Dobraniuk Y. Simulation of the mode of deformation and limiting state of the cylindrical samples' surface at face-end compression.

The research object is cylindrical sample at face-end compression. The research purpose is determining of stress-strain state and limiting strain of the cylindrical samples' lateral surface at face-end compression. Methods based on the statement of the mathematical theory of plasticity and damage accumulation, mathematical analysis, experimental studies and numerical modeling of deformation using of software DEFORM 3D. The theoretical results is the development of analytical representation technique of the description of deformations trajectory in coordinates accumulated strain - the indicator of stress state for lateral surface's points of the cylindrical sample at face-end compression; the technique of analytical models' construction of limiting strain of the samples' lateral surface using the relationship between the deformation components is developed for the first time; the new regularities of limiting strains' changes at non-stationary straining are obtained; the combined technique of numerical, experimental analytical modeling of determining the stress-strain and limiting states of the cylindrical samples' lateral surface is developed; the theorem of the necessary and sufficient conditions of damage function's convexity is formulated and proved. The practical results are the information technologies' development of the stress-strain state and limiting deformation of the cylindrical samples at face-end compression determining; the practical advices concerning the forecasting of limiting material deformation of the lateral surface at face-end compression based on the mathematical models of the limiting state that allows to reduce the amount of experimental research are developed; the recommendations to increasing the accuracy of limiting conditions determination during 3D modeling of the cylindrical sample's compression based on experimental and analytical studies are elaborated. The practical results is the information technologies determining of the stress-strain state and limiting strains of the cylindrical samples at face-end compression are developed; the practical recommendations concerning the forecasting of material's limiting strains of the lateral surface at face-end compression based on the mathematical models of the limiting state that allows to reduce the amount of experimental research are developed; the recommendations to increasing the accuracy of limiting conditions determination during 3D modeling of the cylindrical sample's compression based on experimental analytical studies are developed. The degree of implementation - the results of the thesis put into production in JSC "Bershadskiy ETP" (Vinnitsa region) and the educational process of VNTU (Vinnitsa). The application field is metal forming.