Karpash A. Methodology improvement for the monitoring of stress state in metal structures of long-term operation (by the example of NGVFS)

The dissertation focuses on the stress state monitoring of NGVFS pressure vessels' metal structures of long-term operation. Based on the detailed analysis of methods and technical means of monitoring, diagnostics and sizing, characterizing the stress state of pressure vessels metal, the necessity of the new approach to diagnosing the actual technical state by the level of stresses in the metal, taking into account several informative diagnostic parameters at the same time, is substantiated. The mathematical model was developed, describing the process of deformation and stresses formation of various spatial configurations based on known displacements of a certain set of points of the pressure vessels surface with allowance for the operating standard stresses and stresses with the asymmetrical nature and the occurrence of which requires further study. The conducted experimental research of interrelations nature between informative parameters of nondestructive testing methods and various types of stresses allowed to establish the minimal set of physical parameters, the complex application of which allows to increase the accuracy of stress value determination in the metal of pressure vessel walls.