bluuebunny/crossref_metadata_2025_split huggingface dataset:
Estimation of the Medico-Ecological Component of Life Quality at the Level of Risk of Morbidity with Mass Non-Infectious Diseases
Authors: Prusakova A. V. , Prusakov V. M. 
Published: May 2019

For an objective assessment of the quality of life (QOL) in areas with different environmental pressures and the development of recommendations for improving medical care, population studies of children are used. The purpose of this study is to assess the risk of a general incidence of mass noncommunicable diseases (МND) of the child population of industrial cities with various environmental pressures as an indicator of QOL. To assess the anthropogenic load in industrial cities, atmospheric air pollution with harmful substances was analyzed. The assessment of the influence of local factors of cities was determined by relative and attributable risks of morbidity using synchronous annual and corresponding to the studied time interval values of background and estimated morbidity, and the influence of common background factors by the value of initial background morbidity at the beginning of the long-term observation period. To assess and rank changes in QOL in areas with different environmental loads, we used the results of the analysis of the long-term risk dynamics of the minority disease of children’s population with long-term exposure to a complex of general and local environmental factors of industrial cities of the Irkutsk region. To do this, we used the criteria developed by the authors for assessing the degree of tension of the medico-ecological situation and the strength of the impact of environmental factors on them by the relative risk levels of the minimum level and the corresponding QOL levels for the specified component.QOL in terms of the minimum number of children’s diseases in the period under review decreases as a whole due to the increasing influence of general background (regional) factors throughout the region, and in the studied cities in addition from the influence of local adverse factors, including anthropogenic pollution of atmospheric air.A significant decrease in the local anthropogenic load is accompanied by a decrease in the associated additional МND and the severity of the additional to the background decrease in QOL in the industrial cities of the region, especially in Angarsk.
Assessment of the Validity of the Psycho-Cardiological Comorbidity Index in the Practice of a Cardiologist
Authors: Dorofeikova M. V. , Zadvorev S. F. , Petrova N. N. , Yakovlev A. A. 
Published: May 2019

Background. The feasibility of creating a screening Index for the comorbidity of mental disorders and cardiovascular diseases in the practice of the cardiologist dictates the need to validate existing algorithms.Aim. To validate the previously proposed Index of psychocardiac comorbidity in prediction of outpatient recommendation of psycho-pharmacotherapy for cardiology patients.Materials and methods. Medical records of 302 consecutive patients of cardiac in-patient department were retrospectively analyzed with ROC-curve to estimate the predictive value of previously proposed Index of psychocardiac comorbidity for out-patient recommendation of psycho-pharmacotherapy.Results. The prevalence of outpatient psycho-pharmacotherapy in the examined patients was 15.2 %; this group of patients was more polymorbid and was characterized by a higher proportion of women and a higher prevalence of a labile course of arterial hypertension. The sedative antipsychotics, non-benzodiazepine tranquilizers and mood stabilizers were predominant pharmacological groups. An analysis of reproducibility of Index of psychocardiac comorbidity was provided on a cohort of cardiology in-patient department (n = 302). Index calculated by using the formula I = C + 3(6)×Q + 3×W + 8×A (C – number of Comorbid diagnoses, Q – Quake in the chest, palpitations or arrhythmia, onset before 55 (3 points) or 50 (6 points) years; W – Women; A – labile Arterial hypertension). Area under ROC-curve in validation cohort was 0.828 ± 0.035 (p < 0.001). Positive predictive value of Index was maximal for the score of ≥ 13.Conclusion. The proposed Index of psychocardiac comorbidity is a valid tool to predict the prescription of psychopharmacotherapy in cardiology patients.
Failure of Hose Clamp
Authors: Craft C. Howard 
Published: May 2019

