted
from the Dartmouth Engineering Design model (Frye, 1997). Because the Food
for the World activity that we encountered was designed in order to introduce
you to the idea of deliberately applying science and
mathematics to deliberately design a device that had behaviors that
you could predict and were mathematically optimized, the problems were not necessarily full
blown. Therefore, your ability to legitimately document some of the steps
in the engineering design process was somewhat limited this first time around.
For example, you did not have to identify the need for the engineering solution
for the problem we tackled. The need was already posed on the handouts or
software that we provided to you.
Assemble the design team
When problems get complex we need people on our design team who understand
science and mathematics, who understand mechanics and statics of materials
and the forces that act on the members of the bridge. For our immediate
part of the problem, we were all satisfactory designers, but what about
other parts of the problem that our bridge problem did not include? Could
we have been able to determine if our final design would be easy to construct,
easy to pre manufacture, easy to maintain, look good in the landscape and
environment? It is possible that our team would have needed to be joined
by a variety of others with the necessary expertise to tackle such a complex
design problem.
Identification of the need
In our first problem, the bridge, we designed a bridge for a construction
firm, what was the need? What were the problems defined? These are questions
that are somewhat debatable. Let us see if we can take a stab at it.
The need was for our company to establish
a new product really. Was it not? Bridge construction is situational. A
solution that worked in one location may not work in another. We wanted
to continue to do business with the general contractor. A changing need
was that the bridge needs to support varying weights. Why should one bridge
test be used to develop a specification? Why not deliver a design that is
so strong it could support any number of any variety of vehicles at any height?
Consumers want (need) such a product. A major problem is how to make the
fit for the situation where it is to be located.
Define the problem: Identify the constraints
and criteria for success
In our first problem, we had our constraints
pretty much spelled out on the challenge sheet. We had to deliver a product
that supported the road bed and the truck. We would be successful if we
delivered exactly that product. However, there were other constraints and
criteria were there not? For example,
would we want to construct the product if we had to invent our own new structural
material? Could we not design a bridge that met the criteria by using regular,
stock material? There may have been others.
Please be mindful to consider the extensive list of questions and considerations
that Holtzapple and Reese (2005) suggest when it comes to identifying constraints
and criteria. They provide an excellent battery of considerations. Constraints are limitations within which the solution
must be constrained. Criteria are targets that
the product’s performance must meet. Constraints might be characterized
by the following questions. What materials should be considered? What costs
should be limited? Who should be involved in the design and testing? What
is the competition doing? What should the bridge look like? Should the product’s
ease of construction be a consideration? Criteria might include that the
bridge be able to hold a specified weight, that it be made from high tensile
steel on the outside trusses and rust proofing on ties and struts. Each member
must be 3 inches in cross sectional area. Each truss subsection must be preassemble
and lifted into place with a crane…et cetera. From this account it is easy
to see how constraints and criteria are able to be used to create specifications. This is an important step in defining
the problem.
Search
Search for existing designs and how they work. When there are multiple
components to a design solution, part of the solution may already exist
and simply needs to be purchased. Other partial components to the solution
may need to be designed by your team. For example, there may already be an
acceptable structural steel for most of the truss members. It can be purchased
in bulk when it is time to manufacture the cords. However, your research
may determine that there is not an acceptable tempered steel available and
you have to design a heat treating process of your own.
Develop designs
Is it not true that when you and your design partner set out to design
the bridge that you had several possible solutions? You should have sketched
out all of your ideas and described them to your engineering design team.
Analysis
As you may recall, several of the teams actually designed trusses that
did not support the specified weights. All
of these designs were sketched, or should have been sketched by your team.
You looked at each design. Several, after you analyzed
them with the simulator, were not going to satisfy the problem. Then you
may have found a design that seemed the most likely based on your simulation,
the team had various opinions about its success based on their respective
expertise. In a small way, since this was an introductory experience, these
steps of realization represent the Feasibility Study, the Preliminary Design,
and the Detailed Design (see Holtzapple & Reese, 2005).
It is important to note that up to this point, your thinking was somewhat
DIVERGENT. You were open to the possibilities
of alternatives.
Please be mindful to consider the extensive list of questions and considerations
that Holtzapple and Reese suggest when it comes to being a creative engineer.
Is this not something that can be implemented with your students?
Decision
You must choose the best solution that meets the specifications you developed
and is also within the constraints that you imposed and that you identified.
