Results of studies of the oscillations of pipelines conveying a two-phase slug flow are presented in the paper. A viscoelastic model of the theory of beams and the Winkler base model are used in the study of pipeline oscillations with a gas-containing slug flowing inside. The Boltzmann-Volterra hereditary theory of the viscoelasticity is used to describe the viscoelastic properties of the pipeline material and earth bases. The effect of gas and liquid phases flow rates, influence of tensile forces in the longitudinal direction of the pipeline, parameters of Winkler bases, parameters of singularity in the heredity kernels and geometric parameters of the pipeline on the oscillations of structures with viscoelastic properties are numerically studied. It is revealed that an increase in the length of the gas bubble zone leads to a decrease in the amplitude and oscillation frequency of the pipeline. The critical rates for a two-phase slug flow are determined. It is revealed that an increase in the soil density of the bases leads to an increase in the critical rate of gas flow. It is shown that an account of viscoelastic properties of structure material and earth bases leads to a decrease in the critical flow rate.

The effect of investigation results on viscoelastic properties of the material and bases on vibration fatigue of a pipeline conveying pulsating fluid flow is given in the paper. A mathematical model of viscoelastic pipeline vibrations based on the theory of beams was developed when a pulsating fluid flows through it. A computational algorithm has been developed to solve vibration problems of composite pipelines conveying pulsating fluid. Stability and amplitude-time characteristics of vibrations of composite pipelines conveying pulsating fluid were studied at wide range of parameters variation of deformable systems and fluid flow.

The article considers the problem of vibrations of straight sections of the pipeline based on the theory of beams. A mathematical model of the dynamics of a straight viscoelastic pipe with a pulsating fluid is developed. The speed of a pulsating fluid is assumed to be harmonically fluctuating and has the following form: V(t) = υ0 (1 + μ1cosϖt). The mathematical model of the problem is simplified using the Bubnov-Galerkin approach to the solution of a set of common integro-differential equations with time as an independent variable. A numerical approach based on the removal of the singularity in the relaxation kernel of the integral operator is used to solve integro-differential equations. A numerical approach for the unknowns was used to get the system of algebraic equations. The Gauss technique is used to resolve a set of algebraic equations. The dynamics of fluid-transporting viscoelastic pipes have difficulties that can be solved computationally.

Research on the problems of creating effective control and diagnostic systems allows us to single out the following areas: development of the theory and methods for diagnosing and predicting the strength and reliability of structures, theoretical and experimental studies of fracture processes and the corresponding changes in characteristics and parameters, i.e. carriers of information about the processes occurring in the material during destruction; creation of information-measuring systems designed to register and analyze the information necessary to resolve the issue of the state of the structure; development of software for measuring equipment, including not only the main programs for generating and processing incoming information, but auxiliary subroutines that provide information compression, increase the reliability of measurement results, defect recognition, decision making. The article is devoted to the methods of acoustic-emission control of metal structures and the development of a computerized system for its implementation. The basics of organizing a software-algorithmic system for locating and processing acoustic emission signals are considered, including: methods for discretizing models of sensors and acoustic emission signals, which make it possible to obtain computational schemes such as a digital filter that provide effective algorithmic implementation; description of fragments of an experimental software-algorithmic system for processing acoustic emission signals, illustrating the principle of constructing software tools in an arbitrarily chosen computing area, the structure of the software organization of computational processes for locating an acoustic emission signal, which ensure the construction of the corresponding subsystem of a computer complex for acoustic-emission control, both in single-antenna and in a multi-antenna version.