scholarly journals Dynamic Fatigue Tests Of Landing Gears

2020 ◽  
Vol 2020 (12) ◽  
pp. 69-77
Author(s):  
Zbigniew Skorupka
Keyword(s):  
Fatigue Tests ◽  
Landing Gear ◽  
Structural Components ◽  
Fatigue Wear ◽  
Testing Method ◽  
Operation Conditions ◽  
Full Structure ◽  
Drop Tests ◽  
Landing Gears ◽  
Main Components

Abstract Landing gears are one of the main components of an aircraft. The landing gear is used not only during take-off and landing but also, in most cases, during ground manoeuvres. Due to its function, the landing gear is also one of the key safety components of the aircraft due to dissipating landing loads acting on the aircraft. The mentioned loads come from both the vertical and horizontal speeds during touchdown and by the aircraft’s losing the speed by braking. The landing gear is then loaded with constantly changing forces acting in various directions during every landing, with the only difference coming from their magnitude. The repeatable loading conditions cause significant wear of the landing gear. This wear can be divided into two categories, one is the wear of consumable parts such as the brake linings and the other is the fatigue wear of the structural components. The latter type of wear is much more dangerous due to its slow, and in many cases, unnoticeable progression. Fatigue wear can be estimated by numerical analyses – this method works with a great degree of probability on single components but due to the complexity of the landing gear as a whole it is not precise enough to be applied to the full structure. In order to evaluate the fatigue of the whole landing gear the best method accepted by regulations is the laboratory testing method. It involves a series of various drop tests resembling the real landing condition distribution. The aim of the tests is to check the fatigue wear of the landing gear and to prove its reliability for certification and/or operational purposes. In this paper the author describes the basics of the landing gear fatigue wear, possibilities of its evaluation and presents laboratory dynamic method used for extensive tests in life-like operation conditions.

Verification of Methods Used for Fatigue Testing of Small Steel Specimens Taken from Existing Structures

2016 ◽  
Vol 250 ◽  
pp. 232-237
Author(s):  
Tomasz Tomaszewski ◽  
Janusz Sempruch ◽  
Przemysław Strzelecki
Keyword(s):  
Fatigue Testing ◽  
Experimental Tests ◽  
Fatigue Tests ◽  
Steel Plates ◽  
Existing Structures ◽  
Testing Method ◽  
Standard Specimens ◽  
Different Thickness ◽  
Small Steel

This paper presents results of fatigue tests performed on standard specimens and minispecimens taken from two EN 1.4301 acid-resistant steel plates of different thickness. The tests were required for determination of the state of vibrating machines made from the same material. The results confirmed that the proposed testing method can be used for experimental tests.

Nonlinear Grey-box Identification of a Landing Gear based on Drop Test Data

2020 ◽  
Author(s):  
Elias Dias Rossi Lopes ◽  
Helon Vicente Hultmann Ayala
Keyword(s):  
Control Design ◽  
Simulated Data ◽  
Federal Aviation Administration ◽  
Landing Gear ◽  
Drop Test ◽  
Equivalent Stiffness ◽  
Gear Design ◽  
Drop Tests ◽  
Adequate Evaluation ◽  
Stiffness And Damping

In many aircraft applications, especially on an antiskid control design, it is important to understand and consider the gear walk phenomenon, which is characterized by the deflection on the landing gear structure due the high braking force acting at the tire contact with the ground. This phenomenon is observed on drop tests, and its prediction on landing gear design depends on an adequate evaluation of the equivalent stiffness and damping of the structure, which is difficult, since they depend on the mechanism configuration. In this paper, it is presented a grey-box identification methodology for estimating these parameters of the landing gear, based on simulated data of a drop test. As the drop tests are mandatory obligatory for certificating modern aircraft according to e.g. Federal Aviation Regulations (FARs) by the Federal Aviation Administration (FAA), we hope to introduce a method based on measurements that are available at the design phase. The method will be useful to decrease men/hour costs and increase reliability by enabling better and more accurate anti-skid design.

