Behavior analysis method for product design support a study on modeling of behavior and functions

Recent industrial globalization has increased the number of unanticipated product failures and troubles caused by using them in unexpected ways or situations. Developing new type of products to meet recent requirements for product innovation may also cause unanticipated troubles due to lack of knowledge. It is important to obviate such troubles in advance in the product design phase. In addition to predicting ways and situations of use as much as possible, it is required to develop a methodology for modeling relations between product functions and ways/situations of use and then analyzing functional phenomena which depend on the ways/situations. The authors proposed a method for realizing it in which product functions, behavior and physical phenomena caused by the ways/situations are modeled by graphs such as function decomposition trees and Petri nets and then interaction among them are analyzed by integrating those models. The integration of the product function model and the behavior model is performed by finding functions which are realized by parts of the behavior. However, there are “static functions”, which are not realized by any behavior. In this paper, the conventional method is enhanced so that it can deal with this type of functions. Investigating static functions indicated that they are realized by keeping the state of the concerned part of the product unchanged. This can be regarded that transition from the state to itself is repeated. Based on this concept, we defined a unit of the Petri net for describing a static function. Incorporating this unit in the conventional behavior model enabled the conventional method to deal with that type of functions.