Serhiienko S. Creation of methods for three-dimensional modeling, design, calculation and implementation of multi-component structures in the production of large DC machines

The dissertation work is purposed to the creation of methods for three-dimensional modeling and design of multi-component structures in production of large direct current machines (LDCMs) to solve urgent issues of increasing the reliability of their design and ensuring flexibility of production. The distribution of stresses and deformations within the LDCM frame was calculated to determine critical loads associated with the specifics of the performance of technological operations. The design and calculation of the stressed-strained state of the LDCM body parts during manufacturing and operation were considered. At the same time, both classical electromagnetic forces and efforts during the performance of technological operations necessary for mechanical processing and assembly of such objects, as well as during transportation, were taken into account for the first time. In terms of determining mechanical stresses, it was established that the safety margins of the designed structure allow ensuring the strength of the frame elements during the manufacture of LDCMs and safe operation during operation without restrictions on loads and operating modes. Three-dimensional analysis of the stressed-strained state of the structure during technological operations, namely tilting, lifting and moving the frame of the LDCMs without poles and with poles, showed that the values of mechanical stresses and deformations that arise in the joints of the basic version of the frame exceed the permissible limits, which leads to significant deformation of the structure. The work designed the structure of the frame with additional stiffening ribs and performed calculations of the stressed-strained state of the unit. The analysis of the reinforced structure showed that during technological operations, the mechanical stresses that arise do not exceed the permissible ones, and all deformations are in the elastic zone for the used material. Scientific novelty of the work: 1. A new method for calculating of the stressed-strained state of a large DC machine frame has been created for the first time, which, unlike existing ones, allows taking into account technological and basic force factors in a three-dimensional formulation. 2. The algorithm for setting boundary conditions for three-dimensional models of structural components of electrical machines has been improved in terms of a detailed description of loads at different moments of the production and operation cycle. 3. The algorithm and methodology for testing of electric machines have been improved in terms of their compliance with the requirements of the implemented modern European standards. 4. Existing engineering methods for determining the stressed-strained state based on classical strength theory have been further developed in terms of improving the accuracy of stress distribution based on mathematical modeling of the structure, taking into account the three-dimensional distribution of technological and basic force factors. Practical significance of the obtained results: 1. The developed method for determining the stressed-strained state of the LDCMs frame, taking into account the loads that arise during technological operations during the manufacturing process and during the operation of the finished product, allows confirming the operability of the housing design not only for the main operating modes, but also for technological operations (lifting, turning over). 2. Based on the developed method, the creation of additional stiffeners was justified, which provides reinforcement of the structure of the LDCMs frame to prevent unacceptable deformations during technological operations. 3. Recommendations have been developed for testing of DC electric machines, based on the implemented modern European standards.