The Crack Growth Evaluation of A335 P22 Steels by Acoustic Emission

2005 ◽  
Vol 297-300 ◽  
pp. 2083-2089
Author(s):  
Gee Wook Song ◽  
Jung Seob Hyun ◽  
Sung Ho Chang ◽  
Bum Shin Kim
Keyword(s):  
Acoustic Emission ◽  
Crack Propagation ◽  
Crack Growth ◽  
Compact Tension ◽  
Fatigue Tests ◽  
Remaining Service Life ◽  
Operation Conditions ◽  
Long Time ◽  
Actual Operation ◽  
Stress Ratios

Acoustic emission (AE) technique was used to investigate fatigue crack growth on compact tension specimens of aging materials at room temperature. Test materials have been sampled steam pipe serviced the actual operation conditions for a long time in fossil power plant. The compact tension test specimens were subjected to load stress ratios of 0.33, 0.5, and 0.66. All the fatigue tests were performed at a frequency of 1Hz. The test results indicate that acoustic emission counts show reasonable correlation with crack propagation rates for applied stress ratios. When the crack growth rates increase, AE’s counts and energies show increment. Also, the higher stress ratios, the faster crack propagation rates. Based on these relationships it may be possible to predict the remaining service life of fatigue-damaged steam pipes.

Transient Modeling of a Lithium Bromide – Water Absorption Chiller

2013 ◽  
Vol 388 ◽  
pp. 83-90 ◽  
Author(s):  
Ang Li ◽  
Wai Soong Loh ◽  
Kim Choon Ng
Keyword(s):  
Water Absorption ◽  
Cooling Tower ◽  
Lithium Bromide ◽  
Cooling Water ◽  
Coefficient Of Performance ◽  
Absorption Chiller ◽  
Transient Model ◽  
Operation Conditions ◽  
Operation Process ◽  
Main Components

This article presents a thermodynamic framework for a lithium bromide – water absorption chiller, in which a transient model is developed to simulate the operation process. Local energy and mass balance within the main components like absorber, regenerator, condenser, evaporator and solution heat exchanger is respected to investigate the behavior of the chiller. Experimental correlations are used to predict heat transfer of the related working fluids. The cooling water is set to typical cooling tower conditions of tropical countries such as Singapore. The coefficient of performance (COP) is evaluated against a range of heat source temperatures from 75oC to 100oC. The results indicate the operation conditions of the chiller at its maximum COP is 95oC to 100oC.

High-Cycle Fatigue Life of AZ31 and AZ61 Magnesium Alloys

2013 ◽  
Vol 211 ◽  
pp. 83-88
Author(s):  
Marek Cieśla
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Magnesium Alloys ◽  
High Cycle Fatigue ◽  
Fatigue Tests ◽  
Test Material ◽  
Cycle Fatigue ◽  
Structural Components ◽  
Asymmetry Coefficient ◽  
Fatigue Fractography

Usefulness of the magnesium alloys for construction of structural components is determined, apart from their low density, by a number of favourable mechanical properties and in the case of their use for components of transport means additionally by good fatigue strength. In this study, 12 mm diameter extruded rods of AZ31 and AZ61 magnesium alloys were used as test material. After extrusion the rods were annealed at a temperature of 400°C, with a 60 min soaking period and subsequent cooling in air. Cylindrical specimens with a diameter of d0 = 8 mm were made for the fatigue test under high-cycle rotary bending conditions with the cycle asymmetry coefficient R = -1. The tests were carried out for a limited fatigue strength range. Examination of microstructure of tested alloys and fatigue fractography were also performed. During the high-cycle fatigue tests it was found that the AZ61 alloy has a longer fatigue life. Based on the obtained results, fatigue life characteristics of the tested materials were drawn up.

