Garanenko T. Development of the process of forming a hollow blade from titanium alloys for gas turbine engines

The dissertation solves the actual scientific and technical problem of developing the process of forming a fragment of the hollow blade of a gas turbine engine, taking into account the laws of viscoplastic deformation of titanium alloys in isothermal conditions. The design of a fragment of a hollow metal blade of a fan of corrugated type is offered, taking into account the factor of decrease in weight of a blade feather at the expense of constructive - technological decisions at preservation of operational parameters (properties of static and dynamic durability). A comparative static and dynamic analysis of the operating loads of the fan blade of solid and hollow construction was performed using the ANSIS software package. In the simulation process, the regular part of the scapula feather without end zones (tail part and end feather) was considered. It is shown that the radial and equivalent stresses from inertial forces during rotation of the blades are 10-15% lower for hollow blades. Based on the analysis, the feasibility of the selected cross-sectional structure of the hollow blade fragment is proved. The development of the technology of obtaining a typical cross-section is based on obtaining a hollow blade of limited length experimentally. The technology of manufacturing hollow blades is based on a combination of two processes of pressure welding and forming in the mode of superplasticity. The method of experimental - analytical construction of deformation curves on the basis of bending tests is developed. The method is based on the solution of the system of equations of equilibrium of moments of internal and external forces at pure bending of blanks. To confirm the correctness of the obtained viscoplastic models for the titanium alloy VT6, a comparison was made with the data used in scientific practice. For this purpose, the properties of the material (foreign analogue of VT6) from the database of the DEFORM-3D software package were used as a comparison, the simulation results of which are recognized by most countries of the world. At the junction of the curves, the error is 16-18%. The dependence curve according to DEFORM data in comparison with the obtained dependences according to the developed method, allowed to estimate the error in the range of 16-20%. By the nature of the behavior of the curves obtained by the developed method, the dependence complements the dependence, which is built on the data of DEFORM and continues it. The results of the study showed that the curves of viscoplastic deformation of these materials can be used to calculate technological processes. The peculiarity of determining the value of the ultimate accumulated plastic deformation is taken into account, which takes into account the stiffness index of the stress state scheme. For the corresponding temperature and velocity conditions of deformation, it was experimentally established that the maximum value of plastic deformations for titanium alloys corresponds to the temperature range of polymorphic transformations. For the first time, for the process of forming the cross-sectional structure of the hollow blade of the corrugated type by the pressure of the gas medium, the factors limiting the deformation process are established: - the maximum accumulated plastic deformations occur in the wall of the corrugated filler in the local edge zone adjacent to the junction of the filler with the cladding. Their value depends on the relative height of the corrugation. In this place there is a destruction at molding at achievement of the maximum plastic accumulated deformations of limiting size. - the formation of under-molding of the cladding is difficult at the junction of the cladding and speech due to resistance to deformation of the corrugated filler. It is shown that this factor limits the height of the cross section of the hollow blade. The maximum height of the cross section of the hollow blade depends on the ratio of the thicknesses of the corrugation and the skin. In the works performed in co-authorship, the applicant should obtain scientific results that are scientific novelty and practical significance in creating mathematical models of the process of plastic formation of a hollow blade fragment and in analyzing the results of numerical calculation, development of experimental-analytical method for viscoplastic deformation model. isothermal conditions, development and implementation of an experimental method for determining the limit deformations in viscoplastic forming of titanium sheet alloys under hot plastic deformations in isothermal conditions for use in the Cockroft-Letem-Okha deformability criterion, formulation and analysis of experimental results, development of technological process structure new technical solutions, development of recommendations for the implementation of processes and their testing at enterprises in the industry.