Kontaktwechselwirkung einer Rohrleitung mit der Reparaturbandage aus einem Kompositwerkstoff

In der vorliegenden Arbeit wird die Kontaktaufgabe über die Wechselwirkung einer langen Zylinderschale mit einer koaxialen zylindrischen Bandage aus einem Verbundwerkstoff untersucht. Der Verbundwerkstoff wird als ein homogenes orthotropes Material mit bekannten effektiven elastischen Eigenschaften modelliert. Basierend auf der klassischen Schalentheorie werden die Grundgleichungen für die Kontaktaufgabe sowie allgemeine Lösungen für die Durchbiegungen und Schnittgrößen formuliert. Die unbekannten Integrationskonstanten sowie die Kontaktfläche werden numerisch mit Hilfe des Programmpakets Maple ermittelt. Drei charakteristische Längen der Bandage, bei denen der Übergang von einemKontaktschema der Wechselwirkung zu einem anderen erfolgt, wurden ermittelt. Es wurde festgestellt, dass die Änderung des Innendrucks nicht zum Übergang von einem Kontaktschema zu einem anderen führt. Der Charakter der Kontaktwechselwirkung wird durch geometrische Parameter derVerbindung und elastische Materialeigenschaften der Schale und der Bandage bestimmt.In the present work the contact interaction of a long cylindrical shell with a coaxial cylindrical wrap made of a composite material is investigated. The composite material is modeled as a homogeneous orthotropic medium with known effective elastic properties. Based on the classical shell theory governing equations for the contact problems and general solutions to the deflections and internal forces are formulated. The unknown integration constants and the contact surface area are determined numerically using the software package Maple. Three characteristic lengths of the wrap, for which the transition from one contact mode to another takes place, have been determined. It was found that the change in the internal pressure does not affect the transition between the contact modes. The nature of the contact interaction is determined by the geometric parameters of the contact pair and elastic material properties of the shell and the repair wra

Влияние технологического натяжения на эффективность упрочнения трубопроводов композитными бандажами

A mathematical model for the contact interaction of a cylindrical pipe with a composite band during its repair is constructed. A system of governing equations of the contact problem is formulated by using the Timoshenko theory of shells. An analysis of possible solutions is carried out for various combinations of geometric and elastic properties of shells. The possibility of pretension of a prepreg in order to improve the efficiency of repair is considered. The numerical results obtained allow one to establish the desired level of pretension for various repair situations

Effect of Technological Tensioning on the Efficiency of Reinforcement of Pipelines with Composite Bands

A mathematical model for the contact interaction of a cylindrical pipe with a composite band during its repair is constructed. A system of governing equations of the contact problem is formulated by using the Timoshenko theory of shells. An analysis of possible solutions is carried out for various combinations of geometric and elastic properties of shells. The possibility of pretension of a prepreg in order to improve the efficiency of repair is considered. The numerical results obtained allow one to establish the desired level of pretension for various repair situations

Расчетно-экспериментальные исследования механических характеристик композитных матереалов

Research and use of composite materials for scientific experiments, engineering activities, as well as industrial purposes has expanded significantly, since the development of technologies for the production of composite materials has made it possible to create and research new types of their physical and chemical properties, reinforcement schemes and fiber lengths, etc. This paper presents the results of computational and experimental studies of the elastic and damping properties of a composite material. The studies were carried out on samples of laminated fiberglass, the dimensions of which are 160 × 16 × 4 mm, cut in three directions, in the direction of the warp, weft and at an angle of 45 degrees, five samples were cut in each direction. To study the mechanical properties of the obtained cantilever samples, the electrodynamic shaker was used. The study of damping properties was carried out by the Oberst method based on the experiment of the frequency response characteristics of cantilever samples. The determination of Young's moduli of laminated fiberglass samples was carried out by the dynamic method, and also the theory of vibrations of continuous systems was used. The experimental data obtained are compared with the results of numerical solutions performed by the finite element method (FEM). Geometric and finite element models were constructed and the natural frequencies and vibration modes of the samples were determined. Frequency and phase response characteristics are given. To reduce the error according to the results of the experiment, statistical processing was carried out. The values of the mathematical expectation and the standard deviation of the mechanical loss coefficient are calculated. The estimation of the measurement error was made on the assumption of the normal distribution of the error.В работе представлены результаты расчетно-экспериментальных исследований упругих и демпфирующих свойств композитного материала. Исследования проводились над образцами стеклопластика СТФ, вырезанных в трех направлениях. Исследование демпфирующих свойств выполнено методом Оберста на основе экспериментальных амплитудно-частотных характеристик консольных образцов. Определение модулей Юнга образцов стеклопластика выполнено динамическим методом. Проведено сравнение полученных экспериментальных данных с результатами численных решений, выполненных методом конечных элементов. Построены геометрические и конечно-элементные модели и определены собственные частоты и формы колебаний образцов. Приводятся амплитудно-частотные и фазо-частотные характеристики

Substantiating promising technical solutions for turbo- expander power plants based on the research into working processes and states

One of the most rational methods of energy utilization of compressed gas in pipelines is to use turbo-expander installations. In particular, these are autonomous turbo-expander power stations. A fundamentally new concept has been devised to improve the technical and economic performance of this type of machines. This concept is not focused on a separate aspect of the plant's operation but on their entire set. In particular, physical principles, structures, and technologies were considered as an object of research. First, effective parameters of gas-dynamic flows and heat-mass transfer were determined based on the modeling of work processes. Secondly, progressive designs of turbo-expander units have been created. Thirdly, technologies for the production of parts and assemblies of turbo-expander units have been developed, which combine, unlike the traditional ones, different types of strengthening for contacting parts in their pair. A method of parametric modeling was used to substantiate the technical solutions of the elements of turbo-expander power plants. This makes it possible to determine the technical characteristics of these installations under a certain set of parameters. By purposeful variation, a recommended set of their parameters was determined, which ensure the improvement of the most important technical characteristics. A specialized database was built, which contains an array of information about the regularities of the influence of variation of significant parameters on various characteristics of turbo-expander power plants. Already on this basis, the problems of synthesis of successful technical solutions of turbo-expander power plants are solved. As a result, their high energy efficiency is ensured. Thus, the efficiency of the expander was achieved at the level of 86 % while the resource increased by 20–25 %. All these solutions were implemented in a number of unique turbo-expander units. Their effectiveness has been demonstrated during operatio