Landing gear ground manoeuvre statistics from automatic dependent surveillance-broadcast transponder data

2021 ◽  
pp. 1-35
Author(s):  
J. Hoole ◽  
P. Sartor ◽  
J.D. Booker ◽  
J.E. Cooper ◽  
X.V. Gogouvitis ◽  
...  
Keyword(s):  
Big Data ◽  
Landing Gear ◽  
Cyclic Loads ◽  
Limited Availability ◽  
Significant Variability ◽  
Load Spectra ◽  
Fatigue Design ◽  
Left And Right

ABSTRACT Landing gear are exposed to cyclic loads from the ground manoeuvres that aircraft perform in-service. Variability is observed in the loading magnitude associated with ground manoeuvres, along with the per-flight variability in ground manoeuvre occurrence and sequencing. Whilst loading magnitude variability has been widely characterised, significant assumptions are required regarding manoeuvre occurrence and sequencing when constructing landing gear load spectra for fatigue design. These assumptions are required due to the limited availability of data concerning ground manoeuvre occurrence and sequencing relating to aircraft in-service and require validation to facilitate the design of more efficient components. ‘Big-Data’ approaches, employing Automatic Dependent Surveillance-Broadcast (ADS-B) transponder data, enable aircraft ground tracks to be identified. This paper presents a methodology to characterise the variability in ground manoeuvre occurrence and sequencing using ADS-B data sourced from Flightradar24® for a wide-body aircraft fleet. Using statistics generated for the fleet, it was identified that significant variability exists in the occurrence and sequencing of turning and braking manoeuvres. The statistics also validate existing assumptions, including that the proportional share of left and right turning manoeuvres is equal. Finally, this paper discusses the utility of ADS-B datasets for constructing landing gear load spectra and monitoring of landing gear in-service.

Low Cycle Fatigue Strength of X65 Pipeline Girth Welds

2004 ◽  
Author(s):  
Koji Gotoh ◽  
Stig Berge
Keyword(s):  
Low Cycle Fatigue ◽  
Cyclic Strain ◽  
Test Series ◽  
Cyclic Loads ◽  
Plastic Strains ◽  
Maximum Strain ◽  
Cycle Fatigue ◽  
Fatigue Design ◽  
Large Water ◽  
Girth Welds

During pipe laying at large water depth using S-lay over a stinger, the pipe may be subjected to reversed plastic strains which could lead to low cycle fatigue failure. X65 pipeline girth welds with wall thickness 22mm were tested in cyclic strain control. Undermatched and overmatched welds were tested. Two types of cyclic strain programs were applied. In the first test series the welds were subjected to a tensile-tensile cyclic strain, simulating pipe going over the stinger, to validate that a pipe going over a stinger would not violate criteria for low cycle fatigue design. In the second test series, the specimens were initially pre-strained to 2% and subsequently fatigue-cycled with a maximum strain of 2% to obtain design criteria for a pipe laying stationary over the stinger for a period of time, subjected to cyclic loads due to waves. The results are presented in terms of Δε–N curves, with proposed design curves for the two types of welds.

scholarly journals Comparison of Safety Factor Values for Soderberg and DIN 743 Fatigue Analyses

2021 ◽  
Vol 7 (2) ◽  
pp. 11-21
Author(s):  
Beatriz Henriques ◽  
Mariana Carvalho ◽  
Sérgio Tavares ◽  
Paulo De Castro
Keyword(s):  
Safety Factor ◽  
Cyclic Load ◽  
High Cycle Fatigue ◽  
Load Capacity ◽  
Cyclic Loads ◽  
Correction Factors ◽  
Fatigue Design ◽  
Different Types ◽  
Machine Elements ◽  
Critical Aspects