For the bridge, it was throughout the analysis that you chose your best
design. After that point, things became CONVERGENT.
Now you started focusing on the BEST solution. And you proceeded to develop
it. You did one more preliminary design. You “tweaked” the materials. You
went to the materials menu to find just the right materials. You may have
also had to adjust your design because you discovered that tube shaped members
were going to provide more load bearing per pound.
The two products pictured below were developed in order to help people,
who have problems gripping small objects, hold a razor - blade and handle
- better. The design team developed the new products for a personal hygiene
company. Several things are worth noting. The first is that this design team
actually went all the way to develop two competing prototype designs. The
reason that they wanted to actually develop the two prototypes is because
they wanted to experience how each design felt to the hand. As it turns out,
they chose the second oval looking design because it felt better to the hand
for people who may suffer from arthritis. A professor, who suffers from a
hand condition from a past surgery was their test subject. It is important
to note that the team was performing concurrent engineering as opposed to
sequential engineering, as also noted by Holtzapple and Reese. They not only
developed competing prototypes, but the packaging designers did not wait around
for the final decision to be made regarding which design would win. Instead
they developed packing for each design. The team assembled was exactly the
sort of team needed for an interdisciplinary design effort.
Design 1 competing with the solution below.
Design 2 competing with the solution above.
Please be mindful to consider the extensive list of questions and considerations
Holtzapple and Reese suggest when it comes to searching for a solution.
They provide an excellent battery of considerations.
A decision matrix can be used by the design
team to decide which solution is the best one to pursue and develop further.
In the matrix below, a design team has decided that the most important criteria
that all alternative solutions must meet are cost, ease of operation, safety,
portability, durability, use of standard parts. These criteria are listed
in the Criteria column of the matrix. Then the team deliberated on the relative
importance of each criterion. They decided on weightings to assign to each
criterion. Notice that the weights all add up to 100. It could be stated
that cost is 30% of what should be considered when deciding on the best solution.
Each alternative solution is identified in the matrix across the top row
as solutions 1 through 5. The design team next discusses how solution 1 should
be rated in terms of cost. They decided that on a scale of 1 to 10, Solution
1 was rated as a 6 in terms of cost. Next multiply the rating (6) by the
weight (30) to come up with an overall score for that criterion for that
solution. Notice that Solution 1 scores 180 when it comes to cost. Repeat
this rating and weighting process for each criterion for each solution. The
sum of each column represents each solution’s total score. What is the best
solution based on this process? According to the matrix below, it is Solution
5 with a high score of 860.
This decision matrix was developed by Dr.
Ali Abul-Fadl of North Carolina A&T State University.
When one considers this process as an engineering design process, is it
not something that could be implemented in your classroom?
Test prototype and verify the solution
Once the solution was chosen, you have to begin compiling the specifications, parts, bills of materials, engineering sketches,
and the like in order to plan and carry out the production and analysis
of a prototype and to plan for reporting to management. This may include
sketches and draftings like you see below. The plans below are mechanical.
Communication: Communicate the design to
management
Once the details seem to be in order an in-depth narrative and drawings
would be used to communicate the design to management.
The picture below might be used to show a water pump interface that may
have been contracted. The picture is of a PowerPoint slide that might be
used in a presentation to the company’s management.
Now that you have reviewed the engineering
design process, compare it to the process used in the Food for the World
Challege. Return to the top of this page and click on the Engineering Notebook
link.
Return to Top of Page
Outcomes:
Teachers will understand the engineering profession, the roles that engineers
play, and the engineering design process.
Success Indicators:
Improved comprehension of the engineering profession and the engineering
design process
Looking Inside
the Classroom: A Cooperative Learning Snapshot
For professional development, we did not really
have time to go over do's and don't's for cooperative learning, like what
you may have students do when they are working as an engineering design
team. Below is a simple account of how a teacher delegated and provided
structure for a cooperative learning activity. See what you can gather from
it as you analyze it.
Ms. Thompson wanted her technological studies students
to develop an understanding of the interaction of technology and an aging
society. The first task that she presented to her students was to identify
some of the problems that senior citizens face as they move from their 60s
into their 70s. Before the students divided into their assigned groups, Ms.
Thompson provided them with a handout that explained each group member’s
responsibilities.
·
The group leader
manages group discussions and delegates research assignments to the group
members.
·
The recorder
keeps notes on the group’s deliberations and research findings, and he or
she helps the group members organize their work into portfolios.