Abstract
A helicopter rapidly lost altitude and struck a tree, causing a fire and severe damage. The hose clamp which was the subject of this investigation was one of two used on a short length of hose between the turbocharger and the carburetion system. The purpose of this examination was to determine whether the hose failed during or before the accident. Fracture in the failed clamp was accompanied by obvious permanent deformation and evidence of local shearing at the ends of the perforation where fracture occurred, and in the adjacent perforation. The first test involved tightening the clamps to failure with a torque wrench. In no case did the band material fracture. In a second attempt to duplicate the failure, a tensile testing machine was used to pull the two fittings apart while the hose was clamped in place. When the testing machine was operated at maximum head travel (approximately 20 in. per min.), one of the hose clamps broke in the same manner as the clamp in question. The manner of failure during the tension test indicated this clamp failed at the time of the crash because of a sudden separation between the turbocharger and the remainder of the aircraft.
Failure of a Main Landing Gear on a Light Airplane
Authors: Howard Craft C. 
Published: May 2019

Abstract
Initial investigation showed that a landing gear failure was the result of a hard landing with no evidence of contributory factors. The objective of reexamination was to determine whether there was any evidence of metallurgical failure. The landing gear was primarily an AISI type 6150 Cr-V steel flat spring attached at the top end to the fuselage and at the bottom end to the axle. Failure occurred at the clamping point near the top end of this spring. The failure showed evidence of severe brinelling at one corner in the clamping area. The fracture surfaces were clean, fresh, and indicative of a shock type of failure pattern. Closer examination, however, showed a fatigue crack at one corner. At this point, there was definite evidence of progression and oxidation. It was concluded that the corner in question was subjected to repeated brinelling resulting from normal landing loads, probably accentuated by looseness in the clamping device. The resulting residual tensile stress lowered the effective fatigue strength at that point against drag and side loads.
Failure Analyses of Steel Breech Chambers Used With Aircraft Cartridge Ignition Starters
Authors: Perkins Philip C. , Daniels Raymond D. , Gillies A. Bruce 
Published: May 2019

Abstract
Cartridge-pneumatic starter systems are used on military aircraft. In the cartridge mode used for alert starts, the starter turbine is driven by hot gases produced through the controlled burning of a solid propellant cartridge within a closed chamber (the breech chamber/cartridge chamber assembly). Premature failures of steel breech chambers have been prevalent enough to cause serious concern. The breech chamber is fabricated from a 4340 Ni-Cr-Mo steel forging heat treated to a hardness in the range HRC 40 to 45. The failures have taken several forms, including fracture and unzipping of the chamber dome, burn-through of the dome, and shearing of bayonet locking lugs. Factors identified as significant in the failures are the pressure developed in the chamber and internal corrosion of the chamber in an environment that can produce stress-corrosion cracking. The interior configuration of the chamber and the stress distribution also have a bearing upon the failure modes. Several failures are reviewed to illustrate the problems.
Study of Inclusions in a Failed Aero-Engine Component
Authors: Tauqir A. , Salam I. , Hashmi F.H. , Khan A.Q. 
Published: May 2019

Abstract
The cause of the fatigue failure in the retaining ring of the compressor region of an aero-engine turbine was found to be the presence of a high concentration of nonmetallic inclusions. The results of chemical analysis were used to estimate the phases present. The most frequently observed inclusions were spinel solid solutions of the type MO middot; N2O3, where M = Fe, Mn, or Mg and N = Cr or Al. The detrimental inclusions were corundum, calcium aluminates, cristobalite, and silicates. The most detrimental phases were traced on the surfaces of the specimens fractured using impact loading; the comparison is being made with the polished surfaces and the tensile specimen fracture surfaces. The inclusions in the failed retaining ring were compared with the ones in a similar component obtained from a used engine. In the case of the latter, a large number of fine and elongated (Mn, Cr, Fe)S inclusions were present along with spinels. The nondeformable, rigid oxide particles are considered more undesirable than the sulfides as far as fatigue life of the component is concerned. It has been reported that the presence of sulfides may eliminate the stresses due to oxides.
Failure Analysis of Silica Phenolic Nozzle Liners
Authors: Katcher M. 
Published: May 2019

