Studying the interaction of a reservoir with an ideal compressible fluid with an elastic half-space

We solve in a flat formulation the problem of harmonic oscillations for a basin with an ideal compressible fluid on an elastic half-space exposed to a localized surface vibration load. The problem reduces to an integral equation (IE) of the first kind for the amplitude of the contact hydrodynamic pressure with a kernel that depends on the difference and the sum of arguments. The IE was solved by the factorization method. A semi-analytical method is presented for determining the main parameters of the contact interaction in hydroelastic systems «liquid-soil» taking into account the effect of natural and man-made vibration loads on them. This makes it possible to identify the conditions for the occurrence of dynamic modes that are dangerous for the construction integrity and to estimate their frequencies range depending on defining characteristics of the system.

Optimization of the stereo system calibration parameters for photogrammetric measurements in the conditions of field experiments

Optical methods for deformation diagnostics and surface shape measurement are often used in scientific research and industry. Most of these methods are based on the triangulation of a set of two-dimensional points from different images corresponding to the three-dimensional points of an object in space. Triangulation is based on the stereo system calibration parameters, which are determined before the experiment. Measurements during conditions with increased vibration loads can lead to a change in the relative position of the cameras of the stereo system (decalibration). This leads to a change in the actual calibration parameters and an increase in the measurement error. This work aims to solve the problem of increasing the measurement accuracy of the photogrammetric method in the case of high vibration loads. For this, it is proposed to use an optimization algorithm for calibration parameters to minimize the reprojection error of three-dimensional points calculated using triangulation. The paper presents the results of a computer simulation of decalibration of a video camera stereo system, an algorithm for optimizing the external parameters of a stereo system, and an assessment of its performance.

Effect of Piping System Vibration (FIV, AIV, PIV) on Pipe Support Loads

Integrity of a piping system is a prerequisite for personnel safety and operational reliability in industries where pipelines are critical means of transferring products from one process point to the other, such as power plants, refinery plants, and chemical industries. An essential aspect of designing a reliable piping system is to design supports of suitable load carrying capacity. This also depends on accurate determination of expected support loads including loads due to vibration of the system. Piping design codes such as ASME B31.3 and B31.1 provide a general framework but do not address vibration and its impact from a detailed perspective. In many situations, the potential impact of vibration is overlooked during support load determination. In recent piping system construction, the effect of vibration has increased due to increase in fluid flow rates and use of high strength thin wall materials. Common factors that contribute to vibration include: turbulent flow (flow induced vibration, FIV), relief valve operation (acoustic induced vibration, AIV), rotating and reciprocating equipment (pulsation induced vibrations, PIV). The effect of vibration depends on the strength of excitation and the flexibility of the piping system. As vibration of the piping system increases, loads transfer to the pipe supports also increase. Catastrophic failure of a piping system can occur if its natural frequency lock-in with the frequency of the excitation source. For holistic system integrity, the loads induced due to vibrations need to be accounted for in the support design. In this paper, we investigate the contributions of the various vibration loads in a piping system, the effect of neglecting the various vibration loads on the system integrity, and an empirical method to readily determine the vibration loads to reduce cost and time require in support design processes.

Influence of vibration loads on the strength of sheet composite elements of ship structures

