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Sample records for airplanes structure fatigue

  1. 14 CFR 23.574 - Metallic damage tolerance and fatigue evaluation of commuter category airplanes.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... evaluation of commuter category airplanes. 23.574 Section 23.574 Aeronautics and Space FEDERAL AVIATION... COMMUTER CATEGORY AIRPLANES Structure Fatigue Evaluation § 23.574 Metallic damage tolerance and fatigue evaluation of commuter category airplanes. For commuter category airplanes— (a) Metallic damage tolerance....

  2. 14 CFR 23.574 - Metallic damage tolerance and fatigue evaluation of commuter category airplanes.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... evaluation of commuter category airplanes. 23.574 Section 23.574 Aeronautics and Space FEDERAL AVIATION... COMMUTER CATEGORY AIRPLANES Structure Fatigue Evaluation § 23.574 Metallic damage tolerance and fatigue evaluation of commuter category airplanes. For commuter category airplanes— (a) Metallic damage tolerance....

  3. 77 FR 55105 - Aging Airplane Program: Widespread Fatigue Damage; Correction

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-07

    ... establish a limit of validity of the engineering data that supports the structural maintenance program... tables. This document corrects the errors in those tables. DATES: This corrective action becomes... entitled ``Aging Airplane Program: Widespread Fatigue Damage'' (77 FR 30877), which corrected a final...

  4. 14 CFR 23.574 - Metallic damage tolerance and fatigue evaluation of commuter category airplanes.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Metallic damage tolerance and fatigue... COMMUTER CATEGORY AIRPLANES Structure Fatigue Evaluation § 23.574 Metallic damage tolerance and fatigue... evaluation of the strength, detail design, and fabrication must show that catastrophic failure due to...

  5. 75 FR 69745 - Aging Airplane Program: Widespread Fatigue Damage

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-15

    ... airplanes to establish a limit of validity of the engineering data that supports the structural maintenance... validity of the engineering data that supports the structural maintenance program (LOV); 2. Demonstrate... 17, 2006. \\3\\ 71 FR 19928 The FAA proposed that design approval holders for those airplanes...

  6. Fatigue of titanium alloys in a supersonic-cruise airplane environment

    NASA Technical Reports Server (NTRS)

    Imig, L. A.

    1976-01-01

    The test programs conducted by several aerospace companies and NASA, summarized in this paper, studied several titanium materials previously identified as having high potential for application to supersonic cruise airplane structures. These studies demonstrate that the temperature (560 K) by itself produced no significant degradation of the materials. However, the fatigue resistance of titanium-alloy structures, in which thermal and loading effects are combined, has been studied insufficiently. The predominant topic for future study of fatigue problems in Mach 3 structures should be the influences of thermal stress particularly, the effects of thermal stress on failure location.

  7. 77 FR 30877 - Aging Airplane Program: Widespread Fatigue Damage; Technical Amendment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-24

    ... Airplane Program: Widespread Fatigue Damage,'' (75 FR 69746). In that final rule the FAA revised the... actions (see Damage Tolerance Data for Repairs and Alterations, 72 FR 70486). Change to Table 1 of Sec... Administration 14 CFR Parts 26, 121, and 129 RIN 2120-AI05 Aging Airplane Program: Widespread Fatigue...

  8. 14 CFR 25.571 - Damage-tolerance and fatigue evaluation of structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...) of this section. (2) The service history of airplanes of similar structural design, taking due... strength. It must be shown by analysis, supported by test evidence, or by the service history of airplanes... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Fatigue Evaluation §...

  9. Vibration Response of Airplane Structures

    NASA Technical Reports Server (NTRS)

    Theodorsen, Theodore; Gelalles, A G

    1935-01-01

    This report presents test results of experiments on the vibration-response characteristics of airplane structures on the ground and in flight. It also gives details regarding the construction and operation of vibration instruments developed by the National Advisory Committee for Aeronautics.

  10. Fatigue handbook: Offshore steel structures

    SciTech Connect

    Almarnaess, A.

    1985-01-01

    The contents of this book are: Overview of Offshore Steel Structures; Loads on Ocean Structures; Fracture Mechanics As a Tool in Fatigue Analysis; Basic Fatigue Properties of Welded Joints; Significance of Defects; Improving the Fatigue Strength of Welded Joints; Effects of Marine Environment and Cathodic Protection on Fatigue of Structural Steels Fatigue of Tubular Joints; Unstable Fracture; Fatigue Life Calculations; and Fatigue in Building Codes Background and Applications.

  11. 14 CFR 23.574 - Metallic damage tolerance and fatigue evaluation of commuter category airplanes.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Metallic damage tolerance and fatigue evaluation of commuter category airplanes. 23.574 Section 23.574 Aeronautics and Space FEDERAL AVIATION..., corrosion, defects, or damage will be avoided throughout the operational life of the airplane....

  12. 14 CFR 23.574 - Metallic damage tolerance and fatigue evaluation of commuter category airplanes.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Metallic damage tolerance and fatigue evaluation of commuter category airplanes. 23.574 Section 23.574 Aeronautics and Space FEDERAL AVIATION..., corrosion, defects, or damage will be avoided throughout the operational life of the airplane....

  13. The structure of airplane fabrics

    NASA Technical Reports Server (NTRS)

    Walen, E Dean

    1920-01-01

    This report prepared by the Bureau of Standards for the National Advisory Committee for Aeronautics supplies the necessary information regarding the apparatus and methods of testing and inspecting airplane fabrics.

  14. Residual strength and crack propagation tests on C-130 airplane center wings with service-imposed fatigue damage

    NASA Technical Reports Server (NTRS)

    Snider, H. L.; Reeder, F. L.; Dirkin, W. J.

    1972-01-01

    Fourteen C-130 airplane center wings, each containing service-imposed fatigue damage resulting from 4000 to 13,000 accumulated flight hours, were tested to determine their fatigue crack propagation and static residual strength characteristics. Eight wings were subjected to a two-step constant amplitude fatigue test prior to static testing. Cracks up to 30 inches long were generated in these tests. Residual static strengths of these wings ranged from 56 to 87 percent of limit load. The remaining six wings containing cracks up to 4 inches long were statically tested as received from field service. Residual static strengths of these wings ranged from 98 to 117 percent of limit load. Damage-tolerant structural design features such as fastener holes, stringers, doublers around door cutouts, and spanwise panel splices proved to be effective in retarding crack propagation.

  15. Variable-Structure Control of a Model Glider Airplane

    NASA Technical Reports Server (NTRS)

    Waszak, Martin R.; Anderson, Mark R.

    2008-01-01

    A variable-structure control system designed to enable a fuselage-heavy airplane to recover from spin has been demonstrated in a hand-launched, instrumented model glider airplane. Variable-structure control is a high-speed switching feedback control technique that has been developed for control of nonlinear dynamic systems.

  16. 14 CFR 23.573 - Damage tolerance and fatigue evaluation of structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Damage tolerance and fatigue evaluation of structure. 23.573 Section 23.573 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF... operational life of the airplane must be consistent with the initial detectability and subsequent growth...

  17. 14 CFR 25.571 - Damage-tolerance and fatigue evaluation of structure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... which could cause catastrophic failure of the airplane; and (iii) An analysis, supported by test.... Inspection thresholds for the following types of structure must be established based on crack growth analyses... locations and modes of damage due to fatigue, corrosion, or accidental damage. Repeated load and...

  18. 77 FR 54856 - Airworthiness Directives; The Boeing Company Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-06

    ... review copies of the referenced service information at the FAA, Transport Airplane Directorate, 1601 Lind... structural integrity of older transport category airplanes, the FAA concluded that the incidence of fatigue... for all airplanes in the transport fleet. Since the establishment of the SSI Supplemental...

  19. Fatigue life estimation program for Part 23 airplanes, `AFS.FOR`

    SciTech Connect

    Kaul, S.K.

    1993-12-31

    The purpose of this paper is to introduce to the general aviation industry a computer program which estimates the safe fatigue life of any Federal Aviation Regulation (FAR) Part 23 airplane. The algorithm uses the methodology (Miner`s Linear Cumulative Damage Theory) and the various data presented in the Federal Aviation Administration (FAA) Report No. AFS-120-73-2, dated May 1973. The program is written in FORTRAN 77 language and is executable on a desk top personal computer. The program prompts the user for the input data needed and provides a variety of options for its intended use. The program is envisaged to be released through issuance of a FAA report, which will contain the appropriate comments, instructions, warnings and limitations.

  20. Design Oriented Structural Modeling for Airplane Conceptual Design Optimization

    NASA Technical Reports Server (NTRS)

    Livne, Eli

    1999-01-01

    The main goal for research conducted with the support of this grant was to develop design oriented structural optimization methods for the conceptual design of airplanes. Traditionally in conceptual design airframe weight is estimated based on statistical equations developed over years of fitting airplane weight data in data bases of similar existing air- planes. Utilization of such regression equations for the design of new airplanes can be justified only if the new air-planes use structural technology similar to the technology on the airplanes in those weight data bases. If any new structural technology is to be pursued or any new unconventional configurations designed the statistical weight equations cannot be used. In such cases any structural weight estimation must be based on rigorous "physics based" structural analysis and optimization of the airframes under consideration. Work under this grant progressed to explore airframe design-oriented structural optimization techniques along two lines of research: methods based on "fast" design oriented finite element technology and methods based on equivalent plate / equivalent shell models of airframes, in which the vehicle is modelled as an assembly of plate and shell components, each simulating a lifting surface or nacelle / fuselage pieces. Since response to changes in geometry are essential in conceptual design of airplanes, as well as the capability to optimize the shape itself, research supported by this grant sought to develop efficient techniques for parametrization of airplane shape and sensitivity analysis with respect to shape design variables. Towards the end of the grant period a prototype automated structural analysis code designed to work with the NASA Aircraft Synthesis conceptual design code ACS= was delivered to NASA Ames.

  1. Aerodynamic Heating and Fatigue

    NASA Technical Reports Server (NTRS)

    Kroll, Wilhelmina D.

    1959-01-01

    A review of the physical condition's under which future airplanes will operate has been made and the necessity for considering fatigue in the design has been established. A survey of the literature shows what phases of elevated-temperature fatigue have been investigated. Other studies that would yield data of particular interest to the designer of aircraft structures are indicated.

  2. Fatigue performance of welded aluminum deck structures

    SciTech Connect

    Haagensen, P.J.; Ranes, M.; Kluken, A.O.; Kvale, I.

    1996-12-01

    Aluminum alloys are used increasingly in load carrying structures where low weight and low maintenance costs are at a premium. Helicopter decks, structures for living quarters and personnel transfer bridges between platforms are examples of offshore applications. While these structures are not usually subjected to high fatigue loads, the increasing use of aluminum in high speed ships, and more recently in highway bridge structures, makes the question of fatigue performance more important. In this paper the fatigue properties of small scale weldments in an AA6005 alloy are compared with the results of fatigue tests on full scale sections of welded extrusions in the same material, which were used in an aluminum bridge deck structure. The fatigue performance is also compared with the fatigue clauses in the new British design code BS8118 for aluminium structures and the proposed Eurocode 9. The prospects of using a new joining technique, friction stir welding (FSW), in the production of large scale panels for deck and ship hull structures is discussed. The FSW process is described briefly, and some fatigue test data are presented.

  3. Predicting the Fatigue life of Structures

    NASA Technical Reports Server (NTRS)

    Besuner, P. M.; Harris, D. O.; Thomas, J. M.; Allison, D. E.; Bannantine, J. M.; Brown, S. B.; Davis, C. S.; Derbalian, G. A.; Eischen, J. W.; Fowler, G. F.; Osteraas, J. D.; Robinson, J. N.; Sire, R. A.; Vroman, G. A.

    1985-01-01

    Report reviews fracture-mechanics technology for predicting life expectancy of structural components subjected to cyclic loads. Report covers analytical tools for modeling and forecasting subcritical fatigue-crack growth in structures. It emphasizes use of tools in practical, day-to-day problems of engineering design, development, and decisionmaking.

  4. Fatigue studies of polyurethane sandwich structures

    NASA Astrophysics Data System (ADS)

    Sharma, S. C.; Krishna, M.; Narasimha Murthy, H. N.; Sathyamoorthy, M.; Bhattacharya, Debes

    2004-10-01

    The fatigue characteristics of polyurethane foam-cored (PUF) composite sandwich structures were investigated using three-point bending tests carried out according to ASTM C 393. Three types of specimens (epoxy/glass-PUF-epoxy/glass, polyester/glass-PUF-polyester/glass, and epoxy/glass-PUF-polyester/glass) were considered for investigation. Experimental results indicate that degradation of stiffness occurs due to debonding and sliding between the skin and the foam during fatigue cycles. Epoxy/glass-PUF-epoxy/glass sandwich structures exhibit higher bending strength along with higher stiffness degradation than the other two types of sandwich panels, due to higher initial fatigue loading. The lowest fatigue properties have been obtained for the polyester/glass-PUF-polyester/glass sandwich panel specimens. Better performance of the epoxy/glass-PUF-epoxy/glass sandwich panels is most likely due to the superior properties of the outer thin skins. Most of the specimens fail within the foam region and not at the skin level. This situation is possibly due to debonding between the foam and the skin. The fatigue damage development in the foam and skin has been investigated using scanning electron microscopy.

  5. 14 CFR 27.571 - Fatigue evaluation of flight structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Fatigue evaluation of flight structure. 27... AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Fatigue Evaluation § 27.571 Fatigue evaluation of flight structure. (a) General. Each portion of the flight structure...

  6. 14 CFR 27.571 - Fatigue evaluation of flight structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Fatigue evaluation of flight structure. 27... AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Fatigue Evaluation § 27.571 Fatigue evaluation of flight structure. (a) General. Each portion of the flight structure...

  7. 14 CFR 27.571 - Fatigue evaluation of flight structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Fatigue evaluation of flight structure. 27... AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Fatigue Evaluation § 27.571 Fatigue evaluation of flight structure. (a) General. Each portion of the flight structure...

  8. 14 CFR 27.571 - Fatigue evaluation of flight structure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fatigue evaluation of flight structure. 27... AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Fatigue Evaluation § 27.571 Fatigue evaluation of flight structure. (a) General. Each portion of the flight structure...

  9. 14 CFR 27.571 - Fatigue evaluation of flight structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Fatigue evaluation of flight structure. 27... AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Fatigue Evaluation § 27.571 Fatigue evaluation of flight structure. (a) General. Each portion of the flight structure...

  10. Fatigue tests on big structure assemblies of concorde aircraft

    NASA Technical Reports Server (NTRS)

    Nguyen, V. P.; Perrais, J. P.

    1972-01-01

    Fatigue tests on structural assemblies of the Concorde supersonic transport aircraft are reported. Two main sections of the aircraft were subjected to pressure, mechanical load, and thermal static tests. The types of fatigue tests conducted and the results obtained are discussed. It was concluded that on a supersonic aircraft whose structural weight is a significant part of the weight analysis, many fatigue and static strength development tests should be made and fatigue and thermal tests of the structures are absolutely necessary.

  11. Fatigue reliability of cracked engineering structures

    NASA Astrophysics Data System (ADS)

    Lanning, David Bruce, Jr.

    1997-12-01

    This study investigates the reliability of engineering structures containing fatigue cracks. Stress concentrations and welded joints are probable locations for the initiation and propagation of fatigue cracks. Due to the many unknowns of loading, materials properties, crack sizes and crack shapes present at these locations, a statistics-based reliability analysis is valuable in the careful consideration of these many different random factors involved in a fatigue life analysis, several of which are expanded upon in this study. The basic problem of a crack near a stress concentration is first considered. A formulation for the aspect ratio (a/c) of a propagating semi-elliptical fatigue crack located at the toe of a welded T-joint is developed using Newman and Raju's stress intensity factor for a cracked flat plate with a weld magnification factor and compared to that of a cracked flat plate, and the reliability in terms of fatigue lifetime is calculated with the aid of Paris' crack propagation equation for membrane and bending loadings. Crack closure effects are then introduced in the consideration of short crack effects, where crack growth rates typically may exceed those found using traditional linear elastic fracture mechanics solutions for long cracks. The probability of a very small, microstructurally influenced crack growing to a size influenced by local plastic conditions is calculated utilizing the probability of a crack continuing to grow past an obstacle, such as a grain boundary. The result is then combined with the probability for failure defined using the crack closure-modified Paris equation to find an overall reliability for the structure. Last, the probability of fracture is determined when a crack front encounters regions of non-uniform toughness, such as typical in the heat affected zone of a welded joint. An expression for the effective crack lengths of the dissimilar regions is derived, and used in a weakest-link fracture model in the evaluation

  12. A comparative study of ship hull structures fatigue assessment methods

    NASA Astrophysics Data System (ADS)

    Petinov, Sergei V.; Polezhayeva, Helena A.; Yermolayeva, Natalya S.

    1992-07-01

    Several methods of fatigue assessment in ship hull structures are compared. The analysis is focused on fatigue problems of hull structures concerning: evaluation, the design state of fatigue damage of a structure formulation, and the adequacy of methods and data bases for the purpose of the analyses. To illustrate the discussion, examples of allowable nominal stress at a given fatigue life calculation are presented for bottom frame web slot and for a bottom longitudinal transverse bulkhead bracket connection in the case of a container ship. The low cycle (local strain) method is regarded as the most advantageous at present almost in all practical problems connected to fatigue.

  13. Fatigue Reliability of Gas Turbine Engine Structures

    NASA Technical Reports Server (NTRS)

    Cruse, Thomas A.; Mahadevan, Sankaran; Tryon, Robert G.

    1997-01-01

    The results of an investigation are described for fatigue reliability in engine structures. The description consists of two parts. Part 1 is for method development. Part 2 is a specific case study. In Part 1, the essential concepts and practical approaches to damage tolerance design in the gas turbine industry are summarized. These have evolved over the years in response to flight safety certification requirements. The effect of Non-Destructive Evaluation (NDE) methods on these methods is also reviewed. Assessment methods based on probabilistic fracture mechanics, with regard to both crack initiation and crack growth, are outlined. Limit state modeling techniques from structural reliability theory are shown to be appropriate for application to this problem, for both individual failure mode and system-level assessment. In Part 2, the results of a case study for the high pressure turbine of a turboprop engine are described. The response surface approach is used to construct a fatigue performance function. This performance function is used with the First Order Reliability Method (FORM) to determine the probability of failure and the sensitivity of the fatigue life to the engine parameters for the first stage disk rim of the two stage turbine. A hybrid combination of regression and Monte Carlo simulation is to use incorporate time dependent random variables. System reliability is used to determine the system probability of failure, and the sensitivity of the system fatigue life to the engine parameters of the high pressure turbine. 'ne variation in the primary hot gas and secondary cooling air, the uncertainty of the complex mission loading, and the scatter in the material data are considered.

  14. Structural response of transport airplanes in crash situations

    NASA Technical Reports Server (NTRS)

    Thomson, R. G.; Caiafa, C.

    1983-01-01

    This report highlights the results of contractural studies of transport accident data undertaken in a joint research program sponsored by the FAA and NASA. From these accident data studies it was concluded that the greatest potential for improved transport crashworthiness is in the reduction of fire related fatalities. Accident data pertaining to fuselage integrity, main landing gear collapse, fuel tank rupture, wing breaks, tearing of tank lower surfaces, and engine pod scrubbing are discussed. In those accidents where the energy absorbing protective capability of the fuselage structure is expended and the airplane experiences major structural damage, trauma caused fatalities are also discussed. The dynamic performance of current seat/restraint systems are examined but it is concluded that the accident data does not adequately define the relationship between occupant response and the dynamic interaction with the seat, floor and fuselage structure.

  15. Aircraft fatigue and crack growth considering loads by structural component

    NASA Technical Reports Server (NTRS)

    Yost, J. D.

    1994-01-01

    The indisputable 1968 C-130 fatigue/crack growth data is reviewed to obtain additional useful information on fatigue and crack growth. The proven Load Environment Model concept derived empirically from F-105D multichannel recorder data is refined to a simpler method by going from 8 to 5 variables in the spectra without a decrease in accuracy. This approach provides the true fatigue/crack growth and load environment by structural component for both fatigue and strength design. Methods are presented for defining fatigue scatter and damage at crack initiation. These design tools and criteria may be used for both metal and composite aircraft structure.

  16. 14 CFR 29.571 - Fatigue evaluation of structure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fatigue evaluation of structure. 29.571... § 29.571 Fatigue evaluation of structure. (a) General. An evaluation of the strength of principal... (including tolerance to flaws). The structure must be shown by analysis supported by test evidence and,...

  17. Airframe structural optimization for maximum fatigue life

    NASA Technical Reports Server (NTRS)

    Schrage, D. P.; Sareen, A. K.

    1990-01-01

    A methodology is outlined for optimization of airframe structures under dynamic constraints to maximize service life of specified fatigue-critical components. For practical airframe structures, this methodology describes the development of sensitivity analysis and computational procedures for constraints on the steady-state dynamic response displacements and stresses. Strain energy consideration is used for selection of structural members for modification. Development of a design model and its relation to an analysis model, as well as ways to reduce the dimensionality of the problem via approximation concepts, are described. This methodology is demonstrated using an elastic stick model for the MH-53J helicopter to show service life improvements of the hinge fold region.

  18. Fatigue

    MedlinePlus

    ... to help you find out what's causing your fatigue and recommend ways to relieve it. Fatigue itself is not a disease. Medical problems, treatments, and personal habits can add to fatigue. These include Taking certain medicines, such as antidepressants, ...

  19. 76 FR 3054 - Airworthiness Directives; The Boeing Company Model 777 Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-19

    ... Analysis of the effectiveness of applicable non- destructive inspection techniques to detect cracking and...). As airplanes gain service experience, or as the result of post- certification testing and evaluation... and testing of fatigue cracking of principal structural elements (PSE) on Model 777 airplanes,...

  20. Effect of interaction on landing-gear behavior and dynamic loads in a flexible airplane structure

    NASA Technical Reports Server (NTRS)

    Cook, Francis E; Milwitzky, Benjamin

    1956-01-01

    The effects of interaction between a landing gear and a flexible airplane structure on the behavior of the landing gear and the loads in the structure have been studied by treating the equations of motion of the airplane and the landing gear as a coupled system. The landing gear is considered to have nonlinear characteristics typical of conventional gears, namely, velocity-squared damping, polytropic air-compression springing, and exponential tire force-deflection characteristics. For the case where only two modes of the structure are considered, an equivalent three-mass system is derived for representing the airplane and landing-gear combination, which may be used to simulate the effects of structural flexibility in jig drop tests of landing gears. As examples to illustrate the effects of interaction, numerical calculations, based on the structural properties of two large airplanes having considerably different mass and flexibility characteristics, are presented.

  1. Acoustically induced structural fatigue of piping systems

    SciTech Connect

    Eisinger, F.L.; Francis, J.T.

    1999-11-01

    Piping systems handling high-pressure and high-velocity steam and various process and hydrocarbon gases through a pressure-reducing device can produce severe acoustic vibration and metal fatigue in the system. It has been previously shown that the acoustic fatigue of the piping system is governed by the relationship between fluid pressure drop and downstream Mach number, and the dimensionless pipe diameter/wall thickness geometry parameter. In this paper, the devised relationship is extended to cover acoustic fatigue considerations of medium and smaller-diameter piping systems.

  2. Computational simulation of acoustic fatigue for hot composite structures

    NASA Technical Reports Server (NTRS)

    Singhal, Surendra N.; Murthy, Pappu L. N.; Chamis, Christos C.; Nagpal, Vinod K.; Sutjahjo, Edhi

    1991-01-01

    Predictive methods/computer codes for the computational simulation of acoustic fatigue resistance of hot composite structures subjected to acoustic excitation emanating from an adjacent vibrating component are discussed. Select codes developed over the past two decades at the NASA Lewis Research Center are used. The codes include computation of acoustic noise generated from a vibrating component, degradation in material properties of a composite laminate at use temperature, dynamic response of acoustically excited hot multilayered composite structure, degradation in the first ply strength of the excited structure due to acoustic loading, and acoustic fatigue resistance of the excited structure, including the propulsion environment. Effects of the laminate lay-up and environment on the acoustic fatigue life are evaluated. The results show that, by keeping the angled plies on the outer surface of the laminate, a substantial increase in the acoustic fatigue life is obtained. The effect of environment (temperature and moisture) is to relieve the residual stresses leading to an increase in the acoustic fatigue life of the excited panel.

  3. Fatigue

    MedlinePlus

    Bennett RM. Fibromyalgia, chronic fatigue syndrome, and myofascial pain. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine . 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 274. Thames TA, Karrh ...

  4. 14 CFR 29.571 - Fatigue Tolerance Evaluation of Metallic Structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Fatigue Tolerance Evaluation of Metallic... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Fatigue Evaluation § 29.571 Fatigue Tolerance Evaluation of Metallic Structure. (a) A fatigue tolerance evaluation...

  5. Nonlinear analyses of composite aerospace structures in sonic fatigue

    NASA Technical Reports Server (NTRS)

    Mei, Chuh

    1993-01-01

    This report summarizes the semiannual research progress, accomplishments, and future plans performed under the NASA Langley Research Center Grant No. NAG-1-1358. The primary research effort of this project is the development of analytical methods for the prediction of nonlinear random response of composite aerospace structures subjected to combined acoustic and thermal loads. The progress, accomplishments, and future plates on four sonic fatigue research topics are described. The sonic fatigue design and passive control of random response of shape memory alloy hybrid composites presented in section 4, which is suited especially for HSCT, is a new initiative.

  6. Advances in Fatigue and Fracture Mechanics Analyses for Aircraft Structures

    NASA Technical Reports Server (NTRS)

    Newman, J. C., Jr.

    1999-01-01

    This paper reviews some of the advances that have been made in stress analyses of cracked aircraft components, in the understanding of the fatigue and fatigue-crack growth process, and in the prediction of residual strength of complex aircraft structures with widespread fatigue damage. Finite-element analyses of cracked structures are now used to determine accurate stress-intensity factors for cracks at structural details. Observations of small-crack behavior at open and rivet-loaded holes and the development of small-crack theory has lead to the prediction of stress-life behavior for components with stress concentrations under aircraft spectrum loading. Fatigue-crack growth under simulated aircraft spectra can now be predicted with the crack-closure concept. Residual strength of cracked panels with severe out-of-plane deformations (buckling) in the presence of stiffeners and multiple-site damage can be predicted with advanced elastic-plastic finite-element analyses and the critical crack-tip-opening angle (CTOA) fracture criterion. These advances are helping to assure continued safety of aircraft structures.

  7. Fatigue Testing of TBC on Structural Steel by Cyclic Bending

    NASA Astrophysics Data System (ADS)

    Musalek, Radek; Kovarik, Ondrej; Medricky, Jan; Curry, Nicholas; Bjorklund, Stefan; Nylen, Per

    2015-01-01

    For applications with variable loading, fatigue performance of coated parts is of utmost importance. In this study, fatigue performance of conventional structural steel coated with thermal barrier coating (TBC) was evaluated in cyclic bending mode by "SF-Test" device. Testing was carried out at each stage of the TBC preparation process, i.e., for as-received and grit-blasted substrates, as well as for samples with Ni-based bond-coat and complete TBC: bond-coat with YSZ-based top-coat. Comparison of results obtained for different loading amplitudes supplemented by fractographic analysis enabled identification of dominating failure mechanisms and demonstrated applicability of the high-frequency resonant bending test for evaluation of fatigue resistance alteration at each stage of the TBC deposition process.

  8. Design for prevention of acoustic fatigue. [of aircraft structures

    NASA Technical Reports Server (NTRS)

    Smith, H. W.

    1983-01-01

    It is pointed out that new noise prediction methods and acoustic life estimation methods have matured to the point where they can be combined into a unified engineering procedure. "Life derivatives" can be extracted from parametric charts to furnish design data for preventing acoustic fatigue. The acoustic fatigue life is shown to be sensitive to the damping ratio through the use of life derivatives. The localized nature of propeller noise can be quantified with an "isodecibel" contour diagram.Even though the peak sound pressure level may be high, the directional derivatives show the noise decay rates with distance. Acoustic fatigue design is discussed from the overall design methodology and is shown to be similar to other structural design problems. While nonlinearities present a formidable design engineering problem, they are manageable by proven semi-empirical techniques. For new design problems, it is imperative to determine whether the data base completely spans the design variables.

  9. Structural fatigue test results for large wind turbine blade sections

    NASA Technical Reports Server (NTRS)

    Faddoul, J. R.; Sullivan, T. L.

    1982-01-01

    In order to provide quantitative information on the operating life capabilities of wind turbine rotor blade concepts for root-end load transfer, a series of cantilever beam fatigue tests was conducted. Fatigue tests were conducted on a laminated wood blade with bonded steel studs, a low cost steel spar (utility pole) with a welded flange, a utility pole with additional root-end thickness provided by a swaged collar, fiberglass spars with both bonded and nonbonded fittings, and, finally, an aluminum blade with a bolted steel fitting (Lockheed Mod-0 blade). Photographs, data, and conclusions for each of these tests are presented. In addition, the aluminum blade test results are compared to field failure information; these results provide evidence that the cantilever beam type of fatigue test is a satisfactory method for obtaining qualitative data on blade life expectancy and for identifying structurally underdesigned areas (hot spots).

  10. Structural fatigue in the 34-meter HA-Dec antennas

    NASA Technical Reports Server (NTRS)

    Vanhek, R. A.; Saldua, B. P.

    1990-01-01

    Structural modifications to the 34-m hour-angle-declination antennas, coupled with the use of the antennas beyond their intended lifespans, have led to structural fatigue, as evidenced by damage to the declination drive gear and cracks on the structural members and gussets. An analysis and simulation were made of the main antenna structural members. The analysis showed that the total stress to the antenna structure substantially exceeds the maximum levels recommended by the American Institute of Steel Construction (AISC). Although each of the separate static conditions of stress is only 50 percent of the total stress and does not reach the AISC reduced yield limit, fatigue can and did occur, causing the material to crack in the weakest places.

  11. A computer program for cyclic plasticity and structural fatigue analysis

    NASA Technical Reports Server (NTRS)

    Kalev, I.

    1980-01-01

    A computerized tool for the analysis of time independent cyclic plasticity structural response, life to crack initiation prediction, and crack growth rate prediction for metallic materials is described. Three analytical items are combined: the finite element method with its associated numerical techniques for idealization of the structural component, cyclic plasticity models for idealization of the material behavior, and damage accumulation criteria for the fatigue failure.

  12. Mechanisms for fatigue and wear of polysilicon structural thinfilms

    SciTech Connect

    Alsem, Daniel Henricus

    2006-01-01

    Fatigue and wear in micron-scale polysilicon structural films can severely impact the reliability of microelectromechanical systems (MEMS). Despite studies on fatigue and wear behavior of these films, there is still an on-going debate regarding the precise physical mechanisms for these two important failure modes. Although macro-scale silicon does not fatigue, this phenomenon is observed in micron-scale silicon. It is shown that for polysilicon devices fabricated in the MUMPs foundry and SUMMiT process stress-lifetime data exhibits similar trends in ambient air, shorter lifetimes in higher relative humidity environments and no fatigue failure at all in high vacuum. Transmission electron microscopy of the surface oxides of the samples show an approximate four-fold thickening of the oxide at stress concentrations after fatigue failure, but no thickening after fracture in air or after fatigue cycling in vacuo. It is found that such oxide thickening and fatigue failure (in air) occurs in devices with initial oxide thicknesses of ~4-20 nm. Such results are interpreted and explained by a reaction layer fatigue mechanism; specifically, moisture-assisted subcritical cracking within a cyclic stress-assisted thickened oxide layer occurs until the crack reaches a critical size to cause catastrophic failure. Polysilicon specimens from the SUMMiT process are used to study wear mechanisms in micron-scale silicon in ambient air. Worn parts are examined by analytical scanning and transmission electron microscopy, while temperature changes are monitored using infrared microscopy. These results are compared with the development of values of static coefficients of friction (COF) with number of wear cycles. Observations show amorphous debris particles (~50-100 nm) created by fracture through the silicon grains (~500 nm), which subsequently oxidize, agglomerate into clusters and create plowing tracks. A nano-crystalline layer (~20-200 nm) forms at worn regions. No dislocations or

  13. The Dynairship. [structural design criteria and feasibility analysis of an airplane - airship

    NASA Technical Reports Server (NTRS)

    Miller, W. M., Jr.

    1975-01-01

    A feasibility analysis for the construction and use of a combination airplane-airship named 'Dynairship' is undertaken. Payload capacities, fuel consumption, and the structural design of the craft are discussed and compared to a conventional commercial aircraft (a Boeing 747). Cost estimates of construction and operation of the craft are also discussed. The various uses of the craft are examined (i.e, in police work, materials handling, and ocean surveillance), and aerodynamic configurations and photographs are shown.

  14. Analytical investigation of the landing dynamics of a large airplane with a load-control system in the main landing gear

    NASA Technical Reports Server (NTRS)

    Mcgehee, J. R.; Carden, H. D.

    1979-01-01

    The results of an evaluation of an active load-control landing gear computer program (ACOLAG) for predicting the landing dynamics of airplanes with passive and active main gears are presented. ACOLAG was used in an analytical investigation of the landing dynamics of a large airplane with both passive and active main gears. It was concluded that the program is valid for predicting the landing dynamics of airplanes with both passive and active main gears. It was shown that the active gear reduces airframe-gear forces and airplane motions following initial impact, and has the potential for significant reductions in structural fatigue damage relative to that which occurs with the passive gear.

  15. Computational Simulation of Composite Structural Fatigue

    NASA Technical Reports Server (NTRS)

    Minnetyan, Levon; Chamis, Christos C. (Technical Monitor)

    2005-01-01

    Progressive damage and fracture of composite structures subjected to monotonically increasing static, tension-tension cyclic, pressurization, and flexural cyclic loading are evaluated via computational simulation. Constituent material properties, stress and strain limits are scaled up to the structure level to evaluate the overall damage and fracture propagation for composites. Damage initiation, growth, accumulation, and propagation to fracture due to monotonically increasing static and cyclic loads are included in the simulations. Results show the number of cycles to failure at different temperatures and the damage progression sequence during different degradation stages. A procedure is outlined for use of computational simulation data in the assessment of damage tolerance, determination of sensitive parameters affecting fracture, and interpretation of results with insight for design decisions.

  16. Computational Simulation of Composite Structural Fatigue

    NASA Technical Reports Server (NTRS)

    Minnetyan, Levon

    2004-01-01

    Progressive damage and fracture of composite structures subjected to monotonically increasing static, tension-tension cyclic, pressurization, and flexural cyclic loading are evaluated via computational simulation. Constituent material properties, stress and strain limits are scaled up to the structure level to evaluate the overall damage and fracture propagation for composites. Damage initiation, growth, accumulation, and propagation to fracture due to monotonically increasing static and cyclic loads are included in the simulations. Results show the number of cycles to failure at different temperatures and the damage progression sequence during different degradation stages. A procedure is outlined for use of computational simulation data in the assessment of damage tolerance, determination of sensitive parameters affecting fracture, and interpretation of results with insight for design decisions.

  17. Equivalent linearization for fatigue life estimates of a nonlinear structure

    NASA Technical Reports Server (NTRS)

    Miles, R. N.

    1989-01-01

    An analysis is presented of the suitability of the method of equivalent linearization for estimating the fatigue life of a nonlinear structure. Comparisons are made of the fatigue life of a nonlinear plate as predicted using conventional equivalent linearization and three other more accurate methods. The excitation of the plate is assumed to be Gaussian white noise and the plate response is modeled using a single resonant mode. The methods used for comparison consist of numerical simulation, a probabalistic formulation, and a modification of equivalent linearization which avoids the usual assumption that the response process is Gaussian. Remarkably close agreement is obtained between all four methods, even for cases where the response is significantly linear.

  18. Effects of Range of Stress and of Special Notches on Fatigue Properties of Aluminum Alloys Suitable for Airplane Propellers

    NASA Technical Reports Server (NTRS)

    Dolan, Thomas J

    1942-01-01

    Laboratory tests were made to obtain information on the load-resisting properties of X76S-T aluminum alloy when subjected to static, impact, and repeated loads. Results are presented from static-load test of unnotched specimens in tension and in torsion and of notched specimens in tension. Charpy impact values obtained from bend tests on notched specimens and tension impact values for both notched and unnotched specimens tested at several different temperatures are included. The endurance limits obtained from repeated bending fatigue tests made on three different types of testing machine are given for unnotched polished specimens, and the endurance limits of notched specimens subjected to six different ranges of bending stress are also reported. The results indicated that: (a) polished rectangular specimens had an endurance limit about 30 percent less than that obtained for round specimens; (b) a comparison of endurance limits obtained from tests on three different types of machine indicated that there was no apparent effect of speed of testing on the endurance limit for the range of speeds used (1,750 to 13,000 rpm). (c) the fatigue strength (endurance limit) of the X76S-T alloy was greatly decreased by the presence of a notch in the specimens; (d) no complete fractures of the entire specimens occurred in notched fatigue specimens when subjected to stress cycles for which the mean stress at the notch during the cycle was a compressive stress; for this test condition a microscopic cracking occurred near the root of the notch and was used as a criterion of failure of the specimen. (e) as the mean stress at the notch was decreased from a tensile (+) stress to a compressive (-) stress, it was found that the alternating stress that could be superimposed on the mean stress in the cycle without causing failure of the specimens was increased.

  19. 76 FR 8316 - Special Conditions: Gulfstream Model GVI Airplane; Interaction of Systems and Structures

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-14

    ... stability of the airplane. These systems include the GVI's flight control systems, autopilots, stability... special condition for airplanes equipped with flight control systems, autopilots, stability augmentation... before flight. Certain elements of the control system, such as mechanical and hydraulic components,...

  20. Determination of airplane model structure from flight data by using modified stepwise regression

    NASA Technical Reports Server (NTRS)

    Klein, V.; Batterson, J. G.; Murphy, P. C.

    1981-01-01

    The linear and stepwise regressions are briefly introduced, then the problem of determining airplane model structure is addressed. The MSR was constructed to force a linear model for the aerodynamic coefficient first, then add significant nonlinear terms and delete nonsignificant terms from the model. In addition to the statistical criteria in the stepwise regression, the prediction sum of squares (PRESS) criterion and the analysis of residuals were examined for the selection of an adequate model. The procedure is used in examples with simulated and real flight data. It is shown that the MSR performs better than the ordinary stepwise regression and that the technique can also be applied to the large amplitude maneuvers.

  1. Heat sink structural design concepts for a hypersonic research airplane

    NASA Technical Reports Server (NTRS)

    Taylor, A. H.; Jackson, L. R.

    1977-01-01

    Hypersonic research aircraft design requires careful consideration of thermal stresses. This paper relates some of the problems in a heat sink structural design that can be avoided by appropriate selection of design options including material selection, design concepts, and load paths. Data on several thermal loading conditions are presented on various conventional designs including bulkheads, longerons, fittings, and frames. Results indicate that conventional designs are inadequate and that acceptable designs are possible by incorporating innovative design practices. These include nonintegral pressure compartments, ball-jointed links to distribute applied loads without restraining the thermal expansion, and material selections based on thermal compatibility.

  2. 14 CFR 29.571 - Fatigue evaluation of structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... elements, detail design points, and fabrication techniques must show that catastrophic failure due to... available, service experience to be of fatigue tolerant design. The fatigue tolerance evaluation must... limitations of geometry, inspectability, or good design practice. Under these circumstances, the...

  3. Structural integrity and fatigue crack propagation life assessment of welded and weld-repaired structures

    NASA Astrophysics Data System (ADS)

    Alam, Mohammad Shah

    2005-11-01

    Structural integrity is the science and technology of the margin between safety and disaster. Proper evaluation of the structural integrity and fatigue life of any structure (aircraft, ship, railways, bridges, gas and oil transmission pipelines, etc.) is important to ensure the public safety, environmental protection, and economical consideration. Catastrophic failure of any structure can be avoided if structural integrity is assessed and necessary precaution is taken appropriately. Structural integrity includes tasks in many areas, such as structural analysis, failure analysis, nondestructive testing, corrosion, fatigue and creep analysis, metallurgy and materials, fracture mechanics, fatigue life assessment, welding metallurgy, development of repairing technologies, structural monitoring and instrumentation etc. In this research fatigue life assessment of welded and weld-repaired joints is studied both in numerically and experimentally. A new approach for the simulation of fatigue crack growth in two elastic materials has been developed and specifically, the concept has been applied to butt-welded joint in a straight plate and in tubular joints. In the proposed method, the formation of new surface is represented by an interface element based on the interface potential energy. This method overcomes the limitation of crack growth at an artificial rate of one element length per cycle. In this method the crack propagates only when the applied load reaches the critical bonding strength. The predicted results compares well with experimental results. The Gas Metal Arc welding processes has been simulated to predict post-weld distortion, residual stresses and development of restraining forces in a butt-welded joint. The effect of welding defects and bi-axial interaction of a circular porosity and a solidification crack on fatigue crack propagation life of butt-welded joints has also been investigated. After a weld has been repaired, the specimen was tested in a universal

  4. Flight and analytical investigations of a structural mode excitation system on the YF-12A airplane

    NASA Technical Reports Server (NTRS)

    Goforth, E. A.; Murphy, R. C.; Beranek, J. A.; Davis, R. A.

