FUZZY AMENDMENT TO THE HYPOTHESIS OF LINEAR ACCUMULATION OF FATIGUE DAMAGE FOR EXPANSION JOINTS

In view of the shortcomings which exist in the Miner's hypothesis of linear accumulation when studying the fatigue damage of expansion joints, it is proposed in this paper, to employ the Fuzzy Sets Theory and set up the subordinate degree equation of cyclic stress-sigma with the number of cycles n. The contribution of each cyclic stress to the fatigue damage of expansion joints is then put to fuzzy permutation according to the Relative Hamming Distance. On this basis, an amendment to the Miner's hypothesis is derived, which is illustrated by examples at the end of the paper. The method proposed in this paper can also be applied to the fatigue accumulation study for other parts and components of pressure vessels and piping.