Reliability Assessment of Mechanical Components Using Fuzzy-Set Theory

Abstract

An approach to assessing the reliability of mechanical components, especially for pressure vessels and piping, is proposed in which the vagueness and fuzziness in variables have been considered. In this method, a fuzzy-random reliability model is developed by using a fuzzy-set theory. This particular theory can be described as a generalization of the classical set theory. Using a fuzzy-set theory, a failure event is defined in a more flexible form than usual. In particular, the concept of nonfuzzy probability of fuzzy events is used to derive a reliability approach which includes the subjectivity of human judgement. Meanwhile, a constructive way for generating a membership function of a fuzzy set is also provided in the paper.

Practical reliability-based analysis of a coil tube spring

“…The maximum cutting stress is represented by substituting equations (15) to (19) into equation (14), as given by…”

“…where d is the axial strain of the coil tube spring, G is the cutting modulus and N is the ef cient cyclomatic number of the coil tube spring. The maximum cutting stress is represented by substituting equations (15) to (19) into equation ( 14), as given by…”

“…As with many reliability-critical mechanical components, a numerical method needs to be introduced to enable reliability analysis of a coil tube spring. D uring the last three decades, there has been considerable research activity about reliability-based analysis of mechanical components, in the area of engineering research, as described in a number of monographs [1][2][3][4][5] and papers [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. This paper focuses on the probabilistic perturbation method for reliabilitybased analysis.…”