    1987-01-01

    A structural excitation system, using an oscillating canard vane to generate force, was mounted on the forebody of the YF-12A airplane. The canard vane was used to excite the airframe structural modes during flight in the subsonic, transonic, and supersonic regimes. Structural modal responses generated by the canard vane forces were measured at the flight test conditions by airframe-mounted accelerometers. Correlations of analytical and experimental aeroelastic results were made. Doublet lattice, steady state double lattice with uniform lag, Mach box, and piston theory all produced acceptable analytical aerodynamic results within the restrictions that apply to each. In general, the aerodynamic theory methods, carefully applied, were found to predict the dynamic behavior of the YF-12A aircraft adequately.

  5. 30 CFR 250.908 - What are the minimum structural fatigue design requirements?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... (incorporated by reference as specified in 30 CFR 250.198), requires that the design fatigue life of each joint... OFFSHORE OIL AND GAS AND SULPHUR OPERATIONS IN THE OUTER CONTINENTAL SHELF Platforms and Structures Platform Approval Program § 250.908 What are the minimum structural fatigue design requirements? (a) API...

  6. 30 CFR 250.908 - What are the minimum structural fatigue design requirements?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., DEPARTMENT OF THE INTERIOR OFFSHORE OIL AND GAS AND SULPHUR OPERATIONS IN THE OUTER CONTINENTAL SHELF Platforms and Structures Platform Approval Program § 250.908 What are the minimum structural fatigue design... Platforms (as incorporated by reference in § 250.198), requires that the design fatigue life of each...

  7. 30 CFR 250.908 - What are the minimum structural fatigue design requirements?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., DEPARTMENT OF THE INTERIOR OFFSHORE OIL AND GAS AND SULPHUR OPERATIONS IN THE OUTER CONTINENTAL SHELF Platforms and Structures Platform Approval Program § 250.908 What are the minimum structural fatigue design... Platforms (as incorporated by reference in § 250.198), requires that the design fatigue life of each...

  8. 30 CFR 250.908 - What are the minimum structural fatigue design requirements?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., DEPARTMENT OF THE INTERIOR OFFSHORE OIL AND GAS AND SULPHUR OPERATIONS IN THE OUTER CONTINENTAL SHELF Platforms and Structures Platform Approval Program § 250.908 What are the minimum structural fatigue design... Platforms (as incorporated by reference in § 250.198), requires that the design fatigue life of each...

  9. Acoustic fatigue life prediction for nonlinear structures with multiple resonant modes

    NASA Technical Reports Server (NTRS)

    Miles, R. N.

    1992-01-01

    This report documents an effort to develop practical and accurate methods for estimating the fatigue lives of complex aerospace structures subjected to intense random excitations. The emphasis of the current program is to construct analytical schemes for performing fatigue life estimates for structures that exhibit nonlinear vibration behavior and that have numerous resonant modes contributing to the response.

  10. Dynamic response and acoustic fatigue of stiffened composite structure

    NASA Technical Reports Server (NTRS)

    Soovere, J.

    1984-01-01

    The results of acoustic fatigue and dynamic response tests performed on L-1011 graphite-epoxy (GrE) aileron and panel components are reported. The aileron featured glass microballoons between the GrE skins. Tests yielded random fatigue data from double and single cantilever coupons and modal data from impedance hammer and loudspeaker impulses. Numerical and sample test data were obtained on combined acoustic and shear loads, acoustic and thermal loads, random fatigue and damping of the integrally stiffened and secondary bonded panels. The fatigue data indicate a fatigue life beyond 10 million cycles. The acoustic data suggested that noise transmission could be enhanced in the integrally stiffened panels, which were more acoustic-fatigue resistant than were the secondary bonded panels.

  11. 14 CFR 25.571 - Damage-tolerance and fatigue evaluation of structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ..., detail design, and fabrication must show that catastrophic failure due to fatigue, corrosion...; (ii) The identification of principal structural elements and detail design points, the failure of... evidence, of the principal structural elements and detail design points identified in paragraph...

  12. 14 CFR 25.571 - Damage-tolerance and fatigue evaluation of structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ..., detail design, and fabrication must show that catastrophic failure due to fatigue, corrosion...; (ii) The identification of principal structural elements and detail design points, the failure of... evidence, of the principal structural elements and detail design points identified in paragraph...

  13. 76 FR 10288 - Airworthiness Directives; The Boeing Company Model 767-200, -300, -300F, and -400ER Series Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-24

    ... straps on 41 airplanes; we have also received a report of a crack found in the ``T'' fitting that... necessary. We are proposing this AD to detect and correct fatigue cracking or corrosion of the fail-safe straps and the ``T'' fittings, which could result in cracking of adjacent structure and...

  14. 76 FR 74655 - Damage Tolerance and Fatigue Evaluation of Composite Rotorcraft Structures

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-01

    ... static strength of composite rotorcraft structures using a damage tolerance evaluation, or a fatigue... also harmonize this standard with international standards for evaluating the fatigue strength of normal... damage and loading conditions. This rule addresses the unique characteristics of composite materials...

  15. Large Area Nondestructive Evaluation of a Fatigue Loaded Composite Structure

    NASA Technical Reports Server (NTRS)

    Zalameda, Joseph N.; Burke, Eric R.; Horne, Michael R.; Madaras, Eric I.

    2016-01-01

    Large area nondestructive evaluation (NDE) inspections are required for fatigue testing of composite structures to track damage initiation and growth. Of particular interest is the progression of damage leading to ultimate failure to validate damage progression models. In this work, passive thermography and acoustic emission NDE were used to track damage growth up to failure of a composite three-stringer panel. Fourteen acoustic emission sensors were placed on the composite panel. The signals from the array were acquired simultaneously and allowed for acoustic emission location. In addition, real time thermal data of the composite structure were acquired during loading. Details are presented on the mapping of the acoustic emission locations directly onto the thermal imagery to confirm areas of damage growth leading to ultimate failure. This required synchronizing the acoustic emission and thermal data with the applied loading. In addition, processing of the thermal imagery which included contrast enhancement, removal of optical barrel distortion and correction of angular rotation before mapping the acoustic event locations are discussed.

  16. Incorporating mesh-insensitive structural stress into the fatigue assessment procedure of common structural rules for bulk carriers

    NASA Astrophysics Data System (ADS)

    Kim, Seong-Min; Kim, Myung-Hyun

    2015-01-01

    This study introduces a fatigue assessment procedure using mesh-insensitive structural stress method based on the Common Structural Rules for Bulk Carriers by considering important factors, such as mean stress and thickness effects. The fatigue assessment result of mesh-insensitive structural stress method have been compared with CSR procedure based on equivalent notch stress at major hot spot points in the area near the ballast hold for a 180 K bulk carrier. The possibility of implementing mesh-insensitive structural stress method in the fatigue assessment procedure for ship structures is discussed.

  17. MLS: Airplane system modeling

    NASA Technical Reports Server (NTRS)

    Thompson, A. D.; Stapleton, B. P.; Walen, D. B.; Rieder, P. F.; Moss, D. G.

    1981-01-01

    Analysis, modeling, and simulations were conducted as part of a multiyear investigation of the more important airplane-system-related items of the microwave landing system (MLS). Particular emphasis was placed upon the airplane RF system, including the antenna radiation distribution, the cabling options from the antenna to the receiver, and the overall impact of the airborne system gains and losses upon the direct-path signal structure. In addition, effort was expended toward determining the impact of the MLS upon the airplane flight management system and developing the initial stages of a fast-time MLS automatic control system simulation model. Results ot these studies are presented.

  18. Designing piping systems against acoustically-induced structural fatigue

    SciTech Connect

    Eisinger, F.L.

    1996-12-01

    Piping systems adapted for handling fluids such as steam and various process and hydrocarbon gases through a pressure-reducing device at high pressure and velocity conditions can produce severe acoustic vibration and metal fatigue in the system. It has been determined that such vibrations and fatigue are minimized by relating the acoustic power level (PWL) to being a function of the ratio of downstream pipe inside diameter D{sub 2} to its thickness t{sub 2}. Additionally, such vibration and fatigue can be further minimized by relating the fluid pressure drop and downstream mach number to a function of the ratio of downstream piping inside diameter to the pipe wall thickness, as expressed by M{sub 2} {Delta}p = f(D{sub 2}/t{sub 2}). Pressure-reducing piping systems designed according to these criteria exhibit minimal vibrations and metal fatigue failures and have long operating life.

  19. Transition behavior in fatigue of human dentin: structure and anisotropy.

    PubMed

    Arola, D; Reid, J; Cox, M E; Bajaj, D; Sundaram, N; Romberg, E

    2007-09-01

    The influence of tubule orientation on the transition from fatigue to fatigue crack growth in human dentin was examined. Compact tension (CT) and rectangular beam specimens were prepared from the coronal dentin of molars with three unique tubule orientations (i.e., 0 degrees , 45 degrees and 90 degrees). The CT specimens (N=25) were used to characterize fatigue crack initiation and steady-state cyclic extension, whereas the rectangular beams (N=132) were subjected to 4-pt flexure and used in quantifying the stress-life fatigue response. The transition behavior was analyzed using both the Kitagawa-Takahashi and El Haddad approaches. Results showed that both the fatigue crack growth and stress-life responses were dependent on the tubule orientation. The average Paris Law exponent for crack growth perpendicular (90 degrees) to the tubules (m=13.3+/-1.1) was significantly greater (p<0.05) than that for crack growth oblique (45 degrees) to the tubules (m=11.5+/-1.87). Similarly, the fatigue strength of dentin with 90 degrees tubule orientation was significantly lower (p<0.05) than that for the other two orientations, regardless of the range of cyclic stress. The apparent endurance strengths of specimens with 0 degrees (44MPa) and 45 degrees (53MPa) orientations were nearly twice that of the 90 degrees (24MPa) orientation. Based on these results, human dentin exhibits the largest degree of anisotropy within the stress-life regime and the transition from fatigue to fatigue crack growth occurs under the lowest cyclic stress range when the tubules are aligned with the cyclic normal stress (90 degrees orientation).

  20. A high temperature fatigue and structures testing facility

    NASA Technical Reports Server (NTRS)

    Bartolotta, Paul A.; Mcgaw, Michael A.

    1987-01-01

    As man strives for higher levels of sophistication in air and space transportation, awareness of the need for accurate life and material behavior predictions for advanced propulsion system components is heightened. Such sophistication will require complex operating conditions and advanced materials to meet goals in performance, thrust-to-weight ratio, and fuel efficiency. To accomplish these goals will require that components be designed using a high percentage of the material's ultimate capabilities. This serves only to complicate matters dealing with life and material behavior predictions. An essential component of material behavior model development is the underlying experimentation which must occur to identify phenomena. To support experimentation, the NASA Lewis Research Center's High Temperature Fatigue and Structures Laboratory has been expanded significantly. Several new materials testing systems have been added, as well as an extensive computer system. The intent of this paper is to present an overview of the laboratory, and to discuss specific aspects of the test systems. A limited discussion of computer capabilities will also be presented.

  1. Sliding contact fatigue damage in layered ceramic structures.

    PubMed

    Kim, J-W; Kim, J-H; Thompson, V P; Zhang, Y

    2007-11-01

    Porcelain-veneered restorations often chip and fracture from repeated occlusal loading, making fatigue studies relevant. Most fatigue studies are limited to uni-axial loading without sliding motion. We hypothesized that bi-axial loading (contact-load-slide-liftoff, simulating a masticatory cycle), as compared with uni-axial loading, accelerates the fatigue of layered ceramics. Monolithic glass plates were epoxy-joined to polycarbonate substrates as a transparent model for an all-ceramic crown on dentin. Uni-and bi-axial cyclic contact was applied through a hard sphere in water, by means of a mouth-motion simulator apparatus. The uni-axial (contact-load-hold-liftoff) and traditional R-ratio fatigue (indenter never leaves the specimen surface) produced similar lifespans, while bi-axial fatigue was more severe. The accelerated crack growth rate in bi-axial fatigue is attributed to enhanced tensile stresses at the trailing edges of a moving indenter. Fracture mechanics descriptions for damage evolution in brittle materials loaded repeatedly with a sliding sphere are provided. Clinical relevance is addressed.

  2. Improved aircraft dynamic response and fatigue life during ground operations using an active control landing gear system

    NASA Technical Reports Server (NTRS)

    Mcgehee, J. R.; Carden, H. D.; Edson, R.

    1978-01-01

    A three-degree-of-freedom aircraft landing analysis incorporating a series-hydraulic active control main landing gear has been developed and verified using preliminary experimental data from drop tests of a modified main landing gear from a 2722 kg (6000 lbm) class of airplane. The verified analysis was also employed to predict the landing dynamics of a supersonic research airplane with an active control main landing gear system. The results of this investigation have shown that this type of active gear is feasible and indicate a potential for improving airplane dynamic response and reducing structural fatigue damage during ground operations by approximately 90% relative to that incurred with the passive gear.

  3. FASTRAN II - FATIGUE CRACK GROWTH STRUCTURAL ANALYSIS (UNIX VERSION)

    NASA Technical Reports Server (NTRS)

    Newman, J. C.

    1994-01-01

    Predictions of fatigue crack growth behavior can be made with the Fatigue Crack Growth Structural Analysis (FASTRAN II) computer program. As cyclic loads are applied to a selected crack configuration with an initial crack size, FASTRAN II predicts crack growth as a function of cyclic load history until either a desired crack size is reached or failure occurs. FASTRAN II is based on plasticity-induced crack-closure behavior of cracks in metallic materials and accounts for load-interaction effects, such as retardation and acceleration, under variable-amplitude loading. The closure model is based on the Dugdale model with modifications to allow plastically deformed material to be left along the crack surfaces as the crack grows. Plane stress and plane strain conditions, as well as conditions between these two, can be simulated in FASTRAN II by using a constraint factor on tensile yielding at the crack front to approximately account for three-dimensional stress states. FASTRAN II contains seventeen predefined crack configurations (standard laboratory fatigue crack growth rate specimens and many common crack configurations found in structures); and the user can define one additional crack configuration. The baseline crack growth rate properties (effective stress-intensity factor against crack growth rate) may be given in either equation or tabular form. For three-dimensional crack configurations, such as surface cracks or corner cracks at holes or notches, the fatigue crack growth rate properties may be different in the crack depth and crack length directions. Final failure of the cracked structure can be modelled with fracture toughness properties using either linear-elastic fracture mechanics (brittle materials), a two-parameter fracture criterion (brittle to ductile materials), or plastic collapse (extremely ductile materials). The crack configurations in FASTRAN II can be subjected to either constant-amplitude, variable-amplitude or spectrum loading. The applied

  4. FASTRAN II - FATIGUE CRACK GROWTH STRUCTURAL ANALYSIS (IBM PC VERSION)

    NASA Technical Reports Server (NTRS)

    Newman, J. C.

    1994-01-01

    Predictions of fatigue crack growth behavior can be made with the Fatigue Crack Growth Structural Analysis (FASTRAN II) computer program. As cyclic loads are applied to a selected crack configuration with an initial crack size, FASTRAN II predicts crack growth as a function of cyclic load history until either a desired crack size is reached or failure occurs. FASTRAN II is based on plasticity-induced crack-closure behavior of cracks in metallic materials and accounts for load-interaction effects, such as retardation and acceleration, under variable-amplitude loading. The closure model is based on the Dugdale model with modifications to allow plastically deformed material to be left along the crack surfaces as the crack grows. Plane stress and plane strain conditions, as well as conditions between these two, can be simulated in FASTRAN II by using a constraint factor on tensile yielding at the crack front to approximately account for three-dimensional stress states. FASTRAN II contains seventeen predefined crack configurations (standard laboratory fatigue crack growth rate specimens and many common crack configurations found in structures); and the user can define one additional crack configuration. The baseline crack growth rate properties (effective stress-intensity factor against crack growth rate) may be given in either equation or tabular form. For three-dimensional crack configurations, such as surface cracks or corner cracks at holes or notches, the fatigue crack growth rate properties may be different in the crack depth and crack length directions. Final failure of the cracked structure can be modelled with fracture toughness properties using either linear-elastic fracture mechanics (brittle materials), a two-parameter fracture criterion (brittle to ductile materials), or plastic collapse (extremely ductile materials). The crack configurations in FASTRAN II can be subjected to either constant-amplitude, variable-amplitude or spectrum loading. The applied

  5. An Energy Based Fatigue Life Prediction Framework for In-Service Structural Components

    SciTech Connect

    H. Ozaltun; M. H.H. Shen; T. George; C. Cross

    2011-06-01

    An energy based fatigue life prediction framework has been developed for calculation of remaining fatigue life of in service gas turbine materials. The purpose of the life prediction framework is to account aging effect caused by cyclic loadings on fatigue strength of gas turbine engines structural components which are usually designed for very long life. Previous studies indicate the total strain energy dissipated during a monotonic fracture process and a cyclic process is a material property that can be determined by measuring the area underneath the monotonic true stress-strain curve and the sum of the area within each hysteresis loop in the cyclic process, respectively. The energy-based fatigue life prediction framework consists of the following entities: (1) development of a testing procedure to achieve plastic energy dissipation per life cycle and (2) incorporation of an energy-based fatigue life calculation scheme to determine the remaining fatigue life of in-service gas turbine materials. The accuracy of the remaining fatigue life prediction method was verified by comparison between model approximation and experimental results of Aluminum 6061-T6. The comparison shows promising agreement, thus validating the capability of the framework to produce accurate fatigue life prediction.

  6. Numerical simulation of the fatigue behavior of additive manufactured titanium porous lattice structures.

    PubMed

    Zargarian, A; Esfahanian, M; Kadkhodapour, J; Ziaei-Rad, S

    2016-03-01

    In this paper, the effects of cell geometry and relative density on the high-cycle fatigue behavior of Titanium scaffolds produced by selective laser melting and electron beam melting techniques were numerically investigated by finite element analysis. The regular titanium lattice samples with three different unit cell geometries, namely, diamond, rhombic dodecahedron and truncated cuboctahedron, and the relative density range of 0.1-0.3 were analyzed under uniaxial cyclic compressive loading. A failure event based algorithm was employed to simulate fatigue failure in the cellular material. Stress-life approach was used to model fatigue failure of both bulk (struts) and cellular material. The predicted fatigue life and the damage pattern of all three structures were found to be in good agreement with the experimental fatigue investigations published in the literature. The results also showed that the relationship between fatigue strength and cycles to failure obeyed the power law. The coefficient of power function was shown to depend on relative density, geometry and fatigue properties of the bulk material while the exponent was only dependent on the fatigue behavior of the bulk material. The results also indicated the failure surface at an angle of 45° to the loading direction. PMID:26706539

  7. Numerical simulation of the fatigue behavior of additive manufactured titanium porous lattice structures.

    PubMed

    Zargarian, A; Esfahanian, M; Kadkhodapour, J; Ziaei-Rad, S

    2016-03-01

    In this paper, the effects of cell geometry and relative density on the high-cycle fatigue behavior of Titanium scaffolds produced by selective laser melting and electron beam melting techniques were numerically investigated by finite element analysis. The regular titanium lattice samples with three different unit cell geometries, namely, diamond, rhombic dodecahedron and truncated cuboctahedron, and the relative density range of 0.1-0.3 were analyzed under uniaxial cyclic compressive loading. A failure event based algorithm was employed to simulate fatigue failure in the cellular material. Stress-life approach was used to model fatigue failure of both bulk (struts) and cellular material. The predicted fatigue life and the damage pattern of all three structures were found to be in good agreement with the experimental fatigue investigations published in the literature. The results also showed that the relationship between fatigue strength and cycles to failure obeyed the power law. The coefficient of power function was shown to depend on relative density, geometry and fatigue properties of the bulk material while the exponent was only dependent on the fatigue behavior of the bulk material. The results also indicated the failure surface at an angle of 45° to the loading direction.

  8. Stall-proof Airplanes

    NASA Technical Reports Server (NTRS)

    Lachmann, G

    1927-01-01

    My lecture has to do with the following questions. Is the danger of stalling necessarily inherent in the airplane in its present form and structure, or can it be diminished or eliminated by suitable means? Do we possess such means or devices and how must they operate? In this connection I will devote special attention to the exhibition of stall-proof airplanes by Fokker under the auspices of the English Air Ministry, which took place in Croyden last April.

  9. 76 FR 36865 - Special Conditions: Gulfstream Model GVI Airplane; Interaction of Systems and Structures

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-23

    ... also affect the aeroelastic stability of the airplane. These systems include the GVI's flight control... flight control systems, autopilots, stability augmentation systems, load alleviation systems, fuel... nonlinearity (rate of displacement of control surface, thresholds or any other system nonlinearities) must...

  10. Blended Buffet-Load-Alleviation System for Fighter Airplane

    NASA Technical Reports Server (NTRS)

    Moses, Robert W.

    2005-01-01

    The capability of modern fighter airplanes to sustain flight at high angles of attack and/or moderate angles of sideslip often results in immersion of part of such an airplane in unsteady, separated, vortical flow emanating from its forebody or wings. The flows from these surfaces become turbulent and separated during flight under these conditions. These flows contain significant levels of energy over a frequency band coincident with that of low-order structural vibration modes of wings, fins, and control surfaces. The unsteady pressures applied to these lifting surfaces as a result of the turbulent flows are commonly denoted buffet loads, and the resulting vibrations of the affected structures are known as buffeting. Prolonged exposure to buffet loads has resulted in fatigue of structures on several airplanes. Damage to airplanes caused by buffeting has led to redesigns of airplane structures and increased support costs for the United States Air Force and Navy as well as the armed forces of other countries. Time spent inspecting, repairing, and replacing structures adversely affects availability of aircraft for missions. A blend of rudder-control and piezoelectric- actuator engineering concepts was selected as a basis for the design of a vertical-tail buffet-load-alleviation system for the F/A-18 airplane. In this system, the rudder actuator is used to control the response of the first tail vibrational mode (bending at a frequency near 15 Hz), while directional patch piezoelectric actuators are used to control the second tail vibrational mode (tip torsion at a frequency near 45 Hz). This blend of two types of actuator utilizes the most effective features of each. An analytical model of the aeroservoelastic behavior of the airplane equipped with this system was validated by good agreement with measured results from a full-scale ground test, flight-test measurement of buffet response, and an in-flight commanded rudder frequency sweep. The overall performance of the

  11. Functional and structural balances of homologous sensorimotor regions in multiple sclerosis fatigue.

    PubMed

    Cogliati Dezza, I; Zito, G; Tomasevic, L; Filippi, M M; Ghazaryan, A; Porcaro, C; Squitti, R; Ventriglia, M; Lupoi, D; Tecchio, F

    2015-03-01

    Fatigue in multiple sclerosis (MS) is a highly disabling symptom. Among the central mechanisms behind it, an involvement of sensorimotor networks is clearly evident from structural and functional studies. We aimed at assessing whether functional/structural balances of homologous sensorimotor regions-known to be crucial for sensorimotor networks effectiveness-decrease with MS fatigue increase. Functional connectivity measures at rest and during a simple motor task (weak handgrip of either the right or left hand) were derived from primary sensorimotor areas electroencephalographic recordings in 27 mildly disabled MS patients. Structural MRI-derived inter-hemispheric asymmetries included the cortical thickness of Rolandic regions and the volume of thalami. Fatigue symptoms increased together with the functional inter-hemispheric imbalance of sensorimotor homologous areas activities at rest and during movement, in absence of any appreciable parenchymal asymmetries. This finding supports the development of compensative interventions that may revert these neuronal activity imbalances to relieve fatigue in MS.

  12. Al-Li alloy AA2198's very high cycle fatigue crack initiation mechanism and its fatigue thermal effect

    NASA Astrophysics Data System (ADS)

    Xu, Luopeng; Cao, Xiaojian; Chen, Yu; Wang, Qingyuan

    2015-10-01

    AA2198 alloy is one of the third generation Al-Li alloys which have low density, high elastic modulus, high specific strength and specific stiffness. Compared With the previous two generation Al-Li alloys, the third generation alloys have much improved in alloys strength, corrosion resistance and weldable characteristic. For these advantages, the third generation Al-Li alloys are used as aircraft structures, such as C919 aviation airplane manufactured by China and Russia next generation aviation airplane--MS-21. As we know, the aircraft structures are usually subjected to more than 108 cycles fatigue life during 20-30 years of service, however, there is few reported paper about the third generation Al-Li alloys' very high cycle fatigue(VHCF) which is more than 108 cycles fatigue. The VHCF experiment of AA2198 have been carried out. The two different initiation mechanisms of fatigue fracture have been found in VHCF. The cracks can initiate from the interior of the testing material with lower stress amplitude and more than 108 cycles fatigue life, or from the surface or subsurface of material which is the dominant reason of fatigue failures. During the experiment, the infrared technology is used to monitor the VHCF thermal effect. With the increase of the stress, the temperature of sample is also rising up, increasing about 15 °C for every 10Mpa. The theoretical thermal analysis is also carried out.

  13. Static-fatigue behavior of structural ceramics in a corrosive environment. Final report

    SciTech Connect

    Swab, J.J.; Leatherman, G.L.

    1990-06-01

    Flexure testing was used to determine the effects of sodium sulfate induced corrosion on the static fatigue behavior of several structural ceramics between 800 C and 1200 C. The results showed that the static fatigue behavior of a high purity, full-dense alumina and a Ce-TZP are unaffected by this corrosive environment. However, the static fatigue behavior of a MgO-doped Si3N4 and, to a lesser degree, a Y-TZP are affected by the introduction of sodium sulfate.

  14. Lewis Structures Technology, 1988. Volume 3: Structural Integrity Fatigue and Fracture Wind Turbines HOST

    NASA Technical Reports Server (NTRS)

    1988-01-01

    The charter of the Structures Division is to perform and disseminate results of research conducted in support of aerospace engine structures. These results have a wide range of applicability to practioners of structural engineering mechanics beyond the aerospace arena. The specific purpose of the symposium was to familiarize the engineering structures community with the depth and range of research performed by the division and its academic and industrial partners. Sessions covered vibration control, fracture mechanics, ceramic component reliability, parallel computing, nondestructive evaluation, constitutive models and experimental capabilities, dynamic systems, fatigue and damage, wind turbines, hot section technology (HOST), aeroelasticity, structural mechanics codes, computational methods for dynamics, structural optimization, and applications of structural dynamics, and structural mechanics computer codes.

  15. 77 FR 4890 - Damage Tolerance and Fatigue Evaluation for Composite Rotorcraft Structures, and Damage Tolerance...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-01

    ... Composite Rotorcraft Structures'' (76 FR 74655), published December 1, 2011, and ``Damage Tolerance and... Tolerance and Fatigue Evaluation for Composite Rotorcraft Structures'' (76 FR 74655). On December 2, 2011... Structures'' (76 FR 75435). In the ``Composite Rotorcraft Structures'' final rule, the FAA amended...

  16. Fatigue Life of Postbuckled Structures with Indentation Damages

    NASA Technical Reports Server (NTRS)

    Davila, Carlos G.; Bisagni, Chiara

    2016-01-01

    The fatigue life of composite stiffened panels with indentation damage was investigated experimentally using single stringer compression specimens. Indentation damage was induced on one of the two flanges of each stringer. The experiments were conducted using advanced instrumentation, including digital image correlation, passive thermography, and in-situ ultrasonic scanning. Specimens with initial indentation damage lengths of 32 millimeters to 56 millimeters were tested quasi-statically and in fatigue, and the effects of cyclic load amplitude and damage size were studied. A means of comparison of the damage propagation rates and collapse loads based on a stress intensity measure and the Paris law is proposed.

  17. Fatigue Life of Postbuckled Structures with Indentation Damage

    NASA Technical Reports Server (NTRS)

    Davila, Carlos G.; Bisagni, Chiara

    2016-01-01

    The fatigue life of composite stiffened panels with indentation damage was investigated experimentally using single stringer compression specimens. Indentation damage was induced on one of the two flanges of the stringer. The experiments were conducted using advanced instrumentation, including digital image correlation, passive thermography, and in-situ ultrasonic scanning. Specimens with initial indentation damage lengths of 37 millimeters to 56 millimeters were tested in fatigue and the effects of cyclic load amplitude and damage size were studied. A means of comparison of the damage propagation rates and collapse loads based on a stress intensity measure and the Paris law is proposed.

  18. 14 CFR 29.571 - Fatigue evaluation of structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... stresses for items in paragraph (a)(1)(i) of this section in all critical conditions throughout the range... expected in operation based on loads or stresses determined under paragraph (a)(1)(ii) of this section... this section must include: (1) In-flight measurements to determine the fatigue loads or stresses...

  19. 76 FR 75435 - Fatigue Tolerance Evaluation of Metallic Structures

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-02

    ... failure may occur due to aging, temperature, moisture absorption, impact damage, or other factors. Since a... operation. About that same time, rotorcraft manufacturers were introducing advanced composite materials for... fatigue-strength reduction effects due to aging, temperature, moisture absorption, impact damage,...

  20. Fatigue analysis of chevron structures with Z shape arms

    NASA Astrophysics Data System (ADS)

    Tecpoyotl Torres, Margarita; Cabello Ruiz, Ramón; Vera Dimas, J. G.; Rodriguez Ramirez, J. Alfredo; Escobedo Alatorre, J. Jesus; Ocampo Diaz, Alejandra

    2015-08-01

    Due to the diversity and multiple energy domains involved, Micro-Electromechanical Systems MEMS devices are vulnerable to several mechanical failures such as fatigue. They been widely used in military applications, radio frequency systems, pressure sensors, automotive industry, among several others. Most MEMS devices contain moving parts that are subjected to cyclic loading, which degrade the devicés efficiency. Due to the high importance of MEMS in various applications, it is necessary to know their lifetime to prevent any damage or process discontinuity to which the system is subject. There have been several investigations in particular on the fatigue analysis in presence of cracks, however in terms of lifetime under cycling load, information is not abundant. The fatigue analysis can be performed for characterizing the ability of materials to support many cycles. Some parts of systems are exposed to strong stress level experiences during its usable lifetime, so the analysis must be focused on them. In this paper, a simulated fatigue analysis of classic, Z-shape and optimized chevron with Z shape arms is shown. Simulations are made using Ansys 15.0, to obtain the arms lifetime of the system because they are subjected to greater stresses in the presence of cyclic loading.

  1. An Investigation of High-Cycle Fatigue Models for Metallic Structures Exhibiting Snap-Through Response

    NASA Technical Reports Server (NTRS)

    Przekop, Adam; Rizzi, Stephen A.; Sweitzer, Karl A.

    2007-01-01

    A study is undertaken to develop a methodology for determining the suitability of various high-cycle fatigue models for metallic structures subjected to combined thermal-acoustic loadings. Two features of this problem differentiate it from the fatigue of structures subject to acoustic loading alone. Potentially large mean stresses associated with the thermally pre- and post-buckled states require models capable of handling those conditions. Snap-through motion between multiple post-buckled equilibrium positions introduces very high alternating stress. The thermal-acoustic time history response of a clamped aluminum beam structure with geometric and material nonlinearities is determined via numerical simulation. A cumulative damage model is employed using a rainflow cycle counting scheme and fatigue estimates are made for 2024-T3 aluminum using various non-zero mean fatigue models, including Walker, Morrow, Morrow with true fracture strength, and MMPDS. A baseline zero-mean model is additionally considered. It is shown that for this material, the Walker model produces the most conservative fatigue estimates when the stress response has a tensile mean introduced by geometric nonlinearity, but remains in the linear elastic range. However, when the loading level is sufficiently high to produce plasticity, the response becomes more fully reversed and the baseline, Morrow, and Morrow with true fracture strength models produce the most conservative fatigue estimates.

  2. Balance Fatigue Design of Cast Steel Nodes in Tubular Steel Structures

    PubMed Central

    Wang, Libin; Jin, Hui; Li, Jing

    2013-01-01

    Cast steel nodes are being increasingly popular in steel structure joint application as their advanced mechanical performances and flexible forms. This kind of joints improves the structural antifatigue capability observably and is expected to be widely used in the structures with fatigue loadings. Cast steel node joint consists of two parts: casting itself and the welds between the node and the steel member. The fatigue resistances of these two parts are very different; the experiment results showed very clearly that the fatigue behavior was governed by the welds in all tested configurations. This paper focuses on the balance fatigue design of these two parts in a cast steel node joint using fracture mechanics and FEM. The defects in castings are simulated by cracks conservatively. The final crack size is decided by the minimum of 90% of the wall thickness and the value deduced by fracture toughness. The allowable initial crack size could be obtained through the integral of Paris equation when the crack propagation life is considered equal to the weld fatigue life; therefore, the two parts in a cast steel node joint will have a balance fatigue life. PMID:24163621

  3. The X-15 airplane - Lessons learned

    NASA Technical Reports Server (NTRS)

    Dana, William H.

    1993-01-01

    The X-15 rocket research airplane flew to an altitude of 354,000 ft and reached Mach 6.70. In almost 200 flights, this airplane was used to gather aerodynamic-heating, structural loads, stability and control, and atmospheric-reentry data. This paper describes the origins, design, and operation of the X-15 airplane. In addition, lessons learned from the X-15 airplane that are applicable to designing and testing the National Aero-Space Plane are discussed.

  4. Effects of Aging Structures and Humidity on Fatigue Properties of Maraging Steel

    NASA Astrophysics Data System (ADS)

    Hayashi, Kousuke; Nagano, Takanori; Moriyama, Michihiko; Wang, Xishu; Kawagoishi, Norio

    Effects of aging structures and humidity on fatigue properties of 350 grade 18% Ni maraging steel were investigated under rotating bending in relative humidity of 25% and 85%. Aging conditions tested were a conventional single aging and a double one which was aged at low temperature after the conventional aging. In each aging, under and peak aged steels were prepared. Tensile strength was increased by the double aging without reduction of the ductility. Proportional relation between fatigue limit and Vickers hardness held until 750HV in low humidity. However fatigue strength was largely decreased by high humidity, especially in the peak aged steel at the single aging. The decrease in fatigue strength by high humidity was mainly caused by the acceleration of a crack initiation due to the anodic dissolution. The acceleration of a crack initiation was larger in the steel peak aged at the single aging with larger precipitated particles.

  5. Analysis of fatigue, fatique-crack propagation, and fracture data. [design of metallic aerospace structural components

    NASA Technical Reports Server (NTRS)

    Jaske, C. E.; Feddersen, C. E.; Davies, K. B.; Rice, R. C.

    1973-01-01

    Analytical methods have been developed for consolidation of fatigue, fatigue-crack propagation, and fracture data for use in design of metallic aerospace structural components. To evaluate these methods, a comprehensive file of data on 2024 and 7075 aluminums, Ti-6A1-4V, and 300M and D6Ac steels was established. Data were obtained from both published literature and unpublished reports furnished by aerospace companies. Fatigue and fatigue-crack-propagation analyses were restricted to information obtained from constant-amplitude load or strain cycling of specimens in air at room temperature. Fracture toughness data were from tests of center-cracked tension panels, part-through crack specimens, and compact-tension specimens.

  6. Relationship between pore structure and mechanical properties of ordinary concrete under bending fatigue

    SciTech Connect

    Zhang, B.

    1998-05-01

    Progressive macro damage of concrete under fatigue loading is caused by the change of its internal micro-meso properties such as pore structure. In this study, porosity, pore size distribution, and specific surface area of ordinary concrete at different fatigue stages were investigated using mercury intrusion, helium flow, and nitrogen adsorption (BET) methods. These properties changed with increasing loading cycles and could be taken as micro-meso damage parameters to evaluate macro fatigue damage of concrete. Test results showed that both porosity in mortar (mainly macro pores) and interface between mortar and coarse aggregates (interfacial cracks) developed at a similar rate. The corresponding residual bending fatigue strength and dynamic bending Young`s modulus were also obtained and their relationships with these micro-meso properties were established. The intrinsic bending strength and intrinsic bending Young`s modulus were predicted from these relationships.

  7. Applicability of WaveWatch-III wave model to fatigue assessment of offshore floating structures

    NASA Astrophysics Data System (ADS)

    Zou, Tao; Kaminski, Miroslaw Lech

    2016-09-01

    In design and operation of floating offshore structures, one has to avoid fatigue failures caused by action of ocean waves. The aim of this paper is to investigate the applicability of WaveWatch-III wave model to fatigue assessment of offshore floating structures. The applicability was investigated for Bluewaters' FPSO (Floating Production, Storage and Offloading) which had been turret moored at Sable field for half a decade. The waves were predicted as sea-state time series consisting of one wind sea and one swell. The predicted waves were compared with wave data obtained from ERA-interim and buoy measurements. Furthermore, the fatigue calculations were also carried out for main deck and side shell locations. It has been concluded that predicted fatigue damages of main deck using WaveWatch-III are in a very good agreement regardless of differences in predicted wind waves and swells caused by differences in wave system partitioning. When compared to buoy measurements, the model underestimates fatigue damages of side shell by approximately 30 %. The reason for that has been found in wider directional spreading of actual waves. The WaveWatch-III wave model has been found suitable for the fatigue assessment. However, more attention should be paid on relative wave directionality, wave system partitioning and uncertainty analysis in further development.

  8. Enhancing fatigue life of cylinder-crown integrated structure by optimizing dimension

    NASA Astrophysics Data System (ADS)

    Zhang, Weiwei; Wang, Xiaosong; Wang, Zhongren; Yuan, Shijian

    2015-03-01

    Cylinder-crown integrated hydraulic press (CCIHP) is a new press structure. The hemispherical hydraulic cylinder also functions as a main portion of crown, which has lower weight and higher section modulus compared with the conventional hydraulic cylinder and press crown. As a result, the material strength capacity is better utilized. During the engineering design of cylinder-crown integrated structure, in order to increase the fatigue life, structural optimization on the basis of the adaptive macro genetic algorithms (AMGA) is first conducted to both reduce weight and decrease peak stress. It is shown that the magnitude of the maximum principal stress is decreased by 28.6%, and simultaneously the total weight is reduced by 4.4%. Subsequently, strain-controlled fatigue test is carried out, and the stress-strain hysteresis loops and cyclic hardening curve are obtained. Based on linear fit, the fatigue properties are calculated and used for the fatigue life prediction. It is shown that the predicted fatigue life is significantly increased from 157000 to 1070000 cycles after structural optimization. Finally, according to the optimization design, a 6300 kN CCIHP has been manufactured, and priority application has been also suggested.

  9. Results of a Cyclic Load Test of an RB-47E Airplane

    NASA Technical Reports Server (NTRS)

    Huston, Wilber B.

    1959-01-01

    Results of a cyclic load test made by NASA on an EB-47E airplane are given. The test reported on is for one of three B-47 airplanes in a test program set up by the U. S. Air Force to evaluate the effect of wing structural reinforcements on fatigue life. As a result of crack development in the upper fuselage longerons of the other two airplanes in the program, a longeron and fuselage skin modification was incorporated early in the test. Fuselage strain-gage measurements made before and after the longeron modification and wing strain-gage measurements made only after wing reinforcement are summarized. The history of crack development and repair is given in detail. Testing was terminated one sequence short of the planned end of the program with the occurrence of a major crack in the lower right wing skin.

  10. A Summary of the Fatigue Properties of Wind Turbine Materials

    SciTech Connect

    SUTHERLAND, HERBERT J.

    1999-10-07

    Modern wind turbines are fatigue critical machines that are typically used to produce electrical power from the wind. The materials used to construct these machines are subjected to a unique loading spectrum that contains several orders of magnitude more cycles than other fatigue critical structures, e.g., an airplane. To facilitate fatigue designs, a large database of material properties has been generated over the past several years that is specialized to materials typically used in wind turbines. In this paper, I review these fatigue data. Major sections are devoted to the properties developed for wood, metals (primarily aluminum) and fiberglass. Special emphasis is placed on the fiberglass discussion because this material is current the material of choice for wind turbine blades. The paper focuses on the data developed in the U.S., but cites European references that provide important insights.

  11. Excitation, response, and fatigue life estimation methods for the structural design of externally blown flaps

    NASA Technical Reports Server (NTRS)

    Ungar, E. E.; Chandiramani, K. L.; Barger, J. E.

    1972-01-01

    Means for predicting the fluctuating pressures acting on externally blown flap surfaces are developed on the basis of generalizations derived from non-dimensionalized empirical data. Approaches for estimation of the fatigue lives of skin-stringer and honeycomb-core sandwich flap structures are derived from vibration response analyses and panel fatigue data. Approximate expressions for fluctuating pressures, structural response, and fatigue life are combined to reveal the important parametric dependences. The two-dimensional equations of motion of multi-element flap systems are derived in general form, so that they can be specialized readily for any particular system. An introduction is presented of an approach to characterizing the excitation pressures and structural responses which makes use of space-time spectral concepts and promises to provide useful insights, as well as experimental and analytical savings.

  12. 77 FR 50576 - Damage Tolerance and Fatigue Evaluation of Composite Rotorcraft Structures; OMB Approval of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-22

    ... and Fatigue Evaluation of Composite Rotorcraft Structures,'' published in the Federal Register (76 FR... impractical. In a correction document (77 FR 4890), published February 1, 2012, the FAA revised the DATES... Evaluation of Composite Rotorcraft Structures; OMB Approval of Information Collection AGENCY:...

