A group decision making method for sustainable design using intuitionistic fuzzy preference relations in the conceptual design stage

Achieving sustainability in product life cycle involves the complex decision making process such as the selection of conceptual schemes and manufacturing processes, and disposing method of end-of-life. Morphological matrix is simple and useful tool for mapping design requirements in conceptual design for new product design and redesign of out-of-date product. Although conceptual design using morphological matrix as an important step in the product development could achieve sustainability requirements through accurate choice, quantitative decision making method is seldom considered in selection of function solution principle for sustainability. Meanwhile, uncertainties of sustainability attributes in conceptual stage generally are not also considered in these morphological matrix. To solve these problems, this paper put forward an approach based on morphological matrix to satisfy sustainability requirements in product conceptual stage considering vagueness and uncertainty through intuitionistic fuzzy number. The aim of this paper is to quantify conceptual schemes considering sustainability attributes using group decision making and intuitionistic fuzzy preference relations. The decision makers’ weights are calculated based on theirs experiences and knowledge on the function, manufacturing, economic, environment, recycle and social properties of product. The morphological matrix is used to establish the relationship between function and solution principles based on sustainability information, then the preference degree are obtained from multiple experts employing intuitionistic fuzzy judgment matrix. The preference degree for each solution principle is quantified by intuitionistic fuzzy numbers through membership, non-membership and hesitancy degree to express the linguistic terminology. To ensure the consistency and consensus issues of preference relations, an additive consistency method is employed, and correction factor is used for achieving modification automatically of judgment matrix when the consistency requirement is not met. Finally, the integrated multi-criteria decision model for function solution principle is established to carry out the final sustainability decision problem in early design stage. The feasibility and validity of proposed method is proved through a practical example for spindle system design of CNC.