·
The analyst
helps group members implement strategies for finding information about aging.
·
The presenter
helps summarize the research findings and presents a summary to the rest
of the class.
The handout also gets the students started on the
right track by suggesting some first steps for the way the group members
interact. It suggests questions that the group can ask to decide how to continue
with their research. For example:
·
What sources
should they use to find research?
·
What terms
should they use that will lead them to articles, books, and Web sites?
·
What are some
of the issues that relate to the aged?
Once they understood what their roles would be within
the group and how they would get started, each group assembled at an assigned
table in the laboratory-classroom.
In one group, for example, Adrianne was the leader.
She went over the rules for planning discussion and said, “Speak one at a
time, and be patient with each other.” She started reviewing the list of
responsibilities with the group. Because Caleba was the last person to complete
the World Wide Web module in the technological studies laboratory-classroom,
the group decided quickly that he would serve as the group’s analyst. Cameron
had just completed the multimedia module, so he was elected as the presenter,
and because Davin had just finished a keyboarding class last semester with
an “A,” the group chose him as the recorder.
To get started with a research strategy, the students
began going through the questions listed on Ms. Thompson’s handout. Davin
recorded the group’s ideas on some note paper. Then Ms. Thompson said, “Davin,
once you all are finished recording your strategies, you might want to slide
your table closer to computer number five. Its hooked up to the Internet.”
While she looked around the laboratory -classroom at the other groups, she
asked, “Adrianne, what are some of the issues that your group has identified
that relate to aging?” Adrianne replied, “Well, we are just getting to that
part of the work, but the one thing we thought of so far is that it is a
problem if you are elderly and poor. Some elderly people get put in homes.
Cameron was saying that when his grandmother was sick, they put her in a nursing
home, and she got totally depressed.” “That’s exactly the sort of thing
you should be researching,” replied Ms. Thompson, and then she went across
the room to check on another group.
With their worktable pulled up right next to the
computers, the group had room to spread out. Davin was at computer number
four recording notes on the word processor, and Caleba was on computer number
five browsing through the public library’s online catalog. He noticed one
book on aging. Because her father did not mind taking her to the library,
Adrianne volunteered to check the book out that evening.
She also volunteered to interview her grandmother. Caleba
began using a search engine to find more information on the World Wide Web,
and he hit a “gold mine”— a Web site dedicated to designing housing for retired
and elderly people. During this process, Cameron used some of the terms he
and Adrianne identified to search in Ms. Thompson’s database of resources
that are kept in the laboratory-classroom. He was able to find an article
on community design in one of Ms. Thompson’s teacher journals.
Next, Caleba worked with Davin
to get their notes recorded, and Adrianne took over the Web search. She found
a site with an article about integrating medical technology into the houses
of the elderly, the terminally ill, and patients who live in remote locations.
“Telemedicine, sounds like one possible solution,” exclaimed Adrianne. Ms.
Thompson told Cameron that he should start taking notes on the community
design article. She suggested that their group’s focus for the next step
in the unit could be designing suitable living space for senior citizens.
Ms. Thompson then warned the groups that they had
five minutes remaining before they had to arrange the furniture, computers,
and books. She wanted to leave sufficient time at the end of class for each
group to share their preliminary findings. Davin printed out the notes he
kept of the work they accomplished in the last 40 minutes and let Cameron
look over them. “In the next unit, someone else gets to be recorder,” Davin
said. Adrianne reminded Cameron that he should be ready to develop the group’s
brief multimedia presentation tomorrow, and she promised to have the results
of the library research and interview. In the last five minutes of class,
when it was Cameron’s turn to share, he told the rest of the class that his
group had discovered that two big concerns for some poor seniors citizens
were inadequate housing and lack of healthcare.
The next day Ms.
Thompson led a discussion on the ways technology may cause problems for senior
citizens and ways that technology might also improve or solve problems for
senior citizens. She gave the groups 30 minutes to complete their research.
After that point, she asked the groups to decide how to organize their findings
for a formal presentation. During each presentation, Ms. Thompson led discussion
on the problems that the groups identified. After she helped summarize the
findings for the whole class, she announced that each group should take five
minutes to decide what problems they would like to solve. Adrianne’s group
decided to find ways to improve the housing problem of the elderly by trying
to design a retirement community complete with telemedicine in each senior
citizen’s home. During the rest of class that day, Ms. Thompson went from
one group to the next to help each write design briefs that students would
use in managing their technological problem solving activity.