  13. 78 FR 76980 - Special Conditions: Airbus, A350-900 Series Airplane; Interaction of Systems and Structures

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-20

    ... stability of the airplane. Such systems include flight control systems, autopilots, stability augmentation... these special conditions for airplanes equipped with flight control systems, autopilots, stability... before flight. Certain elements of the control system, such as mechanical and hydraulic components,...

  14. Biomechanical and structural response of healing Achilles tendon to fatigue loading following acute injury

    PubMed Central

    Freedman, Benjamin R.; Sarver, Joseph J.; Buckley, Mark R.; Voleti, Pramod B.; Soslowsky, Louis J.

    2013-01-01

    Achilles tendon injuries affect both athletes and the general population, and their incidence is rising. In particular, the Achilles tendon is subject to dynamic loading at or near failure loads during activity, and fatigue induced damage is likely a contributing factor to ultimate tendon failure. Unfortunately, little is known about how injured Achilles tendons respond mechanically and structurally to fatigue loading during healing. Knowledge of these properties remains critical to best evaluate tendon damage induction and the ability of the tendon to maintain mechanical properties with repeated loading. Thus, this study investigated the mechanical and structural changes in healing mouse Achilles tendons during fatigue loading. Twenty four mice received bilateral full thickness, partial width excisional injuries to their Achilles tendons (IACUC approved) and twelve tendons from six mice were used as controls. Tendons were fatigue loaded to assess mechanical and structural properties simultaneously after 0, 1, 3, and 6 weeks of healing using an integrated polarized light system. Results showed that the number of cycles to failure decreased dramatically (37-fold, p<0.005) due to injury, but increased throughout healing, ultimately recovering after 6 weeks. The tangent stiffness, hysteresis, and dynamic modulus did not improve with healing (p<0.005). Linear regression analysis was used to determine relationships between mechanical and structural properties. Of tendon structural properties, the apparent birefringence was able to best predict dynamic modulus (R2=0.88–0.92) throughout healing and fatigue life. This study reinforces the concept that fatigue loading is a sensitive metric to assess tendon healing and demonstrates potential structural metrics to predict mechanical properties. PMID:24280564

  15. 77 FR 3187 - Airworthiness Directives; the Boeing Company Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-23

    ...-3189] [FR Doc No: 2012-1202] DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14 CFR Part... certain Model 767-200 and -300 series airplanes. This proposed AD was prompted by reports of fatigue... identified in this proposed AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management,...

  16. Modeling Delamination in Postbuckled Composite Structures Under Static and Fatigue Loads

    NASA Technical Reports Server (NTRS)

    Bisagni, Chiara; Brambilla, Pietro; Bavila, Carlos G.

    2013-01-01

    The ability of the Abaqus progressive Virtual Crack Closure Technique (VCCT) to model delamination in composite structures was investigated for static, postbuckling, and fatigue loads. Preliminary evaluations were performed using simple Double Cantilever Beam (DCB) and Mixed-Mode Bending (MMB) specimens. The nodal release sequences that describe the propagation of the delamination front were investigated. The effect of using a sudden or a gradual nodal release was evaluated by considering meshes aligned with the crack front as well as misaligned meshes. Fatigue simulations were then performed using the Direct Cyclic Fatigue (DCF) algorithm. It was found that in specimens such as the DCB, which are characterized by a nearly linear response and a pure fracture mode, the algorithm correctly predicts the Paris Law rate of propagation. However, the Abaqus DCF algorithm does not consider different fatigue propagation laws in different fracture modes. Finally, skin/stiffener debonding was studied in an aircraft fuselage subcomponent in which debonding occurs deep into post-buckling deformation. VCCT was shown to be a robust tool for estimating the onset propagation. However, difficulties were found with the ability of the current implementation of the Abaqus progressive VCCT to predict delamination propagation within structures subjected to postbuckling deformations or fatigue loads.

  17. Air resistance measurements on actual airplane parts

    NASA Technical Reports Server (NTRS)

    Weiselsberger, C

    1923-01-01

    For the calculation of the parasite resistance of an airplane, a knowledge of the resistance of the individual structural and accessory parts is necessary. The most reliable basis for this is given by tests with actual airplane parts at airspeeds which occur in practice. The data given here relate to the landing gear of a Siemanms-Schuckert DI airplane; the landing gear of a 'Luftfahrzeug-Gesellschaft' airplane (type Roland Dlla); landing gear of a 'Flugzeugbau Friedrichshafen' G airplane; a machine gun, and the exhaust manifold of a 269 HP engine.

  18. Structure-phase states evolution in Al-Si alloy under electron-beam treatment and high-cycle fatigue

    SciTech Connect

    Konovalov, Sergey Alsaraeva, Krestina Gromov, Victor Semina, Olga; Ivanov, Yurii

    2015-10-27

    By methods of scanning and transmission electron diffraction microscopy the analysis of structure-phase states and defect substructure of silumin subjected to high-intensity electron beam irradiation in various regimes and subsequent fatigue loading up to failure was carried out. It is revealed that the sources of fatigue microcracks are silicon plates of micron and submicron size are not soluble in electron beam processing. The possible reasons of the silumin fatigue life increase under electron-beam treatment are discussed.

  19. Advances in Fatigue and Fracture Mechanics Analyses for Metallic Aircraft Structures

    NASA Technical Reports Server (NTRS)

    Newman, J. C., Jr.

    2000-01-01

    This paper reviews some of the advances that have been made in stress analyses of cracked aircraft components, in the understanding of the fatigue and fatigue-crack growth process, and in the prediction of residual strength of complex aircraft structures with widespread fatigue damage. Finite-element analyses of cracked metallic structures are now used to determine accurate stress-intensity factors for cracks at structural details. Observations of small-crack behavior at open and rivet-loaded holes and the development of small-crack theory has lead to the prediction of stress-life behavior for components with stress concentrations under aircraft spectrum loading. Fatigue-crack growth under simulated aircraft spectra can now be predicted with the crack-closure concept. Residual strength of cracked panels with severe out-of-plane deformations (buckling) in the presence of stiffeners and multiple-site damage can be predicted with advanced elastic-plastic finite-element analyses and the critical crack-tip-opening angle (CTOA) fracture criterion. These advances are helping to assure continued safety of aircraft structures.

  20. The NASA Lewis Research Center High Temperature Fatigue and Structures Laboratory

    NASA Technical Reports Server (NTRS)

    Mcgaw, M. A.; Bartolotta, P. A.

    1987-01-01

    The physical organization of the NASA Lewis Research Center High Temperature Fatigue and Structures Laboratory is described. Particular attention is given to uniaxial test systems, high cycle/low cycle testing systems, axial torsional test systems, computer system capabilities, and a laboratory addition. The proposed addition will double the floor area of the present laboratory and will be equipped with its own control room.

  1. 77 FR 50576 - Fatigue Tolerance Evaluation of Metallic Structures; OMB Approval of Information Collection

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-22

    ... (76 FR 75435) on December 2, 2011. In that rule, the FAA addresses advances in structural fatigue... document (77 FR 4890), published February 1, 2012, the FAA revised the DATES section of the final rule... Policy Group, Rotorcraft Directorate, ASW-111, Federal Aviation Administration, 2601 Meacham Blvd.,...

  2. Improving the fatigue resistance of adhesive joints in laminated wood structures

    NASA Technical Reports Server (NTRS)

    Laufenberg, Theodore L.; River, Bryan H.; Murmanis, Lidija L.; Christiansen, Alfred W.

    1988-01-01

    The premature fatigue failure of a laminated wood/epoxy test beam containing a cross section finger joint was the subject of a multi-disciplinary investigation. The primary objectives were to identify the failure mechanisms which occurred during the finger joint test and to provide avenues for general improvements in the design and fabrication of adhesive joints in laminated wood structures.

  3. Split mandrel versus split sleeve coldworking: Dual methods for extending the fatigue life of metal structures

    NASA Technical Reports Server (NTRS)

    Rodman, Geoffrey A.; Creager, Matthew

    1994-01-01

    It is common practice to use split sleeve coldworking of fastener holes as a means of extending the fatigue life of metal structures. In search of lower manufacturing costs, the aerospace industry is examining the split mandrel (sleeveless) coldworking process as an alternative method of coldworking fastener holes in metal structures. The split mandrel process (SpM) significantly extends the fatigue life of metal structures through the introduction of a residual compressive stress in a manner that is very similar to the split sleeve system (SpSl). Since the split mandrel process is significantly less expensive than the split sleeve process and more adaptable to robotic automation, it will have a notable influence upon other new manufacture of metal structures which require coldworking a significant number of holes, provided the aerospace community recognizes that the resulting residual stress distributions and fatigue life improvement are the same for both processes. Considerable testing has validated the correctness of that conclusion. The findings presented in this paper represent the results of an extensive research and development program, comprising data collected from over 400 specimens fabricated from 2024-T3 and 7075-T651 aluminum alloys in varied configurations, which quantify the benefits (fatigue enhancement and cost savings) of automating a sleeveless coldworking system.

  4. Re-assessment of offshore structures using the revised HSE fatigue guidance

    SciTech Connect

    Stacey, A.; Sharp, J.V.

    1995-12-31

    The re-assessment of existing North Sea structures is an increasingly important issue as the age of platforms increases. Over 50 from a total of approximately 180 fixed installations in the UK sector are now over 15 years old. Fatigue damage has been the main reason for repairs to North Sea structures and the risk of this continues. The fatigue guidance of the Offshore Safety Division of the Health and Safety Executive (HSE) has recently been revised and published. Fundamental changes have been made to this guidance with several new recommendations including joint classification, basic design S-N curves for welded joints, the thickness effect, the effects of environment and the treatment of low and high stress ranges. To quantify the effects of the new guidance on the fatigue life assessment of offshore strictures, the HSE commissioned a study which included a deep water and a shallow water fixed steel structure and a twin-pontoon semi-submersible. These structures are typical of those operating in the North Sea. These were re-assessed with respect to fatigue lives and the results compared with predictions based on the 1990 guidance. The results and general conclusions are presented in this paper.

  5. Fatigue Crack Growth Database for Damage Tolerance Analysis

    NASA Technical Reports Server (NTRS)

    Forman, R. G.; Shivakumar, V.; Cardinal, J. W.; Williams, L. C.; McKeighan, P. C.

    2005-01-01

    The objective of this project was to begin the process of developing a fatigue crack growth database (FCGD) of metallic materials for use in damage tolerance analysis of aircraft structure. For this initial effort, crack growth rate data in the NASGRO (Registered trademark) database, the United States Air Force Damage Tolerant Design Handbook, and other publicly available sources were examined and used to develop a database that characterizes crack growth behavior for specific applications (materials). The focus of this effort was on materials for general commercial aircraft applications, including large transport airplanes, small transport commuter airplanes, general aviation airplanes, and rotorcraft. The end products of this project are the FCGD software and this report. The specific goal of this effort was to present fatigue crack growth data in three usable formats: (1) NASGRO equation parameters, (2) Walker equation parameters, and (3) tabular data points. The development of this FCGD will begin the process of developing a consistent set of standard fatigue crack growth material properties. It is envisioned that the end product of the process will be a general repository for credible and well-documented fracture properties that may be used as a default standard in damage tolerance analyses.

  6. Substrate Creep on The Fatigue Life of A Model Dental Multilayer Structure

    SciTech Connect

    Zhou, J; Huang, M; Niu, X; soboyejo, W

    2006-10-09

    In this paper, we investigated the effects of substrate creep on the fatigue behavior of a model dental multilayer structure, in which a top glass layer was bonded to a polycarbonate substrate through a dental adhesive. The top glass layers were ground using 120 grit or 600 grit sand papers before bonding to create different sub-surface crack sizes and morphologies. The multilayer structures were tested under cyclic Hertzian contact loading to study crack growth and obtain fatigue life curves. The experiment results showed that the fatigue lives of the multilayer structures were impaired by increasing crack sizes in the sub-surfaces. They were also significantly reduced by the substrate creep when tested at relatively low load levels i.e. P{sub m} < 60 N (Pm is the maximum magnitude of cyclic load). But at relatively high load levels i.e. P{sub m} > 65 N, slow crack growth (SCG) was the major failure mechanisms. A modeling study was then carried out to explore the possible failure mechanisms over a range of load levels. It is found that fatigue life at relatively low load levels can be better estimated by considering the substrate creep effect (SCE).

  7. Monitoring of hidden fatigue crack growth in multi-layer aircraft structures using high frequency guided waves

    NASA Astrophysics Data System (ADS)

    Chan, H.; Masserey, B.; Fromme, P.

    2015-03-01

    Varying loading conditions of aircraft structures result in stress concentration at fastener holes, where multi-layered components are connected, potentially leading to the development of hidden fatigue cracks in inaccessible layers. High frequency guided waves propagating along the structure allow for the structural health monitoring (SHM) of such components, e.g., aircraft wings. Experimentally the required guided wave modes can be easily excited using standard ultrasonic wedge transducers. However, the sensitivity for the detection of small, potentially hidden, fatigue cracks has to be ascertained. The type of multi-layered model structure investigated consists of two adhesively bonded aluminum plate-strips with a sealant layer. Fatigue experiments were carried out and the growth of fatigue cracks at the fastener hole in one of the metallic layers was monitored optically during cyclic loading. The influence of the fatigue cracks of increasing size on the scattered guided wave field was evaluated. The sensitivity and repeatability of the high frequency guided wave modes to detect and monitor the fatigue crack growth was investigated, using both standard pulse-echo equipment and a laser interferometer. The potential for hidden fatigue crack growth monitoring at critical and difficult to access fastener locations from a stand-off distance was ascertained. The robustness of the methodology for practical in situ ultrasonic monitoring of fatigue crack growth is discussed.

  8. Application of ultrasonic signature analysis for fatigue detection in complex structures

    NASA Technical Reports Server (NTRS)

    Zuckerwar, A. J.

    1974-01-01

    Ultrasonic signature analysis shows promise of being a singularly well-suited method for detecting fatigue in structures as complex as aircraft. The method employs instrumentation centered about a Fourier analyzer system, which features analog-to-digital conversion, digital data processing, and digital display of cross-correlation functions and cross-spectra. These features are essential to the analysis of ultrasonic signatures according to the procedure described here. In order to establish the feasibility of the method, the initial experiments were confined to simple plates with simulated and fatigue-induced defects respectively. In the first test the signature proved sensitive to the size of a small hole drilled into the plate. In the second test, performed on a series of fatigue-loaded plates, the signature proved capable of indicating both the initial appearance and subsequent growth of a fatigue crack. In view of these encouraging results it is concluded that the method has reached a sufficiently advanced stage of development to warrant application to small-scale structures or even actual aircraft.

  9. Crash Tests of Protective Airplane Floors

    NASA Technical Reports Server (NTRS)

    Carden, H. D.

    1986-01-01

    Energy-absorbing floors reduce structural buckling and impact forces on occupants. 56-page report discusses crash tests of energy-absorbing aircraft floors. Describes test facility and procedures; airplanes, structural modifications, and seats; crash dynamics; floor and seat behavior; and responses of anthropometric dummies seated in airplanes. Also presents plots of accelerations, photographs and diagrams of test facility, and photographs and drawings of airplanes before, during, and after testing.

  10. Vibration fatigue analysis and multi-axial effect in testing of aerospace structures

    NASA Astrophysics Data System (ADS)

    Aykan, Murat; Çelik, Mehmet

    2009-04-01

    The work reported in this paper compared the fatigue damage accumulated under uni-axial loading (a procedure promoted by the vibration testing standards) to that induced by multi-axial loading. The comparison was performed for a helicopter structural element (the flare dispenser bracket of the self-defensive system's Chaff), which is exposed to the particular combination of wide-band random with sinusoidal vibrations, which is characteristic to the helicopter dynamic environment. The evaluation of the fatigue damage induced by these loads requires the calculation or measurement of the structure's dynamic response in terms of stresses or strains, and the application of the appropriate methodology to this response. In this work, dynamic response was calculated in the frequency domain based on the relations between the power spectral density matrixes of the excitations to that of the responses for a linear system. The transfer matrix that relates the excitation to the responses was evaluated numerically. The power spectral densities of the responses evaluated at different locations on the structure were used in the determination of the responses' statistics (the counting of the loading cycles), which, combined with an appropriate physics of failure model (fatigue model), enabled the evaluation of the accumulated fatigue damage. The uni-axial-induced fatigue was evaluated from vibration tests of the kind promoted by military standards (it is assumed that axis-by-axis loading is cumulatively equal to multi-axial loading), and compared to that evaluated by analysis for the multi-axial loading. Also a numerical comparison of the effects of the two kinds of loading was performed. The results showed that the error of uni-axial testing varied for a wide range of parameters. The work led to the conclusion that simultaneous multi-axis vibration testing can improve significantly the laboratory's vibration simulation realism.

  11. 77 FR 26996 - Airworthiness Directives; Airbus Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-08

    ... airplanes. This proposed AD was prompted by reports that medium-head fasteners were installed in lieu of... demonstrated could have an affect on panel fatigue life. This proposed AD would require repetitive inspections... 35 in Airbus A320 final assembly line. Investigations revealed that medium head fasteners,...

  12. 78 FR 8054 - Airworthiness Directives; Airbus Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-05

    ...) inspection for cracking of the area around the fasteners of the landing plate of the wing bottom skin panel... the inspection of the area around the fasteners of the landing plate of the wing bottom skin panel... A310 series airplanes. The existing AD currently requires repetitive inspections for fatigue...

  13. 77 FR 60658 - Airworthiness Directives; Airbus Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-04

    ... rule'' under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); 3. Will not... airplanes. This proposed AD was prompted by a report of two fatigue cracks on the left-hand and right-hand... proposed AD would require a high frequency eddy current (HFEC) inspection for any cracking on the...

  14. Monitoring of surface-fatigue crack propagation in a welded steel angle structure using guided waves and principal component analysis

    NASA Astrophysics Data System (ADS)

    Lu, Mingyu; Qu, Yongwei; Lu, Ye; Ye, Lin; Zhou, Limin; Su, Zhongqing

    2012-04-01

    An experimental study is reported in this paper demonstrating monitoring of surface-fatigue crack propagation in a welded steel angle structure using Lamb waves generated by an active piezoceramic transducer (PZT) network which was freely surface-mounted for each PZT transducer to serve as either actuator or sensor. The fatigue crack was initiated and propagated in welding zone of a steel angle structure by three-point bending fatigue tests. Instead of directly comparing changes between a series of specific signal segments such as S0 and A0 wave modes scattered from fatigue crack tips, a variety of signal statistical parameters representing five different structural status obtained from marginal spectrum in Hilbert-huang transform (HHT), indicating energy progressive distribution along time period in the frequency domain including all wave modes of one wave signal were employed to classify and distinguish different structural conditions due to fatigue crack initiation and propagation with the combination of using principal component analysis (PCA). Results show that PCA based on marginal spectrum is effective and sensitive for monitoring the growth of fatigue crack although the received signals are extremely complicated due to wave scattered from weld, multi-boundaries, notch and fatigue crack. More importantly, this method indicates good potential for identification of integrity status of complicated structures which cause uncertain wave patterns and ambiguous sensor network arrangement.

  15. Monitoring of surface-fatigue crack propagation in a welded steel angle structure using guided waves and principal component analysis

    NASA Astrophysics Data System (ADS)

    Lu, Mingyu; Qu, Yongwei; Lu, Ye; Ye, Lin; Zhou, Limin; Su, Zhongqing

    2011-11-01

    An experimental study is reported in this paper demonstrating monitoring of surface-fatigue crack propagation in a welded steel angle structure using Lamb waves generated by an active piezoceramic transducer (PZT) network which was freely surface-mounted for each PZT transducer to serve as either actuator or sensor. The fatigue crack was initiated and propagated in welding zone of a steel angle structure by three-point bending fatigue tests. Instead of directly comparing changes between a series of specific signal segments such as S0 and A0 wave modes scattered from fatigue crack tips, a variety of signal statistical parameters representing five different structural status obtained from marginal spectrum in Hilbert-huang transform (HHT), indicating energy progressive distribution along time period in the frequency domain including all wave modes of one wave signal were employed to classify and distinguish different structural conditions due to fatigue crack initiation and propagation with the combination of using principal component analysis (PCA). Results show that PCA based on marginal spectrum is effective and sensitive for monitoring the growth of fatigue crack although the received signals are extremely complicated due to wave scattered from weld, multi-boundaries, notch and fatigue crack. More importantly, this method indicates good potential for identification of integrity status of complicated structures which cause uncertain wave patterns and ambiguous sensor network arrangement.

  16. 14 CFR 23.571 - Metallic pressurized cabin structures.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Metallic pressurized cabin structures. 23... AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Structure Fatigue Evaluation § 23.571 Metallic pressurized cabin structures. For normal, utility, and...

  17. 14 CFR 23.571 - Metallic pressurized cabin structures.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Metallic pressurized cabin structures. 23... AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Structure Fatigue Evaluation § 23.571 Metallic pressurized cabin structures. For normal, utility, and...

  18. Fracture mechanics. [review of fatigue crack propagation and technology of constructing safe structures

    NASA Technical Reports Server (NTRS)

    Hardrath, H. F.

    1974-01-01

    Fracture mechanics is a rapidly emerging discipline for assessing the residual strength of structures containing flaws due to fatigue, corrosion or accidental damage and for anticipating the rate of which such flaws will propagate if not repaired. The discipline is also applicable in the design of structures with improved resistance to such flaws. The present state of the design art is reviewed using this technology to choose materials, to configure safe and efficient structures, to specify inspection procedures, to predict lives of flawed structures and to develop reliability of current and future airframes.

  19. Fatigue crack growth monitoring in multi-layered structures using guided ultrasonic waves

    NASA Astrophysics Data System (ADS)

    Kostson, E.; Fromme, P.

    2009-11-01

    This contribution investigates the application of low frequency guided ultrasonic waves for monitoring fatigue crack growth at fastener holes in the 2nd layer of multi-layered plate structures, a common problem in aerospace industry. The model multi-layered structure investigated consists of two aluminum plate-strips adhesively bonded using a structural paste adhesive. Guided ultrasonic waves were excited using multiple piezoelectric discs bonded to the surface of the multi-layered structure. The wave propagation in the tensile specimen was measured using a laser interferometer and compared to numerical simulations. Thickness and width mode shapes of the excited flexural waves were identified from Semi-Analytical Finite Element (SAFE) calculations. Experiments and 3D Finite Element (FE) simulations show a change in the scattered field around fastener holes caused by a defect in the 2nd layer. The amplitude of the guided ultrasonic wave was monitored during fatigue experiments at a single point. The measured changes in the amplitude of the ultrasonic signal due to fatigue crack growth agree well with FE simulations.

  20. High-strain fiber bragg gratings for structural fatigue testing of military aircraft

    NASA Astrophysics Data System (ADS)

    Davis, Claire; Tejedor, Silvia; Grabovac, Ivan; Kopczyk, James; Nuyens, Travis

    2012-09-01

    This paper reports on an experimental program of work which investigates the reliability, durability, and packaging of fiber Bragg gratings (FBGs) for application as distributed strain sensors during structural fatigue testing of military platforms. The influence of the FBG fabrication process on sensor reliability is investigated. In addition, methodologies for broad-area packaging and surface-mounting of FBG sensing arrays to defense platforms are developed and tested.

  1. Time needed to board an airplane: A power law and the structure behind it

    NASA Astrophysics Data System (ADS)

    Frette, Vidar; Hemmer, Per C.

    2012-01-01

    A simple model for the boarding of an airplane is studied. Passengers have reserved seats but enter the airplane in arbitrary order. Queues are formed along the aisle, as some passengers have to wait to reach the seats for which they have reservation. We label a passenger by the number of his or her reserved seat. In most cases the boarding process is much slower than for the optimal situation, where passenger and seat orders are identical. We study this dynamical system by calculating the average boarding time when all permutations of N passengers are given equal weight. To first order, the boarding time for a given permutation (ordering) of the passengers is given by the number s of sequences of monotonically increasing values in the permutation. We show that the distribution of s is symmetric on [1,N], which leads to an average boarding time (N+1)/2. We have found an exact expression for s and have shown that the full distribution of s approaches a normal distribution as N increases. However, there are significant corrections to the first-order results, due to certain correlations between passenger ordering and the substrate (seat ordering). This occurs for some cases in which the sequence of the seats is partially mirrored in the passenger ordering. These cases with correlations have a boarding time that is lower than predicted by the first-order results. The large number of cases with reduced boarding times have been classified. We also give some indicative results on the geometry of the correlations, with sorting into geometry groups. With increasing N, both the number of correlation types and the number of cases belonging to each type increase rapidly. Using enumeration we find that as a result of these correlations the average boarding time behaves like Nα, with α≃0.69, as compared with α=1.0 for the first-order approximation.

  2. Nonlinear analyses of composite aerospace structures in sonic fatigue

    NASA Technical Reports Server (NTRS)

    Mei, Chuh

    1992-01-01

    The primary research effort of this project is the development of analytical methods for the prediction of nonlinear random response of composite aerospace structures subjected to combined acoustic and thermal loads. The progress, accomplishments, and future plans of three random response research topics are discussed, namely acoustics-structure interactions using boundary/finite element methods, nonlinear vibrations of beams and composite plates under harmonic and random excitations, and numerical simulation of the nonlinear response of composite plates under combined thermal and acoustic loading.

  3. Fatigue in aerostructures--where structural health monitoring can contribute to a complex subject.

    PubMed

    Boller, Christian; Buderath, Matthias

    2007-02-15

    An overview of the aircraft design and maintenance process is given with specific emphasis on the fatigue design as well as the phenomenon of the ageing aircraft observed over the life cycle. The different measures taken to guarantee structural integrity along the maintenance process are addressed. The impact of structural health monitoring as a means of possibly revolutionizing the current aircraft structural monitoring and design process is emphasized and comparison is made to jet engines and helicopters, where health monitoring has already found the respective breakthrough.

  4. Fatigue in aerostructures--where structural health monitoring can contribute to a complex subject.

    PubMed

    Boller, Christian; Buderath, Matthias

    2007-02-15

    An overview of the aircraft design and maintenance process is given with specific emphasis on the fatigue design as well as the phenomenon of the ageing aircraft observed over the life cycle. The different measures taken to guarantee structural integrity along the maintenance process are addressed. The impact of structural health monitoring as a means of possibly revolutionizing the current aircraft structural monitoring and design process is emphasized and comparison is made to jet engines and helicopters, where health monitoring has already found the respective breakthrough. PMID:17255052

  5. Thermography Inspection for Early Detection of Composite Damage in Structures During Fatigue Loading

    NASA Technical Reports Server (NTRS)

    Zalameda, Joseph N.; Burke, Eric R.; Parker, F. Raymond; Seebo, Jeffrey P.; Wright, Christopher W.; Bly, James B.

    2012-01-01

    Advanced composite structures are commonly tested under controlled loading. Understanding the initiation and progression of composite damage under load is critical for validating design concepts and structural analysis tools. Thermal nondestructive evaluation (NDE) is used to detect and characterize damage in composite structures during fatigue loading. A difference image processing algorithm is demonstrated to enhance damage detection and characterization by removing thermal variations not associated with defects. In addition, a one-dimensional multilayered thermal model is used to characterize damage. Lastly, the thermography results are compared to other inspections such as non-immersion ultrasonic inspections and computed tomography X-ray.

  6. Wear and fatigue behavior of nano-structured dental resin composites.

    PubMed

    Turssi, Cecilia P; Ferracane, Jack L; Ferracane, Lucas L

    2006-07-01

    Theoretically, nano-structured dental resin composites are purported to have increased wear and fatigue resistance compared with microfill composites and may favor the achievement of restoratives with better long-term performance. This study sought to assess the behavior of nano-structured composites resulting from either abrasion and fatigue loading. Ten specimens (12 x 5 x 2.5 mm) were prepared from each of five composites: Ceram-X mono, Filtek Supreme, Grandio, Premise, and Heliomolar (serving as the microfill control). A surface profile was recorded using a three-dimensional profiling system, and the specimens were subjected to 10(5) cycles of three-body abrasion in the new OHSU oral wear simulator. A second profile was generated and the before and after profiles were fit and analyzed. The volume loss and maximum depth of the wear facet on each specimen were calculated. Another 30 specimens (25 x 2 x 2 mm) were tested for flexural fatigue limit (FFL) in four-point bending via the staircase method. The test was carried out until 10(4) cycles were completed or until fracturing the specimen. One-way ANOVA and Tukey's test demonstrated greater volumetric loss for Grandio and Ceram-X than that observed for the remaining composites. Kruskal-Wallis and the least significant difference test ascertained that Heliomolar, Grandio, and Supreme showed significantly higher FFL than Ceram-X and Premise. In terms of wear and fatigue resistance, nano-structured composites may perform either similarly or comparatively worse than a microfilled composite.

  7. Synthesis, crystal structure and anti-fatigue effects of some benzamide derivatives.

    PubMed

    Wu, Xianglong; Fan, Wutu; Pan, Yalei; Zhai, Yuankun; Niu, Yinbo; Li, Chenrui; Mei, Qibing

    2014-01-01

    A series of benzamide derivatives such as 1-(1,3-benzodioxol-5-ylcarbonyl) piperidine (1-BCP) were synthesized by the reaction of substituted benzoic acids with piperidine, morpholine or pyrrolidine using a novel method. The crystals of these benzamide derivatives were obtained by recrystallization. Structures of target and intermediate compounds were determined via FT-IR, 1H-NMR and elemental analysis and X-ray crystallography of select examples. The crystal structures of these compounds have potential applications to identify the binding site for allosteric modulators of the α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor. The anti-fatigue effects of the benzamide derivatives in weight-loaded forced swimming mice were investigated in a swimming endurance capacity test used as an indicator of fatigue. The swimming times to exhaustion were longer in the b3, d3, and e3 groups than in the caffeine group (p<0.05). In conclusion, b3, d3 and e3 enhanced the forced swimming capacity of mice. The mechanism of the anti-fatigue effects will be studied in the future. PMID:24441653

  8. Effect of Buckling Modes on the Fatigue Life and Damage Tolerance of Stiffened Structures

    NASA Technical Reports Server (NTRS)

    Davila, Carlos G.; Bisagni, Chiara; Rose, Cheryl A.

    2015-01-01

    The postbuckling response and the collapse of composite specimens with a co-cured hat stringer are investigated experimentally and numerically. These specimens are designed to evaluate the postbuckling response and the effect of an embedded defect on the collapse load and the mode of failure. Tests performed using controlled conditions and detailed instrumentation demonstrate that the damage tolerance, fatigue life, and collapse loads are closely tied with the mode of the postbuckling deformation, which can be different between two nominally identical specimens. Modes that tend to open skin/stringer defects are the most damaging to the structure. However, skin/stringer bond defects can also propagate under shearing modes. In the proposed paper, the effects of initial shape imperfections on the postbuckling modes and the interaction between different postbuckling deformations and the propagation of skin/stringer bond defects under quasi-static or fatigue loads will be examined.

  9. Fatigue of composites

    NASA Technical Reports Server (NTRS)

    Salkind, M. J.

    1972-01-01

    The failure mechanisms in the fatigue of composite materials are analyzed in terms of the requirements for designing fatigue-critical composite structures. Fiber reinforced polymers, fiber reinforced metals, fatigue of composite structures, and composite design considerations are discussed. It is concluded that composite materials offer the engineer the opportunity for tailoring stiffness in different directions for designing dynamic components.

  10. Tensile, Fracture, Fatigue Life, and Fatigue Crack Growth Rate Behavior of Structural Materials for the ITER Magnets: The European Contribution

    NASA Astrophysics Data System (ADS)

    Nyilas, A.; Nikbin, K.; Portone, A.; Sborchia, C.

    2004-06-01

    Fatigue crack growth rates (FCGR) are determined for R ratios between 0.1 - 0.7 at 7 K for three full-size Mock-up Models of the ITER Toroidal Field coil case produced by modified Type 316LN alloys. A representative forged block of Model 3 is additionally manufactured to determine its improved spatial tensile properties and compare it to former Model 3 data. From the new candidate jacket materials, developed for the ITER Central Solenoid coil, a batch is investigated to assess the fatigue life behavior at 7 K. Furthermore, the 4 K test facility, a 630 kN load capacity hydraulic machine has been used to allow fatigue life investigations under four point bending of the full-size jackets with artificial surface flaws. Cyclic life results have been assessed for the heat affected zone, weld, and base metal. The results are used in the fatigue analysis of the coil. Residual stresses resulting from jacket welding have been determined using two different techniques. First by distortion measurements of sliced pieces of the weld section and secondly by neutron diffraction measurements. In addition, tensile and fracture tests have been performed at 7 K with Al 7075, a candidate alloy for the pre-compression system of the CS coil.

  11. Effect of electron beam treatment on structural change in titanium alloy VT-0 at high-cycle fatigue

    NASA Astrophysics Data System (ADS)

    Konovalov, S. V.; Komissarova, I. A.; Kosinov, D. A.; Ivanov, Yu F.; Ivanova, O. V.; Gromov, V. E.

    2016-09-01

    Changes in the surface of the fractured structure of commercially pure titanium VT1-0 under treatment by low-energy high-current electron beams and the subsequent cycle fatigue to the failure were analyzed by transmission scanning and transmission electron diffraction microscopy. The increase in the fatigue life of samples in 2.2 times after treatment by electron beams was established. An assumption was made that the increase in the fatigue life of titanium, grade VT1-0, was due to the formation of a lamellar substructure conditioned by high-velocity crystallization of the titanium surface layer.

  12. 14 CFR 29.573 - Damage Tolerance and Fatigue Evaluation of Composite Rotorcraft Structures.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Damage Tolerance and Fatigue Evaluation of... Requirements Fatigue Evaluation § 29.573 Damage Tolerance and Fatigue Evaluation of Composite Rotorcraft... practice, the applicant must do a fatigue evaluation in accordance with paragraph (e) of this section....

  13. 14 CFR 27.573 - Damage Tolerance and Fatigue Evaluation of Composite Rotorcraft Structures.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Damage Tolerance and Fatigue Evaluation of... Requirements Fatigue Evaluation § 27.573 Damage Tolerance and Fatigue Evaluation of Composite Rotorcraft... practice, the applicant must do a fatigue evaluation in accordance with paragraph (e) of this section....

  14. 78 FR 28729 - Airworthiness Directives; The Boeing Company Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-16

    ..., 2012) Nord Wind Airlines reported the status of compliance of its airplanes with the NPRM (77 FR 65506... Airplanes AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: We are... series airplanes. That AD currently requires modifying the nacelle strut and wing structure,...

  15. A structural health monitoring fastener for tracking fatigue crack growth in bolted metallic joints

    NASA Astrophysics Data System (ADS)

    Rakow, Alexi Schroder

    Fatigue cracks initiating at fastener hole locations in metallic components are among the most common form of airframe damage. The fastener hole site has been surveyed as the second leading initiation site for fatigue related accidents of fixed wing aircraft. Current methods for inspecting airframes for these cracks are manual, whereby inspectors rely on non-destructive inspection equipment or hand-held probes to scan over areas of a structure. Use of this equipment often demands disassembly of the vehicle to search appropriate hole locations for cracks, which elevates the complexity and cost of these maintenance inspections. Improved reliability, safety, and reduced cost of such maintenance can be realized by the permanent integration of sensors with a structure to detect this damage. Such an integrated system of sensors would form a structural health monitoring (SHM) system. In this study, an Additive, Interleaved, Multi-layer Electromagnetic (AIME) sensor was developed and integrated with the shank of a fastener to form a SHM Fastener, a new SHM technology targeted at detection of fastener hole cracks. The major advantages of the SHM Fastener are its installation, which does not require joint layer disassembly, its capability to detect inner layer cracks, and its capability to operate in a continuous autonomous mode. Two methods for fabricating the proposed SHM Fastener were studied. The first option consisted of a thin flexible printed circuit film that was bonded around a thin metallic sleeve placed around the fastener shank. The second option consisted of coating sensor materials directly to the shank of a part in an effort to increase the durability of the sensor under severe loading conditions. Both analytical and numerical models were developed to characterize the capability of the sensors and provide a design tool for the sensor layout. A diagnostic technique for crack growth monitoring was developed to complete the SHM system, which consists of the

  16. Comment on ``Time needed to board an airplane: A power law and the structure behind it''

    NASA Astrophysics Data System (ADS)

    Bernstein, Noam

    2012-08-01

    Frette and Hemmer [Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.85.011130 85, 011130 (2012)] recently showed that for a simple model for the boarding of an airplane, the mean time to board scales as a power law with the number of passengers N and the exponent is less than 1. They note that this scaling leads to the prediction that the “back-to-front” strategy, where passengers are divided into groups from contiguous ranges of rows and each group is allowed to board in turn from back to front once the previous group has found their seats, has a longer boarding time than would a single group. Here I extend their results to a larger number of passengers using a sampling approach and explore a scenario where the queue is presorted into groups from back to front, but allowed to enter the plane as soon as they can. I show that the power law dependence on passenger numbers is different for large N and that there is a boarding time reduction for presorted groups, with a power law dependence on the number of presorted groups.

  17. Evaluating Changes in Tendon Crimp with Fatigue Loading as an ex vivo Structural Assessment of Tendon Damage

    PubMed Central

    Freedman, Benjamin R.; Zuskov, Andrey; Sarver, Joseph J.; Buckley, Mark R.; Soslowsky, Louis J.

    2015-01-01

    The complex structure of tendons relates to their mechanical properties. Previous research has associated the waviness of collagen fibers (crimp) during quasi-static tensile loading to tensile mechanics, but less is known about the role of fatigue loading on crimp properties. In this study (IACUC approved), mouse patellar tendons were fatigue loaded while an integrated plane polariscope simultaneously assessed crimp properties. We demonstrate a novel structural mechanism whereby tendon crimp amplitude and frequency are altered with fatigue loading. In particular, fatigue loading increased the crimp amplitude across the tendon width and length, and these structural alterations were shown to be both region and load dependent. The change in crimp amplitude was strongly correlated to mechanical tissue laxity (defined as the ratio of displacement and gauge length relative to the first cycle of fatigue loading assessed at constant load throughout testing), at all loads and regions evaluated. Together, this study highlights the role of fatigue loading on tendon crimp properties as a function of load applied and region evaluated, and offers an additional structural mechanism for mechanical alterations that may lead to ultimate tendon failure. PMID:25773654

  18. The fatigue evaluation method for a structural stainless steel using the magnetic sensor composed of three pancake coils

    SciTech Connect

    Oka, M.; Tsuchida, Y.; Enokizono, M.; Yakushiji, T.

    2011-06-23

    May metallic structural materials, such as stainless steels, are currently used in our surroundings. If external force is repeatedly added for many years, it is thought that fatigue damage accumulates in stainless steels. When excessive fatigue damage accumulates in these metals, there is a possibility that they are destroyed by fatigue damage accumulation. Therefore, it is important to know the amount of the fatigue damage they have suffered in order to prevent them from being destroyed. We are developing the fatigue evaluation method for stainless steels with a magnetic sensor composed of three pancake type coils. In this research, the inspection object is ferritic stainless steels such as SUS430. The method of fatigue evaluation for ferritic stainless steels uses the three coil type sensor, and shows a good correlation between the number of stress cycles and the output signal of the sensor, even though the correlation between the output signal and an added stress is not completely accurate. This paper describes the evaluation method of fatigue damage in ferritic stainless steel using a magnetic sensor composed of three pancake-type coils.

  19. Comparison of structural response and fatigue endurance of aircraft flap-like box structures subjected to acoustic loading.

    PubMed

    Xiao, Y; White, R G; Aglietti, G S

    2005-05-01

    The results of an extensive test program to characterize the behavior of typical aircraft structures under acoustic loading and to establish their fatigue endurance are presented. The structures tested were the three flap-like box-type of structures. Each structure consisted of one flat (bottom) and one curved (top) stiffener stiffened skin panel, front, and rear spars, and ribs that divided the structures into three bays. The three structures, constructed from three different materials (aircraft standard aluminum alloy, Carbon Fibre Reinforced Plastic, and a Glass Fibre Metal Laminate, i.e., GLARE) had the same size and configuration, with only minor differences due to the use of different materials. A first set of acoustic tests with excitations of intensity ranging from 140 to 160 dB were carried out to obtain detailed data on the dynamic response of the three structures. The FE analysis of the structures is also briefly described and the results compared with the experimental data. The fatigue endurance of the structures was then determined using random acoustic excitation with an overall sound pressure level of 161 dB, and details of crack propagation are reported.

  20. Computational predictive methods for fracture and fatigue

    NASA Astrophysics Data System (ADS)

    Cordes, J.; Chang, A. T.; Nelson, N.; Kim, Y.

