The Disposal Of Stress And Strength Based On Experiential Data And Reliability Analysis

Some quite great progresses in fuzzy reliability theory and its application have been made recent twenty years, but the meanings of some important concepts in fuzzy reliability theory are not accepted by all of people. In order to develop and utilize fuzzy reliability theory, some concepts of fuzzy reliability theory must be studied deep. Firstly, in this paper several well-known uncertainties are compared, the meanings of some important concepts in the Fuzzy Sets Theory are described. How to utilize the concepts in engineering and to make them understandable easily by engineers are discussed. Secondly, three decision-making models based on membership functions are given, and they also can be used to distinguish uncertainty between commonly fuzzy uncertainty and complicated uncertainty in classification. Thirdly, based on the decision-making models mentioned above and the transformation which can be used to transform the fuzzy variable to the random variable, two methods which can be used to obtain the probability density functions from the expertise about the distributions of random variables are discussed. In the above two methods, the method based on membership functions can obtain the probability density functions by transforming the fuzzy variable to the random variable, and the method based on random sets can obtain the probability density functions by synthesizing the random sets which are given to explain the language description of random variable by experts. Finally, the two methods are used to analyses the fuzzy reliability when the probability density functions of intension and stress are unknown. The error between subject reliability and object reliability is discussed in the paper.