Abstract
Two silica phenolic nozzle liners cracked during proof testing. The test consisted of pressuring the nozzles to 14.1 MPa (2050 psia) for 5 to 20 s. It was concluded that the failure was due to longitudinal cracking in the convergent exhaust-nozzle insulators, stemming from the use of silica phenolic tape produced from flawed materials that went undetected by the quality control tests, which at the time, assessed tape strength properties in the warp rather than the bias direction. Once the nozzle manufacturer and its suppliers identified the problem, they changed their quality control procedures and resumed production of nozzle liners with more tightly controlled fiber/fabric materials.
Failure Analysis of Aircraft Landing Gear Components
Authors: Roth M. , Yanishevsky M. , Beaudet P. 
Published: May 2019

Abstract
Despite extensive aircraft landing gear design analyses and tests performed by designers and manufacturers, and the large number of trouble-free landings, aircraft users have experienced problems with and failures of landing gear components. Different data banks and over 200 failure analysis reports were surveyed to provide an overview of structural landing gear component failures as experienced by the Canadian Forces over the last 20 years on more than 20 aircraft types, and to assess trends in failure mechanisms and causes. Case histories were selected to illustrate typical problems, troublesome failure mechanisms, the role of high strength aluminum alloys and steels, and situations where fracture mechanics analyses provided insight into the failures. The two main failure mechanisms were: fatigue occurring mainly in steel components, and corrosion related problems with aluminum alloys. Very few overload failures were noted. A number of causes were identified: design deficiencies and manufacturing defects leading mainly to fatigue failures, and poor materials selection and improper maintenance as the principal causes of corrosion-related failures. The survey showed that a proper understanding of the failure mechanisms and causes, by thorough failure analysis, provides valuable feedback information to designers, operators and maintenance personnel for appropriate corrective actions to be taken.
Helicopter Main Rotor Transmission Output Shaft Failure
Authors: Hutchinson J.W. 
Published: May 2019

Abstract
A helicopter had just taken off when there was a loud bang and the engine started to overspeed. After landing and inspection, the transmission was disassembled. It was discovered that the assembly containing the output shaft to the main rotor had failed. The output shaft assembly was made up of two parts: the output shaft with an integral 10 in. diam upper disc at approximately mid-section; and a 10 in. diam lower disc. During manufacture, the lower disc was attached to the output shaft by an electron beam weld. The fracture had a single fatigue initiation site, coincident with the annular zone of remelted material on the inner surface of the disc. In the lower disc, the fracture was also 80% fatigue, but high stress, low cycle in nature and contained multiple initiation sites coincident with an electron beam weld bead. It was concluded that fatigue in the upper disc resulted from the presence of a metallurgical stress concentration caused by the electron weld beam impingement on the inner surface of the upper disc. An Airworthiness Directive was issued, and the manufacturer issued a mandatory service bulletin outlining a periodic inspection for the output shaft assembly.
Analysis of a Failed UH-1N Helicopter Main Rotor Blade Grip
Authors: Parker D.S. 
Published: May 2019

Abstract
Proper stress analysis during component design is imperative for accurate life and performance prediction. The total stress on a part is comprised of the applied design stress and any residual stress that may exist due to forming or machining operations. Stress-corrosion cracking may be defined as the spontaneous failure of a metal resulting from the combined effects of a corrosive environment and the effective component of tensile stress acting on the structure. However, because of the orientation dependence in aluminum, it is the residual stress occurring in the most susceptible direction that must be considered of primary importance in material selection for design configuration. A Navy UH-1N helicopter main rotor blade grip manufactured from a 2014-T6 aluminum alloy forging failed because of a design flaw that left a high residual tensile stress along the short transverse plane; this in turn provided the necessary condition for stress corrosion to initiate. A complete failure investigation to ascertain the exact cause of the failure was conducted utilizing stereomicroscopic examination, scanning electron microscopy, metallographic inspection and interpretation, energy-dispersive chemical analysis, physical and mechanical evaluation. Stereomicroscopic examination of the opened crack fracture surface revealed one large fan-shaped region that had propagated radially through the thickness of the material from two distinct origin areas on the internal diam of the grip. Higher magnification inspection near the origin area revealed a flat, wood-like appearance. Scanning electron microscopy divulged the presence of substantial mud cracking and intergranular separation on the fracture surface. Metallographic examination revealed intergranular cracking and substantial leaf separation along the elongated grains parallel to the fracture surface. Chemical composition and hardness requirements were found to be as specified. The blade grip failed due to a stress corrosion crack which initiated on the inner diam and propagated in the short transverse direction through the thickness of the component. The high residual tensile stress in the part resulting from the forging and exposed after machining of the inner diam, combined with the presence of moisture, provided the necessary conditions to facilitate crack initiation and propagation.
Analysis of Aircraft Damage from a Lightning Strike
Authors: Gammon Luther M. , Hyatt Michael V. , Narayanan G. Hari , Oberson Henry J. , Singh Harcayal B. 
Published: May 2019

