An innovative function-tree building method based on similarity theory and extension theory

Product design is a goal-directed problem-solving activity. And function is the basic element for conceptual design which is the most creative activity in the process of product design. Injunction solving phase, the main method of target function solving is to find the similitude functions, but the similitude functions' searching is depending on the designers' experience. In this paper, the sensuous association methods are classified based on association characteristics. Then by using similarity theory to calculate the similarity degree of function matter-elements, an evaluation system of similarity is set up among the functions which could help the designers to search the best suitable similitude functions for solving the target functions. At last, a method of function-tree's rebuilding was given by adding the similarity functions to the original function-tree. With this method, the solution space of design problems was enlarged, and the designers could get more innovation ideas supporting by more design information.