Fatigue phenomena are critical aspects of the life cycle of many components or structures. The variety of cyclic load situations led to the emergence, throughout the years, of different types of studies as high-cycle, low-cycle, and fatigue crack growth, among others. Particularly for machine elements, high-cycle fatigue situations are the more frequent, and simplified approaches taking into account the Soderberg criterion have been commonly used. Meanwhile, the German Institute for Standardization put forward a procedure for fatigue design of shafts, DIN 743, based on the use of Smith diagrams and considering separately the safety factor (SF) for static and for cyclic loads. The present paper compares Soderberg and DIN 743 approaches, focusing on SF obtained when load capacity is calculated considering equal correction factors in both methods. A set of representative situations was defined, and the comparison was carried out parametrically using Matlab software. The SF values of the Soderberg method were always found to be lower than those of DIN 743, indicating that the Soderberg method is more conservative than DIN 743.

Fatigue Cracking and Acoustic Emission Regularities in Metals: Crack Origination and Growth

2013 ◽  
Vol 592-593 ◽  
pp. 735-740 ◽  
Author(s):  
Andrey Shanyavskiy ◽  
Mukharbiy Banov
Keyword(s):  
Acoustic Emission ◽  
Fracture Surface ◽  
Turbine Blades ◽  
Fatigue Cracking ◽  
Internal Surface ◽  
Landing Gear ◽  
Cyclic Loads ◽  
Aircraft Structures ◽  
Surface Patterns ◽  
Ae Signals

Specimens of Al-and Ti-alloys and turbine blades of Ni-based alloy were considered in the case of crack origination at the surface, subsurface, and at the inner surface of turbine blades. Aircraft structures such as hydrocylinders of Al-based alloy and landing gear of high-strength-steel were also considered. There was used acoustic emission (AE) monitoring to fix moment of crack occurring and, then, analyzing its growth. Fracture surface features appearance was compared with AE-signals regularities based on fractographic analyses. To indicate the crack origination moment it was introduced α-criterion. This criterion characterized drastically increase in summarized AE-signals appearing in dependence on cyclic loads number. During crack propagation, there was used Elber-portion of opened crack to register AE-signals in cyclic loads. It was demonstrated crack increment in unloading portion of cyclic loads with fatigue striations formation. Two aircraft structures of hydrocylinders and shock strut of landing gear were tested on the special test facilities and AE-monitoring was conducted. Effectiveness of α-criterion using for crack registration in the high-cycle fatigue regime was demonstrated applicably to crack appearance on the internal surface and subsurface. The discovered dependences of summarized AE-signals on number of cycles were compared with fracture surface patterns and briefly discussed.

Ground and Flight Tests of an Unmanned Rotorcraft with Cable-Driven Robotic Landing Gear

2021 ◽  
Author(s):  
Benjamin León ◽  
Julian J. Rimoli ◽  
Claudio V. Di Leo
Keyword(s):  
Performance Metrics ◽  
Mechanical Design ◽  
Cross Coupling ◽  
Landing Gear ◽  
Flight Tests ◽  
Design Metrics ◽  
Systematic Testing ◽  
S 100 ◽  
Left And Right ◽  
And Performance

Robotic landing gear enhances the landing capabilities of vertical take-off and landing aircraft on sloped, rough, and even moving landing surfaces. This research demonstrates the integration and systematic testing of a robotic landing gear system for the commercial S-100 Camcopter, expanding the aircraft’s landing capabilities to currently inaccessible terrains with slopes at and above 15°. An overview of the mechanical design, sensors, and controller as integrated into the S-100 rotorcraft is provided along with expected landing performance from simulations tools. The system is then demonstrated using ground and flight experiments, and performance metrics are found to match design metrics. An asymmetry in left and right leg landings during flight testing is observed and analyzed. Lastly, cross-coupling of pitch and roll rates induced by the rotor is discussed as a cause of the asymmetry on this three-legged rotorcraft.