Abstract
On 16 July 1999, a Boeing 737-800 on final approach for landing sustained a major lightning strike. Damage to the fuselage structure primarily was in the form of melting or partial melting of widely-separated rivets and adjacent Alclad 2024-T3 fuselage skin. The damage was confined to a 0.25-in. (6.4-mm) radii around the affected rivets. The repair process involved removal of the locally-affected material and addition of a skin doubler to restore the aircraft structure to the originally designed condition. Damage features are described briefly.
Investigation of Jet Engine Oil Scavenge Pump Failure
Authors: Cologna L.D. 
Published: May 2019

Abstract
An oil scavenge pump was found to have failed when a protective shear neck fractured during the start of a jet engine. Visual inspection revealed that the driven gear in one of the bearing compartments was frozen as was the corresponding drive gear. Spacer wear and thermal discoloration (particularly on the driven gear) were also observed. The gears were made from 32Cr-Mo-V13 steel, hardened and nitrided to 750 to 950 HV. Micrographic inspection of the gear teeth revealed microstructural changes that, in context, appear to be the result of friction heating. The spacers consist of Cu alloy (AMS4845) bushings force fit into AA2024-T3 Al alloy spacing elements. It was found that uncontrolled fit interference between the two components had led to Cu alloy overstress. Thermal cycling under operating conditions yielded the material. The dilation was directed inward to the shaft, however, because the bushing had only a few microns of clearance. The effect caused the oil to squeeze out, resulting in metal-to-metal contact, and ultimately failure.
Effect of Prior Processing on the Performance of PH 13-8 Mo Stainless Steel Helicopter Components
Authors: Pepi Marc S. , Grendahl Scott M. , Champagne Victor K. 
Published: May 2019

Abstract
The purpose of this investigation was to determine the root cause of the differences noted in the fatigue test data of main rotor spindle assembly retaining rods fabricated from three different vendors, as part of a Second Source evaluation process. ARL performed dimensional verification, accessed overall workmanship, and measured the respective surface roughness of the rods in an effort to identify any discrepancies. Next, mechanical testing was performed, followed by optical and electron microscopy, and chemical analysis. Finally, ARL performed laboratory heat treatments at the required aging temperature and follow-up mechanical testing.
Fatigue Fracture of an Aluminum Main Support Bridge for a Helicopter
Authors: Champagne V.K. 
Published: May 2019

Abstract
This paper summarizes the results of a failure analysis investigation of a fractured main support bridge made of 7075 aluminum alloy from an army helicopter. The part, manufactured by “Contractor IT,” failed component fatigue testing while those of the original equipment manufacturer (OEM) passed. Metallurgical data collected during this investigation indicated that the difference in fatigue life between the components fabricated by IT and by OEM may be attributable to a difference in dimensions at the web where fatigue crack initiation occurred. The webs of the two OEM parts examined had cross-sectional thicknesses significantly larger than the web cross-sectional thicknesses of the IT components. Recommendations included changing the web reference dimension of 0.38 in. to include a tolerance range based upon a fracture mechanics model. Also, the shot peening process should be controlled especially at the critical areas of the web, to assure complete coverage and proper compressive residual stresses.
Ejection Seat Quick-Release Fitting: Quantitative Fractography and Estimation of Local Toughness Using the Topography of the Fracture Surface
Authors: Wolf K. 
Published: May 2019

