Increasing fretting resistance of flexible element pack for rotary machine flexible coupling Part 1. Analysis of the reasons affecting fretting resistance of flexible elements for expansion couplings

It has been made an analysis of the rotor machine flexible coupling (FC) failure reasons. As a result, it has been found out that the flexible coupling trouble-free operation period is limited by the pack of the flexible elements (FE) durability which depends on the fretting resistance of the individual flexible elements (plates) of the pack. The investigations with the use of an electron microscope have proved that there are at least three stages of the FE destruction: the formation of microfractures in the form of caverns at separate points of the FE destruction zone, which microfractures preserve microparticles of the destroyed metal in a confined space; weakening of the compression force affecting the plates and the wear product release from the fracture site; occurrence of abrasive wear resulting in the complete destruction of the FE. There has been substantiated the need in performing the FE stress-strain state analysis and determining the geometric and strain parameters of the strain zone, which can serve as a reserve for increasing the FE fretting resistance. (paper)