    1994-09-01

    The damage-tolerant design philosophy as used by aircraft industries enables aircraft components and aircraft structures to operate safely with minor damage, small cracks, and flaws. Maintenance and inspection procedures insure that damages developed during service remain below design values. When damage is found, repairs or design modifications are implemented and flight is resumed. Design and redesign guidelines, such as military specifications MIL-A-83444, have successfully reduced the incidence of damage and cracks. However, fatigue cracks continue to appear in aircraft well before the design life has expired. The F16 airplane, for instance, developed small cracks in the engine mount, wing support, bulk heads, the fuselage upper skin, the fuel shelf joints, and along the upper wings. Some cracks were found after 600 hours of the 8000 hour design service life and design modifications were required. Tests on the F16 plane showed that the design loading conditions were close to the predicted loading conditions. Improvements to analytic methods for predicting fatigue crack growth adjacent to holes, when multiple damage sites are present, and in corrosive environments would result in more cost-effective designs, fewer repairs, and fewer redesigns. The overall objective of the research described in this paper is to develop, verify, and extend the computational efficiency of analysis procedures necessary for damage tolerant design. This paper describes an elastic/plastic fracture method and an associated fatigue analysis method for damage tolerant design. Both methods are unique in that material parameters such as fracture toughness, R-curve data, and fatigue constants are not required. The methods are implemented with a general-purpose finite element package. Several proof-of-concept examples are given. With further development, the methods could be extended for analysis of multi-site damage, creep-fatigue, and corrosion fatigue problems.

  1. Computational predictive methods for fracture and fatigue

    NASA Technical Reports Server (NTRS)

    Cordes, J.; Chang, A. T.; Nelson, N.; Kim, Y.

    1994-01-01

    The damage-tolerant design philosophy as used by aircraft industries enables aircraft components and aircraft structures to operate safely with minor damage, small cracks, and flaws. Maintenance and inspection procedures insure that damages developed during service remain below design values. When damage is found, repairs or design modifications are implemented and flight is resumed. Design and redesign guidelines, such as military specifications MIL-A-83444, have successfully reduced the incidence of damage and cracks. However, fatigue cracks continue to appear in aircraft well before the design life has expired. The F16 airplane, for instance, developed small cracks in the engine mount, wing support, bulk heads, the fuselage upper skin, the fuel shelf joints, and along the upper wings. Some cracks were found after 600 hours of the 8000 hour design service life and design modifications were required. Tests on the F16 plane showed that the design loading conditions were close to the predicted loading conditions. Improvements to analytic methods for predicting fatigue crack growth adjacent to holes, when multiple damage sites are present, and in corrosive environments would result in more cost-effective designs, fewer repairs, and fewer redesigns. The overall objective of the research described in this paper is to develop, verify, and extend the computational efficiency of analysis procedures necessary for damage tolerant design. This paper describes an elastic/plastic fracture method and an associated fatigue analysis method for damage tolerant design. Both methods are unique in that material parameters such as fracture toughness, R-curve data, and fatigue constants are not required. The methods are implemented with a general-purpose finite element package. Several proof-of-concept examples are given. With further development, the methods could be extended for analysis of multi-site damage, creep-fatigue, and corrosion fatigue problems.

  2. The Development of German Army Airplanes During the War

    NASA Technical Reports Server (NTRS)

    Wilhelm, Hoff

    1921-01-01

    The author, who was a captain of the Reserves in the Technical Department of the Aviation Division (Board of Airplane Experts) during the war, shows what means were taken for the creation of new airplane types and what tests were employed for trying out their flying properties, capacities and structural reliability. The principal representative types of each of the classes of airplanes are described and the characteristics of the important structural parts are discussed. Data regarding the number of airplanes at the front and the flying efficiency of the various classes of airplanes are given.

  3. Creep-fatigue effects in structural materials used in advanced nuclear power generating systems

    SciTech Connect

    Brinkman, C. R.

    1980-01-01

    Various aspects of time-dependent fatigue behavior of a number of structural alloys in use or planned for use in advanced nuclear power generating systems are reviewed. Materials included are types 304 and 316 stainless steel, Fe-2 1/4 Cr-1 Mo steel, and alloy 800H. Examples of environmental effects, including both chemical and physical interaction, are presented for a number of environments. The environments discussed are high-purity liquid sodium, high vacuum, air, impure helium, and irradiation damage, including internal helium bubble generation.

  4. Structural contribution to the ferroelectric fatigue in lead zirconate titanate ceramics

    NASA Astrophysics Data System (ADS)

    Hinterstein, M.; Rouquette, J.; Haines, J.; Papet, Ph.; Glaum, J.; Knapp, M.; Eckert, J.; Hoffman, M.

    2014-09-01

    Many ferroelectric devices are based on doped lead zirconate titanate (PZT) ceramics with compositions near the morphotropic phase boundary (MPB), at which the relevant material's properties approach their maximum. Based on a synchrotron x-ray diffraction study of MPB PZT, bulk fatigue is unambiguously found to arise from a less effective field induced tetragonal-to-monoclinic transformation, at which the degradation of the polarization flipping is detected by a less intense and more diffuse anomaly in the atomic displacement parameter of lead. The time dependence of the ferroelectric response on a structural level down to 250 μs confirms this interpretation in the time scale of the piezolectric strain response.

  5. 14 CFR 129.23 - Transport category cargo service airplanes: Increased zero fuel and landing weights.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... probability of sudden fatigue failure is not noticeably increased; (3) The flutter, deformation, and vibration... performance operating limitations in part 121 or the equivalent. (f) The Airplane Flight Manual for...

  6. 14 CFR 129.23 - Transport category cargo service airplanes: Increased zero fuel and landing weights.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... probability of sudden fatigue failure is not noticeably increased; (3) The flutter, deformation, and vibration... performance operating limitations in part 121 or the equivalent. (f) The Airplane Flight Manual for...

  7. Random Vibration Tests for Prediction of Fatigue Life of Diffuser Structure for Gas Dynamic Laser

    NASA Astrophysics Data System (ADS)

    Maurer, O. F.; Banaszak, D. L.

    1980-01-01

    Static and dynamic strain measurements which were taken during test stand operations of the gas dynamic laser (GDL) for the AF Airborne Laser Laboratory indicated that higher than expected vibrational stress levels may possibly limit the fatigue life of the laser structure. Particularly the diffuser sidewall structure exhibited large amplitude random vibrations which were excited by the internal gas flow. The diffuser structure consists of two layers of brazed stainless steel, AISI-347, panels. Cooling ducts were milled into the outer face sheet. These in turn are backed by the inner face sheet. So called T-rail stiffeners silver-brazed to the outer face sheets add the required stiffness and divide the sidewall into smaller rectangular plate sections.

  8. Fatigue crack growth properties of a cryogenic structural steel at liquid helium temperature

    SciTech Connect

    Konosu, Shinji; Kishiro, Tomohiro; Ivano, O.; Nunoya, Yoshihiko; Nakajima, Hideo; Tsuji, Hiroshi

    1996-01-01

    The structural materials of the coils of superconducting magnets utilized in thermonuclear fusion reactors are used at liquid helium (4.2 K) temperatures and are subjected to repeated thermal stresses and electromagnetic forces. A high strength, high toughness austenitic stainless steel (12Cr-12Ni-10Mn-5Mo-0.2N) has recently been developed for large, thick-walled components used in such environments. This material is non-magnetic even when subjected to processing and, because it is a forging material, it is advantageous as a structural material for large components. In the current research, a large forging of 12Cr-12Ni-10Mn-5Mo-0.2N austenitic stainless steel, was fabricated to a thickness of 250 mm, which is typical of section thicknesses encountered in actual equipment. The tensile fatigue crack growth properties of the forging were examined at liquid helium temperature as a function of specimen location across the thickness of the forging. There was virtually no evidence of variation in tensile strength or fatigue crack growth properties attributable to different sampling locations in the thickness direction and no effect of thickness due to the forging or solution treatment associated with large forgings was observed.

  9. Autonomous Deicing System For Airplane Wing

    NASA Technical Reports Server (NTRS)

    Hickman, G. A.; Gerardi, J. J.

    1993-01-01

    Prototype autonomous deicing system for airplane includes network of electronic and electromechanical modules at various locations in wings and connected to central data-processing unit. Small, integrated solid-state device, using long coils installed under leading edge, exciting small vibrations to detect ice and larger vibrations to knock ice off. In extension of concept, outputs of vibration sensors and other sensors used to detect rivet-line fractures, fatigue cracks, and other potentially dangerous defects.

  10. Structural characterization and anti-fatigue activity of polysaccharides from the roots of Morinda officinalis.

    PubMed

    Zhang, Hua-Lin; Li, Jun; Li, George; Wang, Dong-mei; Zhu, Long-ping; Yang, De-po

    2009-04-01

    Three polysaccharides MP-1, MP-2, and MP-3 were isolated from hot water extract of Chinese medicine Morinda officinalis through 95% ethanol precipitation and gel-filtration chromatography (DEAE-Sepharose CL-6B column and Sephadex G-75 or G-100 column). MP-1 was identified as an inulin-type fructan with simple linear (2-->1)-linked structure. Both MP-2 and MP-3 were acidic polysaccharides which consisted predominantly of galacturonic acid, arabinose and galactose. Partial structure characterization of MP-3 was carried out by partial acid hydrolysis and periodate oxidation. The total polysaccharides of the herb were tested in mice weight-loaded swimming model and were found to have anti-fatigue activity. PMID:19150459

  11. The Light Airplane

    NASA Technical Reports Server (NTRS)

    Driggs, Ivan H.

    1925-01-01

    This report begins with a review and analysis of the work being done to develop light airplanes in the U.S. and abroad. A technical discussion of the construction and innovations in light airplanes is then presented.

  12. Combining Passive Thermography and Acoustic Emission for Large Area Fatigue Damage Growth Assessment of a Composite Structure

    NASA Technical Reports Server (NTRS)

    Zalameda, Joseph N.; Horne, Michael R.; Madaras, Eric I.; Burke, Eric R.

    2016-01-01

    Passive thermography and acoustic emission data were obtained for improved real time damage detection during fatigue loading. A strong positive correlation was demonstrated between acoustic energy event location and thermal heating, especially if the structure under load was nearing ultimate failure. An image processing routine was developed to map the acoustic emission data onto the thermal imagery. This required removing optical barrel distortion and angular rotation from the thermal data. The acoustic emission data were then mapped onto thermal data, revealing the cluster of acoustic emission event locations around the thermal signatures of interest. By combining both techniques, progression of damage growth is confirmed and areas of failure are identified. This technology provides improved real time inspections of advanced composite structures during fatigue testing.Keywords: Thermal nondestructive evaluation, fatigue damage detection, aerospace composite inspection, acoustic emission, passive thermography

  13. Overview Of Structural Behavior and Occupant Responses from Crash Test of a Composite Airplane

    NASA Technical Reports Server (NTRS)

    Jones, Lisa E.; Carden, Huey D.

    1995-01-01

    As part of NASA's composite structures crash dynamics research, a general aviation aircraft with composite wing, fuselage and empennage (but with metal subfloor structure) was crash tested at the NASA Langley Research Center Impact Research Facility. The test was conducted to determine composite aircraft structural behavior for crash loading conditions and to provide a baseline for a similar aircraft test with a modified subfloor. Structural integrity and cabin volume were maintained. Lumbar loads for dummy occupants in energy absorbing seats wer substantially lower than those in standard aircraft seats; however, loads in the standard seats were much higher that those recorded under similar conditions for an all-metallic aircraft.

  14. Aeronautical fatigue: Key to safety and structural integrity; Proceedings of the 16th ICAF Symposium, Tokyo, Japan, May 22-24, 1991

    NASA Astrophysics Data System (ADS)

    Kobayashi, Akira

    The present conference on aeronautical fatigue examines its relationship to safety and structural integrity and encompasses multisite damage, aging aircraft, aluminum-lithium alloys, and composite materials. Specific issues addressed include an assessment of the C-141's structural life, fleet fatigue crack prediction, damage-tolerance analyses for several types of aircraft, rotor and gearbox fatigue, and general remarks on the maintenance of safety for an aging fleet of aircraft. Also addressed are the fatigue qualification of high-thickness composite rotor components, analyses of fatigue life for carbon-epoxy composites, a damage-tolerant Al-Li alloy 8090 sheet, the role of fatigue testing in aircraft design, development, and certification, and the effects of prior damage on crack propagation in Al alloys. (For individual items see A93-13627 to A93-13646)

  15. 75 FR 71346 - Special Conditions: Boeing Model 787-8 Airplane; Lightning Protection of Fuel Tank Structure To...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-23

    ..., 2009 (74 FR 52698). Several comments were received from two commenters (Cessna and NATCA). Cessna 1.... The Boeing Model 787-8 airplane will incorporate a fuel tank nitrogen generation system (NGS) that... Features The 787 will have a fuel tank NGS that is intended to control fuel tank flammability. This NGS...

  16. Creep and Creep-Fatigue Crack Growth at Structural Discontinuities and Welds

    SciTech Connect

    Dr. F. W. Brust; Dr. G. M. Wilkowski; Dr. P. Krishnaswamy; Mr. Keith Wichman

    2010-01-27

    The subsection ASME NH high temperature design procedure does not admit crack-like defects into the structural components. The US NRC identified the lack of treatment of crack growth within NH as a limitation of the code and thus this effort was undertaken. This effort is broken into two parts. Part 1, summarized here, involved examining all high temperature creep-fatigue crack growth codes being used today and from these, the task objective was to choose a methodology that is appropriate for possible implementation within NH. The second part of this task, which has just started, is to develop design rules for possible implementation within NH. This second part is a challenge since all codes require step-by-step analysis procedures to be undertaken in order to assess the crack growth and life of the component. Simple rules for design do not exist in any code at present. The codes examined in this effort included R5, RCC-MR (A16), BS 7910, API 579, and ATK (and some lesser known codes). There are several reasons that the capability for assessing cracks in high temperature nuclear components is desirable. These include: (1) Some components that are part of GEN IV reactors may have geometries that have sharp corners - which are essentially cracks. Design of these components within the traditional ASME NH procedure is quite challenging. It is natural to ensure adequate life design by modeling these features as cracks within a creep-fatigue crack growth procedure. (2) Workmanship flaws in welds sometimes occur and are accepted in some ASME code sections. It can be convenient to consider these as flaws when making a design life assessment. (3) Non-destructive Evaluation (NDE) and inspection methods after fabrication are limited in the size of the crack or flaw that can be detected. It is often convenient to perform a life assessment using a flaw of a size that represents the maximum size that can elude detection. (4) Flaws that are observed using in-service detection

  17. Reducing fatigue damage for ships in transit through structured decision making

    USGS Publications Warehouse

    Nichols, J.M.; Fackler, P.L.; Pacifici, K.; Murphy, K.D.; Nichols, J.D.

    2014-01-01

    Research in structural monitoring has focused primarily on drawing inference about the health of a structure from the structure’s response to ambient or applied excitation. Knowledge of the current state can then be used to predict structural integrity at a future time and, in principle, allows one to take action to improve safety, minimize ownership costs, and/or increase the operating envelope. While much time and effort has been devoted toward data collection and system identification, research to-date has largely avoided the question of how to choose an optimal maintenance plan. This work describes a structured decision making (SDM) process for taking available information (loading data, model output, etc.) and producing a plan of action for maintaining the structure. SDM allows the practitioner to specify his/her objectives and then solves for the decision that is optimal in the sense that it maximizes those objectives. To demonstrate, we consider the problem of a Naval vessel transiting a fixed distance in varying sea-state conditions. The physics of this problem are such that minimizing transit time increases the probability of fatigue failure in the structural supports. It is shown how SDM produces the optimal trip plan in the sense that it minimizes both transit time and probability of failure in the manner of our choosing (i.e., through a user-defined cost function). The example illustrates the benefit of SDM over heuristic approaches to maintaining the vessel.

  18. Power Law Versus Exponential Form of Slow Crack Growth of Advanced Structural Ceramics: Dynamic Fatigue

    NASA Technical Reports Server (NTRS)

    Choi, Sung R.; Gyekenyesi, John P.

    2002-01-01

    The life prediction analysis based on an exponential crack velocity formulation was examined using a variety of experimental data on glass and advanced structural ceramics in constant stress-rate ("dynamic fatigue") and preload testing at ambient and elevated temperatures. The data fit to the strength versus In (stress rate) relation was found to be very reasonable for most of the materials. It was also found that preloading technique was equally applicable for the case of slow crack growth (SCG) parameter n > 30. The major limitation in the exponential crack velocity formulation, however, was that an inert strength of a material must be known priori to evaluate the important SCG parameter n, a significant drawback as compared to the conventional power-law crack velocity formulation.

  19. Characterization of Fatigue Behavior of Composite Sandwich Structures at Sub-Zero Temperatures

    NASA Astrophysics Data System (ADS)

    Soni, Samirkumar M.; Gibson, Ronald F.; Ayorinde, Emmanuel O.

    This chapter summarizes recent studies of the flexural fatigue characteristics of foam core carbon/epoxy and glass/epoxy composite sandwich beams over the temperature range from 22°C to -60°C. Core shear was found to be the dominant fatigue failure mode for the test specimens over this temperature range. Significant increases in the useful fatigue life with brittle type core shear failure were observed at low temperatures by comparison with the corresponding room temperature behavior. Fatigue failure at the subzero temperatures was catastrophic and without any significant early warning, but the corresponding failures at room temperature were preceded by relatively slow but steadily increasing losses of stiffness. Two different approaches were used to investigate stiffness reductions during fatigue tests, and both approaches led to the same conclusions. Static finite element analyses confirmed the experimentally observed locations of fatigue crack initiation.

  20. 14 CFR 25.907 - Propeller vibration and fatigue.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Propeller vibration and fatigue. 25.907... AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant General § 25.907 Propeller vibration and fatigue. This section does not apply to fixed-pitch wood propellers of conventional design....

  1. 14 CFR 25.907 - Propeller vibration and fatigue.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Propeller vibration and fatigue. 25.907... AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant General § 25.907 Propeller vibration and fatigue. This section does not apply to fixed-pitch wood propellers of conventional design....

  2. 14 CFR 25.907 - Propeller vibration and fatigue.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Propeller vibration and fatigue. 25.907... AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant General § 25.907 Propeller vibration and fatigue. This section does not apply to fixed-pitch wood propellers of conventional design....

  3. 14 CFR 25.907 - Propeller vibration and fatigue.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Propeller vibration and fatigue. 25.907... AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant General § 25.907 Propeller vibration and fatigue. This section does not apply to fixed-pitch wood propellers of conventional design....

  4. 14 CFR 25.907 - Propeller vibration and fatigue.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Propeller vibration and fatigue. 25.907... AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant General § 25.907 Propeller vibration and fatigue. This section does not apply to fixed-pitch wood propellers of conventional design....

  5. Strain-cycling fatigue behavior of ten structural metals tested in liquid helium (4 K), in liquid nitrogen (78 K), and in ambient air (300 K)

    NASA Technical Reports Server (NTRS)

    Nachtigall, A. J.

    1974-01-01

    Strain-cycling fatigue behavior of 10 different structural alloys and metals was investigated in liquid helium (4 K), in liquid nitrogen (78 K), and in ambient air (300 K). At high cyclic lives, fatigue resistance increased with decreasing temperature for all the materials investigated. At low cyclic lives, fatigue resistance generally decreased with decreasing temperature for the materials investigated. Only for Inconel 718 did fatigue resistance increase with decreasing temperature over the entire life range investigated. Comparison of the experimental fatigue behavior with that predicted by the Manson method of universal slopes showed that the fatigue behavior of these materials can be predicted for cryogenic temperatures by using material tensile properties obtained at those same temperatures.

  6. 78 FR 24338 - Airworthiness Directives; The Boeing Company Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-25

    ... airplanes. This AD was prompted by reports of early fatigue cracks at chem-mill areas on the crown skin panels. This AD requires repetitive inspections for cracking of the fuselage skin along chem-mill steps at certain crown skin and shear wrinkle areas, and repair if necessary. We are issuing this AD...

  7. 77 FR 55681 - Airworthiness Directives; The Boeing Company Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-11

    ... (76 FR 72863). For certain airplanes, that NPRM proposed to require using redefined flight cycle... on the proposal (76 FR 72863, November 28, 2011) and the FAA's response. Request To Correct Certain Fatigue Cracking Assertions Boeing reported that the NPRM (76 FR 72863, November 28, 2011), in...

  8. 77 FR 52212 - Airworthiness Directives; The Boeing Company Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-29

    ... analysis of the predicted crack growth rate is used to establish the repetitive intervals of 1,400 flight cycles. These repetitive intervals must include the variability of crack growth rate between airplanes... inspected by the repairs in the Boeing SRM. This is the main cause for the fatigue cracking addressed...

  9. Effect of welding structure on high-cycle and low-cycle fatigue properties for MIG welded A5083 aluminum alloys at cryogenic temperatures

    NASA Astrophysics Data System (ADS)

    Yuri, Tetsumi; Ogata, Toshio; Saito, Masahiro; Hirayama, Yoshiaki

    2001-07-01

    High-cycle and low-cycle fatigue properties of aluminum alloy A5083 base and A5183 weld metals and the effect of welding structure on their fatigue properties have been investigated at cryogenic temperatures in order to evaluate the long-life reliability and safety of the structural materials used in liquid hydrogen supertankers and storage tanks and to develop a welding process for these applications. In the high-cycle fatigue tests, the S-N curves of A5083 base and A5183 weld metals shifted to higher stress levels, i.e., the longer life side at lower test temperatures. The ratios of 10 6-cycles fatigue strength (FS) to tensile strength (TS) for A5183 weld metals were slightly lower than those of A5083 base metals at each test temperature. Although the ratios of FS to TS for austenitic stainless steels weld metals at 4 K decreased substantially to about 0.4, that of A5183 weld metal was 0.65 even at 4 K and it indicated an excellent high-cycle fatigue property. Fatigue crack initiation sites in A5183 weld metals were occurred from the blowholes if the blowholes were located in the vicinity of the specimen surfaces. However, effects of the blowholes on high-cycle fatigue properties are not clear or significant. In the low-cycle fatigue tests, the fatigue lives of A5183 weld metals were slightly shorter than those of A5083 base metals at cryogenic temperatures. However, the fatigue lives of A5183 weld metals at 4 K were superior to that of conventional A5083 weld metals. The deterioration of low-cycle fatigue properties of A5183 weld metals at cryogenic temperatures were due to the intergranular fracture surface observed in fatigue crack propagation regions.

  10. Thermal evaluation of the mean fatigue limit of a complex structure

    NASA Astrophysics Data System (ADS)

    Arnould, Olivier; Bremond, Pierre; Hild, Francois

    2005-03-01

    The study deals with the long-term reliability of a high precision pressure sensor using bellows mainly made of electroplated Ni. Bellows are expected to stay in service for many decades. Their high cycle fatigue behavior has to be known to assess the probability of airtightness loss. A specific high cycle fatigue setup, put in a resonant machine that is displacement-controlled, has been designed. An infrared thermographic technique is used to determine the mean fatigue limit of bellows. Increases in the mean temperature of the bellows with the displacement range are monitored. Several authors empirically relate the mean fatigue limit of a flat specimen to a rapid temperature change. A similar analysis is performed in the present case by using the bellows mean temperature. Finite element computations allow us to estimate a mean fatigue stress threshold for electroplated Ni. This result is compared with those obtained mechanically in a Woehler diagram.

  11. Empirical modeling of environment-enhanced fatigue crack propagation in structural alloys for component life prediction

    NASA Technical Reports Server (NTRS)

    Richey, Edward, III

    1995-01-01

    This research aims to develop the methods and understanding needed to incorporate time and loading variable dependent environmental effects on fatigue crack propagation (FCP) into computerized fatigue life prediction codes such as NASA FLAGRO (NASGRO). In particular, the effect of loading frequency on FCP rates in alpha + beta titanium alloys exposed to an aqueous chloride solution is investigated. The approach couples empirical modeling of environmental FCP with corrosion fatigue experiments. Three different computer models have been developed and incorporated in the DOS executable program. UVAFAS. A multiple power law model is available, and can fit a set of fatigue data to a multiple power law equation. A model has also been developed which implements the Wei and Landes linear superposition model, as well as an interpolative model which can be utilized to interpolate trends in fatigue behavior based on changes in loading characteristics (stress ratio, frequency, and hold times).

  12. 14 CFR 25.571 - Damage-tolerance and fatigue evaluation of structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ..., corrosion, or accidental damage. Repeated load and static analyses supported by test evidence and (if... accidental damage. Repeated load and static analyses supported by test evidence and (if available) service... catastrophic failure of the airplane; and (iii) An analysis, supported by test evidence, of the...

  13. Effects of Processing Residual Stresses on Fatigue Crack Growth Behavior of Structural Materials: Experimental Approaches and Microstructural Mechanisms

    NASA Astrophysics Data System (ADS)

    Lammi, Christopher J.; Lados, Diana A.

    2012-01-01

    Fatigue crack growth mechanisms of long cracks through fields with low and high residual stresses were investigated for a common structural aluminum alloy, 6061-T61. Bulk processing residual stresses were introduced in the material by quenching during heat treatment. Compact tension (CT) specimens were fatigue crack growth (FCG) tested at varying stress ratios to capture the closure and K max effects. The changes in fatigue crack growth mechanisms at the microstructural scale are correlated to closure, stress ratio, and plasticity, which are all dependent on residual stress. A dual-parameter Δ K- K max approach, which includes corrections for crack closure and residual stresses, is used uniquely to connect fatigue crack growth mechanisms at the microstructural scale with changes in crack growth rates at various stress ratios for low- and high-residual-stress conditions. The methods and tools proposed in this study can be used to optimize existing materials and processes as well as to develop new materials and processes for FCG limited structural applications.

  14. 14 CFR 91.323 - Increased maximum certificated weights for certain airplanes operated in Alaska.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Civil Air Regulations (14 CFR part 4a, 1964 ed.) if that airplane is operated in the State of Alaska by... structural soundness of the airplane and the terrain to be traversed. (d) The maximum certificated...

  15. 14 CFR 91.323 - Increased maximum certificated weights for certain airplanes operated in Alaska.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Civil Air Regulations (14 CFR part 4a, 1964 ed.) if that airplane is operated in the State of Alaska by... structural soundness of the airplane and the terrain to be traversed. (d) The maximum certificated...

  16. Application of fracture mechanics and half-cycle theory to the prediction of fatigue life of aerospace structural components

    NASA Technical Reports Server (NTRS)

    Ko, William L.

    1989-01-01

    The service life of aircraft structural components undergoing random stress cycling was analyzed by the application of fracture mechanics. The initial crack sizes at the critical stress points for the fatigue crack growth analysis were established through proof load tests. The fatigue crack growth rates for random stress cycles were calculated using the half-cycle method. A new equation was developed for calculating the number of remaining flights for the structural components. The number of remaining flights predicted by the new equation is much lower than that predicted by the conventional equation. This report describes the application of fracture mechanics and the half-cycle method to calculate the number of remaining flights for aircraft structural components.

  17. Stochastic model for fatigue crack size and cost effective design decisions. [for aerospace structures

    NASA Technical Reports Server (NTRS)

    Hanagud, S.; Uppaluri, B.

    1975-01-01

    This paper describes a methodology for making cost effective fatigue design decisions. The methodology is based on a probabilistic model for the stochastic process of fatigue crack growth with time. The development of a particular model for the stochastic process is also discussed in the paper. The model is based on the assumption of continuous time and discrete space of crack lengths. Statistical decision theory and the developed probabilistic model are used to develop the procedure for making fatigue design decisions on the basis of minimum expected cost or risk function and reliability bounds. Selections of initial flaw size distribution, NDT, repair threshold crack lengths, and inspection intervals are discussed.

  18. 78 FR 73457 - Airworthiness Directives; the Boeing Company Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-06

    ... issued AD 84-19-01, the upper deck tension ties have been identified as structure that is susceptible to... data that support the established structural maintenance program. For certain airplanes, this proposed... Commercial Airplanes, Attention: Data & Services Management, P.O. Box 3707, MC 2H-65, Seattle, WA...

  19. Selective Reinforcement to Improve Fracture Toughness and Fatigue Crack Growth Resistance in Metallic Structures

    NASA Technical Reports Server (NTRS)

    Farley, Gary L.; Newman, John A.; James, Mark A.

    2004-01-01

    Experimental and analytical investigations of the fatigue crack growth and fracture response of aluminum selectively reinforced compact tension specimens were performed. It was shown that selective reinforcement significantly improved these responses primarily through load sharing by the reinforcement. With the appropriate combination of reinforcement architecture and mechanical properties, as well as reinforcement to base aluminum interface properties, fatigue cracks can be arrested using selective reinforcement. Maximum load associated with fracture increased up to 20 percent for the cases investigated and crack growth at maximum load increased as much as 150 percent. For both fatigue crack growth and fracture, the three most influential properties identified within the bounds of this investigation that influence this response are reinforcement width, reinforcement stiffness and interface stiffness. Considerable coupling occurs between the different fiber architecture and material properties and how they influence fatigue crack growth and fracture responses.

  20. Combining passive thermography and acoustic emission for large area fatigue damage growth assessment of a composite structure

    NASA Astrophysics Data System (ADS)

    Zalameda, Joseph N.; Horne, Michael R.; Madaras, Eric I.; Burke, Eric R.

    2016-05-01

    Passive thermography and acoustic emission data were obtained for improved real time damage detection during fatigue loading. A strong positive correlation was demonstrated between acoustic energy event location and thermal heating, especially if the structure under load was nearing ultimate failure. An image processing routine was developed to map the acoustic emission data onto the thermal imagery. This required removing optical barrel distortion and angular rotation from the thermal data. The acoustic emission data were then mapped onto thermal data, revealing the cluster of acoustic emission event locations around the thermal signatures of interest. By combining both techniques, progression of damage growth is confirmed and areas of failure are identified. This technology provides improved real time inspections of advanced composite structures during fatigue testing.

  1. Evaluation of flawed composite structural components under static and cyclic loading. [fatigue life of graphite-epoxy composite materials

    NASA Technical Reports Server (NTRS)

    Porter, T. R.

    1979-01-01

    The effects of initial defects on the fatigue and fracture response of graphite-epoxy composite laminates are presented. The structural laminates investigated were a typical angle ply laminate, a polar/hoop wound pressure vessel laminate, and a typical engine fan blade laminate. Defects investigated were full and half penetration circular holes, full and half penetration slits, and countersink holes. The effects of the defect size and type on the static fracture strength, fatigue performance, and residual static strength are shown as well as the results of loadings on damage propagation in composite laminates. The data obtained were used to define proof test levels as a qualification procedure in composite structure subjected to cyclic loading.

  2. Fatigue flaw growth and NDI evaluation for preventing through cracks in spacecraft tankage structures

    NASA Technical Reports Server (NTRS)

    Pettit, D. E.; Hoeppner, D. W.

    1972-01-01

    A program was conducted to determine the fatigue-crack propagation behavior of parent and welded 2219-T87 aluminum alloy sheet under controlled cyclic stress conditions in room temperature air and 300 F air. Specimens possessing an initial surface defect of controlled dimensions were cycled under constant load amplitude until the propagating fatigue crack penetrated the back surface of the specimen. A series of precracked specimens were prepared to determine optimum penetrant, X-ray, ultrasonic, and eddy current nondestructive inspection procedures.

  3. Fatigue crack detection in thick steel structures with piezoelectric wafer active sensors

    NASA Astrophysics Data System (ADS)

    Gresil, M.; Yu, L.; Giurgiutiu, V.

    2011-04-01

    This paper presents a set of numerical and experimental results on the use of guided waves for structural health monitoring (SHM) of crack growth during a fatigue test in a thick steel plate used for civil engineering application. The capability of embedded piezoelectric wafer active sensors (PWAS) to perform in situ nondestructive evaluation (NDE) is explored. Numerical simulation and experimental tests are used to prove that PWAS can perform active SHM using guided wave pitch-catch method and passive SHM using acoustic emission (AE). Multi-physics finite element (MPFEM) codes are used to simulate the transmission and reception of guided waves in a 1-mm plate and their diffraction by a through hole. The MP-FEM approach permitted that the input and output variables be expressed directly in electric terms while the two-ways electromechanical conversion was done internally in the MP-FEM formulation. The analysis was repeated for several hole sizes and a damage index performances was tested. AE simulation was performed with the MP-FEM approach in a 13-mm plate in the shape of the compact tension (CT) fracture mechanics specimen. The AE event was simulated as a pulse of defined duration and amplitude. The electrical signal measured at a receiver PWAS was simulated. Daubechies wavelet transform was used to process the signal and identify its Lamb modes and FFT frequency contents. Experimental tests were performed with PWAS transducers acting as passive receivers of AE signals. The 8-mm thick flange of an I beam was instrumented on one side with PWAS transducers and on the other side with conventional AE transducers (PAC R15I) acting as comparison witnesses. An AE source was simulated using 0.5- mm pencil lead breaks; the PWAS transducers were able to pick up AE signal with good strength. Subsequently, PWAS transducers and R15I sensors were applied to a 13-mm CT specimen subjected to accelerated fatigue testing. The PWAS and R15I transducers signals were collected with

  4. Turbulence descriptors for scaling fatigue loading spectra of wind turbine structural components

    NASA Astrophysics Data System (ADS)

    Kelley, N. D.

    1994-07-01

    The challenge for the designer in developing a new wind turbine is to incorporate sufficient strength in its components to safely achieve a 20- or 30-year service life. To accomplish this, the designer must understand the load and stress distributions (in a statistical sense at least) that the turbine is likely to encounter during its operating life. Sources of loads found in the normal operating environment include start/stop cycles, emergency shutdowns, the turbulence environment associated with the specific site and turbine location, and extreme or 'rare' events that can challenge the turbine short-term survivability. Extreme events can result from an operational problem (e.g., controller failure) or violent atmospheric phenomena (tornadic circulations, strong gust fronts). For the majority of the operating time, however, the character of the turbulent inflow is the dominant source of the alternating stress distributions experienced by the structural components. Methods of characterizing or scaling the severity of the loading spectra (or the rate of fatigue damage accumulation) must be applicable to a wide range of turbulent inflow environments - from solitary isolation to the complex flows associated with multi-row wind farms. The metrics chosen must be related to the properties of the turbulent inflow and independent of the nature of local terrain features.

  5. Mechanisms for Fatigue of Micron-Scale Silicon StructuralFilms

    SciTech Connect

    Alsem, Daan Hein; Pierron, Olivier N.; Stach, Eric A.; Muhlstein,Christopher L.; Ritchie, Robert O.

    2006-11-03

    Although bulk silicon is not susceptible to fatigue,micron-scale silicon is. Several mechanisms have been proposed to explainthis surprising behavior although the issue remains contentious. Here wedescribe published fatigue results for micron-scale thin siliconfilms andfind that in general they display similar trends, in that lower cyclicstresses result in larger number of cycles to failure in stress-lifetimedata. We further show that one of two classes of mechanisms is invariablyproposed to explain the phenomenon. The first class attributes fatigue toa surface effect caused by subcritical (stable) cracking in thesilicon-oxide layer, e.g., reaction-layer fatigue; the second classproposes that subcritical cracking in the silicon itself is the cause offatigue in Si films. It is our contention that results to date fromsingle and poly crystalline silicon fatigue studies provide no convincingexperimentalevidence to support subcritical cracking in the silicon.Conversely, the reaction-layer mechanism is consistent with existingexperimental results, and moreover provides a rational explanation forthe marked difference in fatigue behavior of bulk and micron-scalesilicon.

  6. Airplane design for gusts

    NASA Technical Reports Server (NTRS)

    Houbolt, J. C.

    1977-01-01

    There are two basic approaches used for the structural design of aircraft due to dust encounter. One is a discrete gust approach, the other is based on power spectral techniques. Both of these approaches are explained in this report. Tacit to the above approaches is the assumption that loading on the airplane arises primarily from vertical gusts. A study of atmospheric turbulence was made not only on the vertical component, but on the longitudinal and transverse gust components as well. An analysis was made to establish the loads that develop when explicit consideration is given to both the vertical and head-wind components. The results are reported. Also included in this report are brief comments on gust effects during approach and landing.

  7. Crash tests of four low-wing twin-engine airplanes with truss-reinforced fuselage structure

    NASA Technical Reports Server (NTRS)

    Williams, M. S.; Fasanella, E. L.

    1982-01-01

    Four six-place, low-wing, twin-engine, general aviation airplane test specimens were crash tested under controlled free flight conditions. All airplanes were impacted on a concrete test surface at a nomial flight path velocity of 27 m/sec. Two tests were conducted at a -15 deg flight path angle (0 deg pitch angle and 15 deg pitch angle), and two were conducted at a -30 deg flight path angle (-30 deg pitch angle). The average acceleration time histories (crash pulses) in the cabin area for each principal direction were calculated for each crash test. In addition, the peak floor accelerations were calculated for each test as a function of aircraft fuselage longitudinal station number. Anthropomorphic dummy accelerations were analyzed using the dynamic response index and severity index (SI) models. Parameters affecting the dummy restraint system were studied; these parameters included the effect of no upper torso restraint, measurement of the amount of inertia-reel strap pullout before locking, measurement of dummy chest forward motion, and loads in the restraints. With the SI model, the dummies with no shoulder harness received head impacts above the concussive threshold.

  8. The Airplane Experiment.

    ERIC Educational Resources Information Center

    Larson, Lee; Grant, Roderick

    1991-01-01

    Presents an experiment to investigate centripetal force and acceleration that utilizes an airplane suspended on a string from a spring balance. Investigates the possibility that lift on the wings of the airplane accounts for the differences between calculated tension and measured tension on the string. (MDH)

  9. Metal Airplane Construction

    NASA Technical Reports Server (NTRS)

    1926-01-01

    It has long been thought that metal construction of airplanes would involve an increase in weight as compared with wood construction. Recent experience has shown that such is not the case. This report describes the materials used, treatment of, and characteristics of metal airplane construction.

  10. Probabilistic Failure Assessment For Fatigue

    NASA Technical Reports Server (NTRS)

    Moore, Nicholas; Ebbeler, Donald; Newlin, Laura; Sutharshana, Sravan; Creager, Matthew

    1995-01-01

    Probabilistic Failure Assessment for Fatigue (PFAFAT) package of software utilizing probabilistic failure-assessment (PFA) methodology to model high- and low-cycle-fatigue modes of failure of structural components. Consists of nine programs. Three programs perform probabilistic fatigue analysis by means of Monte Carlo simulation. Other six used for generating random processes, characterizing fatigue-life data pertaining to materials, and processing outputs of computational simulations. Written in FORTRAN 77.

  11. Experimental Evaluation of Fatigue Crack Initiation from Corroded Hemispherical Notches in Aerospace Structural Materials

    NASA Technical Reports Server (NTRS)

    Garcia, Daniel B.; Forman, Royce; Shindo, David

    2010-01-01

    A test program was developed and executed to evaluate the influence of corroded hemispherical notches on the fatigue crack initiation and propagation in aluminum 7075-T7351, 4340 steel, and D6AC steel. Surface enhancements such as shot peening and laser shock peening were also incorporated as part of the test effort with the intent of improving fatigue performance. In addition to the testing, fracture mechanics and endurance limit based analysis methods were evaluated to characterize the results with the objective of challenging typical assumptions used in modeling fatigue cracks from corrosion pits. The results specifically demonstrate that the aluminum and steel alloys behave differently with respect to fatigue crack initiation from hemispherical corrosion pits. The aluminum test results were bounded by the fracture mechanics and endurance limit models while exhibiting a general insensitivity to the residual stress field generated by shot peening. The steel specimens were better characterized by the endurance limit fatigue properties and did exhibit sensitivities to residual stresses from the shot peening and laser shock peening

  12. Fatigue behaviour of Nitinol peripheral stents: the role of plaque shape studied with computational structural analyses.

    PubMed

    Dordoni, Elena; Meoli, Alessio; Wu, Wei; Dubini, Gabriele; Migliavacca, Francesco; Pennati, Giancarlo; Petrini, Lorenza

    2014-07-01

    Fatigue resistance of Nitinol stents implanted into femoro-popliteal arteries is a critical issue for the particular biomechanical environment of this district. Hip and knee joint movements due to the cyclic daily activity expose the superficial femoral artery (SFA), and therefore the implanted stents, to quite large and cyclic deformations influencing stent fatigue resistance. Objective of this work is to provide a tool based on finite element analysis able to evaluate the biomechanical effect of SFA on stent fatigue resistance. Computer simulations of the treatment of stenotic vessel by angioplasty and stenting and of the subsequent in vivo loading conditions (axial compression and bending) were carried out. Three different stenotic vessel models were defined, by keeping a constant stenosis rate and changing the plaque sharpness and number of stenoses. The fatigue behaviour was analysed comparing the amplitude and mean value distribution of the first principal strain in the whole stent for the different simulated conditions. Results showed that the maximum mean strain is similar in all the models, while the alternating strain is related to both plaque shape and loading conditions. In conclusion, this study confirms the requisite of replicating in vivo loading conditions. It also reveals the importance of taking into account the thickness variation of the vessel in the stenotic zone in the assessment of the stent fatigue resistance.

  13. Analytical and experimental investigation of aircraft metal structures reinforced with filamentary composites. Phase 2: Structural fatigue, thermal cycling, creep, and residual strength

    NASA Technical Reports Server (NTRS)

    Blichfeldt, B.; Mccarty, J. E.

