scholarly journals КОЭФФИЦИЕНТЫ ДЕГРАДАЦИИ ПРОЧНОСТИ СИЛОВЫХ ЭЛЕМЕНТОВ КУПОЛА ПАРАШЮТА ПОСЛЕ ДЛИТЕЛЬНОЙ ЭКСПЛУАТАЦИИ ИЛИ ХРАНЕНИЯ

2019 ◽  
pp. 62-71
Author(s):  
Петр Александрович Фомичев ◽  
Игорь Михайлович Сила
Keyword(s):  
Service Life ◽  
Breaking Load ◽  
Strength Characteristics ◽  
Test Results ◽  
Structural Elements ◽  
Term Operation ◽  
Lower Confidence ◽  
Strength Tests ◽  
Normal Law

The technique of processing the test results to the destruction of samples cut from slings and dome fabric after prolonged use or storage of the parachute is described. The normal law of load distribution before failure is adopted.It is proposed to find the minimum breaking load as the lower confidence limit depending on the number of tested samples and a confidence probability of 0.99.The results of strength tests of samples from the parachutes of the landing D-5 series 2 of 1983, the spare Z-5 of 1984, and the rescue S-5K series 2 of 1989 are presented.A total of 301 samples were tested, including 54 samples from slings D-5, 48 samples from slings Z-5 and S-5K, samples from fabrics of domes on the base and weft. Samples from slings were cut out at the edge of the dome, in the middle, at the arc buckles.Fabric samples were cut radially from the top to the edge of the dome. The dependence of the strength characteristics on the location of the samples along the length of the slings or the dome panel has not been established.There are no gross errors in the tests according to the Grubbs criterion.The strength degradation coefficients of the slings and fabrics of the domes are determined as the ratio of the breaking load after long-term operation or storage to the initial values adopted during the design.The proximity of the degradation coefficients of slings and dome fabrics was noted. Based on the set of test results in order to obtain the minimum values of the degradation coefficients, a linear dependence on the life of the parachute is established.This period should be counted from the year the parachute was made.The dependence of the minimum degradation coefficients (maximum degradation) on the service life makes it possible to assess the drop in the strength characteristics of the structural elements with increasing service life. This dependence allows you to predict the maximum allowable landing speed when deciding on the extension of the life of the parachute.

scholarly journals УСТАНОВЛЕНИЕ ОГРАНИЧЕНИЙ ПО МАКСИМАЛЬНЫМ СКОРОСТЯМ ДЕСАНТИРОВАНИЯ С УЧЕТОМ ДЕГРАДАЦИИ ПРОЧНОСТНЫХ ХАРАКТЕРИСТИК МАТЕРИАЛОВ КУПОЛА ПАРАШЮТА. СООБЩЕНИЕ 2. ЗАВИСИМОСТЬ МАКСИМАЛЬНЫХ СКОРОСТЕЙ ДЕСАНТИРОВАНИЯ ОТ ДЕГРАДАЦИИ ПРОЧНОСТИ

2019 ◽  
pp. 61-68
Author(s):  
Петр Александрович Фомичев
Keyword(s):  
Initial Conditions ◽  
Maximum Load ◽  
Strength Characteristics ◽  
Fall Rate ◽  
Motion Equations ◽  
Term Operation ◽  
Strength Tests ◽  
Parachute System ◽  
The Moment

Part 2 is a continuation of Part 1 [1], which proposed the dependence of the maximum permissible loads on the parachute on the degradation coefficients of the power structure elements strength characteristics. The condition of equality of safety factors for elements after the long-term operation and during design was adopted. The results of calculating the speeds and loads on the parachute were compared with published experimental data. In particular, for the rescue parachute, calculations were made of the fall rate at the moment of the beginning of filling the dome and the maximum load, depending on the aircraft speed. The fall rate is calculated numerically using the motion equations of the dummy-parachute system with given initial conditions. This speed almost coincides with that measured experimentally. Quite satisfactory coordination takes place and for the maximum load. In accordance with the methodology, N. A. Lobanov maximum load depends on the speed at the time of the parachute full opening. This speed is largely determined by the value of the empirical generalized coefficient K. The numerical value of K should be found for a particular parachute from the condition of matching the calculated and experimentally measured loads. The analysis of maximum landing speeds flight limitations from the degradation coefficients of the structural materials strength characteristics was carried out for two cases. The first corresponds to the constancy of the time of separation from the aircraft until the introduction of the parachute dome into operation. The second corresponds to the accounting for the dependence of this time on the aircraft speed. Calculations of the dependence of the maximum allowable aircraft speed on the degradation coefficients were performed in the widest possible range of the generalized coefficients K variation for the dome and lines fabric. The spare Z-5 and landing D-5 series 2 parachutes are considered. The dependences of the maximum permissible landing speeds on the strength degradation coefficients of the framework elements of these parachutes have been established. The actual value of these coefficients must be established by means of destructive strength tests

scholarly journals TESTS OF LOADING STRUCTURES OF A SPECIAL ROLLING STOCK AFTER LONG OPERATION

