טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentBenmoshe Alon
SubjectMeasurement of Structural Complexity and Functional
Complexity in Mechanical Design
DepartmentDepartment of Mechanical Engineering
Supervisors Professor Reuven Katz
Dr. A. Zonnenshain


Abstract

Classic mechanical engineering design became multidisciplinary, with hardware and software interfaces, manufacturing and assembly design aspects added into the design process. As systems became more complex and the demand for shorter time to market have raised, an 'efficient design' became a necessity.

Any technical application can be met by various solutions, some are more complex than others. However, designing a complex system for a simple task is probably poor engineering practice.

We question the interaction between two aspects of such efficiency of design. Structural complexity of systems that is a measure of design itself and measured by the number of model parts with their interactions and functional complexity that is a measure of system probability to successfully comply with functional requirements - the higher the probability the lower system's functional complexity. While structurally complex design is sometimes regarded as poor engineering, we assume that the linkage between structural complexity and probability to comply with requirements is a significant measure for design goodness and want to explore this linkage.

Three equivalent systems have been tested for structural complexity and functional complexity.  An original design of the systems presents a monotonic linkage between the two - the higher structural complexity is, the lower the functional complexity.  Next, systems' designs have been modified to improve probability of success and reduce structural complexity. The modified systems were tested again, and same behavior have been presented. All three modified systems presented better actual performance (reduced functional complexity) and lower structural complexity, while the monotonic behavior remained with the best (lower) functional complexity measured for the most structurally complex system and vice versa.

We conclude that structural complexity and functional complexity are measurable for mechanical systems. Engineer awareness to complexity measurement methods can reduce structural complexity in a thoughtful manner, so that functional complexity is maintained or even reduced.