    1972-01-01

    Specimens representative of metal aircraft structural components reinforced with boron filamentary composites were manufactured and tested under cyclic loading, cyclic temperature, or continuously applied loading to evaluate some of the factors that affect structural integrity under cyclic conditions. Bonded, stepped joints were used throughout to provide composite-to-metal transition regions at load introduction points. Honeycomb panels with titanium or aluminum faces reinforced with unidirectional boron composite were fatigue tested at constant amplitude under completely reversed loading. Results indicated that the matrix material was the most fatigue-sensitive part of the design, with debonding initiating in the stepped joints. However, comparisons with equal weight all-metal specimens show a 10 to 50 times improved fatigue life. Fatigue crack propagation and residual strength were studied for several different stiffened panel concepts, and were found to vary considerably depending on the configuration. Composite-reinforced metal specimens were also subjected to creep and thermal cycling tests. Thermal cycling of stepped joint tensile specimens resulted in a ten percent decrease in residual strength after 4000 cycles.

  14. Fatigue-induced Reversible/Irreversible Structural-transformation Study of a Ni-based Superalloy Using Combined In-situ Neutron-Diffraction and Thermal Approaches

    SciTech Connect

    Huang, E-Wen; Barabash, Rozaliya; Clausen, Bjorn; Liu, Yee-Lang; Kai, Ji-Jung; Ice, Gene E; Woods, Kyle P.; Liaw, Peter K

    2010-01-01

    Cyclic loading and the subsequent fatigue damage have been investigated with the in-situ neutron-diffraction and thermal characterization for a single-phase, polycrystal nickel-based alloy. The lattice-strain evolution is compared with the bulk parameters, such as the applied stress and the thermal response as a function of the fatigue cycles. The in-situ neutron-diffraction and thermal-evolution results identify the development of the five fatigue-damage stages. Fatigue damage is observed with bulk hardening, softening, and eventual saturation evident in both the diffraction patterns and the thermal-evolution features. An increase in the dislocation density and the formation of the patterned-dislocation structure are responsible for hardening within the early cycles. With further cyclic loading, the rearrangements of the dislocations result in the cyclic softening. The transition to saturation cycles is characterized by the anisotropy of the lattice strain evolution. The nonmonotonic thermal response and the irreversible anisotropy of the lattice-strain evolution are observed in the final saturation fatigue cycles. The fatigue-damage microstructure and dislocation-substructure evolution are studied with diffraction-profile analyses and complemented by the transmission-electron microscopy. The fluctuations of the differential dislocation density and size of the patterned substructure along with the in-situ thermal measurements reveal a second-order-kind structural transition and indicate the development of the irreversible fatigue-induced microstructure.

  15. Summary of Information Relating to Gust Loads on Airplanes

    NASA Technical Reports Server (NTRS)

    Donely, Philip

    1950-01-01

    Available information on gust structure, airplane reactions, and pertinent operating statistics has been examined. This report attempts to coordinate this information with reference to the prediction of gust loads on airplanes. The material covered represents research up to October 1947. (author)

  16. 78 FR 14469 - Airworthiness Directives; The Boeing Company Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-06

    ... in depressurization of the airplane in flight. Actions Since Existing AD (75 FR 61337, October 5... inspections to find cracking of the web, strap, inner chords, inner chord angle of the forward edge frame of... the adjacent body structure and could result in depressurization of the airplane in flight. DATES:...

  17. Assessment of the service life of structural steels by using degradation models with allowance for fatigue and creep of the material

    NASA Astrophysics Data System (ADS)

    Volkov, I. A.; Egunov, V. V.; Igumnov, L. A.; Kazakov, D. A.; Korotkikh, Yu. G.; Mitenkov, F. M.

    2015-11-01

    A mathematical model is developed within the framework of equations of damaged medium mechanics to describe the processes of viscoplastic straining and damage accumulation in structural steels with allowance for fatigue and creep of the material. A model of damage summation due to interaction of low-cycle fatigue and creep of the material is proposed. Material parameters and scalar functions of equations of mechanics of damaged media are determined. Viscoplastic straining and fatigue-induced damage accumulation in 08Kh18N10T and 12Kh18N9 are studied numerically, and the data obtained are compared with available results of physical experiments.

  18. Low-cycle thermal fatigue

    NASA Technical Reports Server (NTRS)

    Halford, G. R.

    1986-01-01

    A state-of-the-art review is presented of the field of thermal fatigue. Following a brief historical review, the concept is developed that thermal fatigue can be viewed as processes of unbalanced deformation and cracking. The unbalances refer to dissimilar mechanisms occurring in opposing halves of thermal fatigue loading and unloading cycles. Extensive data summaries are presented and results are interpreted in terms of the unbalanced processes involved. Both crack initiation and crack propagation results are summarized. Testing techniques are reviewed, and considerable discussion is given to a technique for thermal fatigue simulation, known as the bithermal fatigue test. Attention is given to the use of isothermal life prediction methods for the prediction of thermal fatigue lives. Shortcomings of isothermally-based life prediction methods are pointed out. Several examples of analyses and thermal fatigue life predictions of high technology structural components are presented. Finally, numerous dos and don'ts relative to design against thermal fatigue are presented.

  19. Fatigue methodology III; Proceedings of the AHS National Technical Specialists' Meeting on Advanced Rotorcraft Structures, Scottsdale, AZ, Oct. 3-5, 1989

    SciTech Connect

    Not Available

    1989-01-01

    Papers on rotorcraft and fatigue methodology are presented, covering topics such as reliability design for rotorcraft, a comparison between theory and fatigue test data on stress concentration factors, the retirement lives of rolling element bearings, hydrogen embrittlement risk analysis for high hardness steel parts, and rotating system load monitoring with minimum fixed system instrumentation. Additional topics include usage data collection to improve structural integrity of operational helicopters, usage monitory of military helicopters, improvements to the fatigue substantiation of the H-60 composite tail rotor blade, helicopter surviellance programs, and potential application of automotive fatigue technology in rotorcraft design. Also, consideration is given to fatigue evaluation of C/MH-53 E main rotor damper threaded joints, SH-2F airframe fatigue test program, a ply termination concept for improving fracture and fatigue strength of composite laminates, the analysis and testing of composite panels subject to muzzle blast effects, the certification plan for an all-composite main rotor flexbeam, and the effects of stacking sequence on the flexural strength of composite beams.

  20. A damage-based approach for the fatigue design of composite structures

    NASA Astrophysics Data System (ADS)

    Quaresimin, Marino

    2016-07-01

    The paper illustrates a fatigue design strategy, based on the physics of the damage evolution, under development by the Composite Group at DTG-University of Padova. After a brief introduction, where the motivations of the work are analysed, examples of damage mechanisms at the microscopic scale are discussed. Then the procedures for the quantitative description of these mechanisms are illustrated.

  1. General airplane performance

    NASA Technical Reports Server (NTRS)

    Rockfeller, W C

    1939-01-01

    Equations have been developed for the analysis of the performance of the ideal airplane, leading to an approximate physical interpretation of the performance problem. The basic sea-level airplane parameters have been generalized to altitude parameters and a new parameter has been introduced and physically interpreted. The performance analysis for actual airplanes has been obtained in terms of the equivalent ideal airplane in order that the charts developed for use in practical calculations will for the most part apply to any type of engine-propeller combination and system of control, the only additional material required consisting of the actual engine and propeller curves for propulsion unit. Finally, a more exact method for the calculation of the climb characteristics for the constant-speed controllable propeller is presented in the appendix.

  2. The Bristol "Badminton" Airplane

    NASA Technical Reports Server (NTRS)

    1926-01-01

    The Bristol Badminton, Type 99 airplane has a radial aircooled engine (a Bristol Jupiter 9 cylinder 450 HP.) and three fuel tanks. It is a single seat biplane weighing 1,840 lbs. empty and 2,460 lbs. loaded.

  3. Abrasion behavior of aluminum and composite skin coupons, stiffened skins and stiffened panels representative of transport airplane structures

    NASA Technical Reports Server (NTRS)

    Jackson, K. E.

    1985-01-01

    A three-phase investigation was conducted to compare the friction and wear response of aluminum and graphite-epoxy composite materials when subjected to loading conditions similar to those experienced by the skin panels on the underside of a transport airplane during an emergency belly landing on a runway surface. The first phase involved a laboratory test which used a standard belt sander to provide the sliding abrasive surface. Small skin-coupon test specimens were abraded over a range of pressures and velocities to determine the effects of these variables on the coefficient of friction and wear rate. The second phase involved abrading I-beam stiffened skins on actual runway surface over the same range of pressures and velocities used in the first phase. In the third phase, large stiffened panels which most closely resembled transport fuelage skin construction were abraded on a runway surface. This report presents results from each phase of the investigation and shows comparisons between the friction and wear behavior of the aluminum and graphite-epoxy composite materials.

  4. Mixed-Mode Fracture and Fatigue Analysis of Cracked 3D Complex Structures using a 3D SGBEM-FEM Alternating Method

    NASA Astrophysics Data System (ADS)

    Bhavanam, Sharada

    The aim of this thesis is to numerically evaluate the mixed-mode Stress Intensity Factors (SIFs) of complex 3D structural geometries with arbitrary 3D cracks using the Symmetric Galerkin Boundary Element Method-Finite Element Method (SGBEM-FEM) Alternating Method. Various structural geometries with different loading scenarios and crack configurations were examined in this thesis to understand the behavior and trends of the mixed-mode SIFs as well as the fatigue life for these complex structural geometries. Although some 3D structures have empirical and numerical solutions that are readily available in the open literature, some do not; therefore this thesis presents the results of fracture and fatigue analyses of these 3D complex structures using the SGBEM-FEM Alternating Method to serve as reference for future studies. Furthermore, there are advantages of using the SGBEM-FEM Alternating Method compared to traditional FEM methods. For example, the fatigue-crack-growth and fatigue life can be better estimated for a structure because different fatigue models (i.e. Walker, Paris, and NASGRO) can be used within the same framework of the SGBEM-FEM Alternating Method. The FEM (un-cracked structure)/BEM(crack model) meshes are modeled independently, which speeds up the computation process and reduces the cost of human labor. A simple coarse mesh can be used for all fracture and fatigue analyses of complex structures. In this thesis, simple coarse meshes were used for 3D complex structures, which were below 5000 elements as compared to traditional FEM, which require meshes where the elements range on the order of ˜250,000 to ˜106 and sometimes even more than that.

  5. Effect of fatigue loading on structure and functional behaviour of fascicles from energy-storing tendons.

    PubMed

    Thorpe, Chavaunne T; Riley, Graham P; Birch, Helen L; Clegg, Peter D; Screen, Hazel R C

    2014-07-01

    Tendons can broadly be categorized according to their function: those that act purely to position the limb and those that have an additional function as energy stores. Energy-storing tendons undergo many cycles of large deformations during locomotion, and so must be able to extend and recoil efficiently, rapidly and repeatedly. Our previous work has shown rotation in response to applied strain in fascicles from energy-storing tendons, indicating the presence of helical substructures which may provide greater elasticity and recovery. In the current study, we assessed how preconditioning and fatigue loading affect the ability of fascicles from the energy-storing equine superficial digital flexor tendon to extend and recoil. We hypothesized that preconditioned samples would exhibit changes in microstructural strain response, but would retain their ability to recover. We further hypothesized that fatigue loading would result in sample damage, causing further alterations in extension mechanisms and a significant reduction in sample recovery. The results broadly support these hypotheses: preconditioned samples showed some alterations in microstructural strain response, but were able to recover following the removal of load. However, fatigue loaded samples showed visual evidence of damage and exhibited further alterations in extension mechanisms, characterized by decreased rotation in response to applied strain. This was accompanied by increased hysteresis and decreased recovery. These results suggest that fatigue loading results in a compromised helix substructure, reducing the ability of energy-storing tendons to recoil. A decreased ability to recoil may lead to an impaired response to further loading, potentially increasing the likelihood of injury.

  6. It's time to reinvent the general aviation airplane

    NASA Technical Reports Server (NTRS)

    Stengel, Robert F.

    1988-01-01

    Current designs for general aviation airplanes have become obsolete, and avenues for major redesign must be considered. New designs should incorporate recent advances in electronics, aerodynamics, structures, materials, and propulsion. Future airplanes should be optimized to operate satisfactorily in a positive air traffic control environment, to afford safety and comfort for point-to-point transportation, and to take advantage of automated manufacturing techniques and high production rates. These requirements have broad implications for airplane design and flying qualities, leading to a concept for the Modern Equipment General Aviation (MEGA) airplane. Synergistic improvements in design, production, and operation can provide a much needed fresh start for the general aviation industry and the traveling public. In this investigation a small four place airplane is taken as the reference, although the proposed philosophy applies across the entire spectrum of general aviation.

  7. Class 2 design update for the family of commuter airplanes

    NASA Technical Reports Server (NTRS)

    Creighton, Thomas R.; Hendrich, Louis J.

    1987-01-01

    This is the final report of seven on the design of a family of commuter airplanes. This design effort was performed in fulfillment of NASA/USRA grant NGT-8001. Its contents are as follows: (1) the class 1 baseline designs for the commuter airplane family; (2) a study of takeoff weight penalties imposed on the commuter family due to implementing commonality objectives; (3) component structural designs common to the commuter family; (4) details of the acquisition and operating economics of the commuter family, i.e., savings due to production commonality and handling qualities commonality are determined; (5) discussion of the selection of an advanced turboprop propulsion system for the family of commuter airplanes, and (6) a proposed design for an SSSA controller design to achieve similar handling for all airplanes. Final class 2 commuter airplane designs are also presented.

  8. Contact fatigue of a silicon carbide with a heterogeneous grain structure

    SciTech Connect

    Padture, N.P.; Lawn, B.R.

    1995-06-01

    A comparative study of cyclic fatigue damage from Hertzian contacts in silicon carbide ceramics with homogeneous microstructure (fine, equiaxed grains, strong grain boundaries) and heterogeneous microstructure (coarse, contiguous elongate grains, weak interphase boundaries) is presented. Observations of the surface and subsurface damage patterns using optical microscopy reveal fundamentally different cyclic fatigue mechanisms: in the homogeneous material, by slow growth of a well-developed cone crack outside the contact area; in the heterogeneous material, by progressive mechanical degradation within a distributed damage zone below the contact area. Scanning electron micrographs of the latter material show copious fine debris in the damage zone, consistent with a degradation mechanism by frictional attrition by forward-reverse sliding at the weak interphase boundaries. Acoustic emission is recorded during both load and unload half-cycles, confirming hysteresis in the sliding process. Flexure tests indicate initially slight strength losses from the cyclic contact damage in both microstructures, followed by accelerated losses at higher numbers of cycles. The underlying basis for establishing an analytical model of damage accumulation in the heterogeneous microstructure in terms of shear-fault sliding, and for designing microstructures for optimal properties in fatigue and wear applications, is foreshadowed.

  9. Stresses Produced in Airplane Wings by Gusts

    NASA Technical Reports Server (NTRS)

    Kussner, Hans Georg

    1932-01-01

    Accurate prediction of gust stress being out of the question because of the multiplicity of the free air movements, the exploration of gust stress is restricted to static method which must be based upon: 1) stress measurements in free flight; 2) check of design specifications of approved type airplanes. With these empirical data the stress must be compared which can be computed for a gust of known intensity and structure. This "maximum gust" then must be so defined as to cover the whole ambit of empiricism and thus serve as prediction for new airplane designs.

  10. Structural response to discrete and continuous gusts of an airplane having wing bending flexibility and a correlation of calculated and flight results

    NASA Technical Reports Server (NTRS)

    Houbolt, John C; Kordes, Eldon E

    1954-01-01

    An analysis is made of the structural response to gusts of an airplane having the degrees of freedom of vertical motion and wing bending flexibility and basic parameters are established. A convenient and accurate numerical solution of the response equations is developed for the case of discrete-gust encounter, an exact solution is made for the simpler case of continuous-sinusoidal-gust encounter, and the procedure is outlined for treating the more realistic condition of continuous random atmospheric turbulence, based on the methods of generalized harmonic analysis. Correlation studies between flight and calculated results are then given to evaluate the influence of wing bending flexibility on the structural response to gusts of two twin-engine transports and one four-engine bomber. It is shown that calculated results obtained by means of a discrete-gust approach reveal the general nature of the flexibility effects and lead to qualitative correlation with flight results. In contrast, calculations by means of the continuous-turbulence approach show good quantitative correlation with flight results and indicate a much greater degree of resolution of the flexibility effects.

  11. Safety and design in airplane construction

    NASA Technical Reports Server (NTRS)

    Teichmann, Alfred

    1934-01-01

    The author gives a survey of the principles of stress analysis and design of airplane structures, and discusses the fundamental strength specifications and their effect on the stress analysis as compared with the safety factors used in other branches of engineering.

  12. Fatigue failure kinetics and structural changes in lead-free interconnects due to mechanical and thermal cycling

    NASA Astrophysics Data System (ADS)

    Fiedler, Brent Alan

    Environmental and human health concerns drove European parliament to mandate the Reduction of Hazardous Substances (RoHS) for electronics. This was enacted in July 2006 and has practically eliminated lead in solder interconnects. There is concern in the electronics packaging community because modern lead-free solder is rich in tin. Presently, near-eutectic tin-silver-copper solders are favored by industry. These solders are stiffer than the lead-tin near-eutectic alloys, have a higher melting temperature, fewer slip systems, and form intermetallic compounds (IMC) with Cu, Ni and Ag, each of which tend to have a negative effect on lifetime. In order to design more reliable interconnects, the experimental observation of cracking mechanisms is necessary for the correct application of existing theories. The goal of this research is to observe the failure modes resulting from mode II strain and to determine the damage mechanisms which describe fatigue failures in 95.5 Sn- 4.0 Ag - 0.5 Cu wt% (SAC405) lead-free solder interconnects. In this work the initiation sites and crack paths were characterized for SAC405 ball-grid array (BGA) interconnects with electroless-nickel immersion-gold (ENIG) pad-finish. The interconnects were arranged in a perimeter array and tested in fully assembled packages. Evaluation methods included monotonic and displacement controlled mechanical shear fatigue tests, and temperature cycling. The specimens were characterized using metallogaphy, including optical and electron microscopy as well as energy dispersive spectroscopy (EDS) and precise real-time electrical resistance structural health monitoring (SHM). In mechanical shear fatigue tests, strain was applied by the substrates, simulating dissimilar coefficients of thermal expansion (CTE) between the board and chip-carrier. This type of strain caused cracks to initiate in the soft Sn-rich solder and grow near the interface between the solder and intermetallic compounds (IMC). The growth near

  13. Probabilistic Fatigue Damage Program (FATIG)

    NASA Technical Reports Server (NTRS)

    Michalopoulos, Constantine

    2012-01-01

    FATIG computes fatigue damage/fatigue life using the stress rms (root mean square) value, the total number of cycles, and S-N curve parameters. The damage is computed by the following methods: (a) traditional method using Miner s rule with stress cycles determined from a Rayleigh distribution up to 3*sigma; and (b) classical fatigue damage formula involving the Gamma function, which is derived from the integral version of Miner's rule. The integration is carried out over all stress amplitudes. This software solves the problem of probabilistic fatigue damage using the integral form of the Palmgren-Miner rule. The software computes fatigue life using an approach involving all stress amplitudes, up to N*sigma, as specified by the user. It can be used in the design of structural components subjected to random dynamic loading, or by any stress analyst with minimal training for fatigue life estimates of structural components.

  14. Creep-Fatigue Interaction Testing

    NASA Technical Reports Server (NTRS)

    Halford, Gary R.

    2001-01-01

    Fatigue fives in metals are nominally time independent below 0.5 T(sub Melt). At higher temperatures, fatigue lives are altered due to time-dependent, thermally activated creep. Conversely, creep rates are altered by super. imposed fatigue loading. Creep and fatigue generally interact synergistically to reduce material lifetime. Their interaction, therefore, is of importance to structural durability of high-temperature structures such as nuclear reactors, reusable rocket engines, gas turbine engines, terrestrial steam turbines, pressure vessel and piping components, casting dies, molds for plastics, and pollution control devices. Safety and lifecycle costs force designers to quantify these interactions. Analytical and experimental approaches to creep-fatigue began in the era following World War II. In this article experimental and life prediction approaches are reviewed for assessing creep-fatigue interactions of metallic materials. Mechanistic models are also discussed briefly.

  15. 14 CFR 23.627 - Fatigue strength.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Fatigue strength. The structure must be designed, as far as practicable, to avoid points of stress concentration where variable stresses above the fatigue limit are likely to occur in normal service....

  16. 14 CFR 23.627 - Fatigue strength.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Fatigue strength. The structure must be designed, as far as practicable, to avoid points of stress concentration where variable stresses above the fatigue limit are likely to occur in normal service....

  17. 14 CFR 23.627 - Fatigue strength.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Fatigue strength. The structure must be designed, as far as practicable, to avoid points of stress concentration where variable stresses above the fatigue limit are likely to occur in normal service....

  18. 14 CFR 23.627 - Fatigue strength.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Fatigue strength. The structure must be designed, as far as practicable, to avoid points of stress concentration where variable stresses above the fatigue limit are likely to occur in normal service....

  19. 14 CFR 23.627 - Fatigue strength.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Fatigue strength. The structure must be designed, as far as practicable, to avoid points of stress concentration where variable stresses above the fatigue limit are likely to occur in normal service....

  20. 14 CFR 36.7 - Acoustical change: Transport category large airplanes and jet airplanes.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... airplanes and jet airplanes. 36.7 Section 36.7 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION... § 36.7 Acoustical change: Transport category large airplanes and jet airplanes. (a) Applicability. This section applies to all transport category large airplanes and jet airplanes for which an acoustical...

  1. 14 CFR 36.7 - Acoustical change: Transport category large airplanes and jet airplanes.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... airplanes and jet airplanes. 36.7 Section 36.7 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION... § 36.7 Acoustical change: Transport category large airplanes and jet airplanes. (a) Applicability. This section applies to all transport category large airplanes and jet airplanes for which an acoustical...

  2. 76 FR 63172 - Airworthiness Directives; The Boeing Company Model 767 Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-12

    ... flight cycles after January 2, 2007 (the effective date of AD 2006-24-04 (71 FR 68432, November 27, 2006....5. This AD results from reported fatigue cracking in the vertical inner chord and the forward outer... flight loads of the horizontal stabilizer, and consequent loss of controllability of the airplane....

  3. 61 FR 13785 - Airworthiness Directives; de Havilland Model DHC-8-100 and -300 Series Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    1996-03-28

    ... structure where black film thermal insulation is used; repair, if necessary; and replacement of black... corrosion forming on areas of the airplane structure where the black film covers the thermal insulation... detect corrosion on areas of the airplane structure where black film thermal insulation is used,...

  4. Buffet characteristics of the F-8 supercritical wing airplane

    NASA Technical Reports Server (NTRS)

    Deangelis, V. M.; Monaghan, R. C.

    1977-01-01

    The buffet characteristics of the F-8 supercritical wing airplane were investigated. Wing structural response was used to determine the buffet characteristics of the wing and these characteristics are compared with wind tunnel model data and the wing flow characteristics at transonic speeds. The wingtip accelerometer was used to determine the buffet onset boundary and to measure the buffet intensity characteristics of the airplane. The effects of moderate trailing edge flap deflections on the buffet onset boundary are presented. The supercritical wing flow characteristics were determined from wind tunnel and flight static pressure measurements and from a dynamic pressure sensor mounted on the flight test airplane in the vicinity of the shock wave that formed on the upper surface of the wing at transonic speeds. The comparison of the airplane's structural response data to the supercritical flow characteristics includes the effects of a leading edge vortex generator.

  5. The Effect of a Non-Gaussian Random Loading on High-Cycle Fatigue of a Thermally Post-Buckled Structure

    NASA Technical Reports Server (NTRS)

    Rizzi, Stephen A.; Behnke, marlana N.; Przekop, Adam

    2010-01-01

    High-cycle fatigue of an elastic-plastic beam structure under the combined action of thermal and high-intensity non-Gaussian acoustic loadings is considered. Such loadings can be highly damaging when snap-through motion occurs between thermally post-buckled equilibria. The simulated non-Gaussian loadings investigated have a range of skewness and kurtosis typical of turbulent boundary layer pressure fluctuations in the vicinity of forward facing steps. Further, the duration and steadiness of high excursion peaks is comparable to that found in such turbulent boundary layer data. Response and fatigue life estimates are found to be insensitive to the loading distribution, with the minor exception of cases involving plastic deformation. In contrast, the fatigue life estimate was found to be highly affected by a different type of non-Gaussian loading having bursts of high excursion peaks.

  6. The evolution of airplanes

    NASA Astrophysics Data System (ADS)

    Bejan, A.; Charles, J. D.; Lorente, S.

    2014-07-01

    The prevailing view is that we cannot witness biological evolution because it occurred on a time scale immensely greater than our lifetime. Here, we show that we can witness evolution in our lifetime by watching the evolution of the flying human-and-machine species: the airplane. We document this evolution, and we also predict it based on a physics principle: the constructal law. We show that the airplanes must obey theoretical allometric rules that unite them with the birds and other animals. For example, the larger airplanes are faster, more efficient as vehicles, and have greater range. The engine mass is proportional to the body size: this scaling is analogous to animal design, where the mass of the motive organs (muscle, heart, lung) is proportional to the body size. Large or small, airplanes exhibit a proportionality between wing span and fuselage length, and between fuel load and body size. The animal-design counterparts of these features are evident. The view that emerges is that the evolution phenomenon is broader than biological evolution. The evolution of technology, river basins, and animal design is one phenomenon, and it belongs in physics.

  7. Automatic Stability of Airplanes

    NASA Technical Reports Server (NTRS)

    Haus, FR

    1932-01-01

    It is endeavored in this report to give a full outline of the problem of airplane stability and to classify the proposed solutions systematically. Longitudinal stability, which can be studied separately, is considered first. The combination of lateral and directional stabilities, which cannot be separated, will be dealt with later.

  8. Fatigue of fiberglass beam substructures

    SciTech Connect

    Mandell, J.F.; Combs, D.W.; Samborsky, D.D.

    1995-09-01

    Composite material beams representative of wind turbine blade substructure have been designed, fabricated, and tested under constant amplitude flexural fatigue loading. Beam stiffness, strength, and fatigue life are predicted based on detailed finite element analysis and the materials fatigue database developed using standard test coupons and special high frequency minicoupons.Beam results are in good agreement with predictions when premature adhesive and delamination failures are avoided in the load transfer areas. The results show that fiberglass substructures can be designed and fabricated to withstand maximum strain levels on the order of 8,000 microstrain for about 10{sup 6} cycles with proper structural detail design and the use of fatigue resistant laminate constructions. The study also demonstrates that the materials fatigue database and accurate analysis can be used to predict the fatigue life of composite substructures typical of blades.

  9. Creep-fatigue response of structural ceramics: 1, Comparison of flexure, tension, and compression testing

    SciTech Connect

    Ferber, M.K.; Jenkins, M.G.; Nolan, T.A.; Yeckley, R.

    1990-12-31

    The stress sensitivities of the creep rates of commercially available Al{sub 2}O{sub 3} and Si{sub 3}N{sub 4} ceramics were measured at elevated temperatures using tension, compression, and flexure specimens. Pronounced differences in creep deformation behavior in compression and tension were observed for both ceramics. These differences were attributed to the generation of a creep-induced damage zone under tensile loading which accelerated the creep rate. The evolution of this damage zone was confirmed by (1) fractographic studies of failed tensile samples and (2) the observed stress-dependence of the creep failure strain. The creep rate-stress data generated fromn the flexure creep testing were found to be in fair agreement with results predicted from a creep deformation model. Differences between experimental and predicted creep behavior were attributed to the failure of the model to account for primary creep. This model was also capable of describing differences in the fatigue-life characteristics of a silicon nitride measured in flexure and tension.

  10. Creep-fatigue response of structural ceramics: 1, Comparison of flexure, tension, and compression testing

    SciTech Connect

    Ferber, M.K.; Jenkins, M.G.; Nolan, T.A. ); Yeckley, R. )

    1990-01-01

    The stress sensitivities of the creep rates of commercially available Al{sub 2}O{sub 3} and Si{sub 3}N{sub 4} ceramics were measured at elevated temperatures using tension, compression, and flexure specimens. Pronounced differences in creep deformation behavior in compression and tension were observed for both ceramics. These differences were attributed to the generation of a creep-induced damage zone under tensile loading which accelerated the creep rate. The evolution of this damage zone was confirmed by (1) fractographic studies of failed tensile samples and (2) the observed stress-dependence of the creep failure strain. The creep rate-stress data generated fromn the flexure creep testing were found to be in fair agreement with results predicted from a creep deformation model. Differences between experimental and predicted creep behavior were attributed to the failure of the model to account for primary creep. This model was also capable of describing differences in the fatigue-life characteristics of a silicon nitride measured in flexure and tension.

  11. High Speed Research Program Sonic Fatigue

    NASA Technical Reports Server (NTRS)

    Rizzi, Stephen A. (Technical Monitor); Beier, Theodor H.; Heaton, Paul

    2005-01-01

    The objective of this sonic fatigue summary is to provide major findings and technical results of studies, initiated in 1994, to assess sonic fatigue behavior of structure that is being considered for the High Speed Civil Transport (HSCT). High Speed Research (HSR) program objectives in the area of sonic fatigue were to predict inlet, exhaust and boundary layer acoustic loads; measure high cycle fatigue data for materials developed during the HSR program; develop advanced sonic fatigue calculation methods to reduce required conservatism in airframe designs; develop damping techniques for sonic fatigue reduction where weight effective; develop wing and fuselage sonic fatigue design requirements; and perform sonic fatigue analyses on HSCT structural concepts to provide guidance to design teams. All goals were partially achieved, but none were completed due to the premature conclusion of the HSR program. A summary of major program findings and recommendations for continued effort are included in the report.

  12. Phase 2 program on ground test of refanned JT8D turbofan engines and nacelles for the 727 airplane. Volume 4: Airplane evaluation and analysis

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The retrofit of JT8D-109 (refan) engines are evaluated on a 727-200 airplane in terms of airworthiness, performance, and noise. Design of certifiable hardware, manufacture, and ground testing of the essential nacelle components is included along with analysis of the certifiable airplane design to ensure airworthiness compliance and to predict the in-flight performance and noise characteristics of the modified airplane. The analyses confirm that the 727 refan airplane is certifiable. The refan airplane range would be 15% less that of the baseline airplane and block fuel would be increased by 1.5% to 3%. However, with this particular 727-200 model, with a brake release gross weight of 172,500 lb (78,245 kg), it is possible to operate the airplane (with minor structural modifications) at higher gross weights and increase the range up to 15% over the 727-200 (baseline) airplane. The refan airplane FAR Part 36 noise levels would be 6 to 8 EPNdB (effective perceived noise in decibels) below the baseline. Noise footprint studies showed that approach noise contour areas are small compared to takeoff areas. The 727 refan realizes a 68% to 83% reduction in annoyance-weighted area when compared to the 727-200 over a range of gross weights and operational procedures.

  13. Empirical modeling of environment-enhanced fatigue crack propagation in structural alloys for component life prediction. Final report

    SciTech Connect

    Richey, E. III

    1995-10-01

    This research aims to develop the methods and understanding needed to incorporate time and loading variable dependent environmental effects on fatigue crack propagation (FCP) into computerized fatigue life prediction codes such as NASA FLAGRO (NASGRO). In particular, the effect of loading frequency on FCP rates in alpha + beta titanium alloys exposed to an aqueous chloride solution is investigated. The approach couples empirical modeling of environmental FCP with corrosion fatigue experiments. Three different computer models have been developed and incorporated in the DOS executable program. UVAFAS. A multiple power law model is available, and can fit a set of fatigue data to a multiple power law equation. A model has also been developed which implements the Wei and Landes linear superposition model, as well as an interpolative model which can be utilized to interpolate trends in fatigue behavior based on changes in loading characteristics (stress ratio, frequency, and hold times).

  14. CONDENSED MATTER: STRUCTURE, MECHANICAL AND THERMAL PROPERTIES: Neutron Diffraction Measurements of a Thermally Fatigued Single Crystal Superalloy

    NASA Astrophysics Data System (ADS)

    Sun, Guang-Ai; Chen, Bo; Wu, Er-Dong; Li, Jin-Chao; Pirling, T.; Hughes, D.

    2009-08-01

    The thermally fatigued single crystal superalloy DZ125L is investigated by neutron diffraction measurements. The measurements, made using the phi angle oscillating method, provide more detailed and reliable data than those with the phi angle fixed. Diffraction studies show that the influence of thermal fatigue on the lattice parameters of the alloy is very limited. The stress analysis reveals that triaxial elastic hydrostatic stress plays a major role during thermal fatigue. The magnitude of the macrostress increases with the fatigue cycles, with the stress of the γ phase increasing more significantly than that of the γ' phase, and becoming fragile after many cycles. The changes in the microstrain are dependent on the reflection planes. The microstrains at the center of the sample are released by the thermal fatigue in comparison with those at the outlying locations, which has been attributed to the advance of the dislocation slips.

  15. 59 FR- Airworthiness Directives; de Havilland Model DHC-8-100 and -300 Series Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    1994-09-27

    ... of the airplane structure where black film thermal insulation is used, and repair, if necessary; and... thermal insulation blankets. The actions specified by the proposed AD are intended to prevent degradation... forming on areas of the airplane structure where black Orcon film covers the thermal insulation...

  16. 61 FR 51062 - Airworthiness Directives; de Havilland Model DHC-7 Series Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    1996-09-30

    ... areas of the airplane structure where black film thermal insulation blankets are used. The actions... airplane structure where black Orcon film covers the thermal insulation blankets. Investigation revealed... maintenance records to determine if any insulation blankets have been repaired or changed during service,...

  17. 63 FR 50755 - Airworthiness Directives; Bombardier Model DHC-8-100 and -300 Series Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    1998-09-23

    ... airplane structure where black film thermal insulation is used; repair, if necessary; and replacement of black insulation blankets with certain aluminized (silver) insulation. This amendment is prompted by... the airplane structure where black film thermal insulation is used; repair, if necessary;...

  18. Exploring Venus by Solar Airplane

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.

    2001-01-01

    A solar-powered airplane is proposed to explore the atmospheric environment of Venus. Venus has several advantages for a solar airplane. At the top of the cloud level, the solar intensity is comparable to or greater than terrestrial solar intensities. The Earthlike atmospheric pressure means that the power required for flight is lower for Venus than that of Mars, and the slow rotation of Venus allows an airplane to be designed for continuous sunlight, with no energy storage needed for night-time flight. These factors mean that Venus is perhaps the easiest planet in the solar system for flight of a long-duration solar airplane.

  19. Automated airplane surface generation

    SciTech Connect

    Smith, R.E.; Cordero, Y.; Jones, W.

    1996-12-31

    An efficient methodology and software axe presented for defining a class of airplane configurations. A small set of engineering design parameters and grid control parameters govern the process. The general airplane configuration has wing, fuselage, vertical tall, horizontal tail, and canard components. Wing, canard, and tail surface grids axe manifested by solving a fourth-order partial differential equation subject to Dirichlet and Neumann boundary conditions. The design variables are incorporated into the boundary conditions, and the solution is expressed as a Fourier series. The fuselage is described by an algebraic function with four design parameters. The computed surface grids are suitable for a wide range of Computational Fluid Dynamics simulation and configuration optimizations. Both batch and interactive software are discussed for applying the methodology.

  20. Mechanical control of airplanes

    NASA Technical Reports Server (NTRS)

    Boykow, H

    1929-01-01

    Before undertaking a detailed description of an automatic-control mechanism, I will state briefly the fundamental conditions for such devices. These are: 1) it must be sensitive at one or more reference values; 2) it must stop the angular motions of the airplane not produced by the pilot; and 3) it must be possible to switch it off and on by a simple hand lever.

  1. Strength calculations on airplanes

    NASA Technical Reports Server (NTRS)

    Baumann, A

    1925-01-01

    Every strength calculation, including those on airplanes, must be preceded by a determination of the forces to be taken into account. In the following discussion, it will be assumed that the magnitudes of these forces are known and that it is only a question of how, on the basis of these known forces, to meet the prescribed conditions on the one hand and the practical requirements on the other.

  2. Chronic Fatigue Syndrome

    MedlinePlus

    Chronic fatigue syndrome (CFS) is a disorder that causes extreme fatigue. This fatigue is not the kind of tired feeling that ... activities. The main symptom of CFS is severe fatigue that lasts for 6 months or more. You ...

  3. Dynamic Breaking Tests of Airplane Parts

    NASA Technical Reports Server (NTRS)

    Hertel, Heinrich

    1933-01-01

    The static stresses of airplane parts, the magnitude of which can be determined with the aid of static load assumptions, are mostly superposed by dynamic stresses, the magnitude of which has been but little explored. The object of the present investigation is to show how the strength of airplane parts can best be tested with respect to dynamic stresses with and without superposed static loading, and to what extent the dynamic strength of the parts depends on their structural design. Experimental apparatus and evaluation methods were developed and tried for the execution of vibration-strength tests with entire structural parts both with and without superposed static loading. Altogether ten metal spars and spar pieces and two wooden spars were subjected to vibration breaking tests.

  4. Airplane dopes and doping

    NASA Technical Reports Server (NTRS)

    Smith, W H

    1919-01-01

    Cellulose acetate and cellulose nitrate are the important constituents of airplane dopes in use at the present time, but planes were treated with other materials in the experimental stages of flying. The above compounds belong to the class of colloids and are of value because they produce a shrinking action on the fabric when drying out of solution, rendering it drum tight. Other colloids possessing the same property have been proposed and tried. In the first stages of the development of dope, however, shrinkage was not considered. The fabric was treated merely to render it waterproof. The first airplanes constructed were covered with cotton fabric stretched as tightly as possible over the winds, fuselage, etc., and flying was possible only in fine weather. The necessity of an airplane which would fly under all weather conditions at once became apparent. Then followed experiments with rubberized fabrics, fabrics treated with glue rendered insoluble by formaldehyde or bichromate, fabrics treated with drying and nondrying oils, shellac, casein, etc. It was found that fabrics treated as above lost their tension in damp weather, and the oil from the motor penetrated the proofing material and weakened the fabric. For the most part the film of material lacked durability. Cellulose nitrate lacquers, however were found to be more satisfactory under varying weather conditions, added less weight to the planes, and were easily applied. On the other hand, they were highly inflammable, and oil from the motor penetrated the film of cellulose nitrate, causing the tension of the fabric to be relaxed.

  5. Fatigue: an overview.

    PubMed

    Rosenthal, Thomas C; Majeroni, Barbara A; Pretorius, Richard; Malik, Khalid

    2008-11-15

    Fatigue, a common presenting symptom in primary care, negatively impacts work performance, family life, and social relationships. The differential diagnosis of fatigue includes lifestyle issues, physical conditions, mental disorders, and treatment side effects. Fatigue can be classified as secondary to other medical conditions, physiologic, or chronic. The history and physical examination should focus on identifying common secondary causes (e.g., medications, anemia, pregnancy) and life-threatening problems, such as cancer. Results of laboratory studies affect management in only 5 percent of patients, and if initial results are normal, repeat testing is generally not indicated. Treatment of all types of fatigue should include a structured plan for regular physical activity that consists of stretching and aerobic exercise, such as walking. Caffeine and modafinil may be useful for episodic situations requiring alertness. Short naps are proven performance enhancers. Selective serotonin reuptake inhibitors, such as fluoxetine, paroxetine, or sertraline, may improve energy in patients with depression. Patients with chronic fatigue may respond to cognitive behavior therapy. Scheduling regular follow-up visits, rather than sporadic urgent appointments, is recommended for effective long-term management. PMID:19035066

  6. Fatigue of advanced materials

    SciTech Connect

    Dauskardt, R.H.; Ritchie, R.O. . Center for Advanced Materials); Cox, B.N. )

    1993-08-01

    The development of toughened ceramics over the past 10 to 15 years is arguably one of the most important materials breakthroughs of this century. Monolithic and composite ceramic materials having fracture toughnesses up to an order of magnitude higher than those available 20 years ago have been produced using technologies based on scientific understanding and micromechanical models for in situ phase transformation, fiber bridging, ductile-particle toughening, and other toughening mechanisms. The irony of this, however, is that although ceramics can now be seriously considered for many structural applications, they can also, contrary to popular belief, be susceptible to degradation under cyclic fatigue loading. This is true even when the loading is fully compressive. As a result, a great deal of attention is now being paid to ceramic fatigue, largely because of the importance of cyclic loading in many of the potential applications for ceramics, such as gas-turbine and reciprocating engines. However, because the field is in its infancy, only limited fatigue property data have been documented, understanding of salient fatigue mechanisms has not been achieved, and the design of ceramic microstructures for optimum fatigue resistance has yet to be attempted.

  7. Prediction of fatigue crack growth kinetics in the plane structural elements of aircraft in the biaxial stress state

    NASA Astrophysics Data System (ADS)

    Shanyavskij, A. A.; Karaev, K. Z.; Grigor'ev, V. M.; Koronov, M. Z.; Orlov, E. F.

    1991-07-01

    The kinetics of fatigue crack growth in the case of a complex stress state is investigated with particular reference to D16T aluminum alloy. By using simulation models in the form of plane cruciform specimens, the characteristics of fatigue crack growth are investigated under conditions of uniaxial and biaxial tension-compression, with the ratio of the main stresses varying from -1 to 1.5. An algorithm is developed which makes it possible to predict the kinetics of fatigue crack growth and the equivalent stress level under conditions of multiparametric loading.

  8. Fatigue Fractures

    PubMed Central

    Morris, James M.

