Using functional analysis for product decomposition in engineering design: insights from a literature review

Functional Analysis supports product decomposition in the conceptual design phase by defining system functions and flows before committing to specific solutions and technical implementation. Although widely recognized, Functional Analysis practice remains fragmented, with varied methodologies, inconsistent terminology, and limited software support. This study presents a Systematic Literature Review of Functional Analysis applications in engineering design, screening six databases using the PICOC framework and PRISMA 2020 guidelines. Forty peer-reviewed papers were analyzed to identify dominant methods, inputs, outputs, tool usage, application domains, and selection criteria. Results show four main approaches widely adopted in engineering design: Black Box models, Function–Means Trees, Systems Architectures, and hybrid methods. Typical inputs include design requirements, interface characteristics, and customer needs; outputs are mainly flow diagrams, hierarchical decompositions, and systems architectures. Only 20% of studies used dedicated Functional Analysis software, with most relying on general-purpose tools or custom prototypes. Functional Analysis is most common in mechanical and mechatronic systems, with limited adoption in biomedical, aerospace, and naval engineering fields. Key challenges involve scalability, repeatability, cross-disciplinary integration, and balancing systematicity with creativity. An exploratory, literature-informed framework is proposed, linking complexity, detail, usability, and systematicity to the comparative discussion of method choice, supporting comparative interpretation and exploratory method selection for researchers and practitioners and identifying opportunities for advancing Functional Analysis in high-complexity systems.