A Fuzzy Reasoning Model of Two-Dimensional Warranty System

Much of the literature on warranty analysis considers failure models which are indexed by a single variable, such as age or usage. However, there are situations where several characteristics are used together as criteria for judging the eligibility of a failed product. The warranty analysis characterized by a region in a two-dimensional plane with one axis representing age and the other axis representing usage is known as a "two-dimensional" warranty plan. A classical warranty plan requires crisp data obtained from strictly controlled reliability tests. However, in a real situation these requirements might not be fulfilled. In an extreme case, the warranty claims data come from users whose reports are expressed in a vague way. It might be caused by subjective and imprecise perception of failures by a user, by imprecise records of warranty data, or by imprecise records of the rate of usage. This paper suggests different tools appropriate for modeling a two-dimensional warranty plan, and a suitable fuzzy method to handle vague data.