2021 ◽  
Vol 1 (37) ◽  
pp. 5-11
Author(s):  
O. Fomin ◽  
Keyword(s):  
Service Life ◽  
Traffic Safety ◽  
Rolling Stock ◽  
Technical Diagnostics ◽  
Technical Solution ◽  
Essential Requirement ◽  
Term Operation ◽  
Strength Tests ◽  
Long Operation

Traffic safety is an essential requirement for railways. In order to ensure uninterrupted transportation of passengers and goods by rail by the enterprise of JSC "Ukrainian Railways", the task of ensuring the operation of rolling stock outside the assigned line of service remains urgent. Proceeding from this, it follows that it is necessary to carry out tests aimed at creating conditions for the operation of rolling stock while maintaining dynamic and strength characteristics. This article presents the order, scope and results of strength tests of rolling stock after long-term operation on the example of an AS1a-type railroad car. The results of the maximum stress levels, standard deviation, fatigue safety factors, the dependence of the stress level on the speed of movement are obtained. Based on the research results, a technical solution has been developed that allows using technical diagnostics methods to extend the service life of the AS1a type railroad cars after the end of the assigned service life.

Fatigue Strength and Metal Condition in the Context of Gas Turbine Buckets Life Extension

2012 ◽  
Author(s):  
Sergey A. Ivanov ◽  
Alexander I. Rybnikov
Keyword(s):  
Fatigue Strength ◽  
Service Life ◽  
Gas Turbine ◽  
Fatigue Resistance ◽  
Gas Turbines ◽  
Life Extension ◽  
Term Operation ◽  
Life Estimation ◽  
Metal Properties

Criteria for remaining life estimation and methods for enhancing fatigue resistance of heavy-duty gas turbine bucket metal are based on the analysis of changes in the structure and properties of metal after long-term operation. High-cycle fatigue (HCF) resistance is shown to be a decisive characteristic in the residual life estimation of turbine buckets after operation over 100,000 hours. The tests of the buckets from cast and wrought nickel-based alloys after long-term operation demonstrated decreasing of fatigue strength by up to 25%. The metal structure in operation undergoes notable deterioration mainly in phase redistribution. The size and configuration of metal phases are changing also. It caused the changes in metal properties. The decrease of the bucket fatigue strength correlates with the decrease of metal ductility. The reconditioning heat treatment resulted in restoring mechanical properties of metal. The fatigue resistance also increased nearly to the initial level. The influence of operational factors on bucket fatigue strength deterioration has been established. The mechanical damages on bucket airfoil may decrease the fatigue resistance. We found the correlation of endurance limit and damages depth. The procedures for metal properties recovering and buckets service life substantial extension have been developed. It has resulted in the extension of the buckets service life by up to 50% over the assigned life in gas turbines operated by Gazprom.

scholarly journals DEGRADATION DAMAGE OF REINFORCED CONCRETE FRAME IN LONG-TERM EXPLOITATION

2021 ◽  
Vol 9 (4) ◽  
pp. 11-15
Author(s):  
Mikhail Berlinov ◽  
Marina Belinova ◽  
Roman Korol ◽  
Aleksandr Tvorogov
Keyword(s):  
Reinforced Concrete ◽  
Service Life ◽  
Phenomenological Theory ◽  
Reinforced Concrete Frame ◽  
Term Operation ◽  
Concrete Frame ◽  
Aggressive Environment ◽  
Real Work ◽  
Combined Action

A method for calculating a reinforced concrete frame under rheological deformation conditions is proposed, taking into account degradation damage as a result of corrosion during long-term operation, reflecting their real work under the combined action of a load and an aggressive environment based on the modern phenomenological theory of deformation of an elastic-creeping body. The possibility of considering the processes of long-term deformation of reinforced concrete in conditions of long-term exploitation is shown. Analytical dependencies and a calculated example are given for the considered service life.

scholarly journals Method to Evaluate the Resistance–Capacitance Voltage Divider and Uncertainty Analysis