Structural Integrity Assessment of Critical Components of Converted FPSO Hulls

2004 ◽  
Author(s):  
Carlos A. Bardanachvili ◽  
Alexandre M. Pope ◽  
Roberto O. Goulart ◽  
Lena L. Adelson ◽  
Luiz H. M. Alves ◽  
...  
Keyword(s):  
Welded Joints ◽  
Fatigue Cracks ◽  
Design Approach ◽  
Cyclic Loads ◽  
Repair Work ◽  
Fatigue Assessment ◽  
Integrity Assessment ◽  
Fatigue Design ◽  
Hull Structure ◽  
The Cross

Conversion of very (ultra) large crude oil carriers (VLCC,ULCC) into floating production, storage and offloading (FPSO) offshore units has become a common practice in the industry. The conversion planning is complex and demands a careful assessment of the condition of the hull to be converted into a FPSO. The fatigue assessment is especially important at certain components that will experience cyclic loads above the originally allowed in the design of the VLCC (ULCC). A through fatigue assessment of two FPSOs that are now at the final stages of conversion was carried out using current class rules. While for the majority of the hull structure the fatigue design approach used produced satisfactory and conservative results, at the cross tie beam, located at frames in the wing tanks, the fatigue assessment was considered unreliable. This was evident during the conversion stage because a large number of cracks were found in welded joints of the cross tie beams during the hull conversion inspection. A simplified finite element analysis (FEA) showed that the location where the cracks were found was subjected to high cyclic loads during the operation as an oil tanker and that these loads would be also severe during the FPSO operation. Analysis of samples taken from the damaged areas showed that they contained weld toe fatigue cracks. Further FEA was carried out taking into account the displacements from a global structural model, which modelled the hull and the top side structures, in order to estimate the hot spot stresses at the affected welded joints. The additional fatigue assessment demonstrated that the fatigue design approach used needed to be modified to firstly explain the cracks found in the component, secondly to allow for a reliable and conservative estimation of the remaining fatigue life for the cross tie beam after repair work was carried out. The resultant fatigue approach adopted demonstrated that the cross tie beam would not survive the 20 years design requirement of the project unless modifications on the local structural design were undertaken or welded joint fatigue enhancement techniques were applied to the welded joints. To resolve the problem the project decided to adopt a controlled arc welding repair of all cracked joints followed by careful inspection and application of burr machining of weld toes as a fatigue enhancement technique. This paper describes the fatigue assessment undertaken, the suggested modification to the fatigue approach for the assessment of cross tie beams, a description of the repair procedures, non-destructive testing and fatigue enhancement methods adopted by the project.

Analytical Models for Mooring Chain-Soil Interaction

1999 ◽  
Vol 121 (1) ◽  
pp. 1-8 ◽  
Author(s):  
K. Larsen ◽  
G. Svano̸
Keyword(s):  
Computational Models ◽  
Analytical Models ◽  
Soil Conditions ◽  
Soil Parameters ◽  
Cyclic Loads ◽  
Design Procedures ◽  
Fatigue Design ◽  
Soil Effects ◽  
Anchor Design ◽  
Chain Interaction

For most catenary mooring systems, a quite long part of the line is resting on the bottom, even in extreme situations. Hence, a good design of the anchor requires an accurate prediction of the loading from the anchorline, including any soil-chain interaction. This requires that the longitudinal chain-soil characteristics are well described for different soil conditions and that efficient computational models exist. This is particularly important in fatigue design of e.g., suction anchors. Design against fatigue is in many cases critical for these type of anchors. A problem is the lack of design tools handling the soil-chain interaction correctly. Traditionally, the soil effects are neglected completely in a fatigue design process. A consequence in many cases is an expensive overdesign. There exist chain-soil models to be applied together with FEM programs. These are too impractical to use in efficient fatigue design which requires the load assessment due to many seastates. They also suffer from the lack of reliable soil parameters. The paper addresses analytical models of the tension and longitudinal displacement along the part of the line resting on the bottom, assuming the tension at “touch-down” to be known. Hence, only longitudinal chain-soil interaction is considered. The models are based on recently established soil parameters for longitudinal chain-soil interaction. Comparison with FEM computations shows that the analytical models are performing very well in the prediction of cyclic loads. They are therefore a major improvement to the existing design procedures for anchor design.

