Maciej Roskosz

Diagnosis of Supporting Structures of HV Lines Using Magneto-Mechanical Effects

This paper concerns the idea of using magneto-mechanical effects in prophylactic activities to reduce the risk of occurrence of an extensive blackout on high voltage (HV) lines. The subject matter of the paper is related to the event from April 8, 2008, which deprived approximately 600,000 recipients from 18 cities of the West Pomeranian voivodeship of power and caused millions in losses for the national economy. In theoretical considerations, the idea of diagnosing the technical state and level of effort of steel power line towers using the metal magnetic memory method (MMM) is presented, with a consideration of the methodology for obtaining a reference signal from the external magnetic field. The capabilities of the MMM method have been illustrated by examples of active and passive experiments. Finally, the authors indicated the need of IT support of MMM data analysis using a 3D model of the predicted distribution of the magnetic field in the vicinity of the tested object.

Analysis of the similarity between residual magnetic field distribution and the stress and strain state for 7CrMoVTiB10-10 (T/P24) steel

Distributions of the residual magnetic field (RMF) were compared to the results of the calculations of plastic strain and residual stress for samples madeof 7CrMoVTiB10-10 (T/P24)steel. TheRMF was measured on thesurface of samples with a various degree of strain. The calculations of the stress and strain state were conducted by means of the finite elements method with the use of a bilinear model of the material. Qualitative and quantitative relationships were found between plastic strain and the RMF components, as well as between residual stress and the RMF component derivatives. On the basis of the found relationships, thealgorithm fortheevaluation of residual stresswasdeveloped andpreliminarilyverifiedusing themeasurements of the RMF components. The trends of further research aiming to confirm the practical suitability of the developed algorithm for the evaluation of the stress and strain state were formulated.