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Актуальные проблемы авиации и космонавтики - 2015. Том 2
UDK 621
PERSPRCTIVE DIRECTIONS FOR DEVELOPMENT OF NONDESTRUCTIVE CONTROL OF PNEUMATICHYDRAULIC SYSTEM LEAK RESISTANCE
S. V. Titenkov1, A. T. Lelekov2, V. U. Zhuravlev2
Scientific supervisor - V. U. Zhuravlev Foreign language supervisor - M. V. Savelyeva
1JSC «Krasnoyarsk Machine Building Plant» 29, Krasnoyarsky Rabochy Av., Krasnoyarsk, 660037, Russian Federation
2Reshetnev Siberian State Aerospace University 31, Krasnoyarsky Rabochy Av., Krasnoyarsk, 660037, Russian Federation
The applied methods to control leak resistance of products do not meet the new requirements for the developed products. It is possible to improve technologies introduced into the production to control the leak resistance using acoustic emission method.
Keywords: acoustic emission, pneumohydraulic system, leak resistance.
ПЕРСПЕКТИВНЫЕ НАПРАВЛЕНИЯ РАЗВИТИЯ НЕРАЗРУШАЮЩЕГО КОНТРОЛЯ ГЕРМЕТИЧНОСТИ ПНЕВМОГИДРАВЛИЧЕСКИХ СИСТЕМ
С. В. Титенков1, А. Т. Лелеков2, Научный руководитель - В. Ю. Журавлев Руководитель по иностранному языку - М. В. Савельева
1АО «Красноярский машиностроительный завод»
Российская Федерация, 660037, г. Красноярск, просп. им. газ. «Красноярский рабочий», 29
2 Сибирский государственный аэрокосмический университет имени академика М. Ф. Решетнева
Российская Федерация, 660037, г. Красноярск, просп. им. газ. «Красноярский рабочий», 31
Одним из факторов, гарантирующих качество и безотказность работы пневмогидравличе-ских систем (ПГС), является выбор метода неразрушающего контроля герметичности (НКГ) после производственного процесса.
Ключевые слова: акустическая эмиссия, пневмогидравлическая система, герметчность.
The guaranteeing quality and non-failure operation of pneumatichydraulic systems is a choice of a method of nondestructive control of leak resistance after the production process.
Simple and sophisticated pipelines consisting of pipes, storage tanks, pumps, automatic equipment units such as electro - pneumo - pyrovalves, filters, throttles, pneumo - hydraulic actuators, safety and locking valves and others belong to pneumatichydraulic systems. The pneumatichydraulic system is an integral part of various power drives, pressurization systems of tanks, fuel and oil systems of propulsion jets, systems of autonomous ensuring activity (conditioning), systems of stabilization and correction of trajectories of aircraft.
The pneumatichydraulic system before nondestructive control of leak resistance has to pass cleaning, degreasing and preparation of a surface for highly sensitive tests on the resistance.
Now the most widely used methods of nondestructive control of leak resistance are:
- "aquarium" test is control of products with volume to 200 liters filled with air and nitrogen, indication of leak is by bubbles in liquid, the maximum sensitivity is 1*10-1 liter * micrometer of mercury column / sec.
- the soap solution bubble test is covering the controlled demountable and one-piece connections filled with air and nitrogen with soap emulsion of, indication of leak is by bubbles of foam, the maximum sensitivity is 5*10-1 liter * of mercury column / sec.
Секция «Актуальные на учные проблемы в мире (глазами молодых исследователей)»
- pressure loss test is control of product volume to 0,5 litres filled with air, existence of leakage is determined by change of the measured pressure size in a product at the beginning and the end of a certain period, the maximum sensitivity is 10 liter * micrometer of mercury column / sec.
- increasing pressure in a pressure chamber test - leakage is found by a difference between the general pressure of leakage in a pressure chamber on a product without pressure and the general pressure of leakage in a pressure chamber on a product under test pressure, maximum sensitivity is 1*10-2 liter * micrometer of mercury column / sec.
- test probe is performed due to existence of leakage defined by the leak indicator detecting control gas over a surface of possible leaks of products, the maximum sensitivity is 1*10-4 liter * micrometer of mercury column / sec.
- pumping test is subdivided into some techniques; they are to generate vacuum in a cavity of the object, then control gas is given and due to pressure difference if the leak exists, the gas penetrates into the object into the pumped-out cavity; the leakage degree is fixed by a test probe, the maximum sensitivity varies from 1*10 5 to 1*10-9 liter * micrometer of mercury column / sec.
- accumulation under the atmospheric pressure test - there is closed volume of the control gas accumulation around the tested object, if there is leakage the gas penetrates into the object increasing helium concentration in it. Further, a test probe registers helium around the object, indications of a test probe obtained by control concentration are compared, the maximum sensitivity 5*10-5 liter * micrometer of mercury column / sec.
For new products these methods do not meet higher requirement of sensitivity parameter. The task to improve quality and reliability of space equipment with simultaneous increase in term of their storage and operation is for the branch. The enterprises of the aerospace field consider possibilities to use the essentially new modern techniques of nondestructive control of leakage resistance while creating stands of the automated control of both individual knots and assembly units, taking into account technical requirements of industry standards and standards of safety. It is necessary to provide increase in opportunities of types and functions of control. It is also necessary to modernise the normative documents developed 25-30 years ago and include not only domestic, but world experience as well of achievements and openings in this area.
For today the most perspective equipment by means of which it is possible to improve the existing stands of nondestructive control of leak resistance or to develop new stands is: microprocessor defecto-scopes, acoustic ultrasonic tomographs, x-ray tomographs and installations of X-ray television, reusable phosphoric plates with use of digital radiography, shearograph test, highly sensitive portable test probes with sensitivity of 1*10-9 liter * micrometer of mercury column / sec.
The planned tasks to control leak resistance of new products supposes use of several methods by oil and gas companies by means of a plasma test probe, mass spectrometer method, helium test probe, high-vacuum system with a working range of nondestructive control of leak resistance to 1*10-6 liter * micrometer of mercury column / sec.
It is proposed acoustic emission method to add to the available control methods and tests and to improve the number of methods and techniques introduced into the production that will allow to add functions to control not only leak resistance, but durability and reliability as well.
Acoustic emission represents the phenomenon of tension wave generation caused by sudden reorganization in structure of material. Classical sources of acoustic emission are the deformation process connected with growth of defects, for example, a crack or zones of plastic deformation. The sudden movement of an emission source causes emergence of tension waves that extend in the structure of material and reach the converter. In process of tension growth, many of the emission sources available in the material of the object become more active. The electric signals of emission received as a result of transformation by the tension wave sensor amplify, they are registered by the equipment and are exposed to further processing and interpretation.
Acoustic emission differs from the majority of methods of the non-destructive control of leak resistance in two key aspects: material, but not an external source can be a source of a signal, that is the method is passive (not active, as the majority of other control methods); unlike other methods acoustic emission finds the defect movement, but not static heterogeneity, connected with existence of defects, that means acoustic emission finds developing, and, therefore, the most dangerous defects.
Reference
1. Danilin G. A., Remshev E. Yu., Metlyakov D. V., Black L.G., Titov A. V. Model of forecasting of relaxation firmness of dish-shaped springs on level of signals of acoustic issue // Reshetnevsky readings: materials XVII Mezhdunar. Nauch. Conf.: in 2 vol./under the general edition of Yu. Yu. Loginov; Sib state aerospace un-ty. Krasnoyarsk, 2013. P. 1. 522 p.
© Titenkov S. V., Lelekov A. T., Zhuravlev V. U., 2015
