Function flow-based product design process modeling

Traditionally, product design process is divided into multiple phases, and the distributed design flow across these phases emphasizes on task solving and realization within one of the design phases in term of the perspective of designer. Increasing personalized product design demand, however, often leads to frequent redesign of design work mainly due to distortion of ambiguous and discrete customer requirement information by multiple delivering. Since the customer requirement information and requirement function affect both product conceptual design and later product design process, designing an integrated product design process is challenging. The purpose of this research is to develop a systematic product design process model based on requirement function and its function flow, which can acquire, deliver, transfer and realize the unambiguous customer or designer requirement and requirement function. In this study, the definition of requirement, function and requirement function are given, and the mutual relationship among them is analyzed. Then, an integration mode of product design process, which consists of qualitative conceptual design phase and quantitative detail design phase, is proposed according to the nature invariability of function. Furthermore, a new function flow-based product design process model is presented. The function flow, formed by transformation, evolvement and connection of the requirement function, is used to describe the correlation of customer requirement function, designer requirement function, and assembly function along with product design process. A hierarchy model of intermediate product corresponding to this product design process is also established, which includes requirement product, function product, principal product, conceptual product and detail product. Also, a case study is given to validate the model proposed. This product design process modeling method can help transferring different type of requirement functions effectively and avoiding mistake or misunderstanding of solution on design requirement between different phases to the greatest extent.