scholarly journals PSYCHOLOGICAL STRUCTURE OF THE COMMUNICATIVE COMPETENCE OF THE FUTURE COACH

2020 ◽  
Author(s):  
Olena Lakhtadyr ◽  
Halyna Ivanenko ◽  
Olga Kozhanova ◽  
Volodymyr Korotya ◽  
Lilia Yevdokimova
Keyword(s):  
Theoretical Analysis ◽  
Interpersonal Communication ◽  
Systematic Approach ◽  
Communicative Competence ◽  
Structural Components ◽  
Professional Activities ◽  
Psychological Structure ◽  
The Future ◽  
Psychological Influence ◽  
Main Components

Introduction. Developed communicative competence in the coaching profession allows to interact effectively in future professional activities, interpersonal communication and involves the subject’s mastery of strategies of psychological influence and constructive behaviors in interaction. Aim is to analyze different approaches to determining the structural components of communicative competence and to describe the author’s structure of communicative competence of the future coach. Material and methods. Theoretical - analysis, synthesis, generalization, systematization. Empirical- observations, questionnaires, psychological and pedagogical experiment. Results. Applying a systematic approach to the analysis of the structure of communicative competence, we identified four main components: cognitive (cognitive), communicative-speech, social-perceptual and interactive. Conclusions. The proposed and described author’s structure of communicative competence of the future coach contains four components: cognitive, communicativespeech, social-perceptual, interactive, which give the opportunity to reveal the essence and features of the future coach

scholarly journals ON SUBJECT TO FORECAST CAUSAL FACTORS FOR SPONTANEOUS FIRES IN COAL MINES

2020 ◽  
Author(s):  
Vadym Tarasov ◽  
Keyword(s):  
Organic Matter ◽  
Elemental Composition ◽  
Analytical Data ◽  
Chemical Activity ◽  
Spontaneous Ignition ◽  
Mining Operations ◽  
Carbonization Process ◽  
Coal Beds ◽  
Operation Conditions ◽  
Main Components

Regulations for assessment of workable bed hazardous characteristics during the mining operations include the coal metamorphic grade classification indices borrowed from the industrial classifications without any proper scientific justification. For true forecasting the workable bed hazardous characteristics during the mining operations, the method to detect the metamorphic grades by changing the content of main components and moisture in the organic matter has been developed. Purpose. Development of the forecasting technique logical sequence for workable bed liability to spontaneous ignition in different stages of coal metamorphic conversion and their chemical activity during the mining operations. Methods. They are based on assumption of spontaneous fires with three blocks of factors independent of each other. The factors of block one describe the chemical activity of coals. They are defined by their elemental composition and properties at the different stages of bed metamorphic conversion. The second group of impacting factors characterizes the mining and geological conditions of bedding. It includes the coal beds position relative to each other, their occurrence depth, thickness and degree of inclination, presence of geological breaches and adjacent strata properties. The factors of block three is independently connected with the mining operation conditions. The forecasting technique for workable bed liability to spontaneous ignition avoids any stable correlation relationships between the factor parameters of three blocks under consideration. It allows separate consideration of each block and avoid their random correlations with factors of other blocks. Results. The statistical processing result analysis of more than 1000 coal samples with carbon content of 80÷94% has allowed establishing the relationship between the organic matter components and total moisture, as well as their share of participation in carbonization process that reflects the Donets Basin coal metamorphic conversions. Compliance of the initial data with analytical data of different coal deposits has been established. For the first time, the technique has been developed; and organic matter separate components and total moisture participation shares in coal carbonization process indices creation, which is one of evaluation criteria for workable bed metamorphic conversion degree for different deposits, have been established. The revealed regularities of change ambiguity for organic matter elemental composition components and their different participation shares together with the moisture in carbonization process have allowed establishing the distinctive features of the coal metamorphic conversion different stages for true forecasting the workable bed hazardous characteristics during the mining operations. In the course of this approach, the real chemical activity of coals is established by their elemental composition in different stages of bed metamorphic conversions; certain places of long-term contacts between the mine air and coal are differentially forecasted in the mine field. It enables the enhanced automated monitoring of mine air condition and revealing of spontaneous combustion places in early stages of their creation. Scientific novelty. The pattern of change for classification indices of coal industrial classification has been revealed to establish the workable bed hazardous characteristics during the mining operations. Practical relevance. Opportunity to improve the regulatory framework for safe processing of workable beds by establishing the interrelation between fossil coal metamorphic conversions and their elemental composition.

