DETERMINATION OF THE STRESS-STRAIN STATE OF MULTI-COMPONENT AND MULTI-SECTION STATOR FRAMES OF VERTICAL HYDROGENERATORS

Oleg Bohozhavets

Abstract


The subject of the study is the stress-strain state of multi-component and multi-section stator frames of vertical hydrogenerators under operational and emergency loads. The objective of the study is to determine the specific features of the stress-strain state of multi-component, multi-section stator frames of vertical hydrogenerators through a series of three-dimensional finite element analyses and to identify the structural factors governing their overall stiffness, maximum displacements, and local stress concentrations. The research tasks included developing full-scale three-dimensional finite element models of two stator frames with different structural configurations; specifying the foundation restraint conditions and design loads; identifying characteristic stress concentration zones and maximum displacements; and assessing the effect of flange and shell thicknesses on the structure's strength and stiffness. The research methods were based on three-dimensional finite element modeling with representation of the main load-bearing components of the stator frame, followed by analysis of the von Mises equivalent stress fields and resultant displacements. For the first stator frame, the stress-strain state under an emergency loading condition was investigated. For the second stator frame, two structural variants with different flange and shell thicknesses were compared under identical restraint and loading conditions. The results obtained showed that the maximum stresses occur mainly at the joints between stiffening ribs, vertical members, flanges, and annular components of the stator frame. Conclusions. It was established that reducing the thickness of the main load-bearing elements causes a simultaneous increase in equivalent stresses and displacements, thereby reducing the structural stiffness. It was shown that assessment of the structural performance of multi-component stator frames should be based not only on determining the maximum overall displacements but also on analyzing the local stress state of individual load-bearing elements and their joints. The scientific novelty lies in identifying characteristic stress-concentration zones and determining the effects of flange and shell thicknesses on the strength and stiffness of the stator frame. The practical significance lies in the possibility of using the obtained results for verification calculations, comparison of structural variants, and substantiation of the geometric parameters of load-bearing elements of vertical hydrogenerator stator frames.


Keywords


hydrogenerator; stator frame; multi-section structure; multi-component structure; stress-strain state; finite element method; equivalent stress; stator frame stiffness

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DOI: https://doi.org/10.32620/aktt.2026.4sup2.06