The evaluation of conceptual design schemes of mechanical products is an essential problem in the process of its conceptual design.At the stage of conceptual design

whether a correct and objective evaluation can be made on these design schemes will ultimately decide a good or bad performance

even its success or failure.The evaluation of conceptual design is a semi-structural decision-making that includes qualitative indexes and quantitative indexes

so it is difficult to select the best design concepts from a number of schemes.Therefore

an evaluation model based on the engineering fuzzy set theory is developed.First

a detailed hierarchy analysis of evaluation indexes system and constructs some evaluation units according to evaluation indexes system is made.The whole evaluation of schemes is translated into a series of evaluation of basic units or comprehensive cells.Second

a multi-pole fuzzy pattern recognition model based on the engineering fuzzy set theory is established and the relative membership degree matrix can be obtained by the model

the matrix shows the order of excellence.An example is given for demonstration of its application.It shows that the method is feasible and reasonable.