Engineering Design Process

Admittedly, there are many variations to the engineering design process (a review has been completed by Schubert, Jacobitz, & Kim, 2009), with some steps possibly occurring in parallel, and with some others being skipped altogether. The basic flow block diagram in Figure 1, however, outlines the fundamental sequence that is emphasized in Lawrence Tech’s first year course. Within the first few class meetings, the diagram is distributed to and discussed with the students; in addition, some notes are also given to the students that explain what the process is, what purpose it serves, why it is useful, when to use it, where to use it, and briefly how to use it. For clarity throughout this paper, each step is numbered and abbreviated in the following way: 1) Define, 2) Brainstorm, 3) Design, 4) Build, 5) Test, 6) Assess, 7) Refine, 7.5) Retest/assess, 8) Report.

Figure 1: The Engineering Design Process used for projects in the First Year Engineering Design course

2.2 Water-powered vehicle

The water-powered vehicle is a relatively complex multi-component project which is best deployed after the first year students have acquired some design practice by completing at least one smaller-scale project (Gerhart et al., 2011). Teams comprised of three to five students are tasked to develop a small car that operates on a finite amount of “rainwater” (employing conversion of potential to kinetic energy). The project connects to the Grand Challenge of clean water, as well as the importance of alternative forms of energy. As stated in the student assignment hand-out,

The potential energy of 1 inch of rainfall on the average single-story house, if captured at the roof height provides approximately 120 kJ of energy, and even more if the rain can be captured while in motion. Devices to convert and store this energy could be created, utilizing an untapped and readily 1) Assess and

understand need (define the correct

problem) 2) Conceptualize various options 4) Build, fabricate, or model 3) Design using

sound scientific and engineering

principles

5) Test/evaluate 6) Assess test

data 7) Modify, improve refine, and optimize design 8) Report results 7.5) Retest and assess revisions

available energy source. In addition, the rainwater itself could be harvested and stored for a variety of everyday uses thereby conserving energy and precious fresh drinking water sources.

The vehicle must be no more than 18 inches (45.72 cm) long and 12 inches (30.48 cm) wide. They can use 0.5 liter of water with 60 cm height. The water must be captured and drainable (i.e., no water spills), and the student teams are only allowed to use repurposed materials (i.e., nothing bought new). Examples of rainwater cars are shown in Figure 2. The project is scaffolded (i.e., staged) over four weeks. Stages include 1) completing a worksheet defining the problem and determining a team schedule with a plan of action, 2) brainstorming and submitting multiple design ideas, 3) interim testing of vehicle, and 4) final testing and reporting. This timeline allows the students to focus on each step of the engineering design process, and points are awarded for the interim testing a week before final testing. This turned out to be an important aspect to emphasizing the importance of design steps 6 through 7.5, as well as applying systems thinking to complex problems. In general, most teams did not appreciate these important steps before the final (graded) test in class, but after faring worse than assumed, the student teams were much better at testing and refining their projects in subsequent projects. (Assessment results of the incremental gains in appreciating the engineering design process are given in detail in Gerhart & Fletcher, 2011 and Gerhart el al., 2014. Briefly, a significant difference in scoring (i.e., grade difference) between the two projects revealed that out of 40 teams, very few teams were able to reach their goals for the rainwater car assignment; five weeks later, completing another project, 39 of 40 teams achieved 45 of 45 testing points with many also accomplishing goals for bonus points.)

Figure 2: Examples of students’ rainwater vehicles and a test run.

The students’ car projects are judged on two tests. For the first test, the car is to obtain maximum distance; for the second test, the car must land on a specified mark ranging from 5 to 8 meters from the starting line (with the distance unknown until the test date). In other words, the object of the second run is to add sufficient water so that the car lands on the specified target. A score is calculated with the following formula:

S = ( D1 −100W1 − O1 ) − ( ∆2 + 100W2 ) where:

D = Distance car travelled (mm) W = Water spilled over 25 mL (mL) O = Distance off the centerline (mm) ∆ = Distance from the target (mm)

In addition to the design and testing, a written report is required wherein the students must clearly describe the process used to design, build, and test. In particular, the report includes key design features of the car, a brief description of how the engineering design process was used, changes made to the car design after the prototype testing, a description of the repurposed materials used so that the design can be replicated, and all sketches and drawings used during the project.

As indicated in Table 1, the engineering design process steps are “mostly” to “fully implemented” with two exceptions. As expected, the average is low for “assessing test data” (before the final in-class test). At this earlier stage of the course, students have had little to no experience assessing a design test. The lowest average is “report results.” There are two possible explanations. First, even though the students were asked to specifically report on changes made to the car design after prototype testing, it is speculated that the students interpreted

“report results” as reporting final in-class results, which was not possible since the report was due on the same day as the in-class test. Second, many teams assigned a single team member to write the report, so many students would rate this step low.

Regarding the professional skills, Table 1 displays a wide range of averages. Not surprisingly, oral presentation and computer use rank lowest; neither of these were required of the students, although it was hoped that students would perform some graphical design on the computer.

Table 1. Students’ ratings of statements after completion of the Water-powered vehicle

Skill Average Median

Standard deviation

1. Assess and understand the need (define the correct problem) 4.33 4 0.65

2. Conceptualize various options 4.35 4 0.72

3. Design using sound scientific and engineering principles 3.96 4 0.85

4. Build, fabricate, or model 4.36 5 0.81

5. Test/evaluate (before in-class test) 3.97 4.5 1.15

6. Assess test data 3.83 4 1.07

7. Modify, improve, refine, and optimize design 4.36 4.5 0.81

7.5. Test and assess revised design 4.07 4 1.08

8. Report results 3.60 4 1.11

Importance of teamwork for this project 4.47 5 0.71

Practiced teamwork 4.06 4 0.95

Importance of written communication skills for this project 3.42 3 0.96

Practiced written communication skills for this project 3.23 3 0.85

Importance of formal oral presentation skills for this project 2.33 2 1.16

Practiced formal oral presentation skills for this project 2.19 2 1.18

Used the computer (not including note-taking or communication such as email) as a tool for the design, testing, and/or, evaluation

2.42 2 1.32

Practiced the design and fabrication of a multi-component project 3.72 4 1.10

Practiced the design and fabrication of a multi-process project 3.63 4 1.13