    1968-01-01

    Fatigue (or stress) fracture of bone in military recruits has been recognized for many years. Most often it is a metatarsal bone that is involved but the tarsal bones, calcaneus, tibia, fibula, femur, and pelvis are occasionally affected. Reports of such fractures in the ribs, ulna and vertebral bodies may be found in the literature. In recent years, there has been increasing awareness of the occurrence of fatigue fractures in the civilian population. Weekend sportsmen, athletes in an early phase of training, and persons engaged in unaccustomed, repetitive, vigorous activity are potential victims of such a fracture. The signs and symptoms, roentgenographic findings, treatment and etiology of fatigue fractures are dealt with in this presentation. ImagesFigure 1.Figure 2.Figure 3.Figure 4.Figure 5.Figure 6. PMID:5652745

  9. 14 CFR 23.573 - Damage tolerance and fatigue evaluation of structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... damage can be expected to occur. The evaluation must incorporate repeated load and static analyses... demonstrated by tests, or by analysis supported by tests, that the structure is capable of carrying ultimate... analysis supported by tests. (3) The structure must be shown by residual strength tests, or...

  10. 14 CFR 23.573 - Damage tolerance and fatigue evaluation of structure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... damage can be expected to occur. The evaluation must incorporate repeated load and static analyses... demonstrated by tests, or by analysis supported by tests, that the structure is capable of carrying ultimate... analysis supported by tests. (3) The structure must be shown by residual strength tests, or...

  11. 30 CFR 250.908 - What are the minimum structural fatigue design requirements?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... ENFORCEMENT, DEPARTMENT OF THE INTERIOR OFFSHORE OIL AND GAS AND SULPHUR OPERATIONS IN THE OUTER CONTINENTAL SHELF Platforms and Structures Platform Approval Program § 250.908 What are the minimum structural... Constructing Fixed Offshore Platforms (incorporated by reference as specified in 30 CFR 250.198), requires...

  12. Structural Reliability of Ceramics at High Temperature: Mechanisms of Fracture and Fatigue Crack Growth

    SciTech Connect

    Reinhold H. Dauskardt

    2005-08-01

    Final report of our DOE funded research program. Aim of the research program was to provide a fundamental basis from which the mechanical reliability of layered structures may be understood, and to provide guidelines for the development of technologically relevant layered material structures with optimum resistance to fracture and subcritical debonding. Progress in the program to achieve these goals is described.

  13. Trend of airplane flight characteristics

    NASA Technical Reports Server (NTRS)

    Von Koppen, Joachim

    1933-01-01

    This report describes the development of airplane characteristics since the war and indicates the direction development should take in the immediate future. Some of the major topics include: the behavior of an airplane about its lateral, vertical, and longitudinal axes. Behavior at large angles of attack and landing characteristics are also included.

  14. Influence of UFG structure formation on mechanical and fatigue properties in Ti-6Al-7Nb alloy

    NASA Astrophysics Data System (ADS)

    Polyakova, V. V.; Anumalasetty, V. N.; Semenova, I. P.; Valiev, R. Z.

    2014-08-01

    Ultrafine-grained (UFG) Ti alloys have potential applications in osteosynthesis and orthopedics due to high bio-compatibility and increased weight-to- strength ratio. In current study, Ti6Al7Nb ELI alloy is processed through equal channel angular pressing-conform (ECAP-Conform) and subsequent thermomechanical processing to generate a UFG microstructure. The fatigue properties of UFG alloys are compared to coarse grained (CG) alloys. Our study demonstrates that the UFG alloys with an average grain size of ~180 nm showed 35% enhancement of fatigue endurance limit as compared to coarse-grained alloys. On the fracture surfaces of the UFG and CG samples fatigue striations and dimpled relief were observed. However, the fracture surface of the UFG sample looks smoother; fewer amounts of secondary micro-cracks and more ductile rupture were also observed, which testifies to the good crack resistance in the UFG alloy after high-cyclic fatigue tests.

  15. 77 FR 6023 - Airworthiness Directives; Airbus Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-07

    ... adequacy of existing regulations, the service history of airplanes subject to those regulations, and... Federal Aviation Administration 14 CFR Part 39 RIN 2120-AA64 Airworthiness Directives; Airbus Airplanes... airplanes and Model A310-203, -204, - 221, and -222 airplanes. This proposed AD was prompted by a report...

  16. 14 CFR 125.93 - Airplane limitations.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...: AIRPLANES HAVING A SEATING CAPACITY OF 20 OR MORE PASSENGERS OR A MAXIMUM PAYLOAD CAPACITY OF 6,000 POUNDS OR MORE; AND RULES GOVERNING PERSONS ON BOARD SUCH AIRCRAFT Airplane Requirements § 125.93 Airplane... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Airplane limitations. 125.93 Section...

  17. 14 CFR 23.3 - Airplane categories.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Airplane categories. 23.3 Section 23.3... STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES General § 23.3 Airplane categories. (a) The normal category is limited to airplanes that have a seating configuration, excluding...

  18. 14 CFR 23.3 - Airplane categories.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Airplane categories. 23.3 Section 23.3... STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES General § 23.3 Airplane categories... airplanes that have a seating configuration, excluding pilot seats, of nine or less, a maximum...

  19. 14 CFR 23.3 - Airplane categories.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Airplane categories. 23.3 Section 23.3... STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES General § 23.3 Airplane categories. (a) The normal category is limited to airplanes that have a seating configuration, excluding...

  20. Development of FRP composite structural biomaterials: fatigue strength of the fiber/matrix interfacial bond in simulated in vivo environments.

    PubMed

    Latour, R A; Black, J

    1993-10-01

    Fiber/matrix interfacial bonding in fiber reinforced polymer (FRP) composite materials is potentially sensitive to degradation in aqueous environments. Ultimate bond strength (UBS) in carbon fiber/polysulfone (CF/PSF) and polyaramid/polysulfone (K49/PSF) was previously reported to be significantly decreased in two simulated in vivo environments. While UBS is a useful parameter, for orthopedic implant applications the fatigue behavior of the interface is probably a more relevant indicator of long-term composite material performance. In this article, the effects of simulated in vivo environments (saline, exudate) upon the fatigue behavior of the interface of CF/PSF and K49/PSF are reported. The fatigue behavior of both material combinations was linearly dependent on the logarithm of fatigue life in the dry (control), saline, and exudate environments. Testing either material in saline and exudate resulted in significantly lower fatigue strength than in the dry environment; however, results in the two wet environments were indistinguishable. The CF/PSF interface experienced fatigue failure at approximately 10(5) load cycles at a maximum applied load level of only 15% of its ultimate dry bond strength without indication of an endurance limit being reached. These results raise some important questions regarding the durability of CF/PSF composite in load bearing orthopedic applications.

  1. Structure and Composition of Air-Plane Soots and Surrogates Analyzed by Raman Spectroscopy and Laser/Ions Desorption Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Ortega, Ismael; Chazallon, Bertrand; Carpentier, Yvain; Irimiea, Cornelia; Focsa, Cristian; Ouf, François-Xavier; Salm, François; Delhaye, David; Gaffié, Daniel; Yon, Jérôme

    2015-04-01

    Aviation alters the composition of the atmosphere globally and can thus drive climate change and ozone depletion [1]. An aircraft exhaust plume contains species emitted by the engines, species formed in the plume from the emitted species and atmospheric species that become entrained into the plume. The majority of emitted species (gases and soot particles) are produced by the combustion of kerosene with ambient air in the combustion chamber of the engine. Emissions of soot particles by air-planes produce persistent contrails in the upper troposphere in ice-supersaturated air masses that contribute to cloudiness and impact the radiative properties of the atmosphere. These aerosol-cloud interactions represent one of the largest sources of uncertainty in global climate models [2]. Though the formation of atmospheric ice particles has been studied since many years [3], there are still numerous opened questions on nucleation properties of soot particles [4], as the ice nucleation experiments showed a large spread in results depending on the nucleation mode chosen and origin of the soot produced. Most likely one of the reasons behind these discrepancies resides in the different physico-chemical properties (composition, structure) of soot particles produced in different conditions, e.g. with respect to fuel or combustion techniques. In this work, we use Raman microscopy (266, 514 and 785 nm excitation) and ablation techniques (SIMS, Secondary Ions Mass Spectrometry, and Laser Desorption Mass Spectrometry) to characterize soot particles produced from air-plane at different engine regimes simulating a landing and taking-off (LTO) cycle. First, the spectral parameters of the first-order Raman band of various soot samples, collected from three different sources in the frame of the MERMOSE project (http://mermose.onera.fr/): PowerJet SaM-146 turbofan (four engine regimes), CAST generator (propane fuel, four different global equivalence ratios), and Kerosene laboratory flame

  2. 14 CFR 23.573 - Damage tolerance and fatigue evaluation of structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... material variability and environmental conditions on the strength and durability properties of the... established that ensure the strength of each joint. (6) Structural components for which the damage tolerance... supported by test evidence. The extent of damage for residual strength evaluation at any time within...

  3. 75 FR 1527 - Airworthiness Directives; The Boeing Company Model 737-300, -400, and -500 Series Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-12

    ... detect cracks in the fuselage skin along the chem-mill step at stringers S-1 and S-2 right, between... fuselage skin common to stringer S-1 and S-2 left, between STA 827 and STA 847 on an airplane that diverted.... We are issuing this AD to detect and correct fatigue cracking of the fuselage skin panels at the...

  4. Statistical analysis of the time and fatigue strength of aircraft wing structures

    NASA Technical Reports Server (NTRS)

    Kaul, Hans W

    1941-01-01

    The results from stress measurements in flight operation afford data for analyzing the frequency of appearance of certain parts of the static breaking strength during a specified number of operating hours. Appropriate frequency evaluations furnish data for the prediction of the required strength under repeated stress in the wing structures of aircraft of the different stress categories for the specified number of operating hours demanded during the life of a component.

  5. Surface Relief and Internal Structure in Fatigued Stainless Sanicro 25 Steel

    NASA Astrophysics Data System (ADS)

    Polák, Jaroslav; Mazánová, Veronika; Kuběna, Ivo; Heczko, Milan; Man, Jiří

    2016-05-01

    High-resolution images of persistent slip markings developed on the surface of Sanicro 25 stainless steel during cyclic loading obtained from the FIB-produced surface lamella in TEM simultaneously with the underlying dislocation structure are reported. Extrusions, intrusions, incipient cracks, and the dislocation arrangement corresponding to the bands of intensive cyclic slip are documented and discussed in relation to the models of surface relief formation in cyclic loading.

  6. Creep-fatigue modelling in structural steels using empirical and constitutive creep methods implemented in a strip-yield model

    NASA Astrophysics Data System (ADS)

    Andrews, Benjamin J.

    The phenomena of creep and fatigue have each been thoroughly studied. More recently, attempts have been made to predict the damage evolution in engineering materials due to combined creep and fatigue loading, but these formulations have been strictly empirical and have not been used successfully outside of a narrow set of conditions. This work proposes a new creep-fatigue crack growth model based on constitutive creep equations (adjusted to experimental data) and Paris law fatigue crack growth. Predictions from this model are compared to experimental data in two steels: modified 9Cr-1Mo steel and AISI 316L stainless steel. Modified 9Cr-1Mo steel is a high-strength steel used in the construction of pressure vessels and piping for nuclear and conventional power plants, especially for high temperature applications. Creep-fatigue and pure creep experimental data from the literature are compared to model predictions, and they show good agreement. Material constants for the constitutive creep model are obtained for AISI 316L stainless steel, an alloy steel widely used for temperature and corrosion resistance for such components as exhaust manifolds, furnace parts, heat exchangers and jet engine parts. Model predictions are compared to pure creep experimental data, with satisfactory results. Assumptions and constraints inherent in the implementation of the present model are examined. They include: spatial discretization, similitude, plane stress constraint and linear elasticity. It is shown that the implementation of the present model had a non-trivial impact on the model solutions in 316L stainless steel, especially the spatial discretization. Based on these studies, the following conclusions are drawn: 1. The constitutive creep model consistently performs better than the Nikbin, Smith and Webster (NSW) model for predicting creep and creep-fatigue crack extension. 2. Given a database of uniaxial creep test data, a constitutive material model such as the one developed for

  7. Fatigue of insect cuticle.

    PubMed

    Dirks, Jan-Henning; Parle, Eoin; Taylor, David

    2013-05-15

    Many parts of the insect exoskeleton experience repeated cyclic loading. Although the cuticle of insects and other arthropods is the second most common natural composite material in the world, so far nothing is known about its fatigue properties, despite the fact that fatigue undoubtedly limits the durability of body parts in vivo. For the first time, we here present experimental fatigue data of insect cuticle. Using force-controlled cyclic loading, we determined the number of cycles to failure for hind legs (tibiae) and hind wings of the locust Schistocerca gregaria, as a function of the applied cyclic stress. Our results show that, although both are made from cuticle, these two body parts behave very differently. Wing samples showed a large fatigue range, failing after 100,000 cycles when we applied 46% of the stress needed for instantaneous failure [the ultimate tensile strength (UTS)]. Legs, in contrast, were able to sustain a stress of 76% of the UTS for the same number of cycles to failure. This can be explained by the difference in the composition and structure of the material, two factors that, amongst others, also affect the well-known behaviour of engineering composites. Final failure of the tibiae occurred via one of two different failure modes--propagation in tension or buckling in compression--indicating that the tibia is 'optimized' by evolution to resist both failure modes equally. These results are further discussed in relation to the evolution and normal use of these two body parts.

  8. 78 FR 52875 - Airworthiness Directives; the Boeing Company Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-27

    ... airplane reaching its limit of validity (LOV) of the engineering data that support the established... the wing structure to support the limit load condition, and consequent loss of structural integrity of...: Data & Services Management, P.O. Box 3707, MC 2H-65, Seattle, WA 98124-2207; telephone 206-544-...

  9. 78 FR 60679 - Airworthiness Directives; The Boeing Company Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-02

    ...-273-AD; Amendment 39-17604; AD 2013-19-22] RIN 2120-AA64 Airworthiness Directives; The Boeing Company... new airworthiness directive (AD) for all The Boeing Company Model 717-200 airplanes. This AD was... result in damage to the adjacent structure and consequent loss of structural integrity of the...

  10. 77 FR 27142 - Airworthiness Directives; The Boeing Company Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-09

    ... Federal Aviation Administration 14 CFR Part 39 RIN 2120-AA64 Airworthiness Directives; The Boeing Company...). SUMMARY: We propose to adopt a new airworthiness directive (AD) for all The Boeing Company Model 717-200... structure and consequent loss of structural integrity of the airplane. DATES: We must receive comments...

  11. Gamma rays at airplane altitudes

    SciTech Connect

    Iwai, J.; Koss, T.; Lord, J.; Strausz, S.; Wilkes, J.; Woosley, J. )

    1990-03-20

    An examination of the gamma ray flux above 1 TeV in the atmosphere is needed to better understand the anomalous showers from point sources. Suggestions are made for future experiments on board airplanes.

  12. Differential equations in airplane mechanics

    NASA Technical Reports Server (NTRS)

    Carleman, M T

    1922-01-01

    In the following report, we will first draw some conclusions of purely theoretical interest, from the general equations of motion. At the end, we will consider the motion of an airplane, with the engine dead and with the assumption that the angle of attack remains constant. Thus we arrive at a simple result, which can be rendered practically utilizable for determining the trajectory of an airplane descending at a constant steering angle.

  13. Airplane Upset Training Evaluation Report

    NASA Technical Reports Server (NTRS)

    Gawron, Valerie J.; Jones, Patricia M. (Technical Monitor)

    2002-01-01

    Airplane upset accidents are a leading factor in hull losses and fatalities. This study compared five types of airplane-upset training. Each group was composed of eight, non-military pilots flying in their probationary year for airlines operating in the United States. The first group, 'No aero / no upset,' was made up of pilots without any airplane upset training or aerobatic flight experience; the second group, 'Aero/no upset,' of pilots without any airplane-upset training but with aerobatic experience; the third group, 'No aero/upset,' of pilots who had received airplane-upset training in both ground school and in the simulator; the fourth group, 'Aero/upset,' received the same training as Group Three but in addition had aerobatic flight experience; and the fifth group, 'In-flight' received in-flight airplane upset training using an instrumented in-flight simulator. Recovery performance indicated that clearly training works - specifically, all 40 pilots recovered from the windshear upset. However few pilots were trained or understood the use of bank to change the direction of the lift vector to recover from nose high upsets. Further, very few thought of, or used differential thrust to recover from rudder or aileron induced roll upsets. In addition, recovery from icing-induced stalls was inadequate.

  14. An analysis of life expectancy of airplane wings in normal cruising flight

    NASA Technical Reports Server (NTRS)

    Putnam, Abbott A

    1945-01-01

    In order to provide a basis for judging the relative importance of wing failure by fatigue and by single intense gusts, an analysis of wing life for normal cruising flight was made based on data on the frequency of atmospheric gusts. The independent variables considered in the analysis included stress-concentration factor, stress-load relation, wing loading, design and cruising speeds, design gust velocity, and airplane size. Several methods for estimating fatigue life from gust frequencies are discussed. The procedure selected for the analysis is believed to be simple and reasonably accurate, though slightly conservative.

  15. Determination of aerodynamic parameters of a fighter airplane from flight data at high angles of attack

    NASA Technical Reports Server (NTRS)

    Klein, V.; Batterson, J. G.; Abbasy, I.

    1983-01-01

    A procedure for the estimation of airplane model structure and parameters is applied to data from a modern fighter airplane operating within an angle of attack range of 5 to 60 deg. The paper briefly describes the airplane, flight and wind tunnel data available, and the estimation method. The results presented contain basic longitudinal characteristics of the airplane and the estimates of aerodynamic parameters in the yawing-moment equations. These estimates are obtained from small and large amplitude maneuvers. Because the latter set of data was not suitable for airplane identification, some of the large amplitude maneuvers were joined together and then partitioned into subsets according to the values of angle of attack. Each subset was then analyzed as a separate data set. Most of the estimated parameters and functions are in good agreement with the wind tunnel measurements. The estimated lateral parameters in the model equations also demonstrate good prediction capabilities.

  16. 14 CFR 36.7 - Acoustical change: Transport category large airplanes and jet airplanes.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... paragraph (b) of this section: (1) Airplanes with high bypass ratio jet engines. For an airplane that has jet engines with a bypass ratio of 2 or more before a change in type design— (i) The airplane, after... do not have high bypass ratio jet engines. For an airplane that does not have jet engines with...

  17. 14 CFR 36.7 - Acoustical change: Transport category large airplanes and jet airplanes.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... paragraph (b) of this section: (1) Airplanes with high bypass ratio jet engines. For an airplane that has jet engines with a bypass ratio of 2 or more before a change in type design— (i) The airplane, after... do not have high bypass ratio jet engines. For an airplane that does not have jet engines with...

  18. 14 CFR 36.7 - Acoustical change: Transport category large airplanes and jet airplanes.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... paragraph (b) of this section: (1) Airplanes with high bypass ratio jet engines. For an airplane that has jet engines with a bypass ratio of 2 or more before a change in type design— (i) The airplane, after... do not have high bypass ratio jet engines. For an airplane that does not have jet engines with...

  19. Steady properly-banked turns of turbojet-propelled airplanes

    NASA Technical Reports Server (NTRS)

    Miele, Angelo

    1955-01-01

    The problem of a jet-propelled airplane held in a steady turn is treated both in the very general case and also in the particular case when the polar curve can be approximated by a parabola. Once the general solution has been obtained, some typical maneuvers are next studied such as, the turn of maximum bank, of maximum angular velocity, and of minimum radius of curvature. After a brief comparison is made between the turning characteristics of conventional airplanes and jet airplanes, and after the effect of compressibility upon the turn is examined, the effects of the salient aerodynamic and structural parameters upon the behavior of the plane in curvilinear flight are summarized in the conclusions.

  20. Bonded joint strength - Static versus fatigue

    NASA Technical Reports Server (NTRS)

    Johnson, W. S.; Mall, S.

    1984-01-01

    Adhesives are commonly characterized only by their static strength even though they are used in structural joints that are subjected to fatigue loads. This paper reviews the relationship between static and fatigue strength for four different specimen types: single-lap-shear, edge-delamination, double cantilever beam, and cracked-lap-shear. It was found that the ratio of static strength to fatigue strength varied from 2.3 to 4.7, depending on the adhesive and specimen configuration.

  1. 76 FR 72863 - Airworthiness Directives; The Boeing Company Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-28

    ... issued AD 85-12-01, Amendment 39-5073 (50 FR 26690, June 28, 1985), for Model 707 and 720 airplanes, as revised (AD 85-12-01 R1, Amendment 39-5439 (51 FR 36002, October 8, 1986). That AD requires structural...-5439 (51 FR 36002, October 8, 1986). Differences Between the Proposed AD and Service...

  2. 78 FR 65185 - Airworthiness Directives; The Boeing Company Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-31

    ...) of the engineering data that support the established structural maintenance program. This AD requires..., 2013 (78 FR 42720). The NPRM proposed to require for certain airplanes, a modification of the web of... received. Boeing supported the NPRM (78 FR 42720, July 17, 2013). Clarification of Applicability Since...

  3. 77 FR 40828 - Airworthiness Directives; The Boeing Company Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-11

    ... Federal Aviation Administration 14 CFR Part 39 RIN 2120-AA64 Airworthiness Directives; The Boeing Company...). SUMMARY: We propose to adopt a new airworthiness directive (AD) for certain The Boeing Company Model DC-10... structure, which could adversely affect the airplane's continued safe flight and landing. DATES: We...

  4. 77 FR 37793 - Airworthiness Directives; the Boeing Company Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-25

    ...-124-AD; Amendment 39-17099; AD 2012-12-19] RIN 2120-AA64 Airworthiness Directives; the Boeing Company... new airworthiness directive (AD) for certain the Boeing Company Model 777-200, -200LR, and -300ER... ceiling support structure of Section 41, in airplanes incorporating the overhead space utilization...

  5. 78 FR 17290 - Airworthiness Directives; The Boeing Company Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-21

    ... measuring the electrical resistance of the bond from the adapter plate to the airplane structure, and doing corrective actions if necessary. We are issuing this AD to prevent electrical current from flowing through an... Administration is issuing this AD to prevent electrical current from flowing through a motor-operated valve...

  6. 77 FR 36206 - Airworthiness Directives; The Boeing Company Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-18

    ... Procedures (44 FR 11034, February 26, 1979), (3) Will not affect intrastate aviation in Alaska, and (4) Will... proposing this AD to prevent contactor failures, which could result in uncontained hot debris flow due to ELMS contactor breakdown, consequent smoke and heat damage to airplane structure and equipment...

  7. 77 FR 65506 - Airworthiness Directives; The Boeing Company Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-29

    ... modification of the nacelle strut and wing structure, and repair of any damage found during the modification... Commercial Airplanes, Attention: Data & Services Management, P.O. Box 3707, MC 2H-65, Seattle, WA 98124-2207... proposed AD. Discussion On August 29, 2003, we issued AD 2003-18-05, Amendment 39-13296 (68 FR...

  8. Metal fatigue detector

    SciTech Connect

    Veaux, R.C. de la.

    1993-08-24

    A device is described for detecting fatigue of a monitored structure due to flexure, said monitored structure being made of a predetermined material and said device comprising: a substantially flat integral fuse made of said predetermined material and having edges and a plurality of differently configured cut out portions between the edges and defining fuse elements there between designed to fail because of fatigue prior to failure of said monitored structure when said fuse and said monitored structure both experience thee same stress history; means forming parallel elongated slots extending from the cut out portions to one edge to define legs associated with the fuse elements; adhesive means securing said fuse to said monitored structure and extending over at least 75 % of the area of the side of said fuse that is adjacent to said monitored structure but being spaced apart from said fuse elements; whereby said adhesive means ensure that said fuse and said monitored structure are subjected to substantially the same stress history in both tension and compression yet does not inhibit failure of said fuse elements.

  9. 14 CFR 125.355 - Airplane equipment.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...: AIRPLANES HAVING A SEATING CAPACITY OF 20 OR MORE PASSENGERS OR A MAXIMUM PAYLOAD CAPACITY OF 6,000 POUNDS OR MORE; AND RULES GOVERNING PERSONS ON BOARD SUCH AIRCRAFT Flight Release Rules § 125.355 Airplane... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Airplane equipment. 125.355 Section...

  10. 14 CFR 121.605 - Airplane equipment.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Airplane equipment. 121.605 Section 121.605..., FLAG, AND SUPPLEMENTAL OPERATIONS Dispatching and Flight Release Rules § 121.605 Airplane equipment. No person may dispatch or release an airplane unless it is airworthy and is equipped as prescribed in §...

  11. 14 CFR 23.3 - Airplane categories.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Airplane categories. 23.3 Section 23.3 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES General § 23.3 Airplane...

  12. 14 CFR 121.605 - Airplane equipment.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Airplane equipment. 121.605 Section 121.605..., FLAG, AND SUPPLEMENTAL OPERATIONS Dispatching and Flight Release Rules § 121.605 Airplane equipment. No person may dispatch or release an airplane unless it is airworthy and is equipped as prescribed in §...

  13. 76 FR 77934 - Airworthiness Directives; Airbus Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-15

    ... series airplanes. Since we issued AD 2005-23-02, Amendment 39-14360 (70 FR 69067, November 14, 2005), The... certain ACT equipped airplanes, produced after AD 2005-23-02, Amendment 39-14360 (70 FR 69067, November 14...-14360 (70 FR 69067, November 14, 2005). Applicability (c) This AD applies to Airbus airplanes listed...

  14. 14 CFR 125.93 - Airplane limitations.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Airplane limitations. 125.93 Section 125.93...: AIRPLANES HAVING A SEATING CAPACITY OF 20 OR MORE PASSENGERS OR A MAXIMUM PAYLOAD CAPACITY OF 6,000 POUNDS OR MORE; AND RULES GOVERNING PERSONS ON BOARD SUCH AIRCRAFT Airplane Requirements § 125.93...

  15. 14 CFR 121.605 - Airplane equipment.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Airplane equipment. 121.605 Section 121.605..., FLAG, AND SUPPLEMENTAL OPERATIONS Dispatching and Flight Release Rules § 121.605 Airplane equipment. No person may dispatch or release an airplane unless it is airworthy and is equipped as prescribed in §...

  16. 14 CFR 121.605 - Airplane equipment.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Airplane equipment. 121.605 Section 121.605..., FLAG, AND SUPPLEMENTAL OPERATIONS Dispatching and Flight Release Rules § 121.605 Airplane equipment. No person may dispatch or release an airplane unless it is airworthy and is equipped as prescribed in §...

  17. 14 CFR 125.93 - Airplane limitations.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Airplane limitations. 125.93 Section 125.93...: AIRPLANES HAVING A SEATING CAPACITY OF 20 OR MORE PASSENGERS OR A MAXIMUM PAYLOAD CAPACITY OF 6,000 POUNDS OR MORE; AND RULES GOVERNING PERSONS ON BOARD SUCH AIRCRAFT Airplane Requirements § 125.93...

  18. 14 CFR 125.93 - Airplane limitations.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Airplane limitations. 125.93 Section 125.93...: AIRPLANES HAVING A SEATING CAPACITY OF 20 OR MORE PASSENGERS OR A MAXIMUM PAYLOAD CAPACITY OF 6,000 POUNDS OR MORE; AND RULES GOVERNING PERSONS ON BOARD SUCH AIRCRAFT Airplane Requirements § 125.93...

  19. Information obtained from airplane flight tests in the year 1927-1928

    NASA Technical Reports Server (NTRS)

    Hubner, W

    1929-01-01

    The information obtained from flight tests in 1927-1928 covers chiefly the effect of the structural features of an airplane on its stability, controllability, maneuverability and spinning characteristics.

  20. Exploring the optimal pre-sintering temperature on compressive strength and anti-fatigue property of graded zirconia-based glass/zirconia structure.

    PubMed

    Qian, Haixin; Cui, Chang; Su, Tingshu; Zhang, Fuqiang; Sun, Jian

    2016-01-01

    To explore the optimal pre-sintering temperature for graded glass/zirconia material, glass/zirconia specimens were prepared and pre-sintered at 900, 1,000 and 1,100°C respectively, glass infiltration and densification at 1,450°C. Monolith Y-TZP specimens were sintered at 1,450°C. Nanoindentation was used to test Young's modulus and Hardness. Compressive strength test and cycling fatigue test were conducted. Nanoindentation test showed graded change of Young's modulus in glass/zirconia structure. The compressive strength and the number of cycles to failure of specimens pre-sintered at 1,000°C were significantly higher than those of Y-TZP and the specimens pre-sintered at 900 and 1,000°C (p<0.05). It is concluded that when the pre-sintering temperature is set at 1,000°C, the graded glass/zirconia structure exhibits the most optimal compressive strength and anti-fatigue property. PMID:27251987

  1. Development of a fatigue-life methodology for composite structures subjected to out-of-plane load components

    NASA Technical Reports Server (NTRS)

    Sumich, Mark; Kedward, Keith T.

    1991-01-01

    The efforts to identify and implement a fatigue life methodology applicable to demonstrate delamination failures for use in certifying composite rotor blades are presented. The RSRA/X-Wing vehicle was a proof-of-concept stopped rotor aircraft configuration which used rotor blades primarily constructed of laminated carbon fiber. Delamination of the main spar during ground testing demonstrated that significant interlaminar stresses were produced. Analysis confirmed the presence of out-of-plane load components. The wear out (residual strength) methodology and the requirements for its implementation are discussed.

  2. Fatigue Life Methodology for Bonded Composite Skin/Stringer Configurations

    NASA Technical Reports Server (NTRS)

    Krueger, Ronald; Paris, Isabelle L.; OBrien, T. Kevin

    2000-01-01

    A methodology is presented for determining the fatigue life of bonded composite skin/stringer structures based on delamination fatigue characterization data and geometric nonlinear finite element analyses. Results were compared to fatigue tests on stringer flange/skin specimens to verify the approach.

  3. 14 CFR 125.75 - Airplane flight manual.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Airplane flight manual. 125.75 Section 125... Airplane flight manual. (a) Each certificate holder shall keep a current approved Airplane Flight Manual or... approved Airplane Flight Manual or the approved equivalent aboard each airplane it operates. A...

  4. Preliminary Fatigue Studies on Aluminum Alloy Aircraft Engines

    NASA Technical Reports Server (NTRS)

    1938-01-01

    Preliminary information on the complex subject of the fatigue strength of fabricated structural members for aircraft is presented in the test results obtained on several different types of airship girders subjected to axial tension and compression in a resonance fatigue machine. A description of this machine as well as numerous photographs of the fatigue failures are given. There is also presented an extended bibliography on the subject of fatigue strength.

  5. Low cycle fatigue

    NASA Technical Reports Server (NTRS)

    Solomon, H. D. (Editor); Kaisand, L. R. (Editor); Halford, G. R. (Editor); Leis, B. N. (Editor)

    1988-01-01

    The papers contained in this volume focus on various aspects of low cycle fatigue, including cyclic deformation, crack propagation, high-temperature low cycle fatigue, microstructural defects, multiaxial and variable amplitude loading, and life prediction. Papers are presented on the low cycle fatigue of some aluminum alloys, prediction of crack growth under creep-fatigue loading conditions, high-temperature low cycle fatigue behavior and lifetime prediction of a nickel-base ODS alloy, and an integrated approach to creep-fatigue life prediction. Other topics discussed include thermal fatigue testing of coated monocrystalline superalloys, low cycle fatigue of Al-Mg-Si alloys, and the effect of superimposed stresses at high frequency on low cycle fatigue.

  6. Coupled modeling of a directly heated tubular solar receiver for supercritical carbon dioxide Brayton cycle: Structural and creep-fatigue evaluation

    DOE PAGES

    Ortega, Jesus; Khivsara, Sagar; Christian, Joshua; Ho, Clifford; Dutta, Pradip

    2016-06-06

    A supercritical carbon dioxide (sCO2) Brayton cycle is an emerging high energy-density cycle undergoing extensive research due to the appealing thermo-physical properties of sCO2 and single phase operation. Development of a solar receiver capable of delivering sCO2 at 20 MPa and 700 °C is required for implementation of the high efficiency (~50%) solar powered sCO2 Brayton cycle. In this work, extensive candidate materials are review along with tube size optimization using the ASME Boiler and Pressure Vessel Code. Moreover, temperature and pressure distribution obtained from the thermal-fluid modeling (presented in a complementary publication) are used to evaluate the thermal andmore » mechanical stresses along with detailed creep-fatigue analysis of the tubes. For resulting body stresses were used to approximate the lifetime performance of the receiver tubes. A cyclic loading analysis is performed by coupling the Strain-Life approach and the Larson-Miller creep model. The structural integrity of the receiver was examined and it was found that the stresses can be withstood by specific tubes, determined by a parametric geometric analysis. The creep-fatigue analysis display the damage accumulation due to cycling and the permanent deformation on the tubes showed that the tubes can operate for the full lifetime of the receiver.« less

  7. Effect of boron on the low-cycle fatigue behavior and deformation structure of INCONEL 718 at 650 °C

    NASA Astrophysics Data System (ADS)

    Xiao, L.; Chaturvedi, M. C.; Chen, D. L.

    2004-11-01

    Symmetrical push-pull low-cycle fatigue (LCF) tests were performed on INCONEL 718 (IN718) containing 12, 29, 60, and 100 ppm B at 650 °C. The results showed that all the alloys experienced a relatively short period of initial cyclic hardening at low strain amplitudes, followed by a regime of saturation or slightly continuous cyclic softening. The initial cyclic hardening phase decreased with increasing strain amplitudes, and disappeared at the high strain amplitudes. A serrated flow was observed in the plastic regions of cyclic stress-strain hysteresis loops. The saturated cyclic stress amplitude at a given strain amplitude was highest for the alloy with 60 ppm B, and lowest for the alloy with 12 ppm B. The LCF lifetime increased with increasing B concentration up to 60 ppm, and then decreased as the B content increased from 60 to 100 ppm. Fractographic analysis suggested that the fracture mode changed from intergranular to transgranular cracking as the B concentration increased. The characteristic deformation microstructures produced by LCF tests at 650 °C, examined via transmission electron microscopy, were regularly spaced arrays of planar deformation bands on {111} slip planes in all four alloys. A ladderlike structure was observed in some local regions in the alloy with 12 ppm B. Heavily deformed planar deformation bands were observed in the fatigued specimens with 100 ppm B. The mechanism of improvement in the LCF life of IN718 due to B addition is discussed.

  8. Sonic fatigue of launch vehicle components

    SciTech Connect

    Wentz, K.R.; Camden, M.P.

    1997-01-01

    Wright Laboratory has long been a leader in the technologies required for aerospace structures. One of these driving technology areas is that of the dynamic environments of acoustics and vibration to which structures are exposed and required to survive. This paper presents an overview of sonic fatigue of launch vehicle components. An experimental program to develop sonic fatigue design criteria for a proposed thermal protection system is reviewed. Wright Laboratory{close_quote}s experimental facilities utilized to subject structures to simulated launch vehicle environments which are necessary to generate the experimental data required to provide sonic fatigue design criteria are described. {copyright} {ital 1997 American Institute of Physics.}

  9. The Testing of Airplane Fabrics

    NASA Technical Reports Server (NTRS)

    Schraivogel, Karl

    1932-01-01

    This report considers the determining factors in the choice of airplane fabrics, describes the customary methods of testing and reports some of the experimental results. To sum up briefly the results obtained with the different fabrics, it may be said that increasing the strength of covering fabrics by using coarser yarns ordinarily offers no difficulty, because the weight increment from doping is relatively smaller.

  10. Testing a Windmill Airplane ("autogiro")

    NASA Technical Reports Server (NTRS)

    Seiferth, R

    1927-01-01

    In order to clear up the matter ( In the Spanish report it was stated that the reference surface for the calculation of the coefficients c(sub a) and c(sub w) was the area of all four wings, instead of a single wing), the model of a windwill airplane was tested in the Gottingen wind tunnel.

  11. Glues Used in Airplane Parts

    NASA Technical Reports Server (NTRS)

    Allen, S W; Truax, T R

    1920-01-01

    This report was prepared for the National Advisory Committee for Aeronautics and presents the results of investigations conducted by the Forest Products Laboratory of the United States Forest Service on the manufacture, preparation, application, testing and physical properties of the different types of glues used in wood airplane parts.

  12. Paper Airplanes: A Classroom Activity

    ERIC Educational Resources Information Center

    Painter, Richard A.

    1976-01-01

    A learning experience is described for upper elementary or junior high students involving the manufacture, transportation, and marketing of a product for consumers. Steps are given and roles are assigned for students to convert raw material (paper) to a finished product (paper airplanes) and to sell it. (AV)

  13. Safeguards Against Flutter of Airplanes

    NASA Technical Reports Server (NTRS)

    deVries, Gerhard

    1956-01-01

    This report is a complilation of practical rules, derived at the same time from theory and from experience, intended to guide the aeronautical engineer in the design of flutter-free airplanes. Rules applicable to the wing, the ailerons, flaps, tabs,tail surfaces, and fuselage are discussed.

  14. 79 FR 1337 - Special Conditions: Airbus, A350-900 Series Airplane; Crashworthiness-Emergency Landing Conditions

    Code of Federal Regulations, 2014 CFR

    2014-01-08

    ... with a combination of carbon fiber reinforced plastic (CFRP) and metallic structure. This is a novel and unusual design feature for a large transport airplane. Structure fabricated from CFRP may...

  15. Fatigue and fracture -- 1996: Volume 1. PVP-Volume 323

    SciTech Connect

    Mehta, H.S.; Bhandari, S.; Jones, D.; Rahman, S.; Wilkowski, G.; Yoon, K.K.

    1996-12-01

    Fracture mechanics and fatigue evaluations are an important part of the structural integrity analyses to assure safe operation of pressure vessels and piping components during their service life. The papers presented in this volume illustrate the application of fatigue and fracture mechanics techniques to assess the structural integrity of a wide variety of Pressure Vessels and Piping components. The papers are organized in five sections: (1) fatigue and fracture: piping and components; (2) fatigue and fracture: environmental cracking; (3) leak-before-break analyses; (4) fatigue testing and analyses; and (5) probabilistic fracture mechanics analyses in pressure boundary components. Separate abstracts were prepared for most of the papers in this volume.

  16. Characterization of Solder Joint Reliability Using Cyclic Mechanical Fatigue Testing

    NASA Astrophysics Data System (ADS)

    Kim, Choong-Un; Bang, Woong-Ho; Xu, Huili; Lee, Tae-Kyu

    2013-10-01

    This article summarizes the mechanics of two mechanical fatigue methods, cyclic bending fatigue and shear fatigue, in inducing failure in solder joints in package assemblies, and it presents the characteristics of fatigue failures resulting from these methods using example cases of Sn-Pb eutectic and Sn-rich Pb-free solder alloys. Numerical simulation suggests that both testing configurations induce fatigue failure by the crack-opening mode. In the case of bending fatigue, the strain induced by the bending displacement is found to be sensitive to chip geometry, and it induces fatigue cracks mainly at the solder matrix adjacent to the printed circuit board interface. In case of shear fatigue, the failure location is firmly fixed at the solder neck, created by solder mask, where an abrupt change in the solder geometry occurs. Both methods conclude that the Coffin-Manson model is the most appropriate model for the isothermal mechanical fatigue of solder alloys. An analysis of fatigue characteristics using the frame of the Coffin-Manson model produces several insightful results, such as the reason why Pb-free alloys show higher fatigue resistance than Sn-Pb alloys even if they are generally more brittle. Our analysis suggests that it is related to higher work hardening. All these results indicate that mechanical fatigue can be an extremely useful method for fast screening of defective package structures and also in gaining a better understanding of fatigue failure mechanism and prediction of reliability in solder joints.

  17. The airplane: A simulated commercial air transportation study

    NASA Technical Reports Server (NTRS)

    Dauteuil, Mark; Geniesse, Pete; Hunniford, Michael; Lawler, Kathleen; Quirk, Elena; Tognarelli, Michael

    1993-01-01

    The 'Airplane' is a moderate-range, 70 passenger aircraft. It is designed to serve demands for flights up to 10,000 feet and it cruises at 32 ft/s. The major drivers for the design of the Airplane are economic competitiveness, takeoff performance, and weight minimization. The Airplane is propelled by a single Astro 15 electric motor and a Zinger 12-8 propeller. The wing section is a Spica airfoil which, because of its flat bottom, provides simplicity in manufacturing and thus helps to cut costs. The wing is constructed of a single load bearing mainspar and shape-holding ribs coated with Monokote skin, lending to a light weight structural makeup. The fuselage houses the motor, flight deck and passenger compartments as well as the fuel and control actuating systems. The wing will be attached to the top of the fuselage as will the fuel and control actuator systems for easy disassembly and maintenance. The aircraft is maneuvered about its pitch axis by means of an aft elevator on the flat plate horizontal tail. The twin vertical tail surfaces are also flat plates and each features a rudder for both directional and roll control. Along with wing dihedral, the rudders will be used to roll the aircraft. The Airplane is less costly to operate at its own maximum range and capacity as well as at its maximum range and the HB-40's maximum capacity than the HB-40.

  18. 14 CFR 121.207 - Provisionally certificated airplanes: Operating limitations.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Provisionally certificated airplanes... AND OPERATIONS OPERATING REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Airplane Performance Operating Limitations § 121.207 Provisionally certificated airplanes: Operating limitations....

