Using SAPPhIRE for Functional Modelling of Multi-state Systems

Functional modelling has great importance in the design process as it is used to analyse, share, and communicate design concepts across various disciplines and assist designers in concept generation, evaluation, and selection. Functional models primarily represent the functionality of a (desired) system, which means, among others, the transformation of material, energy, and (or) information flows. In past decades, the complexity of technical systems has increased due to technological advancements and the demand for more functionality to be delivered with fewer resources. A complex system is often characterised by multiple states whereby it can achieve different functions at different operating (working) states by changing its topological structure and the interaction among its components. The objective of this work is to develop a functional modelling scheme that provides a comprehensive and rich description of a multi-state system. An integrated functional modelling approach is proposed that involves the causal explanation of how the transition occurs across different operating states within a system, how the system performs a particular function within a single operating state, and how the system transforms the operand of a technical process. This has been achieved through adapting and integrating various features of existing functional modelling techniques where SAPPhIRE—a model of causality—is used as the basis. The proposed approach has been demonstrated through an example case study where a multi-state system—a hairdryer—has been modelled.