Joran W. Booth

Comparing Functional Analysis Methods for Product Dissection Tasks

The purpose of this study is to begin to explore which function identification methods work best for specific design tasks. We use a 3-level within-subject study (n=78) to compare three strategies for identifying functions: energy-flow, top-down, and enumeration. These are tested in a product dissection task with student engineers who have minimal prior experience. Participants were asked to dissect a hair dryer, power drill, and toy dart gun and generate function trees to describe how these work. The function trees were evaluated with several metrics including the total number of functions generated, the number of syntactical errors, and the number of unique (relevant and non-redundant) functions. We found no statistical, practical, or qualitative difference between the trees produced for each method. We also found some generalized findings through surveys that the most difficult aspects of using functional decomposition include identifying functions, choosing function verbs, and drawing the diagram. Together, this may also mean that for novice engineers, simpler methods, such as enumeration, should be taught prior to more complicated methods so students can grasp core concepts such as identifying functions and structuring function diagrams.

EVALUATING THE BOTTOM-UP METHOD FOR FUNCTIONAL DECOMPOSITION IN PRODUCT DISSECTION TASKS

The purpose of this study is to continue to explore which function identification methods work best for specific design tasks. Prior literature describes the top-down and bottom-up approaches as equivalent methods for functional decomposition. Building on our prior work, this study tests the bottom-up method against the top-down and enumeration methods. We used a 3factor within-subject study (n=136). While most of our diagramoriented metrics were not statistically different, we found statistical support that: 1.) students reported that the dissection activity was more useful when using bottom-up, and 2.) that student engineers committed many more syntax errors when using the bottom-up method (by listing parts instead of functions). We believe that both these results are due to the increased focus on individual parts. We do not know if an increased attention to the parts would increase novelty or fixation, and recommend future studies to find out.

Reducing Sketch Inhibition During Concept Generation: Psychophysiological Evidence of the Effect of Interventions

This research investigated the effect of warm-up activities on cognitive states during concept generation. Psychophysiological tools including electroencephalography (EEG) and galvanic skin response (GSR) were used along with self-report measures (NASA TLX). Participants were divided into 3 test conditions: 1) no warm-up activity; 2) simple warm-up activities; 3) sketchinhibition reducing activities. All participants did the same short design task. Results show that those who did a warm-up prior to ideation had a decrease in stress, especially for those who were not personally familiar with the design problem. The art activities especially improved engagement for younger participants. We also saw that females who used the art-based activities reported lower mental workload during ideation and greater pride in their sketches. However, the warm-ups did not produce any difference in the number of ideas or other metrics of performance. These preliminary results indicate that warm-up activities, especially the art-based ones, help reduce inhibition by calming the cognitive state.

The Relationship Between Design Outcomes and Mental States During Ideation

Using electroencephalography (EEG) to predict design outcomes could be used in many applications as it facilitates the correlation of engagement and cognitive workload with ideation effectiveness. It also establishes a basis for the connection between EEG measurements and common constructs in engineering design research. In this paper, we propose a support vector machine (SVM)-based prediction model for design outcomes using EEG metrics and some demographic factors as predictors. We trained and validated the model with more than 100 concepts, and then evaluated the relationship between EEG data and concept-level measures of novelty, quality, and elaboration. The results characterize the combination of engagement and workload that is correlated with good design outcomes. Findings also suggest that EEG technologies can be used to partially replace or augment traditional ideation metrics and to improve the efficacy of ideation research. [DOI: 10.1115/1.4036131]

