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When testing complex objects, it is recommended to use standardized criteria to determine the moment of the end of the transient process (TP) in the measuring circuit (MC). The criteria of the interval type (CIV) analyze the current increment of the TP signal in the MC. The paper considers only TP with first-order dynamics. It is known that the CIV has a significant restriction on its application: when the parameter of the TP model exceeds the critical constant of the criterion (CPC), we get a significant excess of the dynamic error (DE) achieved at the observation interval (OI) over the permissible level (PL) and, consequently, a false positive decision of the CIV about the beginning of the static measurement mode.The paper presents an algorithm of the robust interval criterion (RIC) – as a modification of the CIV-for determining the end point of the TP. Robustness is achieved by using a tunable implicit reference model. The controlled parameter of the RIC is the duration of the OI for the TP signal. Based on this duration, the current value of the PDA and the parameter of the reference model are calculated. The difference between the signals about the expected duration of the TP from the reference model and the moment of decision-making is information for setting the parameters of the RIC. Thus, the optimal value of OI is found.The research was carried out by the method of simulation modeling using the Monte Carlo method. The results of the research are the evaluation of the effectiveness of the robust interval criterion in the case of its application over the entire possible interval of a priori parametric uncertainty in comparison with the results of the functioning of standardized CIV. The obtained statistical results confirm the high reliability of the RIC operation and the absence of false-positive solutions in the analysis of transient signals for first-order dynamical systems.

The strain rate-temperature conditions of manifestation of the effect of high-temperature superplasticity by samples of an 1933 alloy have been established. Features of the structural state, phase composition, and deformation relief of samples of this alloy have been investigated. It has been established that grain-boundary sliding occurs intensely along both boundaries of ultrafine grains and boundaries of coarse polygonized grains parallel to the tension axis of the sample. In near-surface grain-boundary pores and in cracks that were formed and developed at the surface of the working part of these samples in the course of superplastic deformation, fiber structures were detected. The chemical composition of fibers has been investigated. The kinetics of the occurrence of phase transformations in the 1933 alloy in the course of heating of its samples to the temperature of tests has been studied, and probable causes for partial melting of the 1933 alloy have been analyzed. Fracture mechanisms for the samples deformed superplastically under the optimum conditions have been established.

For a series of matrix aluminum alloys, an estimation of the thickness of the grain-boundary liquid phase under the optimum conditions of the manifestation of high-temperature superplasticity has been performed. It has been established that the contribution of grain-boundary sliding to the total deformation under these conditions is determining. It has been shown that the greater values of the thickness of the grain-boundary liquid phase correspond to greater values of the parameter m of the strain-rate sensitivity of the flow stress. The obtained dependences of the thickness of the grain-boundary liquid phase on m indicate that with increasing amount of the liquid phase the grain-boundary sliding progressively acquires features of viscous flow.

The morphology of fiber structures has been studied and the kinetics of their formation and growth at high homological temperatures upon superplastic deformation of the AMg6 and 1420 aluminum-based alloys containing viscous liquid-phase inclusions at the intercrystalline boundaries has been proposed. It has been found that, according to their morphology, the fiber formations can be divided into two types, namely, thin smooth cylindrical fibers and fibers whose specific feature is the presence of one or several droplike formations on their surface. The surface of fibers and grain edges to which the fibers are connected is strongly oxidized; the atomic concentration of magnesium in various regions of fibers and grains is different and is higher than that in the specimen as a whole. It was shown that the fibers were formed upon pore and crack opening as a result of viscous flow of solid-liquid material which is present at the intercrystalline boundaries.

Depending on the loading conditions and the method of making the notch, the KDFF does not always pass through the points A and B. Therefore, to obtain invariant KDFF, the diagrams must be mixed equidistantly to intersection at the points with the coordinates A and B. The correct determination of the growth rate of the fatigue cracks is of great importance for constructing KDFF. THe large number of methods available for this purpose can be divided into three groups [4]. The first group includes the method based on using the experimental dependence of the crack length i on the number of load cycles N for approximate construction of a smooth curve which is then graphically differentiated. The disadvantages of the method include the high labor content, the error Qf processing the results, and subjective data processing.