Lazariev I. Development and improvement of methods for strength analysis of power transformers structure elements.

The research subject are the mechanical processes that determine strength of the elements of the deformable bodies system corresponding to windings and their clamping structure during power transformers manufacturing, shipment and service. The research object are critical stresses of radial stability, limiting bending moments, axial internal forces and displacements in the respective elements of the deformable bodies system under consideration. The aim of the research is development and improvement of methods for calculation and analysis of static and vibration load strength and stability of structure elements of power transformers in order to increase their reliability. The research methods are as follows: in order to solve the formulated problems there were carried out investigations utilising methods of solid mechanics for analysis of stability and strength of the elements operating beyond the elastic limit (determining critical stresses of windings radial stability and windings strength under the action of radial and axial electromagnetic forces due to short circuit), methods of theory of vibrations of systems with lumped and distributed parameters (determining the displacements and internal forces in the active part elements under the action of axial electromagnetic forces due to short circuit that change by differing nonperiodic time functions) methods of analysis of complex statically redundant systems (determining the axial internal forces in the elements of the active part after its lifting and lowering, short circuits, as well as during windings clamping, variation of elements temperatures and insulation materials moisture contents). Introduced at PJSC «Ukrainian research, design and technological transformer institute», Bharat Bijlee Limited (India), Transformers & Rectifiers Ltd (India), «Toshiba Corporation, Hamakawasaki Operation» (Japan), «TurboCare Poland S.A.» (Poland). Area of application: transformer engineering.