Использование листовых композитных элементов при ремонте судовых корпусных конструкций выдвигает как актуальную задачу определения влияния вибрационных нагрузок на прочностные характеристики конструкций с композитными элементами. Имеющиеся методики расчета металлических пластин под действием вибрационных нагрузок не могут быть применены для композитных элементов без дополнительных исследований. Разработаны установка и методика проведения экспериментальных исследований. Нагружения проводились циклами различной продолжительности. Представлены полученные зависимости предела прочности материала от числа циклов нагружения, При этом учитывалась ориентация исследуемых слоев относительно приложенной нагрузки. В процессе исследований установлено, что полимерные покрытия способны поглощать часть вибрационной нагрузки и изменять частоты собственных колебаний конструкции. Разработанная экспериментальная установка и методика испытаний позволяют опытным путем определить напряженно-деформированное состояние конструкции с композитными элементами. The use of sheet composite elements in the repair of ship hull structures puts forward as an urgent task to determine the influence of vibration loads on the strength characteristics of structures with composite elements. The available methods for calculating metal plates under the influence of vibration loads cannot be applied to composite elements without additional research. The setup and methodology for conducting experimental studies have been developed. The loads were carried out in cycles of different duration. The obtained dependences of the ultimate strength of the material on the number of loading cycles are presented, taking into account the orientation of the studied layers relative to the applied load. In the course of research, it was found that polymer coatings are able to absorb part of the vibration load and change the natural vibration frequencies of the structure. The developed experimental setup and test procedure allow us to determine the stress-strain state of the structure with composite elements by experimental means.

EXPERIMENTAL STUDY OF THE PERFORMANCE OF "DRY" SEALS IN THE PRESENCE OF ROTOR VIBRATION

The article presents the results of an experimental study of "dry" seals in the presence of rotary vibration. The descrip-tion of the dynamic stand measurement system is given. An assessment of the influence of vibration loads on leakage through the seal and an analysis of the influence of radial displacement and shaft misalignment on the operation of a "dry" seal are carried out. The analysis of the cause of the vibration defect is presented. The permissible values of the vibration amplitudes of the rotor of the gas pumping unit have been determined.

THEORETICAL STUDY OF THE PERFORMANCE OF "DRY" SEALS IN THE PRES-ENCE OF ROTOR VIBRATION

The article presents the results of monitoring the rotor vibration occurring in gas-pumping units. An assessment of the effect of vibration loads on seal leakage has been carried out. The maximum amplitudes and frequencies of vibration of rotors of gas-pumping units under operating conditions have been determined. A dynamic model of a "dry" seal is proposed, in which axial, angular and bending vibrations of the seal rings are realized. The theoretical definition of the rotor vibration parameters admissible for the operation of "dry" compaction is carried out.

OSCILLATIONS OF LAYED STRUCTURES WITH CONSOLIDATED MECHANICAL CHARACTERISTICS

Modern industry requires the creation and use of materials and structures with improved performance. Such structures include layered structures made of com-posite materials. Layered systems made of high-strength composite materials with different layers have found wide application in aviation technology as elements of the bearing surfaces of aircraft, as well as in many other industries. The use of composite plates in loaded structures is one way to improve the weight characteristics of rocket and space technology. Also layered structural elements are widely used in transport engineering, used in construction practice. Multilayer systems in the conditions of bending deformation are the most rational in terms of strength and rigidity. Thus, the improvement of methods for calculating inhomogeneous layered structures is an urgent task. Along with the methods of non-destructive testing, defectoscopy of structures using hardware methods, analytical research methods remain relevant, which allow to predict the possible destruction of the structure. When designing equipment, it is necessary to take into account the real operating conditions of structures. In the process, the mechanisms work under the action of vibration loads, so determining the dynamic characteristics of structures is an urgent task. This determines the need to study the oscillating processes taking into account the real conditions of vibration load, which will determine the optimal design parameters and modes of operation of the machine with the maximum distance from critical modes that are dangerous. One of the reasons for the destruction of elements of machine-building structures is that they resonate. Therefore, the problem of forced oscillations needs to be solved. To solve this problem, it is necessary to determine the natural frequencies and their corresponding natural forms of oscillations. The paper presents a method of calculating a layered structure to determine the physical characteristics for the whole package, taking into account the physical and mechanical characteristics of each of the layers. This approach allows to determine the dynamic characteristics and stress-strain state of multilayer composite structures, using classical equations for homogeneous struc-tures. This approach greatly simplifies the equation and allows you to find a solution that can be used in the design of structures made of composite materials under vibration loads.