Department of Mechanical Engineering

Mrs. Shraddha Joshi

Degree Candidacy: Doctor of Philosophy in Mechanical Engineering
Date: Thursday, November 21, 2013
Time: 12:00 PM
Location: 108 EIB

Advisor: Dr. Joshua Summers
Committee Members: Dr. Gregory Mocko, Dr. Georges Fadel, and Dr. John DesJardins

Title: Requirements in Conceptual Design


Requirements play critical role in the design process. The broader impact of this research is to develop a systematic understanding of the current use of requirements. The ultimate goal is to develop guidelines and recommendations for more effective use of requirements throughout the design process. Thus, this research begins to answer the question about what is the role of requirements in design process and, specifically, its role in idea generation? The answer to this question is explored in three phases.

The first goal is to understand how requirements are currently taught to students. To that end, two surveys were conducted. First, a review of ten design textbooks was conducted as an initial surrogate for understanding what is formally taught. This was done to understand the use of requirements within the design tools mentioned in the textbooks. Supplementing this, interviews of faculty involved in teaching design courses was conducted with faculty from mechanical engineering, industrial engineering, bioengineering, and materials science and engineering. While the interviews suggest that the use of requirements is distributed throughout the design process, in agreement with common practice, the instruction provided students, based on the survey of textbooks, focuses on requirements tools found exclusively in the conceptual design phase. Thus, a significant gap is identified in terms of lack of sufficient tools explaining the use of requirements.

In order to understand the consequences of lack of tools and to develop a deeper understanding of how students are applying the requirements education imparted to them, a case study analysis was conducted with senior mechanical engineering design students in a capstone course. Data was collected from four teams working in parallel on the same design project in form of requirements documents from initial weeks and the final report deliverable. The findings from this study reveal that there is lack of uniformity in how students elicit requirements in the initial weeks of the project. The completeness and specificity of requirements increase from the initial weeks to the final week, as expected, as the students develop a better understanding of the problem. However, in terms of addressing the requirements, more requirements with one adjunct or numerical value, and thus low specificity, were addressed. Further, it was found that the requirements documents of novice designers (students) changes in multiple ways. Currently, the students do not have tools or methods in place that would allow them to systematically manage the changes in requirements document.

Finally, as a deeper dive into how requirements can impact a specific design activity, an empirical designer study was conducted to explore the impact of requirements elicitation in idea generation. The study was conducted, again, with senior mechanical engineering students at Clemson University. The findings from the experimental study suggest that the students elicit more non-functional requirements compared to functional requirements. However, the ratio of the number of non-functional to functional requirements decreases when considering only the requirements addressed during ideation. Further, comparing the requirements addressed in the solutions generated by the students, it is found that the group that was not primed with the task of eliciting requirements performed better in terms of addressing requirements when compared to other two groups.

Ultimately, the findings from these studies are used to make several recommendations that will allow the students to systematically use the requirements at various design stages and enhance their current use of requirements. This dissertation presents broad and focused research evidence with respect to the role that requirements play in engineering design based on student experiences. This does not imply that professionals behave in a similar manner. However, as the understanding of requirements in the education of the students is further developed, this can have a significant, albeit indirect, impact of the practice in industry as the students graduate.