The three-dimensional structure of frozen-hydrated left- and right-handed forms of bacterial flagellar filaments from an identical serotype

1986 ◽  
Vol 44 ◽  
pp. 298-299
Author(s):  
S. Trachtenberg ◽  
D. J. DeRosier
Keyword(s):  
Ionic Strength ◽  
Basal Body ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Protein Species ◽  
Liquid Environment ◽  
Bacterial Flagellum ◽  
Left And Right ◽  
Rotary Motor ◽  
Helical Parameters

The bacterial cell is propelled through the liquid environment by means of one or more rotating flagella. The bacterial flagellum is composed of a basal body (rotary motor), hook (universal coupler), and filament (propellor). The filament is a rigid helical assembly of only one protein species — flagellin. The filament can adopt different morphologies and change, reversibly, its helical parameters (pitch and hand) as a function of mechanical stress and chemical changes (pH, ionic strength) in the environment.

Advantages of Complementary Stereo Images as Viewed with the Low-Temperature Field-Emission SEM

1992 ◽  
Vol 50 (2) ◽  
pp. 1314-1315
Author(s):  
William P. Wergin ◽  
Eric F. Erbe
Keyword(s):  
Fold Increase ◽  
Horizontal Displacement ◽  
Three Dimensions ◽  
Stereo Image ◽  
Stereo Pair ◽  
Sem Micrograph ◽  
Left And Right ◽  
The Common ◽  
The Brain ◽  
Pair Analysis

The eye-brain complex allows those of us with normal vision to perceive and evaluate our surroundings in three-dimensions (3-D). The principle factor that makes this possible is parallax - the horizontal displacement of objects that results from the independent views that the left and right eyes detect and simultaneously transmit to the brain for superimposition. The common SEM micrograph is a 2-D representation of a 3-D specimen. Depriving the brain of the 3-D view can lead to erroneous conclusions about the relative sizes, positions and convergence of structures within a specimen. In addition, Walter has suggested that the stereo image contains information equivalent to a two-fold increase in magnification over that found in a 2-D image. Because of these factors, stereo pair analysis should be routinely employed when studying specimens.Imaging complementary faces of a fractured specimen is a second method by which the topography of a specimen can be more accurately evaluated.

Histological evaluation of cochlear hair cell damage from noise-induced hearing loss in chinchillas

1990 ◽  
Vol 48 (3) ◽  
pp. 332-333
Author(s):  
R.V. Harrison ◽  
R.J. Mount ◽  
P. White ◽  
N. Fukushima
Keyword(s):  
Hair Cell ◽  
Evoked Potential ◽  
Cell Damage ◽  
Acoustic Trauma ◽  
Histological Evaluation ◽  
Cell Integrity ◽  
Functional Changes ◽  
Cochlear Hair Cell ◽  
Left And Right ◽  
Contralateral Ear

In studies which attempt to define the influence of various factors on recovery of hair cell integrity after acoustic trauma, an experimental and a control ear which initially have equal degrees of damage are required. With in a group of animals receiving an identical level of acoustic trauma there is more symmetry between the ears of each individual, in respect to function, than between animals. Figure 1 illustrates this, left and right cochlear evoked potential (CAP) audiograms are shown for two chinchillas receiving identical trauma. For this reason the contralateral ear is used as control.To compliment such functional evaluations we have devised a scoring system, based on the condition of hair cell stereocilia as revealed by scanning electron microscopy, which permits total stereociliar damage to be expressed numerically. This quantification permits correlation of the degree of structural pathology with functional changes. In this paper wereport experiments to verify the symmetry of stereociliar integrity between two ears, both for normal (non-exposed) animals and chinchillas in which each ear has received identical noise trauma.

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