  19. 14 CFR 121.207 - Provisionally certificated airplanes: Operating limitations.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Provisionally certificated airplanes... AND OPERATIONS OPERATING REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Airplane Performance Operating Limitations § 121.207 Provisionally certificated airplanes: Operating limitations....

  20. 14 CFR 121.207 - Provisionally certificated airplanes: Operating limitations.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Provisionally certificated airplanes... AND OPERATIONS OPERATING REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Airplane Performance Operating Limitations § 121.207 Provisionally certificated airplanes: Operating limitations....

  1. 14 CFR 121.207 - Provisionally certificated airplanes: Operating limitations.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Provisionally certificated airplanes... AND OPERATIONS OPERATING REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Airplane Performance Operating Limitations § 121.207 Provisionally certificated airplanes: Operating limitations....

  2. Self-Repairing Fatigue Damage in Metallic Structures for Aerospace Vehicles Using Shape Memory Alloy Self-healing (SMASH) Technology

    NASA Technical Reports Server (NTRS)

    Wright, M. Clara; Manuel, Michele; Wallace, Terryl; Newman, Andy; Brinson, Kate

    2015-01-01

    This DAA is for the Phase II webinar presentation of the ARMD-funded SMASH technology. A self-repairing aluminum-based composite system has been developed using liquid-assisted healing theory in conjunction with the shape memory effect of wire reinforcements. The metal matrix composite was thermodynamically designed to have a matrix with a relatively even dispersion of low-melting phase, allowing for repair of cracks at a pre-determined temperature. Shape memory alloy wire reinforcements were used within the composite to provide crack closure. Investigators focused the research on fatigue cracks propagating through the matrix in order to optimize and computer model the SMASH technology for aeronautical applications.

  3. Annoyance caused by propeller airplane flyover noise

    NASA Technical Reports Server (NTRS)

    Mccurdy, D. A.; Powell, C. A.

    1984-01-01

    Laboratory experiments were conducted to provide information on quantifying the annoyance response of people to propeller airplane noise. The items of interest were current noise metrics, tone corrections, duration corrections, critical band corrections, and the effects of engine type, operation type, maximum takeoff weight, blade passage frequency, and blade tip speed. In each experiment, 64 subjects judged the annoyance of recordings of propeller and jet airplane operations presented at d-weighted sound pressure levels of 70, 80, and 90 dB in a testing room which simulates the outdoor acoustic environment. The first experiment examined 11 propeller airplanes with maximum takeoff weights greater than or equal to 5700 kg. The second experiment examined 14 propeller airplanes weighting 5700 kg or less. Five jet airplanes were included in each experiment. For both the heavy and light propeller airplanes, perceived noise level and perceived level (Stevens Mark VII procedure) predicted annoyance better than other current noise metrics.

  4. Development and characterization of fatigue resistant Aramid reinforced aluminium laminates (ARALL) for fatigue Critical aircraft components

    NASA Astrophysics Data System (ADS)

    Qaiser, M. H.; Umar, S.; Nauman, S.

    2014-06-01

    The structural weight of an aircraft has always been a controlling parameter that governs its fuel efficiency and transport capacity. In pursuit of achieving light-weight aircraft structures, high design stress levels have to be adopted and materials with high specific strength such as Aluminum etc. are to be deployed. However, an extensive spectrum of fatigue load exists at the aircraft wings and other aerodynamic components that may cause initiation and propagation of fatigue cracks and concludes in a catastrophic rupture. Fatigue is therefore the limiting design parameter in such cases and materials with high fatigue resistance are then required. A major improvement in the fatigue behavior was observed by laminating Kevlar fibers with Aluminum using epoxy. ARALL (Aramid Reinforced ALuminum Laminates) is a fatigue resistant hybrid composite that consists of layers of thin high strength aluminum alloy sheets surface bonded with aramid fibers. The intact aramid fibers tie up the fatigue cracks, thus reducing the stress intensity factor at the crack tip as a result of which the fatigue properties of can be enhanced with orders of magnitude as compared to monolithic high strength Aluminum alloy sheets. Significant amount of weight savings can be achieved in fatigue critical components in comparison with the traditional materials used in aircraft.

  5. Design definition study of a NASA/Navy lift/cruise fan technology V/STOL airplane: Risk assessment addendum to the final report

    NASA Technical Reports Server (NTRS)

    Zabinsky, J. M.; Burnham, R. W.; Flora, C. C.; Gotlieb, P.; Grande, D. L.; Gunnarson, D. W.; Howard, W. M.; Hunt, D.; Jakubowski, G. W.; Johnson, P. E.

    1975-01-01

    An assessment of risk, in terms of delivery delays, cost overrun, and performance achievement, associated with the V/STOL technology airplane is presented. The risk is discussed in terms of weight, structure, aerodynamics, propulsion, mechanical drive, and flight controls. The analysis ensures that risks associated with the design and development of the airplane will be eliminated in the course of the program and a useful technology airplane that meets the predicted cost, schedule, and performance can be produced.

  6. Headache during airplane travel ("airplane headache"): first case in Greece.

    PubMed

    Kararizou, Evangelia; Anagnostou, Evangelos; Paraskevas, George P; Vassilopoulou, Sofia D; Naoumis, Dimitrios; Kararizos, Grigoris; Spengos, Konstantinos

    2011-08-01

    Headache related to airplane flights is rare. We describe a 37-year-old female patient with multiple intense, jabbing headache episodes over the last 3 years that occur exclusively during airplane flights. The pain manifests during take-off and landing, and is located always in the left retro-orbital and frontotemporal area. It is occasionally accompanied by dizziness, but no additional symptoms occur. Pain intensity diminishes and disappears after 15-20 min. Apart from occasional dizziness, no other symptoms occur. The patient has a history of tension-type headache and polycystic ovaries. Blood tests and imaging revealed no abnormalities. Here, we present the first case in Greece. We review the current literature on this rare syndrome and discuss on possible pathophysiology and the investigation of possible co-factors such as anxiety and depression.

  7. Multiscale Fatigue Life Prediction for Composite Panels

    NASA Technical Reports Server (NTRS)

    Bednarcyk, Brett A.; Yarrington, Phillip W.; Arnold, Steven M.

    2012-01-01

    Fatigue life prediction capabilities have been incorporated into the HyperSizer Composite Analysis and Structural Sizing Software. The fatigue damage model is introduced at the fiber/matrix constituent scale through HyperSizer s coupling with NASA s MAC/GMC micromechanics software. This enables prediction of the micro scale damage progression throughout stiffened and sandwich panels as a function of cycles leading ultimately to simulated panel failure. The fatigue model implementation uses a cycle jumping technique such that, rather than applying a specified number of additional cycles, a specified local damage increment is specified and the number of additional cycles to reach this damage increment is calculated. In this way, the effect of stress redistribution due to damage-induced stiffness change is captured, but the fatigue simulations remain computationally efficient. The model is compared to experimental fatigue life data for two composite facesheet/foam core sandwich panels, demonstrating very good agreement.

  8. [Fatigue and depression].

    PubMed

    Hell, Daniel

    2015-04-22

    Fatigue is characterised in an overview of the literature as a specific phenomenon of depression. Its differential diagnosis is discussed. Distinctions and correspondences to burnout are elaborated. Fatigue is not an obligatory symptom of depressive episodes, although it can contribute to depressive developments. The importance of fatigue in depressive episodes and its therapy is shown with the help of a circular model of depression.

  9. Continuous fatigue crack monitoring of bridges: Long-Term Electrochemical Fatigue Sensor (LTEFS)

    NASA Astrophysics Data System (ADS)

    Moshier, Monty A.; Nelson, Levi; Brinkerhoff, Ryan; Miceli, Marybeth

    2016-04-01

    Fatigue cracks in steel bridges degrade the load-carrying capacity of these structures. Fatigue damage accumulation caused by the repetitive loading of everyday truck traffic can cause small fatigue cracks initiate. Understanding the growth of these fatigue cracks is critical to the safety and reliability of our transportation infrastructure. However, modeling fatigue in bridges is difficult due to the nature of the loading and variations in connection integrity. When fatigue cracks reach critical lengths failures occur causing partial or full closures, emergency repairs, and even full structural failure. Given the aging US highway and the trend towards asset management and life extension, the need for reliable, cost effective sensors and monitoring technologies to alert bridge owners when fatigue cracks are growing is higher than ever. In this study, an innovative Long-Term Electrochemical Fatigue Sensor (LTEFS) has been developed and introduced to meet the growing NDT marketplace demand for sensors that have the ability to continuously monitor fatigue cracks. The performance of the LTEFS has been studied in the laboratory and in the field. Data was collected using machined specimens with different lengths of naturally initiated fatigue cracks, applied stress levels, applied stress ratios, and for both sinusoidal and real-life bridge spectrum type loading. The laboratory data was evaluated and used to develop an empirically based algorithm used for crack detection. Additionally, beta-tests on a real bridge structure has been completed. These studies have conclusively demonstrated that LTEFS holds great potential for long-term monitoring of fatigue cracks in steel structures

  10. Analysis of Stresses in German Airplanes

    NASA Technical Reports Server (NTRS)

    Hoff, Wilhelm

    1923-01-01

    This report contains an account of the origin of the views and fundamental principles underlying the construction of German airplanes during the war. The report contains a detailed discussion of the aerodynamic principles and their use in determining the strength of airplanes, the analysis of the strength qualities of materials and in the construction, the calculated strength of air flows and a description of tests made in determining the strength of airplanes.

  11. Compact bone fatigue damage: a microscopic examination.

    PubMed

    Carter, D R; Hayes, W C

    1977-01-01

    Flexural fatigue tests of bovine bone specimens produced fracture surfaces that were transverse on the tension side and oblique on the compression side. Similar fracture patterns were produced by bending tests with a single applied loading. Microscopic examination of flexural fatigue specimens prior to complete established that fatigue fracture is caused by the progressive accumulation of diffuse structural damage. The microdamage observed on the tension side consisted primarily of separation (or debonding) at cement lines and interlamellar cement bands. Tensile cracks in interstitial bone were also observed. The major damage modes on the compression side were oblique cracking and longitudinal splitting. The fatigue fracture patterns observed for the bone specimens correspond to the types of fatigue fractures observed clinically. Compact bone fatigue fractures in areas of longitudinal tensile stresses are generally seen as transverse lesions, whereas fatigue fractures in areas of longitudinal compressive stresses are normally oblique fractures. The diffuse nature of the observed fatigue damage is consistent with the hypothesis that microdamage caused by mechanical loading may serve as a stimulus for in vivo bone remodeling.

  12. Driver fatigue recognition based on supervised LPP and MKSVM

    NASA Astrophysics Data System (ADS)

    Huang, Wei; Zhang, Wei

    2011-06-01

    Driver fatigue is a significant factor in many traffic accidents. In this paper, a novel approach is proposed to recognize driver fatigue. First of all, in order to extract effective feature of fatigue expression from face images, supervised locality preserving projections (SLPP) is adopted, which can solve the problem that LPP ignores the within-class local structure by adopting prior class label information. And then multiple kernels support vector machines (MKSVM) is employed to recognizing fatigue expression, Compared to SVM, which can improve the interpretability of decision function and performance of fatigue recognition. Experimental results are shown to demonstrate the effectiveness of the proposed method.

  13. Fatigue in rheumatic diseases

    PubMed Central

    Sandıkçı, Sevinç Can; Özbalkan, Zeynep

    2015-01-01

    Fatigue is a common and important problem in many diseases including rheumatologic illnesses, and it has a negative impact on health-related quality of life. Fatigue is described as having an impact on multiple aspects of a patient’s life. There is a need for knowledge about causes of and treatments for fatigue to ensure that patient outcomes are improved. There are several effective treatment strategies available for fatigue including pharmacological and non-pharmacological therapies. We aim to provide an overview of fatigue in rheumatologic disorders and some recommendations on its optimal management. PMID:27708942

  14. Cognitive and Physical Fatigue Tasks Enhance Pain, Cognitive Fatigue and Physical Fatigue in People with Fibromyalgia

    PubMed Central

    Dailey, Dana L; Keffala, Valerie J; Sluka, Kathleen A

    2014-01-01

    Objective Fibromyalgia is a condition characterized by chronic widespread muscle pain and fatigue. The primary objective of this study was to determine if pain, perceived cognitive fatigue, and perceived physical fatigue were enhanced in participants with fibromyalgia compared to healthy controls during a cognitive fatigue task, a physical fatigue task and a dual fatigue task. Methods Twenty four people with fibromyalgia and 33 healthy controls completed pain, fatigue and function measures. A cognitive fatigue task (Controlled Oral Word Association Test) and physical fatigue task (Valpar peg test) were done individually and combined for a dual fatigue task. Resting pain, perceived cognitive fatigue and perceived physical fatigue were assessed during each task using visual analogue scales. Function was assessed with shoulder range of motion and grip. Results People with fibromyalgia had significantly higher increases in pain, cognitive fatigue and physical fatigue when compared to healthy controls after completion of a cognitive fatigue task, a physical fatigue task, or a dual fatigue task (p<0.01). People with fibromyalgia performed equivalently on measures of physical performance and cognitive performance on the physical and cognitive fatigue tasks, respectively. Conclusions These data show that people with fibromyalgia show larger increases in pain, perceived cognitive fatigue and perceived physical fatigue to both cognitive and physical fatigue tasks compared to healthy controls. The increases in pain and fatigue during cognitive and physical fatigue tasks could influence subject participation in daily activities and rehabilitation. PMID:25074583

  15. The Anti-fatigue Mechanisms on Alterations of Structures and Performances of Alloy Welded Joints with Ultrasonic Impact Treatment

    NASA Astrophysics Data System (ADS)

    Li, Z. M.; Zhu, Y. L.; Du, X. K.

    The specimens of aluminum alloy welded joint were prepared by gas tungsten arc welding using 2A12 sheets and ER5356 welding wires. Some specimens were full coverage strengthened by ultrasonic impact treatment and the others were not strengthened. The surface layer microstructures of the ultrasonic impact treated and untreated specimens were investigated by optical microscopy and transmission electron microscopy. The surface layer hardness and residual stress distributions along the thickness direction were measured by micro-hardness tester and X-ray diffraction method. The results showed that a grain refinement layer which depth extended up to about 150∼200 μm was produced by ultrasonic impact treatment. The average hardness value of the treated specimens was up to 110 HV, increasing by 45% compared with 76 HV of the untreated specimen. A residual compressive stress layer was also produced by ultrasonic impact treatment, and the depth was close to 900 μm. The maximum residual compressive stress was -285 MPa. At the same time, the anti-fatigue mechanisms on grain refinement, work hardening and residual compressive stress of aluminum alloy welded joint with ultrasonic impact treatment were also discussed.

  16. Light airplane crash tests at three flight-path angles

    NASA Technical Reports Server (NTRS)

    Castle, C. B.; Alfaro-Bou, E.

    1978-01-01

    Three similar twin engine general aviation airplane specimens were crash tested at Langley impact dynamics research facility at 27 m/sec and at flight-path angles of -15 deg, -30 deg, and -45 deg. Other flight parameters were held constant. The test facility, instrumentation, test specimens, and test method are briefly described. Structural damage and accelerometer data for each of the three impact conditions are presented and discussed.

  17. Light Airplane Crash Test at Three Pitch Angles

    NASA Technical Reports Server (NTRS)

    Vaughan, Victor L., Jr.; Alfaro-Bou, Emilio

    1979-01-01

    Three similar twin-engine general-aviation airplane specimens were crash tested at the Langley Impact Dynamics Research Facility at 27 m/sec, a flight-path angle of -15deg, and pithch angles of -15deg, 0deg, and 15deg. Other crash parameters were held constant. The test facility, instrumentation, test specimens, and test method are briefly described. Structural damage and accelerometer data for each of the three impact conditions are presented and discussed.

  18. Fatigue strength of adhesive bonded section beams under torsion

    SciTech Connect

    Tomioka, Noboru; Kakiage, Masashi; Niisawa, Junetsu; Kitagawa, Hideo

    1995-11-01

    Fatigue strength of adhesive bonded box beams was investigated. From results of the fatigue tests, it was seen that the fatigue strength of bonded beams was higher than that of spot welded beams. Fatigue strength of bonded beams was independent of plate thickness and partition. The flexural rigidity of the box beams in the plane of partition can increase without decrease of torsional rigidity and torsional fatigue strength, if the partition is jointed by adhesive bonding instead of spot welding. Since the fatigue strength and rigidity of adhesive bonded joints can be higher than the spot welded joints in the weight saving structures, it is expected that the structural adhesive joints will be employed more in the automobile body structure. For assuring the introduction of this joint more into the automobile body structures, it is necessary that the fatigue tests on the model members of the actual members used in the automobile body structure are conducted, in addition to those of the simple joints such as tension shear and T-type tension, and the property of the fatigue strength on the adhesive bonded members is known. But, the authors now have little data on fatigue tests of the adhesive bonded members. In the present research to be reported, the fatigue tests on adhesive bonded box beams under torsion, which are typical members in automobile body structure, were carried out and the effects of the presence of longitudinal partition and plate thickness on fatigue strength were investigated. Comparing the results of fatigue tests on adhesive bonded box beams with those on spot welded box beams, the property of fatigue strength on these adhesive bonded box beams was cleared.

  19. Fatigue Life Methodology for Bonded Composite Skin/Stringer Configurations

    NASA Technical Reports Server (NTRS)

    Krueger, Ronald; Paris, Isabelle L.; OBrien, T. Kevin; Minguet, Pierre J.

    2001-01-01

    A methodology is presented for determining the fatigue life of composite structures based on fatigue characterization data and geometric nonlinear finite element (FE) analyses. To demonstrate the approach, predicted results were compared to fatigue tests performed on specimens which represented a tapered composite flange bonded onto a composite skin. In a first step, tension tests were performed to evaluate the debonding mechanisms between the flange and the skin. In a second step, a 2D FE model was developed to analyze the tests. To predict matrix cracking onset, the relationship between the tension load and the maximum principal stresses transverse to the fiber direction was determined through FE analysis. Transverse tension fatigue life data were used to -enerate an onset fatigue life P-N curve for matrix cracking. The resulting prediction was in good agreement with data from the fatigue tests. In a third step, a fracture mechanics approach based on FE analysis was used to determine the relationship between the tension load and the critical energy release rate. Mixed mode energy release rate fatigue life data were used to create a fatigue life onset G-N curve for delamination. The resulting prediction was in good agreement with data from the fatigue tests. Further, the prediction curve for cumulative life to failure was generated from the previous onset fatigue life curves. The results showed that the methodology offers a significant potential to Predict cumulative fatigue life of composite structures.

  20. Crash tests of four identical high-wing single-engine airplanes

    NASA Technical Reports Server (NTRS)

    Vaughan, V. L., Jr.; Hayduk, R. J.

    1980-01-01

    Four identical four place, high wing, single engine airplane specimens with nominal masses of 1043 kg were crash tested at the Langley Impact Dynamics Research Facility under controlled free flight conditions. These tests were conducted with nominal velocities of 25 m/sec along the flight path angles, ground contact pitch angles, and roll angles. Three of the airplane specimens were crashed on a concrete surface; one was crashed on soil. Crash tests revealed that on a hard landing, the main landing gear absorbed about twice the energy for which the gear was designed but sprang back, tending to tip the airplane up to its nose. On concrete surfaces, the airplane impacted and remained in the impact attitude. On soil, the airplane flipped over on its back. The crash impact on the nose of the airplane, whether on soil or concrete, caused massive structural crushing of the forward fuselage. The liveable volume was maintained in both the hard landing and the nose down specimens but was not maintained in the roll impact and nose down on soil specimens.

  1. Subsonic Airplane For High-Altitude Research

    NASA Technical Reports Server (NTRS)

    Chambers, Alan; Reed, R. Dale

    1993-01-01

    Report discusses engineering issues considered in design of conceptual subsonic airplane intended to cruise at altitudes of 100,000 ft or higher. Airplane would carry scientific instruments for research in chemistry and physics of atmosphere, particularly, for studies of ozone hole, greenhouse gases, and climatic effects.

  2. 77 FR 34283 - Airworthiness Directives; Airbus Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-11

    ... series airplanes. Comments We have considered the following comment received on the earlier NPRM (76 FR... Manager, Transport Airplane Directorate, Aircraft Certification Service. BILLING CODE 4910-13-P ... Federal Aviation Administration 14 CFR Part 39 RIN 2120-AA64 Airworthiness Directives; Airbus...

  3. Research on the control of airplanes

    NASA Technical Reports Server (NTRS)

    Jones, B Melvill

    1928-01-01

    Our task is to endeavor to obtain precise experimental records of the motion of stalled airplanes, both when left to themselves and when the pilot is trying to control them. The apparatus which we use consists of a box containing tree gyroscopes which are slightly deflected against a spring control when the airplane is turning.

  4. 14 CFR 125.355 - Airplane equipment.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Airplane equipment. 125.355 Section 125.355...: AIRPLANES HAVING A SEATING CAPACITY OF 20 OR MORE PASSENGERS OR A MAXIMUM PAYLOAD CAPACITY OF 6,000 POUNDS OR MORE; AND RULES GOVERNING PERSONS ON BOARD SUCH AIRCRAFT Flight Release Rules § 125.355...

  5. 78 FR 46536 - Airworthiness Directives; Airbus Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-01

    ... Procedures (44 FR 11034, February 26, 1979); 3. Will not affect intrastate aviation in Alaska; and 4. Will... Federal Aviation Administration 14 CFR Part 39 RIN 2120-AA64 Airworthiness Directives; Airbus Airplanes... B4-600R series airplanes. This proposed AD was prompted by reports of cracks found in the bottom...

  6. 14 CFR 125.355 - Airplane equipment.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Airplane equipment. 125.355 Section 125.355...: AIRPLANES HAVING A SEATING CAPACITY OF 20 OR MORE PASSENGERS OR A MAXIMUM PAYLOAD CAPACITY OF 6,000 POUNDS OR MORE; AND RULES GOVERNING PERSONS ON BOARD SUCH AIRCRAFT Flight Release Rules § 125.355...

  7. 14 CFR 125.355 - Airplane equipment.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Airplane equipment. 125.355 Section 125.355...: AIRPLANES HAVING A SEATING CAPACITY OF 20 OR MORE PASSENGERS OR A MAXIMUM PAYLOAD CAPACITY OF 6,000 POUNDS OR MORE; AND RULES GOVERNING PERSONS ON BOARD SUCH AIRCRAFT Flight Release Rules § 125.355...

  8. Multiaxial fatigue low cycle fatigue testing

    NASA Technical Reports Server (NTRS)

    Zamrik, S. Y.

    1985-01-01

    Multiaxial testing methods are reviewed. Advantages and disadvantages of each type test is discussed. Significant multiaxial data available in the literature is analyzed. The yield theories are compared for multiaxial fatigue analysis.

  9. 14 CFR 91.853 - Final compliance: Civil subsonic airplanes.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Final compliance: Civil subsonic airplanes... Noise Limits § 91.853 Final compliance: Civil subsonic airplanes. Except as provided in § 91.873, after... airplane subject to § 91.801(c) of this subpart, unless that airplane has been shown to comply with Stage...

  10. 14 CFR 23.1437 - Accessories for multiengine airplanes.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Equipment Miscellaneous Equipment § 23.1437 Accessories for multiengine airplanes. For multiengine airplanes... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Accessories for multiengine airplanes....

  11. 14 CFR 21.5 - Airplane or Rotorcraft Flight Manual.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Airplane or Rotorcraft Flight Manual. 21.5... CERTIFICATION PROCEDURES FOR PRODUCTS AND PARTS General § 21.5 Airplane or Rotorcraft Flight Manual. Link to an..., 2010. (a) With each airplane or rotorcraft that was not type certificated with an Airplane...

  12. 14 CFR 21.5 - Airplane or Rotorcraft Flight Manual.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Airplane or Rotorcraft Flight Manual. 21.5... CERTIFICATION PROCEDURES FOR PRODUCTS AND PARTS General § 21.5 Airplane or Rotorcraft Flight Manual. (a) With each airplane or rotorcraft that was not type certificated with an Airplane or Rotorcraft Flight...

  13. 14 CFR 91.821 - Civil supersonic airplanes: Noise limits.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 2 2013-01-01 2013-01-01 false Civil supersonic airplanes: Noise limits... Noise Limits § 91.821 Civil supersonic airplanes: Noise limits. Except for Concorde airplanes having... airplane that does not comply with Stage 2 noise limits of part 36 in effect on October 13, 1977,...

  14. 14 CFR 21.5 - Airplane or Rotorcraft Flight Manual.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Airplane or Rotorcraft Flight Manual. 21.5... CERTIFICATION PROCEDURES FOR PRODUCTS AND PARTS General § 21.5 Airplane or Rotorcraft Flight Manual. (a) With each airplane or rotorcraft not type certificated with an Airplane or Rotorcraft Flight Manual...

  15. 14 CFR 91.821 - Civil supersonic airplanes: Noise limits.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 2 2011-01-01 2011-01-01 false Civil supersonic airplanes: Noise limits... Noise Limits § 91.821 Civil supersonic airplanes: Noise limits. Except for Concorde airplanes having... airplane that does not comply with Stage 2 noise limits of part 36 in effect on October 13, 1977,...

  16. 14 CFR 91.853 - Final compliance: Civil subsonic airplanes.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 2 2012-01-01 2012-01-01 false Final compliance: Civil subsonic airplanes... Noise Limits § 91.853 Final compliance: Civil subsonic airplanes. Except as provided in § 91.873, after... airplane subject to § 91.801(c) of this subpart, unless that airplane has been shown to comply with Stage...

  17. 14 CFR 91.853 - Final compliance: Civil subsonic airplanes.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 2 2013-01-01 2013-01-01 false Final compliance: Civil subsonic airplanes... Noise Limits § 91.853 Final compliance: Civil subsonic airplanes. Except as provided in § 91.873, after... airplane subject to § 91.801(c) of this subpart, unless that airplane has been shown to comply with Stage...

  18. 14 CFR 21.5 - Airplane or Rotorcraft Flight Manual.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Airplane or Rotorcraft Flight Manual. 21.5... CERTIFICATION PROCEDURES FOR PRODUCTS AND PARTS General § 21.5 Airplane or Rotorcraft Flight Manual. (a) With each airplane or rotorcraft not type certificated with an Airplane or Rotorcraft Flight Manual...

  19. 14 CFR 91.853 - Final compliance: Civil subsonic airplanes.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 2 2011-01-01 2011-01-01 false Final compliance: Civil subsonic airplanes... Noise Limits § 91.853 Final compliance: Civil subsonic airplanes. Except as provided in § 91.873, after... airplane subject to § 91.801(c) of this subpart, unless that airplane has been shown to comply with Stage...

  20. 14 CFR 125.75 - Airplane flight manual.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Airplane flight manual. 125.75 Section 125... OPERATIONS: AIRPLANES HAVING A SEATING CAPACITY OF 20 OR MORE PASSENGERS OR A MAXIMUM PAYLOAD CAPACITY OF 6... Airplane flight manual. (a) Each certificate holder shall keep a current approved Airplane Flight Manual...

  1. 14 CFR 125.75 - Airplane flight manual.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Airplane flight manual. 125.75 Section 125... OPERATIONS: AIRPLANES HAVING A SEATING CAPACITY OF 20 OR MORE PASSENGERS OR A MAXIMUM PAYLOAD CAPACITY OF 6... Airplane flight manual. (a) Each certificate holder shall keep a current approved Airplane Flight Manual...

  2. 14 CFR 91.821 - Civil supersonic airplanes: Noise limits.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 2 2012-01-01 2012-01-01 false Civil supersonic airplanes: Noise limits... Noise Limits § 91.821 Civil supersonic airplanes: Noise limits. Except for Concorde airplanes having... airplane that does not comply with Stage 2 noise limits of part 36 in effect on October 13, 1977,...

  3. 14 CFR 125.75 - Airplane flight manual.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Airplane flight manual. 125.75 Section 125... OPERATIONS: AIRPLANES HAVING A SEATING CAPACITY OF 20 OR MORE PASSENGERS OR A MAXIMUM PAYLOAD CAPACITY OF 6... Airplane flight manual. (a) Each certificate holder shall keep a current approved Airplane Flight Manual...

  4. Probabilistic fatigue methodology and wind turbine reliability

    SciTech Connect

    Lange, C.H.

    1996-05-01

    Wind turbines subjected to highly irregular loadings due to wind, gravity, and gyroscopic effects are especially vulnerable to fatigue damage. The objective of this study is to develop and illustrate methods for the probabilistic analysis and design of fatigue-sensitive wind turbine components. A computer program (CYCLES) that estimates fatigue reliability of structural and mechanical components has been developed. A FORM/SORM analysis is used to compute failure probabilities and importance factors of the random variables. The limit state equation includes uncertainty in environmental loading, gross structural response, and local fatigue properties. Several techniques are shown to better study fatigue loads data. Common one-parameter models, such as the Rayleigh and exponential models are shown to produce dramatically different estimates of load distributions and fatigue damage. Improved fits may be achieved with the two-parameter Weibull model. High b values require better modeling of relatively large stress ranges; this is effectively done by matching at least two moments (Weibull) and better by matching still higher moments. For this purpose, a new, four-moment {open_quotes}generalized Weibull{close_quotes} model is introduced. Load and resistance factor design (LRFD) methodology for design against fatigue is proposed and demonstrated using data from two horizontal-axis wind turbines. To estimate fatigue damage, wind turbine blade loads have been represented by their first three statistical moments across a range of wind conditions. Based on the moments {mu}{sub 1}{hor_ellipsis}{mu}{sub 3}, new {open_quotes}quadratic Weibull{close_quotes} load distribution models are introduced. The fatigue reliability is found to be notably affected by the choice of load distribution model.

  5. Prolonging Microgravity on Parabolic Airplane Flights

    NASA Technical Reports Server (NTRS)

    Robinson, David W.

    2003-01-01

    Three techniques have been proposed to prolong the intervals of time available for microgravity experiments aboard airplanes flown along parabolic trajectories. Typically, a pilot strives to keep an airplane on such a trajectory during a nominal time interval as long as 25 seconds, and an experimental apparatus is released to float freely in the airplane cabin to take advantage of the microgravitational environment of the trajectory for as long as possible. It is usually not possible to maintain effective microgravity during the entire nominal time interval because random aerodynamic forces and fluctuations in pilot control inputs cause the airplane to deviate slightly from a perfect parabolic trajectory, such that the freely floating apparatus bumps into the ceiling, floor, or a wall of the airplane before the completion of the parabola.

  6. Optimal back-to-front airplane boarding.

    PubMed

    Bachmat, Eitan; Khachaturov, Vassilii; Kuperman, Ran

    2013-06-01

    The problem of finding an optimal back-to-front airplane boarding policy is explored, using a mathematical model that is related to the 1+1 polynuclear growth model with concave boundary conditions and to causal sets in gravity. We study all airplane configurations and boarding group sizes. Optimal boarding policies for various airplane configurations are presented. Detailed calculations are provided along with simulations that support the main conclusions of the theory. We show that the effectiveness of back-to-front policies undergoes a phase transition when passing from lightly congested airplanes to heavily congested airplanes. The phase transition also affects the nature of the optimal or near-optimal policies. Under what we consider to be realistic conditions, optimal back-to-front policies lead to a modest 8-12% improvement in boarding time over random (no policy) boarding, using two boarding groups. Having more than two groups is not effective. PMID:23848727

  7. Fatigue and fracture research in metals

    NASA Technical Reports Server (NTRS)

    Newman, J. C., Jr.; Davidson, J. R.

    1982-01-01

    Fatigue and fracture research on monolithic and laminated metals is discussed. The research concentrated on three areas: stress analyses of two and three dimensional cracked bodies, fatigue crack growth, and fracture toughness. Analytical methods were developed to predict fatigue crack growth and fracture strengths of cracked specimens. Such specimens represent typical aircraft structural details (such as cracks from holes). These specimens were subjected to simple constant amplitude loading and to more complex flight load histories. Test data from both in house tests and from the literature are used to substantiate the analytical methods. These analyses extended the theory of fracture mechanics to deal with fatigue crack growth and fracture of complex crack configurations that are typical of aircraft materials and structural details.

  8. Clinical neurophysiology of fatigue.

    PubMed

    Zwarts, M J; Bleijenberg, G; van Engelen, B G M

    2008-01-01

    Fatigue is a multidimensional concept covering both physiological and psychological aspects. Chronic fatigue is a typical symptom of diseases such as cancer, multiple sclerosis (MS), Parkinson's disease (PD) and cerebrovascular disorders but is also presented by people in whom no defined somatic disease has been established. If certain criteria are met, chronic fatigue syndrome can be diagnosed. The 4-item Abbreviated Fatigue Questionnaire allows the extent of the experienced fatigue to be assessed with a high degree of reliability and validity. Physiological fatigue has been well defined and originates in both the peripheral and central nervous system. The condition can be assessed by combining force and surface-EMG measurements (including frequency analyses and muscle-fibre conduction estimations), twitch interpolation, magnetic stimulation of the motor cortex and analysis of changes in the readiness potential. Fatigue is a well-known phenomenon in both central and peripheral neurological disorders. Examples of the former conditions are multiple sclerosis, Parkinson's disease and stroke. Although it seems to be a universal symptom of many brain disorders, the unique characteristics of the concomitant fatigue also point to a specific relationship with several of these syndromes. As regards neuromuscular disorders, fatigue has been reported in patients with post-polio syndrome, myasthenia gravis, Guillain-Barré syndrome, facioscapulohumeral dystrophy, myotonic dystrophy and hereditary motor and sensory neuropathy type-I. More than 60% of all neuromuscular patients suffer from severe fatigue, a prevalence resembling that of patients with MS. Except for several rare myopathies with specific metabolic derangements leading to exercise-induced muscle fatigue, most studies have not identified a prominent peripheral cause for the fatigue in this population. In contrast, the central activation of the diseased neuromuscular system is generally found to be suboptimal. The

  9. 14 CFR 129.23 - Transport category cargo service airplanes: Increased zero fuel and landing weights.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... fuel and landing weights. (a) Notwithstanding the applicable structural provisions of the transport... fuel weight (maximum weight of the airplane with no disposable fuel and oil) and the structural landing... Administrator finds that— (1) The increase is not likely to reduce seriously the structural strength; (2)...

  10. Managing fatigue in the syncope unit.

    PubMed

    Newton, Julia L

    2012-12-01

    The symptom of fatigue is frequently described by patients attending the syncope unit with a wide range of conditions including vasovagal syncope and postural orthostatic tachycardia syndrome. It is possible that the presence of autonomic dysfunction provides the common pathogenetic mechanism linking neurally mediated hypotension and fatigue. Managing this debilitating symptom can often be challenging but, with a structured approach, immensely rewarding, and as a result improve how patients cope with their disease.

  11. Investigations on the stability, oscillation, and stress conditions of airplanes with tab control. Second partial report : application of the solutions obtained in the first partial report to tab-controlled airplanes.

    NASA Technical Reports Server (NTRS)

    Filzek, B

    1949-01-01

    The first partial report, FB 2000, contained a discussion of the derivation of the equations of motion and their solutions for a tab-controlled airplane; the results obtained there are now to be applied to the longitudinal motion of tab-controlled airplanes. In view of the abundance of structural factors and aerodynamic parameters, a general discussion of the problems is unfeasible. Thus it is demonstrated on the basis of examples what stability, oscillation, and stress conditions are to be expected for tab-controlled airplanes. (author)

  12. 76 FR 4219 - Airworthiness Directives; Airbus Model A330-200 Series Airplanes; Model A330-300 Series Airplanes...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-25

    ... Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and 3. Will not have a significant...-200 Series Airplanes; Model A330-300 Series Airplanes; Model A340-200 Series Airplanes; and Model A340-300 Series Airplanes AGENCY: Federal Aviation Administration (FAA), Department of Transportation...

  13. The FAA aging airplane program plan for transport aircraft

    NASA Technical Reports Server (NTRS)

    Curtis, Dayton; Lewis, Jess

    1992-01-01

    The Federal Aviation Administration (FAA) Aging Airplane Program is focused on five program areas: maintenance, transport airplanes, commuter airplanes, airplane engines, and research. These programs are complementary and concurrent, and have been in effect since 1988. The programs address the aging airplane challenge through different methods, including policies, procedures, and hardware development. Each program is carefully monitored and its progress tracked to ensure that the needs of the FAA, the industry, and the flying public are being met.

  14. Review of sonic fatigue technology

    NASA Technical Reports Server (NTRS)

    Clarkson, B. L.

    1994-01-01

    From the early-1960s until the mid-1980s, there was very little theoretical development for sonic fatigue prediction. Design nomographs based on simple theoretical models and results of specially designed tests were developed for most common aircraft structures. The use of advanced composites in the 1980s, however, generated an increased interest in development of more sophisticated theoretical models because of the possibilities for a much wider range of structural designs. The purpose of this report is to review sonic fatigue technology and, in particular, to assess recent developments. It also suggests a plan for a coordinated program of theoretical and experimental work to meet the anticipated needs of future aerospace vehicles.

  15. Consolidation of fatigue and fatigue-crack-propagation data for design use

    NASA Technical Reports Server (NTRS)

    Rice, R. C.; Davies, K. B.; Jaske, C. E.; Feddersen, C. E.

    1975-01-01

    Analytical methods developed for consolidation of fatigue and fatigue-crack-propagation data for use in design of metallic aerospace structural components are evaluated. A comprehensive file of data on 2024 and 7075 aluminums, Ti-6Al-4V alloy, and 300M steel was established by obtaining information from both published literature and reports furnished by aerospace companies. Analyses are restricted to information obtained from constant-amplitude load or strain cycling of specimens in air at room temperature. Both fatigue and fatigue-crack-propagation data are analyzed on a statistical basis using a least-squares regression approach. For fatigue, an equivalent strain parameter is used to account for mean stress or stress ratio effects and is treated as the independent variable; cyclic fatigue life is considered to be the dependent variable. An effective stress-intensity factor is used to account for the effect of load ratio on fatigue-crack-propagation and treated as the independent variable. In this latter case, crack-growth rate is considered to be the dependent variable. A two term power function is used to relate equivalent strain to fatigue life, and an arc-hyperbolic-tangent function is used to relate effective stress intensity to crack-growth rate.

  16. Research and application of ORACLE performance optimizing technologies for building airplane environment resource database

    NASA Astrophysics Data System (ADS)

    Zhang, Jianjun; Sun, Jianyong; Cheng, Conggao

    2013-03-01

    Many problems exist in processing experimental aircraft vibration (temperature, humidity) data and generating the intermediate calculations during the construction of airplane environment resource database, such as the need to deal with both structural and non-structural data, weak capacity of the client browser for data processing and massive network data transferring etc. To solve the above problems, some strategies on tuning and optimization performance of database are employed base on Oracle11g, which include data storage structure tuning, the memory configuration of the server, the disk I/O tuning and SQL statement tuning. The experimental results show that the performance of airplane environment resource database is enhanced about 80% compared with the database developed in the initial demonstration and validation phase. The application of new optimization strategies to the database construction can lay a sound foundation for finishing building airplane environment resource database.

  17. Fatigue behavior and recommended design rules for an automotive composite

    SciTech Connect

    Corum, J.M.; Battiste, R.L.; Ruggles, M.B.

    1998-11-01

    Fatigue curves (stress vs cycles to failure) were generated under a variety of conditions (temperatures, fluid environments, mean stresses, block loadings) for a candidate automotive structural composite. The results were used to (1) develop observations regarding basic fatigue behavioral characteristics and (2) establish fatigue design rules. The composite was a structural reaction injection-molded polyurethane reinforced with continuous strand, swirl-mat E-glass fibers. Tensile fatigue tests on specimens from a single plaque at {minus}40 F, room temperature, and 250 F provided the basic behavioral characteristics. It was found that when stress was normalized by the at-temperature ultimate tensile strength, the fatigue curves at the three temperatures collapsed into a single master curve. An assessment of the individual stress-strain loops throughout each test showed a progressive loss in stiffness and an increase in permanent strain, both of which are indicative of increasing damage. Fatigue tests on specimens from several plaques were used to develop a design fatigue curve, which was established by using a reduction factor of 20 on average cycles to failure. This factor assures that the stiffness loss during the design life is no greater than 10 percent. Fatigue reduction factors were established to account for various fluids. Reversed stress fatigue tests allowed a mean stress rule to be validated, and block loading tests were used to demonstrate the adequacy of Miner`s rule for cumulative fatigue damage.

  18. Performance analysis of bonded composite doublers on aircraft structures

    SciTech Connect

    Roach, D.