Abstract
After a quick-release fitting of an ejection seat broke, an investigation was performed to determine the manner and cause of crack propagation. Most fractography-based investigations aim to characterize only qualitative characteristics, such as the fracture orientation and origin position, topology, and details of interactions with microstructural features. The aim of this investigation was to use quantitative fractography as a tool to extract information, including striation spacing and size of the stretched zone, in order to make a direct correlation with fracture mechanic concepts. As the crack propagated, striations were created on the fracture surface as a result of service-induced load changes. The size of the striations were measured to estimate crack propagation rate. Remaining lifetime estimates were also made. The dimensions of plastically stretched zones found at the tips of the cracks were evaluated using electron micrograph stereo image pairs to characterize local fracture toughness. To complete the failure analysis, nondestructive evaluation, metallographic examination, and chemical investigations were carried out. No secondary cracks could be found. Most of the broken parts showed that the microstructure, the hardness, and the chemical composition of the Al-alloy were within the specification, but some of the cracked parts were manufactured using a different material than that specified.
Material-Based Failure Analysis of a Helicopter Rotor Hub
Authors: Wanhill R.J.H. 
Published: May 2019

Abstract
A Lynx helicopter from the Royal Netherlands Navy lost a rotor blade during preparation for take-off. The blade loss was due to failure of a rotor hub arm by fatigue. The arm was integral to the titanium alloy rotor hub. An extensive material based failure analysis covered the hub manufacture, service damage, and estimates of service stresses. There was no evidence for failure due to poor material properties. However, fractographic and fracture mechanics analyses of the service failure, a full scale test failure, and specimen test failures indicated that the service fatigue stress history could have been more severe than anticipated. This possibility was subsequently supported by a separate investigation of the assumed and actual fatigue loads and stresses.
Metallurgical Evaluation of Inner Wall Softening in a Tow Flight Missile Case
Authors: Hickey Charles F. 
Published: May 2019

Abstract
Failure occurred in two TOW flight missile cases in unrelated launchings. After an extensive investigation, it was concluded that stress corrosion was the most likely cause of failure. Subsequent to this conclusion, inner wall softening was observed in an unfired TOW flight missile case. Questions arose as to how the softening occurred and whether or not it had contributed to the failures. This report contains the results of a study which resolved that inner wall softening could not have been present in the failed missile cases.
Failure Investigation of a Structural Component of the Main Landing Gear of a Transport Aircraft
Authors: Abdel-Latif A.M. , Roth M. , Yanishcvsky M. 
Published: May 2019

Abstract
The truck beam of the left main landing gear (MGL) of a Boeing 707 airplane collapsed on the ground just after the aircraft was unloaded and refueled. The investigation revealed that failure was caused by the propagation of an intergranular crack originating from the bottom of the pit. The crack reached the critical size and caused failure by stress-corrosion cracking (SCC) under static loading conditions in service. The failed beam was protected by a well adhering paint system. However, the presence of adequate amounts of corrosion preventive compound films (CPC) on the surfaces of the failed beam could not be conclusively established because of the long term service exposure and presence of lubricants.
Failure in Aircraft Parts Made of Ultra-High-Strength Steel
Authors: Holshouser William L. 
Published: May 2019

Abstract
Service failures have occurred in a number of aircraft parts made of quenched and tempered steel heat treated to ultimate tensile strengths of 260,000 to 280,000 psi. Some of these failures have been attributed to “delayed cracking” as a result of hydrogen embrittlement or to stress-corrosion. Because of the serious nature of the failures and because the mechanism of the fracture initiation is not well understood, unusually complete laboratory investigations have been conducted. Three of these investigations are reviewed to illustrate the methods used in studying failures in aircraft parts. The results of the laboratory studies indicate that unusual care is necessary in the processing and fabrication of ultra-high-strength steel and in the design and maintenance of the structures in which it is used.