scholarly journals Structure of the analytical activity of the head of school

2016 ◽  
Vol 5 (1) ◽  
pp. 161-167
Author(s):  
Natalia Nicolaevna Koval
Keyword(s):  
Three Dimensional ◽  
Self Esteem ◽  
School Principal ◽  
Self Management ◽  
Self Awareness ◽  
Structural Components ◽  
Three Dimensional Model ◽  
Head Of School ◽  
Main Components ◽  
Analytical Practice

The article deals with the current pedagogical approaches to the components, structure and description of analytical activity. Different models of analytical activity are reviewed: activity approach (E.V. Naznachilo, N.A. Zinchuk, V.V. Yagupov, N.P. Pichugova), systematic approach (L.P. Polovenko, O.N. Yarygin, and A.A. Korostelev), structural-activity approach (L.M. Plakhova). Within each approach the main components and stages of the analytical activity are described. The emphasis is laid on the three-dimensional model of analytical practice of the school principal: the technology of the analysis of the results of educational system operation (A.A. Korostelev), the element of that is a heuristic algorithm of unmathematical character, consisting of five stages. This technology combined a motivational sense, target, technological levels. The structural components of the analytical activity of the schools head are highlighted and described: value-motivation (personality attitude of leader toward analytical activity, value of parties and her meaningfulness in administrative activity, necessity of personality to improve and develop in this type of activity), goal-oriented (intentional aspect), cognitive-operational (complex of knowledge, abilities, practical skills, necessary for realization of effective and effective analytical activity) and reflective (self-esteem, self-awareness, self-management, self-design their own analytical activities).

scholarly journals Application of Operational Load Monitoring System for Fatigue Estimation of Main Landing Gear Attachment Frame of an Aircraft

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6564
Author(s):  
Michal Dziendzikowski ◽  
Artur Kurnyta ◽  
Piotr Reymer ◽  
Marcin Kurdelski ◽  
Sylwester Klysz ◽  
...  
Keyword(s):  
Landing Gear ◽  
Fatigue Wear ◽  
Operational Load ◽  
Load Monitoring ◽  
Management Paradigms ◽  
Optimal Maintenance ◽  
Fatigue Estimation ◽  
The Individual ◽  
Vertical Landing ◽  
The Impact

In this paper, we present an approach to fatigue estimation of a Main Landing Gear (MLG) attachment frame due to vertical landing forces based on Operational Loads Monitoring (OLM) system records. In particular, the impact of different phases of landing and on ground operations and fatigue wear of the MLG frame is analyzed. The main functionality of the developed OLM system is the individual assessment of fatigue of the main landing gear node structure for Su-22UM3K aircraft due to standard and Touch-And-Go (T&G) landings. Furthermore, the system allows for assessment of stress cumulation in the main landing gear node structure during touchdown and allows for detection of hard landings. Determination of selected stages of flight, classification of different types of load cycles of the structure recorded by strain gauge sensors during standard full stop landings and taxiing are also implemented in the developed system. Based on those capabilities, it is possible to monitor and compare equivalents of landing fatigue wear between airplanes and landing fatigue wear across all flights of a given airplane, which can be incorporated into fleet management paradigms for the purpose of optimal maintenance of aircraft. In this article, a detailed description of the system and algorithms used for landing gear node fatigue assessment is provided, and the results obtained during the 3-year period of system operation for the fleet of six aircraft are delivered and discussed.

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