M.Sc Thesis

M.Sc StudentMichael Press
SubjectCritical Examination of Functional Decomposition and
Morphology as an Engineering Design Teaching
DepartmentDepartment of Aerospace Engineering
Supervisor Dr. Kroll Ehud
Full Thesis textFull thesis text - English Version


Engineering design is a highly complex cognitive process of solving engineering problems by developing new solutions and products. In the past this process was accomplished using intuition and experience, until a realization came that a methodology must be developed in order that novice designers could produce good solutions. One of the methods was developed by the German professors G. Pahl and W. Beitz, who attempted to answer the need by introducing the Systematic Design method also known as the Rational Model.

The Rational Model soon became one of the most common methodologies for engineering design and was embraced by many universities and design schools. This methodology provides the designer with concrete methods and tools for the entire process of design. Especially, the methodology suggests the procedure of functional decomposition and morphology (FD&M) for the phase of conceptual design. It seems that FD&M was adopted by many for the purpose of education due its structured character, although it appears to be scarcely used by expert designers.

Experimental research conducted on students (N=29) in the Faculty of Aerospace Engineering is presented. Participants were both undergraduate and graduate students. It reveals many difficulties and shortcomings of the FD&M method. The research investigates the application of the method for analysis of an existing device and for the purpose of new product design. The research was based on analysis of design reports in the form of submitted homework assignments and of a self-reflection questionnaire that was generated for the purpose of the research.

During the research, ten different problematic aspects were recognized and demonstrated through the analysis of the reports and the answers to the questionnaire. The experimental research indicated that the method of FD&M is somewhat difficult to apply, non-intuitive and most of the time is a hindrance to innovation. The results also show that the method is much more complicated than initially perceived. Students were unable to properly evaluate the quality of theirs results, which led to poor design solutions that often were under developed and thus, required significant effort for their justification and firming up.

One of the most disappointing weaknesses of the method was that it seems to hinder designers from reaching elegant and innovative solutions, because the main mechanism for generating solutions is based on the mere selection of existing working principles (concepts) for realization of subfunctions.

Overall, the method seems to be relatively easy to teach due to its structured nature and consequently, students tend to like it. But judging by the results, it seems that the method should not be taught as the only method for conceptual design and should be treated with awareness of its shortcomings.