Empirical Studies of Functional Decomposition in Early Design

This paper explores functional decomposition in early design. In the first part of this study, we explore how the three most common methods (top-down, energy-flow, enumeration) affect concept generation for novice design teams (n=25). We found that nearly all the features in the final concept could be mapped to the function diagram, though not all the functions mapped to the actual concept. This suggests that there is not much change in system functionality between these two phases, despite being separated by a few weeks. We also found that teams who used top-down and energy-flow performed nearly the same, and teams who used enumeration performed worse than those who used energy-flow. Based on these results, we recommend using either top-down or energy-flow, but not enumeration in early design. We also observed that teams used the diagramming process to reach a consensus and support team communication. The second part of this study evaluates design reports (n=78) from industry engineers taking a distance learning design course. Even though roughly half of the reports used functional decomposition, there was no correlation between using functional decomposition and final design quality as measured by various grade components. We also observed that half of the function diagrams were tree diagrams. This supports prior findings that a top-down, tree-based approach is more intuitive for engineers. Together, these results suggest that functional decomposition is helpful for team communication, but show no direct correlation with design outcome. We also recommend training strategies for teaching decomposition based on differences between the two datasets.Copyright

Art Meets Engineering Design: An Approach for Reducing Sketch Inhibition in Engineers During the Design Process

While much prior work has been done regarding sketching and its impact on design and a few on how to train engineers to sketch, there have been no prior studies in engineering to reduce inhibition to frequent sketching. This paper describes a sketching intervention developed from art teaching aimed at reducing inhibition to sketching and a study to evaluate its effectiveness. In the study, students (n = 55) were tested with pre-mid-post assessments consisting of a mechanical, organic, and design-oriented sketching task and a TLX survey measuring the level of difficulty. The study found that the students overwhelmingly reported their inhibition was lowered, but the short-term TLX data suggested inhibition was higher. However, the TLX data showed a longterm decrease in inhibition-related measures, perhaps suggesting that long-term encouragement to sketch is effective in reducing inhibition to sketch. These results tentatively suggest that sketch inhibition is reduced by actively promoting creativity and sketching, some use of the activities presented here, and by deemphasizing the importance of higher-level skills such as perspective drawing.Copyright

The Design for Additive Manufacturing Worksheet

Additive manufacturing (AM) technologies have become integral to modern prototyping and manufacturing. Therefore, guidelines for using AM are necessary to help users new to the technology. Many others have proposed useful guidelines, but these are rarely written in a way that is accessible to novice users. Most guidelines (1) assume the user has extensive prior knowledge of the process, (2) apply to only a few AM technologies or a very specific application, or (3) describe benefits of the technology that novices already know. In this paper, we present a one-page, visual design for additive manufacturing worksheet for novice and intermittent users which addresses common mistakes as identified by various expert machinists and additive manufacturing facilities who have worked extensively with novices. The worksheet helps designers assess the potential quality of a part made using most AM processes and indirectly suggests ways to redesign it. The immediate benefit of the worksheet is to filter out bad designs before they are printed, thus saving time on manufacturing and redesign. We implemented this as a go-no-go test for a high-volume AM facility where users are predominantly novices, and we observed an 81% decrease in the rate of poorly designed parts. We also tested the worksheet in a classroom, but found no difference between the control and the experimental groups. This result highlights the importance of motivation since the cost of using AM in this context was dramatically lower than real-world costs. This second result highlights the limitations of the worksheet. [DOI: 10.1115/1.4037251]

UNDERSTANDING ABSTRACTION IN DESIGN: A COMPARISON OF THREE FUNCTIONAL ANALYSIS METHODS FOR PRODUCT DISSECTION

In design classes, functional analysis is a process that is typically used to assist students with identifying essential functions to aid in the development of their concepts. However, it has been observed that students sometimes struggle with this part of the design process. In this study, a group of 26 students were studied in a 3-level within-subject study (n = 78) to determine which of three common functional analysis approaches (i.e. top-down, energy-flow, and unstructured) was most effective. Participants were asked to dissect a hair dryer, power drill, and NERF pistol and generate function trees describing how these work. Measures of effectiveness include the number of functions generated, the number of errors, the number of levels of abstraction represented in the tree, and the number of unique subsystems and functions identified. No statistical difference between the approaches was found, and there was also no practical difference between the approaches. These results suggest that for novice engineers, there is no difference between methods used. This possibly indicates that for novice engineers, formal methods may not be any more effective than an unstructured approach.Copyright