Ehiremen Nathaniel Omoarebun

(Advisor: Prof. Dimitri Mavris)

will defend a doctoral thesis entitled,

SPAAD: A Systems Design Methodology for Product and Analysis Architecture Decomposition

On

Friday, April 5 at 8:00 a.m.
Microsoft Teams

Abstract
Increasing complexity in engineering design has resulted from the continuous advancement of technology over the past few decades. Over the years, engineers have explored various ways to manage complexity during the different phases of design and have recently shifted from document-based approaches to model-based approaches in the form of Model-Based Systems Engineering (MBSE). However, MBSE comes with its own set of challenges.

Despite the introduction of MBSE many systems engineering practices are still based on heuristics, and engineers rely on prior experiences or trial and error approaches to implement systems engineering methods. Although existing methodologies outline important aspects of the system design process, they do not define or provide guidance on how these aspects should be achieved. Recently, INCOSE, the systems engineering professional society, has sought to establish formal and theoretical methods in system engineering that are grounded in science and mathematics. Using formal and theoretical methods, a system can be represented and the relationships between its elements can be better understood.

Also, in recent years, Integrated Product and Process Development (IPPD) has emerged as a systematic approach to manage the development of complex systems from early integration through a system's life cycle and could be considered the overall construct for system design problems. A fundamental aspect of the IPPD process is the decomposition aspect of the system. With the emergence of MBSE, Requirements, Functional, Logical, and Physical (RFLP) is an important framework used in system decomposition. However, similar to many MBSE approaches, the RFLP framework operates at a high-level and does not provide guidance on decomposing stakeholder requirements into the system's functional, logical, and physical architecture. This led to the motivating question for this dissertation, with the aim to explore ways to improve and effectively translate the decomposition process within the RFLP framework into a system design that satisfies the stakeholder requirements.

A research objective was identified with the aim to develop and implement a method that facilitates a rigorous system decomposition process in a more formal and structured manner using a set of theoretical foundations based on mathematical principles to effectively characterize a system. From this research objective, an overarching research question for this dissertation was formulated with the aim to establish structure between the product and analysis architectures during system decomposition to allow for the design of better and improved systems, especially during the conceptual stages of design. To improve the decomposition process and create a structure within the RFLP framework, Axiomatic Design Theory (ADT) was identified as the most suitable method that can aid in the structured decomposition of a system, while placing emphasis on minimizing coupling and improving the system's robustness. An in-depth examination of ADT and its potential integration with the RFLP framework revealed several limitations, which this dissertation addresses across the various research areas.

The first research area focuses on improving the requirements process in ADT and RFLP. A requirements analysis process is developed to categorize stakeholder requirements into functional and non-functional requirements, provides a framework to establish the relationships between the different types of requirements, and allow for high-level requirements to be broken down into concrete and clear requirements within the product and analysis architectures. The second research area focuses on integrating concepts from Axiomatic Design Theory (ADT) into the RFLP framework. The Independence axiom from axiomatic design, together with its zigzagging attribute is used to decompose the functional and logical layers of the RFLP framework and help create a structure during design.

The third research area focuses on the identification of suitable analysis methods during system decomposition within the analysis architecture. During conceptual design, the selection of a suitable analysis method may be challenging especially when model data is limited. The ability to properly identify a suitable analysis method facilitates informed decision-making during system design. From a combination of the three research areas, a ten-step methodology, SPAAD, is proposed that outlines the steps to perform a systems decomposition from the stakeholder requirements to the development of the functional, logical, and physical architectures for both the product and analysis architectures or domains.

Committee

• Prof. Dimitri Mavris – School of Aerospace Engineering (advisor)
• Prof. Daniel Schrage – School of Aerospace Engineering
• Prof. Brian German – School of Aerospace Engineering
• Dr. Selçuk Cimtalay – School of Aerospace Engineering
• Dr. Charles Domerçant – Georgia Tech Research Institute