This document presents two developed methods for solving the classification task of medical implant materials based on the compatible use of the Wiener Polynomial and SVM. The high accuracy of the proposed methodology for solving this task are experimentally confirmed. A comparison of the proposed methods with existing ones: Logistic Regression; Linear SVC; Random Forest; SVC (linear kernel); SVC (RBF kernel); Random Forest + Wiener Polynomial is carried out. The duration of training of all methods that described in work is investigated. The article presents the visualization of all method results for solving this task.

Purpose: The main aim of this paper is development, software implementation and use of the alloys selection method for the design of biocompatible materials in medical production. It is based on the use of Ito decomposition and Logistic Regression. Design/methodology/approach: The technology of machine learning is used to solve the

Purpose: To investigate the fatigue crack growth at normal tension and transverse shear of 65G steel with the high tempered martensite microstructure and to build an appropriate fatigue crack growth rate curves. To determine the main and auxiliary fatigue crack growth resistance characteristics, which are necessary for machine parts life-time estimation at rolling contact fatigue conditions. Design/methodology/approach: For determination of fatigue crack growth resistance at normal tension a standard compact specimens with edge crack were tested using a hydraulic testing machine and fatigue testing at transverse shear were performed on the I-beam specimens with the edge longitudinal crack using the original testing setup. For crack growth measurement an optical cathetometer B-630 was used. The crack growth rate V was calculated as crack length increment during loading cycles. The stress intensity factor range K was determined by dependence "K = (1 – R)Kmax accordingly to the standard test methods. To establish crack faces friction factor at transverse shear fragments of fractured beam specimen containing crack faces were cut out and tested as a friction pair according to Amontons Coulomb's law. On the base of test results the fatigue crack growth rate curves in logarithmic coordinates "K vs. V were built. These graphical dependencies for normal tension and transverse shear were used for determination of fatigue crack growth resistance characteristics: fatigue threshold "Kth, fracture toughness "Kfc, "K1-2 and "K2-3 which indicates the beginning and the end of middle-amplitude region of curve, "K*, parameters C and n of Paris’s equation. Metallographic and fractographic analyses were performed on the scanning electronic microscope Zeiss EVO 40XVP. Findings: Empirical dependences of the stress intensity factor range on fatigue crack growth rate at normal tension and transverse shear of 65G steel with the high tempered martensite microstructure are obtained. Based on these graphical dependencies the fatigue thresholds and fracture toughness as well as the parameters of Paris’s equation are determined. Research limitations/implications: The fatigue crack growth on 65G steel under low-, medium- and high-amplitude cyclic loading at normal tension and transverse shear was investigated. The fatigue crack growth rate values for a wide range of stress intensity factor are estimated. On the base of fractographical analysis the features of fracture of high tempered martensite in 65G steel at transverse shear are studied. It is shown that the transverse shear crack faces friction factor for high tempered martensite structure is less than for low tempered martensite. Practical implications: Using the fatigue crack growth resistance characteristics of 65G steel at normal tension and transverse shear and related fatigue crack growth rate curves it is possible to predict the life-time of machine parts made of steels with high tempered martensite structure, working at rolling contact fatigue conditions. Originality/value: Complete fatigue crack growth rate curves of 65G steel with tempered martensite structure at normal tension and transverse shear are built and the fatigue crack growth resistance characteristics for both modes of fracture are determined for the first time.

Purpose: The aim of the proposed research is to establish experimentally the relation between damaging of the tread surface of model wheels and the characteristics of fatigue crack growth resistance of wheel steels "KI th, "KII th, "KI fc, "KII fc), depending on its microstructure. Design/methodology/approach: Characteristics of the fatigue crack growth resistance have been determined on the specimens cut out from the hot rolled plate of thickness 10 mm of the steel which is an analogue of railway wheel steels. To obtain different steel microstructures and its strength level, test specimens were quenched (820°C, in oil) and then tempered at 400°C, 500°C, and 600°C for 2 h. The characteristics of Mode I fatigue crack growth resistance of steel were determined on the basis of fatigue macrocrack growth rate diagrams da/dN–"KI, obtained by the standard method on compact specimens with the thickness of 10 mm at a frequency of 10-15 Hz and the stress ratio R = 0.1 of the loading cycle. The characteristics of Mode II fatigue crack growth resistance were determined on the basis of da/dN–"KII diagrams, obtained by authors method on edge notched specimens with the thickness 3.2 mm at a frequency of 10-15 Hz and R = –1 taking account of the crack face friction. The hardness was measured with a TK-2 hardness meter. Zeiss-EVO40XVP scanning electron microscope was used for microstructural investigations. Rolling contact fatigue testing was carried out on the model specimens of a wheel of thickness 8 mm and diameter 40 mm in contact with a rail of length 220 mm, width 8 mm and height 16 mm. Wheels were manufactured form the above-described steel after different treatment modes. Rails were cut out from a head the full-scale rail of hardness 46 HRC. The damaging was assessed by a ratio of the area with gaps formed by pitting and spalling to the general area of the wheel tread surface using a special stand. Findings: The growth of the damage of the tread surface of the model wheels correlates uniquely with the decrease of the cyclic fracture toughness of the wheel steel "KI fc and "KII fc, determined at Mode I and Mode II fracture mechanisms. These characteristics of the wheel steel can be considered as the determining parameter of this process, in contrast to the fatigue thresholds "KI th and "KII th. Research limitations/implications: Investigations were conducted on model wheels that simulate the damage of real railway wheels tread surface. Practical implications: A relationship between the damage of tread surface of railway wheels and the strength level of wheel steels is determined. Originality/value: The damage of the tread surface of the model wheels during the rolling contact fatigue of the pair wheel-rail increases with the growth of the strength (hardness) of the wheel steel, which corresponds to the statistical data of the operation of the real railway wheels.

The effect of reduction treatment in a high-temperature (600 °C) hydrogen-containing environment on the microstructure and tendency to brittle fracture of YSZ-NiO(Ni) materials for solid oxide fuel cell anodes has been studied. To assess the crack growth resistance of the ceramics, the Vickers indentation technique was adapted, which allowed estimating the microhardness and fracture toughness of the material in the complex. The requirements for high porosity of the anodes to ensure functional properties show that the strength may be an insufficient characteristic of the bearing capacity of the anode. More structurally sensitive characteristics are needed to assess its crack growth resistance. The average levels of microhardness of YSZ-NiO ceramics in the as-sintered state and YSZ-NiO(Ni) cermets(2.0 GPa and 0.8 GPa, respectively) and their fracture toughness (3.75 MPa•m 1/2 and 2.9 MPa•m 1/2 , respectively) were experimentally determined. It was found that the microstructure of YSZ-NiO(Ni) cermet after redox treatment is formed by a YSZ ceramic skeleton with refined Ni-phase grains combined in a network, which provides increased electrical conductivity. Along with higher porosity of the cermet, its fracture toughness is not lower than that of the one-time reduced cermet due to the implementation of the bridging toughening mechanism of fracture.The proposed treatment method allowed forming the microstructure of the anode material, resistant to crack propagation under mechanical load. The propensity of the anode material to brittle fracture on the basis of evaluation of its crack growth resistance and analysis of the microstructure and fracture micromechanism was substantiated. This result is interesting from a theoretical point of view. From a practical point of view, the developed technique allows determining the conditions of redox treatment in the technology of manufacturing fuel cell anodes