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7744
Author(s):  
Yi Luo ◽  
Bin Guo ◽  
Bin Qian ◽  
Lijuan Xu ◽  
Fan Zhang ◽  
...  
Keyword(s):  
Uncertainty Analysis ◽  
Measurement Errors ◽  
Measurement Accuracy ◽  
Dielectric Breakdown ◽  
Voltage Divider ◽  
Test Results ◽  
Term Operation ◽  
Economic Significance ◽  
Capacitance Voltage

The resistance and capacitance parameters of a resistance–capacitance divider may change due to factors such as long-term operation, internal insulation flashover, and dielectric breakdown, which will affect the measurement characteristics of the resistance–capacitance divider. Since it is difficult to separate the voltage divider, and because improper disassembly will damage the insulation of the equipment, measuring the resistance and capacitance parameters of a voltage divider non-destructively has always been a problem. In this paper, an indirect method for evaluating the resistance and capacitance parameters is proposed, and the uncertainty of measurement of this method is determined. Simulation and actual test results show that this method can be used to estimate the resistance–capacitance parameters and has a good level of measurement accuracy. Besides, through the uncertainty analysis, it is concluded that the proposed method can overcome measurement errors within a certain range and has high practicability. Finally, a very practical application scenario of the proposed method is given, showing that the proposed method has good economic significance.

Research into the lubrication of a rotary lip seal using ferrofluid

2021 ◽  
pp. 135065012110537
Author(s):  
Marcin Szczęch
Keyword(s):  
Magnetic Fluid ◽  
Operating Pressure ◽  
Test Results ◽  
Friction Zone ◽  
Lip Seal ◽  
Term Operation ◽  
Lip Seals ◽  
The Magnetic Field ◽  
Lubrication Conditions

The paper presents the results of research into a hybrid seal which is a combination of standard rotary lip seals and a magnetic fluid seal. To maintain the magnetic fluid in the friction zone region, either a specially shaped pole piece was used or the shaft was modified accordingly. The research study concerns the allowable operating pressure and lubrication conditions in short-term and durability tests after which shaft wear was also assessed. Magnetic fluids with different rheological and magnetic properties were considered. The test results showed that the long-term operation of a hybrid seal is possible. The requirements, however, are the appropriate value of the magnetic field and dynamic viscosity of the magnetic fluid.

scholarly journals Assessment of the reinforcing ability of a composite bandage for modern pipeline repair systems

2021 ◽  
Author(s):  
Eugen Savchuk ◽  
Viktor Rubashevskyi ◽  
Sergiy Shukayev
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Comparative Analysis ◽  
Service Life ◽  
Close Agreement ◽  
The Finite Element Method ◽  
Strain Ageing ◽  
Term Operation ◽  
Reinforced Steel

Abstract. The long-term operation of pipelines, which, in many cases, exceeds their regulatory service life, causes the strain ageing of metal, as well as the appearance of local mechano-corrosive damages. In this regard, the use of composites to reinforce worn pipelines constitutes one of today’s most promising technologies. In this study, a comparative analysis was performed between the composite-reinforced steel pipe calculations that were conducted using the finite element method (FEM), and those that were conducted in accordance with the DSTU ISO 24817:2019 standard. The FEM numerical calculations were carried out using the complete factorial experiment design (consisting of three factors at three levels, with twenty-seven calculations in total). Based on the results of these calculations, a regression model was developed to assess the circular deformation of the pipe’s outer surface depending on the thickness of the bandage, the thickness of the pipe, and the internal pressure. The FEM calculations were found to be in close agreement with analytical results.

scholarly journals Prevention of uncontrolled progressive collapse of a high-rise brick building

2018 ◽  
Vol 143 ◽  
pp. 01006
Author(s):  
Oleg Pakhmurin
Keyword(s):  
Climatic Factors ◽  
Progressive Collapse ◽  
Operational Reliability ◽  
Structural Elements ◽  
Load Bearing ◽  
Term Operation ◽  
High Rise ◽  
Failure Diagram ◽  
Stone Walls

In recent years, there is a trend towards increasing the failure rate of buildings and structures as a result of unforeseen situations. This study is aimed at assessing the operational reliability of the structure to prevent emergencies and progressive collapse. The behavior of structures affected by various factors was analyzed. The operational condition of a building with stone walls and a rigid structural frame constructed in the middle of the 20th century was considered. By means of a detailed instrumental examination, effects of long-term operation, climatic factors and violations during construction on the serviceability of the building were analyzed. Geotechnical conditions of the site were investigated. Necessary re-calculations for load-bearing structural elements and foundations were carried out. An expected failure diagram for vertical load-bearing structures of the building is presented. Proposals for preventing progressive collapse were developed on the basis of the author's technique.

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