    1995-08-01

    Researchers contend that composite repairs (or structural reinforcement doublers) offer numerous advantages over metallic patches including corrosion resistance, light weight, high strength, elimination of rivets, and time savings in installation. Their use in commercial aviation has been stifled by uncertainties surrounding their application, subsequent inspection and long-term endurance. The process of repairing or reinforcing airplane structures is time consuming and the design is dependent upon an accompanying stress and fatigue analysis. A repair that is too stiff may result in a loss of fatigue life, continued growth of the crack being repaired, and the initiation of a new flaw in the undesirable high stress field around the patch. Uncertainties in load spectrums used to design repairs exacerbates these problems as does the use of rivets to apply conventional doublers. Many of these repair or structural reinforcement difficulties can be addressed through the use of composite doublers. Primary among unknown entities are the effects of non-optimum installations and the certification of adequate inspection procedures. This paper presents on overview of a program intended to introduce composite doubler technology to the US commercial aircraft fleet. In this project, a specific composite application has been chosen on an L-1011 aircraft in order to focus the tasks on application and operation issues. Through the use of laboratory test structures and flight demonstrations on an in-service L-1011 airplane, this study is investigating composite doubler design, fabrication, installation, structural integrity, and non-destructive evaluation. In addition to providing an overview of the L-1011 project, this paper focuses on a series of fatigue and strength tests which have been conducted in order to study the damage tolerance of composite doublers. Test results to-date are presented.

  19. Flexural fatigue life prediction of closed hat-section using materially nonlinear axial fatigue characteristics

    NASA Technical Reports Server (NTRS)

    Razzaq, Zia

    1989-01-01

    Straight or curved hat-section members are often used as structural stiffeners in aircraft. For instance, they are employed as stiffeners for the dorsal skin as well as in the aerial refueling adjacent area structure in F-106 aircraft. The flanges of the hat-section are connected to the aircraft skin. Thus, the portion of the skin closing the hat-section interacts with the section itself when resisting the stresses due to service loads. The flexural fatigue life of such a closed section is estimated using materially nonlinear axial fatigue characteristics. It should be recognized that when a structural shape is subjected to bending, the fatigue life at the neutral axis is infinity since the normal stresses are zero at that location. Conversely, the fatigue life at the extreme fibers where the normal bending stresses are maximum can be expected to be finite. Thus, different fatigue life estimates can be visualized at various distances from the neural axis. The problem becomes compounded further when significant portions away from the neutral axis are stressed into plastic range. A theoretical analysis of the closed hat-section subjected to flexural cyclic loading is first conducted. The axial fatigue characteristics together with the related axial fatigue life formula and its inverted form given by Manson and Muralidharan are adopted for an aluminum alloy used in aircraft construction. A closed-form expression for predicting the flexural fatigue life is then derived for the closed hat-section including materially nonlinear action. A computer program is written to conduct a study of the variables such as the thicknesses of the hat-section and the skin, and the type of alloy used. The study has provided a fundamental understanding of the flexural fatigue life characteristics of a practical structural component used in aircraft when materially nonlinear action is present.

  20. 78 FR 73993 - Special Conditions: Cessna Model 680 Series Airplanes; Aircraft Electronic System Security...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-10

    ... design feature associated with the architecture and connectivity capabilities of the airplanes' computer... vulnerabilities to the airplanes' systems. The proposed network architecture includes the following connectivity... architecture is novel or unusual for executive jet airplanes by allowing connection to airplane...

  1. Automated visual inspection of an airplane exterior

    NASA Astrophysics Data System (ADS)

    Jovančević, Igor; Orteu, Jean-José; Sentenac, Thierry; Gilblas, Rémi

    2015-04-01

    This paper deals with the inspection of an airplane using a Pan-Tilt-Zoom camera mounted on a mobile robot moving around the airplane. We present image processing methods for detection and inspection of four different types of items on the airplane exterior. Our detection approach is focused on the regular shapes such as rounded corner rectangles and ellipses, while inspection relies on clues such as uniformity of isolated image regions, convexity of segmented shapes and periodicity of the image intensity signal. The initial results are promising and demonstrate the feasibility of the envisioned robotic system.

  2. 77 FR 15291 - Airworthiness Directives; Airbus Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-15

    ...We propose to adopt a new airworthiness directive (AD) for all Airbus Model A300 B4-603, B4-605R, and B4-622R airplanes; Model A300 C4-605R Variant F airplanes; and Model A300 F4-600R series airplanes. This proposed AD was prompted by a report that chafing was detected between the autopilot electrical wiring conduit and the wing bottom skin. This proposed AD would require modifying the wiring......

  3. Shuttle Laser Technology Experiment Facility (LTEF)-to-airplane lasercom experiment: Airplane considerations

    NASA Technical Reports Server (NTRS)

    Kalil, Ford

    1990-01-01

    NASA is considering the use of various airplanes for a Shuttle Laser Technology Experiment Facility (LTEF)-to-Airplane laser communications experiment. As supporting documentation, pertinent technical details are included about the potential use of airplanes located at Ames Research Center and Wallops Flight Facility. The effects and application of orbital mechanics considerations are also presented, including slant range, azimuth, elevation, and time. The pros and cons of an airplane equipped with a side port with a bubble window versus a top port with a dome are discussed.

  4. Elevated temperature biaxial fatigue

    NASA Technical Reports Server (NTRS)

    Jordan, E. H.

    1984-01-01

    A three year experimental program for studying elevated temperature biaxial fatigue of a nickel based alloy Hastelloy-X has been completed. A new high temperature fatigue test facility with unique capabilities has been developed. Effort was directed toward understanding multiaxial fatigue and correlating the experimental data to the existing theories of fatigue failure. The difficult task of predicting fatigue lives for non-proportional loading was used as an ultimate test for various life prediction methods being considered. The primary means of reaching improved undertanding were through several critical non-proportional loading experiments. It was discovered that the cracking mode switched from primarily cracking on the maximum shear planes at room temperature to cracking on the maximum normal strain planes at 649 C.

  5. 78 FR 41684 - Special Conditions: Embraer S.A. Model EMB-550 Airplanes, Sudden Engine Stoppage

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-11

    ... airplane, was published in the Federal Register on September 25, 2012 (77 FR 58970). No comments were... auxiliary power unit (APU) installations, the APU mounts and adjacent supporting airframe structure must be... imposed by each of the following: (a) Sudden APU deceleration due to malfunction or structural...

  6. 75 FR 70863 - Airworthiness Directives; The Boeing Company Model 747 Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-19

    ... structure, as applicable. We are proposing this supplemental NPRM to prevent electrical current from flowing... the electrical bond resistance between the motor operated valve (MOV) actuators and airplane structure... original NPRM was published in the Federal Register on January 31, 2008 (73 FR 5773). That original...

  7. Development of light and small airplanes

    NASA Technical Reports Server (NTRS)

    Lachmann, G

    1926-01-01

    The author has endeavored to select only the most important lines of development and has limited the description of individual airplanes to a few typical examples. Comparisons are presented between German and foreign accomplishments.

  8. Precision controllability of the F-15 airplane

    NASA Technical Reports Server (NTRS)

    Sisk, T. R.; Matheny, N. W.

    1979-01-01

    A flying qualities evaluation conducted on a preproduction F-15 airplane permitted an assessment to be made of its precision controllability in the high subsonic and low transonic flight regime over the allowable angle of attack range. Precision controllability, or gunsight tracking, studies were conducted in windup turn maneuvers with the gunsight in the caged pipper mode and depressed 70 mils. This evaluation showed the F-15 airplane to experience severe buffet and mild-to-moderate wing rock at the higher angles of attack. It showed the F-15 airplane radial tracking precision to vary from approximately 6 to 20 mils over the load factor range tested. Tracking in the presence of wing rock essentially doubled the radial tracking error generated at the lower angles of attack. The stability augmentation system affected the tracking precision of the F-15 airplane more than it did that of previous aircraft studied.

  9. Fire prevention on airplanes. Part I

    NASA Technical Reports Server (NTRS)

    Sabatier, J

    1929-01-01

    Various methods for preventing fires in airplanes are presented with most efforts centering around prevention of backfires, new engine and carburetor designs, as well as investigations on different types of fuels.

  10. 77 FR 58336 - Airworthiness Directives; Airbus Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-20

    ... rule'' under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); 3. Will not... inclusive, 1071 through 1075 inclusive, 1077, 1080, and 1082. (2) Model A340-313 airplane, MSN 0955....

  11. The Kiln Drying of Wood for Airplanes

    NASA Technical Reports Server (NTRS)

    Tiemann, Harry D

    1919-01-01

    This report is descriptive of various methods used in the kiln drying of woods for airplanes and gives the results of physical tests on different types of woods after being dried by the various kiln-drying methods.

  12. A study of commuter airplane design optimization

    NASA Technical Reports Server (NTRS)

    Roskam, J.; Wyatt, R. D.; Griswold, D. A.; Hammer, J. L.

    1977-01-01

    Problems of commuter airplane configuration design were studied to affect a minimization of direct operating costs. Factors considered were the minimization of fuselage drag, methods of wing design, and the estimated drag of an airplane submerged in a propellor slipstream; all design criteria were studied under a set of fixed performance, mission, and stability constraints. Configuration design data were assembled for application by a computerized design methodology program similar to the NASA-Ames General Aviation Synthesis Program.

  13. Airplane-Runway-Performance Monitoring System

    NASA Technical Reports Server (NTRS)

    Middleton, David B.; Person, Lee H., Jr.; Srivatsan, Raghavachari

    1992-01-01

    Airplane-Runway-Performance Monitoring System (ARPMS) increases safety during takeoffs and landings by providing pilots with symbolic "head-up" and "head-down" information pertinent to decisions to continue or abort takeoffs or landings. Provides graphic information concerning where airplane could be stopped. Pilot monitors ground speed and predicted stopping point while looking at actual runway. High potential for incorporation into cockpit environment for entire aerospace community.

  14. Fatigue life prediction under service load considering strengthening effect of loads below fatigue limit

    NASA Astrophysics Data System (ADS)

    Zhao, Lihui; Zheng, Songlin; Feng, Jinzhi

    2014-11-01

    Lightweight design requires an accurate life prediction for structures and components under service loading histories. However, predicted life with the existing methods seems too conservative in some cases, leading to a heavy structure. Because these methods are established on the basis that load cycles would only cause fatigue damage, ignore the strengthening effect of loads. Based on Palmgren-Miner Rule (PMR), this paper introduces a new method for fatigue life prediction under service loadings by taking into account the strengthening effect of loads below the fatigue limit. In this method, the service loadings are classified into three categories: damaging load, strengthening load and none-effect load, and the process for fatigue life prediction is divided into two stages: stage I and stage II, according to the best strengthening number of cycles. During stage I, fatigue damage is calculated considering both the strengthening and damaging effect of load cycles. While during stage II, only the damaging effect is considered. To validate this method, fatigue lives of automobile half shaft and torsion beam rear axle are calculated based on the new method and traditional methods, such as PMR and Modified Miner Rule (MMR), and fatigue tests of the two components are conducted under service loading histories. The tests results show that the percentage errors of the predicted life with the new method to mean life of tests for the two components are -3.78% and -1.76% separately, much lesser than that with PMR and MMR. By considering the strengthening effect of loads below the fatigue limit, the new method can significantly improve the accuracy for fatigue life prediction. Thus lightweight design can be fully realized in the design stage.

  15. Elevated temperature biaxial fatigue

    NASA Technical Reports Server (NTRS)

    Jordan, E. H.

    1985-01-01

    A 3 year experimental program for studying elevated temperature biaxial fatigue of a nickel based alloy Hastelloy-X has been completed. A new high temperature fatigue test facility with unique capabilities has been developed. Effort was directed toward understanding multiaxial fatigue and correlating the experimental data to the existing theories of fatigue failure. The difficult task of predicting fatigue lives for nonproportional loading was used as an ultimate test for various life prediction methods being considered. The primary means of reaching improved understanding were through several critical nonproportional loading experiments. The direction of cracking observed on failed specimens was also recorded and used to guide the development of the theory. Cyclic deformation responses were permanently recorded digitally during each test. It was discovered that the cracking mode switched from primarily cracking on the maximum shear planes at room temperature to cracking on the maximum normal strain planes at 649 C. In contrast to some other metals, loading path in nonproportional loading had little effect on fatigue lives. Strain rate had a small effect on fatigue lives at 649 C. Of the various correlating parameters the modified plastic work and octahedral shear stress were the most successful.

  16. Factors of airplane engine performance

    NASA Technical Reports Server (NTRS)

    Gage, Victor R

    1921-01-01

    This report is based upon an analysis of a large number of airplane-engine tests. It contains the results of a search for fundamental relations between many variables of engine operation. The data used came from over 100 groups of tests made upon several engines, primarily for military information. The types of engines were the Liberty 12 and three models of the Hispano-Suiza. The tests were made in the altitude chamber, where conditions simulated altitudes up to about 30,000 feet, with engine speeds ranging from 1,200 to 2,200 r.p.m. The compression ratios of the different engines ranged from under 5 to over 8 to 1. The data taken on the tests were exceptionally complete, including variations of pressure and temperature, besides the brake and friction torques, rates of fuel and air consumption, the jacket and exhaust heat losses.

  17. The neural mechanisms of re-experiencing mental fatigue sensation: a magnetoencephalography study.

    PubMed

    Ishii, Akira; Karasuyama, Takuma; Kikuchi, Taiki; Tanaka, Masaaki; Yamano, Emi; Watanabe, Yasuyoshi

    2015-01-01

    There have been several studies which have tried to clarify the neural mechanisms of fatigue sensation; however fatigue sensation has multiple aspects. We hypothesized that past experience related to fatigue sensation is an important factor which contributes to future formation of fatigue sensation through the transfer to memories that are located within specific brain structures. Therefore, we aimed to investigate the neural mechanisms of fatigue sensation related to memory. In the present study, we investigated the neural activity caused by re-experiencing the fatigue sensation that had been experienced during a fatigue-inducing session. Thirteen healthy volunteers participated in fatigue and non-fatigue experiments in a crossover fashion. In the fatigue experiment, they performed a 2-back test session for 40 min to induce fatigue sensation, a rest session for 15 min to recover from fatigue, and a magnetoencephalography (MEG) session in which they were asked to re-experience the state of their body with fatigue that they had experienced in the 2-back test session. In the non-fatigue experiment, the participants performed a free session for 15 min, a rest session for 15 min, and an MEG session in which they were asked to re-experience the state of their body without fatigue that they had experienced in the free session. Spatial filtering analyses of oscillatory brain activity showed that the delta band power in the left Brodmann's area (BA) 39, alpha band power in the right pulvinar nucleus and the left BA 40, and beta band power in the left BA 40 were lower when they re-experienced the fatigue sensation than when they re-experienced the fatigue-free sensation, indicating that these brain regions are related to re-experiencing the fatigue sensation. Our findings may help clarify the neural mechanisms underlying fatigue sensation.

  18. Effect of the Fine-Grained Structure on the Fatigue Properties of the Heat-Resistant Nickel-Iron Alloy Inconel 718

    NASA Astrophysics Data System (ADS)

    Mukhtarov, Sh. Kh.; Shakhov, R. V.

    2015-10-01

    It is well known that ultrafine-grained nickel alloys with average grain sizes d = 0.1-1 μm possess improved hot workability and can be used for superplastic forming or rolling. However, microstructure refinement can worsen some performance characteristics of the alloy, for example, heat-resistant or fatigue properties. In the present work, fatigue characteristics of the fine-grained alloy Inconel 718 are investigated. Ultrafine-grained alloys with average grain sizes d = 0.1-1 μm were manufactured by multiple forging with stage-by-stage deformation temperature decrease. During standard heat treatment of the alloy performed to obtain the desired properties, the γ-grain size was controlled by precipitations of δ-phase particles along the boundaries. Results of low-cycle fatigue tests of the fine-grained alloy at room and elevated temperatures are compared with the properties of the coarse-grained alloy.

  19. The measurement of fatigue: a new instrument.

    PubMed

    Schwartz, J E; Jandorf, L; Krupp, L B

    1993-10-01

    Fatigue is a frequent medical symptom which has not been routinely measured. We present a 29-item fatigue assessment instrument, describe its psychometric properties, and use it to differentiate normal fatigue from fatigue related medical disorders. Differences in fatigue across a variety of medical disorders, the reproducibility of the fatigue instrument, and its convergent validity with other fatigue measures are also described.

  20. Piezoelectric Bolt Breakers and Bolt Fatigue Testers

    NASA Technical Reports Server (NTRS)

    Sherrit, Stewart; Badescu, Mircea; Bar-Cohen, Yoseph; Barengoltz, Jack; Heckman, Vanessa

    2008-01-01

    A proposed family of devices for inducing fatigue in bolts in order to break the bolts would incorporate piezoelectric actuators into resonant fixtures as in ultrasonic/ sonic drills/corers and similar devices described in numerous prior NASA Tech Briefs articles. These devices were originally intended primarily for use as safer, more-reliable, more-versatile alternatives to explosive bolts heretofore used to fasten spacecraft structures that must subsequently be separated from each other quickly on command during flight. On Earth, these devices could be used for accelerated fatigue testing of bolts. Fatigue theory suggests that a bolt subjected to both a constant-amplitude dynamic (that is, oscillatory) stress and a static tensile stress below the ultimate strength of the bolt material will fail faster than will a bolt subjected to only the dynamic stress. This suggestion would be applied in a device of the proposed type. The device would be designed so that the device and the bolt to be fatigue-tested or broken would be integral parts of an assembly (see figure). The static tension in the tightened bolt would apply not only the clamping force to hold the joined structures (if any) together but also the compression necessary for proper operation of the piezoelectric actuators as parts of a resonant structural assembly. The constant-amplitude dynamic stress would be applied to the bolt by driving the piezoelectric actuators with a sinusoidal voltage at the resonance frequency of longitudinal vibration of the assembly. The amplitude of the excitation would be made large enough so that the vibration would induce fatigue in the bolt within an acceptably short time. In the spacecraft applications or in similar terrestrial structural-separation applications, devices of the proposed type would offer several advantages over explosive bolts: Unlike explosive bolts, the proposed devices would be reusable, could be tested before final use, and would not be subject to

  1. Summary of V-G and VGH Data Collected on Lockheed Electra Airplanes During Airplane Operations

    NASA Technical Reports Server (NTRS)

    Jewel, Joseph W., Jr.; Fetner, Mary W.

    1961-01-01

    Data obtained by NASA VGH and V-G recorders on several Lockheed Electra airplanes operated over three domestic routes have been analyzed to determine the in-flight accelerations, airspeed practices, and landing accelerations experienced by this particular airplane. The results indicate that the accelerations caused by gusts and maneuvers are comparable to corresponding results for piston-engine transport airplanes. Oscillatory accelerations (apparently caused by the autopilot or control system) appear to occur about one-tenth as frequently as accelerations due to gusts. Airspeed operating practices in rough air generally follow the trends shown by piston-engine transports in that there is no significant difference between the average airspeed in rough or smooth air. Placard speeds were exceeded more frequently by the Electra airplane than by piston-engine transport airplanes. Generally, the landing-impact accelerations were higher than those for piston-engine transports.

  2. Topology optimization in damage governed low cycle fatigue

    NASA Astrophysics Data System (ADS)

    Desmorat, Boris; Desmorat, Rodrigue

    2008-05-01

    Topology optimization is applied here to discuss an optimization problem of fatigue resistance. Fatigue lifetime is maximized by optimizing the shape of a structure in cyclic plasticity combined with Lemaitre damage law. The topology optimization algorithm is detailed. A 3D numerical example is given. To cite this article: B. Desmorat, R. Desmorat, C. R. Mecanique 336 (2008).

  3. Enhanced Capabilities of the NASA Langley Thermal Acoustic Fatigue Apparatus

    NASA Technical Reports Server (NTRS)

    Rizzi, Stephen A.; Turner, Travis L.

    2004-01-01

    This paper presents newly enhanced acoustic capabilities of the Thermal Acoustic Fatigue Apparatus at the NASA Langley Research Center. The facility is a progressive wave tube used for sonic fatigue testing of aerospace structures. Acoustic measurements for each of the six facility configurations are shown and comparisons with projected performance are made.

  4. Ditching Tests of Two Models of the Army B-36 Airplane

    NASA Technical Reports Server (NTRS)

    Fisher, Lloyd J.; Cederborg, Gibson, A.

    1948-01-01

    The ditching characteristics of the Army B-36 airplane were determined by testing 1/20- and 1/30-scale dynamic models in calm water in Langley tank no. 2 and at the outdoor catapult. The scope of the tests consisted of ditching the models at various conditions of simulated damage, landing attitudes, and speeds, with various flap settings using several degrees of restraint of the flap hinges. The ditching behavior was evaluated from recordings of deceleration, length of run, and motions of the models. The results showed that the airplane should be ditched at an attitude of about 9 deg with flaps full down. The probable ditching behavior will be a smooth run with a maximum longitudinal deceleration of 3g to 4g and a landing run of 4 to 5 fuselage lengths. Structural failure of the underside of the fuselage will not seriously affect the behavior of the airplane.

  5. Flutter clearance of the F-14 variable-sweep transition flight experiment airplane, phase 1

    NASA Technical Reports Server (NTRS)

    Kehoe, Michael W.

    1987-01-01

    An F-14 airplane was modified to become the test bed aircraft for the variable sweep transition flight experiment (VSTFE) program. The latter is a laminar flow program designed to measure the effects of wing sweep on boundary layer transition from laminar to turbulent flow. The airplane was modified by adding an upper surface foam-fiberglass glove over a portion of the left wing. Ground vibration and flight flutter testing were accomplished to clear a sufficient flight envelope to conduct the laminar flow experiments. Flight test data indicated satisfactory damping levels and damping trends for the elastic structural modes of the airplane. The data presented include frequency and damping as functions of Mach number.

  6. Design study of technology requirements for high performance single-propeller-driven business airplanes

    NASA Technical Reports Server (NTRS)

    Kohlman, D. L.; Hammer, J.

    1985-01-01

    Developments in aerodyamic, structural and propulsion technologies which influence the potential for significant improvements in performance and fuel efficiency of general aviation business airplanes are discussed. The advancements include such technolgies as natural laminar flow, composite materials, and advanced intermittent combustion engines. The design goal for this parameter design study is a range of 1300 nm at 300 knots true airspeed with a payload of 1200lbs at 35,000 ft cruise altitude. The individual and synergistic effects of various advanced technologies on the optimization of this class of high performance, single engine, propeller driven business airplanes are identified.

  7. The Pressure Distribution Over the Horizontal Tail Surfaces of an Airplane I

    NASA Technical Reports Server (NTRS)

    Norton, F H

    1923-01-01

    This work was undertaken to determine as completely as possible the distribution of pressure over the horizontal tail surfaces of an airplane, and to analyze the relation of this pressure to the structural loads and the longitudinal stability. The investigation is divided into three parts, of which this the first. The first part of the investigation is for the purpose of determining the pressure distribution over two horizontal tail surfaces in uniform free flight; the second part to conduct tests of similar tail planes in the wind tunnel; and the third part to determine the pressure distribution on the horizontal tail surfaces during accelerated flight on the full-size airplane.

  8. Chronic fatigue syndrome

    MedlinePlus

    Bennett RM. Fibromyalgia, chronic fatigue syndrome, and myofascial pain. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine . 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 274. Engleberg NC. Chronic ...

  9. Fatigue and Multiple Sclerosis

    MedlinePlus

    Fatigue - National Multiple Sclerosis Society Skip to navigation Skip to content Menu Navigation National Multiple Sclerosis Society Sign In In Your Area ... help* daily life for: positive-mom* The National MS Society is Here to Help Need More Information? ...

  10. Brain Tumors and Fatigue

    MedlinePlus

    ... tiredness. You may experience a profound lack of energy that can come on suddenly and bring dramatic ... to manage the severity. Respect the Fatigue The energy you’re accustomed to having has been transferred ...

  11. Fatigue Crack Length Sizing Using a Novel Flexible Eddy Current Sensor Array

    PubMed Central

    Xie, Ruifang; Chen, Dixiang; Pan, Mengchun; Tian, Wugang; Wu, Xuezhong; Zhou, Weihong; Tang, Ying

    2015-01-01

    The eddy current probe, which is flexible, array typed, highly sensitive and capable of quantitative inspection is one practical requirement in nondestructive testing and also a research hotspot. A novel flexible planar eddy current sensor array for the inspection of microcrack presentation in critical parts of airplanes is developed in this paper. Both exciting and sensing coils are etched on polyimide films using a flexible printed circuit board technique, thus conforming the sensor to complex geometric structures. In order to serve the needs of condition-based maintenance (CBM), the proposed sensor array is comprised of 64 elements. Its spatial resolution is only 0.8 mm, and it is not only sensitive to shallow microcracks, but also capable of sizing the length of fatigue cracks. The details and advantages of our sensor design are introduced. The working principal and the crack responses are analyzed by finite element simulation, with which a crack length sizing algorithm is proposed. Experiments based on standard specimens are implemented to verify the validity of our simulation and the efficiency of the crack length sizing algorithm. Experimental results show that the sensor array is sensitive to microcracks, and is capable of crack length sizing with an accuracy within ±0.2 mm. PMID:26703608

  12. Fatigue Crack Length Sizing Using a Novel Flexible Eddy Current Sensor Array.

    PubMed

    Xie, Ruifang; Chen, Dixiang; Pan, Mengchun; Tian, Wugang; Wu, Xuezhong; Zhou, Weihong; Tang, Ying

    2015-01-01

    The eddy current probe, which is flexible, array typed, highly sensitive and capable of quantitative inspection is one practical requirement in nondestructive testing and also a research hotspot. A novel flexible planar eddy current sensor array for the inspection of microcrack presentation in critical parts of airplanes is developed in this paper. Both exciting and sensing coils are etched on polyimide films using a flexible printed circuit board technique, thus conforming the sensor to complex geometric structures. In order to serve the needs of condition-based maintenance (CBM), the proposed sensor array is comprised of 64 elements. Its spatial resolution is only 0.8 mm, and it is not only sensitive to shallow microcracks, but also capable of sizing the length of fatigue cracks. The details and advantages of our sensor design are introduced. The working principal and the crack responses are analyzed by finite element simulation, with which a crack length sizing algorithm is proposed. Experiments based on standard specimens are implemented to verify the validity of our simulation and the efficiency of the crack length sizing algorithm. Experimental results show that the sensor array is sensitive to microcracks, and is capable of crack length sizing with an accuracy within ±0.2 mm. PMID:26703608

  13. 78 FR 53078 - Airworthiness Directives; The Boeing Company Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-28

    ... ``significant rule'' under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979), (3) Will..., which, if the chord severs, could result in reduced structural integrity of the diagonal brace load path... hours. The cracking was due to fatigue from normal operating loads. The chords are the main load...

  14. 78 FR 52419 - Airworthiness Directives; The Boeing Company Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-23

    ...-128-AD; Amendment 39-17555; AD 2013-16-17] RIN 2120-AA64 Airworthiness Directives; The Boeing Company... new airworthiness directive (AD) for all The Boeing Company Model 727, 727C, 727-100, 727-100C, 727... any cracked structure. We are issuing this AD to detect and correct fatigue cracking of the...

  15. 75 FR 8479 - Airworthiness Directives; Airbus Model A340-541 and -642 Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-25

    ... condition on an aviation product. The MCAI describes the unsafe condition as: During the A340-600 full scale... condition for the specified products. The MCAI states: During the A340-600 full scale fatigue test, cracks... not corrected, can affect the aircraft structural integrity. Further to this full scale fatigue...

  16. Piezomagnetism and fatigue

    NASA Astrophysics Data System (ADS)

    Erber, T.; Guralnick, S. A.; Desai, R. D.; Kwok, W.

    1997-10-01

    Piezomagnetism refers to a change in the intrinsic magnetization of a material subjected to mechanical actions such as tension or compression. In a ferromagnet such as a mild steel these effects are easily measured: typically a stress of 0022-3727/30/20/008/img6 or 140 MPa induces a magnetic moment of the order of 0022-3727/30/20/008/img7 emu or 0022-3727/30/20/008/img8, resulting in flux densities in the range 10 mG or 0022-3727/30/20/008/img9T in the vicinity of the specimen. Since piezomagnetic effects are due to interactions between the mechanical and magnetic mesostructure of materials microplastic processes that alter the arrangement of the ferromagnetic domain structure affect the intensity of the associated magnetic fields. The progressive degradation of such materials under cyclic loading can therefore be tracked by following the evolution of the piezomagnetic field. Specifically, if the measurements are displayed as loci in a three-dimensional stress 0022-3727/30/20/008/img10 - strain 0022-3727/30/20/008/img11 - field (B) space, the approach to fatigue failure is paralleled by a series of conspicuous geometric transformations of these curves. Complementary information also appears in continuous-time records of B(t): these magnetograms clearly show the abrupt incidence of `infarcts' (microcracks) and the cumulation of phase shifts as the material degrades.

  17. Fatigue life prediction of bonded primary joints

    NASA Technical Reports Server (NTRS)

    Knauss, J. F.

    1979-01-01

    The validation of a proposed fatigue life prediction methodology was sought through the use of aluminum butt and scarf joint and graphite/epoxy butt joint specimens in a constant amplitude fatigue environment. The structural properties of the HYSOL 9313 adhesive system were obtained by mechanical test of molded heat adhesive specimens. Aluminum contoured double cantilever beam specimens were used to generate crack velocity versus stress intensity factor data. The specific objectives were: (1) to ascertain the feasibility of predicting fatigue failure of an adhesive in a primary bonded composite structure by incorporating linear elastic crack growth behavior; and (2) to ascertain if acoustic emission and/or compliance measurement techniques can be used to detect flaws.

  18. Fatigue loading of tendon

    PubMed Central

    Shepherd, Jennifer H; Screen, Hazel R C

    2013-01-01

    Tendon injuries, often called tendinopathies, are debilitating and painful conditions, generally considered to develop as a result of tendon overuse. The aetiology of tendinopathy remains poorly understood, and whilst tendon biopsies have provided some information concerning tendon appearance in late-stage disease, there is still little information concerning the mechanical and cellular events associated with disease initiation and progression. Investigating this in situ is challenging, and numerous models have been developed to investigate how overuse may generate tendon fatigue damage and how this may relate to tendinopathy conditions. This article aims to review these models and our current understanding of tendon fatigue damage. We review the strengths and limitations of different methodologies for characterizing tendon fatigue, considering in vitro methods that adopt both viable and non-viable samples, as well as the range of different in vivo approaches. By comparing data across model systems, we review the current understanding of fatigue damage development. Additionally, we compare these findings with data from tendinopathic tissue biopsies to provide some insights into how these models may relate to the aetiology of tendinopathy. Fatigue-induced damage consistently highlights the same microstructural, biological and mechanical changes to the tendon across all model systems and also correlates well with the findings from tendinopathic biopsy tissue. The multiple testing routes support matrix damage as an important contributor to tendinopathic conditions, but cellular responses to fatigue appear complex and often contradictory. PMID:23837793

  19. Early stage fatigue damage occurs in bovine tendon fascicles in the absence of changes in mechanics at either the gross or micro-structural level.

    PubMed

    Shepherd, Jennifer H; Riley, Graham P; Screen, Hazel R C

    2014-10-01

    Many tendon injuries are believed to result from repetitive motion or overuse, leading to the accumulation of micro-damage over time. In vitro fatigue loading can be used to characterise damage during repeated use and investigate how this may relate to the aetiology of tendinopathy. This study considered the effect of fatigue loading on fascicles from two functionally distinct bovine tendons: the digital extensor and deep digital flexor. Micro-scale extension mechanisms were investigated in fascicles before or after a period of cyclic creep loading, comparing two different measurement techniques - the displacement of a photo-bleached grid and the use of nuclei as fiducial markers. Whilst visual damage was clearly identified after only 300 cycles of creep loading, these visual changes did not affect either gross fascicle mechanics or fascicle microstructural extension mechanisms over the 900 fatigue cycles investigated. However, significantly greater fibre sliding was measured when observing grid deformation rather than the analysis of nuclei movement. Measurement of microstructural extension with both techniques was localised and this may explain the absence of change in microstructural deformation in response to fatigue loading. Alternatively, the data may demonstrate that fascicles can withstand a degree of matrix disruption with no impact on mechanics. Whilst use of a photo-bleached grid to directly measure the collagen is the best indicator of matrix deformation, nuclei tracking may provide a better measure of the strain perceived directly by the cells. PMID:25001495

  20. Early stage fatigue damage occurs in bovine tendon fascicles in the absence of changes in mechanics at either the gross or micro-structural level

    PubMed Central

    Shepherd, Jennifer H.; Riley, Graham P.; Screen, Hazel R.C.

    2014-01-01

    Many tendon injuries are believed to result from repetitive motion or overuse, leading to the accumulation of micro-damage over time. In vitro fatigue loading can be used to characterise damage during repeated use and investigate how this may relate to the aetiology of tendinopathy. This study considered the effect of fatigue loading on fascicles from two functionally distinct bovine tendons: the digital extensor and deep digital flexor. Micro-scale extension mechanisms were investigated in fascicles before or after a period of cyclic creep loading, comparing two different measurement techniques – the displacement of a photo-bleached grid and the use of nuclei as fiducial markers. Whilst visual damage was clearly identified after only 300 cycles of creep loading, these visual changes did not affect either gross fascicle mechanics or fascicle microstructural extension mechanisms over the 900 fatigue cycles investigated. However, significantly greater fibre sliding was measured when observing grid deformation rather than the analysis of nuclei movement. Measurement of microstructural extension with both techniques was localised and this may explain the absence of change in microstructural deformation in response to fatigue loading. Alternatively, the data may demonstrate that fascicles can withstand a degree of matrix disruption with no impact on mechanics. Whilst use of a photo-bleached grid to directly measure the collagen is the best indicator of matrix deformation, nuclei tracking may provide a better measure of the strain perceived directly by the cells. PMID:25001495

  1. Calculation of Airplane Performances Without the Aid of Polar Diagrams

    NASA Technical Reports Server (NTRS)

    Schrenk, Martin

    1928-01-01

    For good profiles the profile-drag coefficient is almost constant in the whole range which comes into consideration for practical flight. This is manifest in the consideration of the Gottingen airfoil tests and is confirmed by the investigations of the writer (measurements of the profile drag during flight by the Betz method), concerning which a detailed report will soon be published. The following deductions proceed from this fact. The formulas developed on the assumptions of a constant profile-drag coefficient afford an extensive insight into the influences exerted on flight performances by the structure of the airplane.

  2. Improving Fatigue Performance of AHSS Welds

    SciTech Connect

    Feng, Zhili; Yu, Xinghua; Erdman, III, Donald L.; Wang, Yanli; Kelly, Steve; Hou, Wenkao; Yan, Benda; Wang, Zhifeng; Yu, Zhenzhen; Liu, Stephen

    2015-03-01

    Reported herein is technical progress on a U.S. Department of Energy CRADA project with industry cost-share aimed at developing the technical basis and demonstrate the viability of innovative in-situ weld residual stresses mitigation technology that can substantially improve the weld fatigue performance and durability of auto-body structures. The developed technology would be costeffective and practical in high-volume vehicle production environment. Enhancing weld fatigue performance would address a critical technology gap that impedes the widespread use of advanced high-strength steels (AHSS) and other lightweight materials for auto body structure light-weighting. This means that the automotive industry can take full advantage of the AHSS in strength, durability and crashworthiness without the concern of the relatively weak weld fatigue performance. The project comprises both technological innovations in weld residual stress mitigation and due-diligence residual stress measurement and fatigue performance evaluation. Two approaches were investigated. The first one was the use of low temperature phase transformation (LTPT) weld filler wire, and the second focused on novel thermo-mechanical stress management technique. Both technical approaches have resulted in considerable improvement in fatigue lives of welded joints made of high-strength steels. Synchrotron diffraction measurement confirmed the reduction of high tensile weld residual stresses by the two weld residual stress mitigation techniques.

  3. Bithermal fatigue - A link between isothermal and thermomechanical fatigue

    NASA Technical Reports Server (NTRS)

    Halford, Gary R.; Mcgaw, Michael A.; Bill, Robert C.; Fanti, Paolo D.

    1988-01-01

    A technique for bithermal fatigue testing is presented in which the tensile and compressive halves of the cycle are conducted isothermally at two significantly different temperatures. With reference to experimental results obtained for a nickel-base superalloy, B1900 + Hf, it is shown that bithermal fatigue testing is a simple alternative to thermomechanical fatigue and can provide a conservative determination of thermomechanical fatigue life for creep damage dominated failure modes. Bithermal fatigue results can be directly related to thermomechanical fatigue results through the use of an appropriate damage rule.

  4. Fatigue evaluation of ASME Class 1 components considering the environmental effects

    SciTech Connect

    Neto, M.M.; Maneschy, E.

    1995-12-01

    A discussion considering fatigue design basis (FDB) and fatigue operating basis (FOB) approaches is presented. These two concepts are applied to evaluate the lifetime of typical ASME 3 class 1 components through simplified and detailed stress analysis. The cumulative usage factor (CUF) calculated using S-N fatigue curves available in the ASME 3 are compared to those obtained by S-N curves modified by the reactor environment. Some recommendations are presented to assess the fatigue in nuclear power plants structures.

  5. 77 FR 18141 - Airworthiness Directives; Fokker Services B.V. Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-27

    ...) fuel quantity indication system (FQIS) probe and the bottom of the tank structure. This condition, if not corrected, could, under certain conditions, result in an ignition source in the tank vapor space... require, for all airplanes, applying sealant below the FQIS probes in the wing tanks; and for...

  6. Light airplane crash tests at impact velocities of 13 and 27 m/sec

    NASA Technical Reports Server (NTRS)

    Alfaro-Bou, E.; Vaughan, V. L., Jr.

    1977-01-01

    Two similar general aviation airplanes were crash tested at the Langley impact dynamics research facility at velocities of 13 and 27 m/sec. Other flight parameters were held constant. The facility, instrumentation, tests specimens, and test method are briefly described. Structural damage and accelerometer data are discussed.

  7. 14 CFR 125.407 - Maintenance log: Airplanes.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Maintenance log: Airplanes. 125.407 Section... Maintenance log: Airplanes. (a) Each person who takes corrective action or defers action concerning a reported... record the action taken in the airplane maintenance log in accordance with part 43 of this chapter....

  8. 78 FR 27310 - Airworthiness Directives; the Boeing Company Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-10

    ... airplanes: AD 2007-16-12, Amendment 39-15151 (72 FR 44740, August 9, 2007), requires changes to existing... 767-200, -300, and -400ER series airplanes: AD 2008-23-15, Amendment 39-15736 (73 FR 70267, November..., -600, - 700, -700C, -800, and -900 series airplanes: AD 2009-12-06, Amendment 39-15929 (74 FR...

  9. A study of the factors affecting the range of airplanes

    NASA Technical Reports Server (NTRS)

    Biermann, David

    1937-01-01

    A study was made of the most important factors affecting the range of airplanes. Numerical examples are given showing the effects of different variables on the range of a two-engine airplane. The takeoff problems of long-range airplanes are analyzed.

  10. 14 CFR 121.570 - Airplane evacuation capability.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Airplane evacuation capability. 121.570... REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Flight Operations § 121.570 Airplane evacuation capability. (a) No person may cause an airplane carrying passengers to be moved on the surface, take off,...

  11. 14 CFR 121.303 - Airplane instruments and equipment.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Airplane instruments and equipment. 121.303... Airplane instruments and equipment. (a) Unless otherwise specified, the instrument and equipment... airspeed limitation and item of related information in the Airplane Flight Manual and pertinent...

  12. 14 CFR 125.91 - Airplane requirements: General.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... AND OPERATIONS: AIRPLANES HAVING A SEATING CAPACITY OF 20 OR MORE PASSENGERS OR A MAXIMUM PAYLOAD CAPACITY OF 6,000 POUNDS OR MORE; AND RULES GOVERNING PERSONS ON BOARD SUCH AIRCRAFT Airplane Requirements... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Airplane requirements: General....

  13. 14 CFR 121.161 - Airplane limitations: Type of route.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... OPERATING REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Aircraft Requirements § 121.161 Airplane... specifications, no certificate holder may operate a turbine-engine-powered airplane over a route that contains a... under standard conditions in still air) of 60 minutes for a two-engine airplane or 180 minutes for...

  14. 14 CFR 121.199 - Nontransport category airplanes: Takeoff limitations.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... airplane can be safely controlled in flight after an engine becomes inoperative) or 115 percent of the... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Nontransport category airplanes: Takeoff... OPERATING REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Airplane Performance...

  15. 14 CFR 121.159 - Single-engine airplanes prohibited.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Single-engine airplanes prohibited. 121.159... REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Aircraft Requirements § 121.159 Single-engine airplanes prohibited. No certificate holder may operate a single-engine airplane under this part....

  16. 14 CFR 121.159 - Single-engine airplanes prohibited.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Single-engine airplanes prohibited. 121.159... REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Aircraft Requirements § 121.159 Single-engine airplanes prohibited. No certificate holder may operate a single-engine airplane under this part....

  17. 78 FR 21074 - Airworthiness Directives; Bombardier, Inc. Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-09

    ... FR 19979, April 14, 2008). For airplanes having S/Ns 7003 through 7990 inclusive: Within 14 days... effective date of this AD. (k) New Replacement of Defective Pitch Feel Simulator Unit For airplanes having S.... Airplanes AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed rulemaking...

  18. 78 FR 4038 - Critical Parts for Airplane Propellers

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-18

    ..., FAA published a notice of proposed rulemaking titled ``Critical Parts for Airplane Propellers'' (76 FR... Federal Aviation Administration 14 CFR Part 35 RIN 2120-AJ88 Critical Parts for Airplane Propellers AGENCY... Administration (FAA) is amending the airworthiness standards for airplane propellers. This action would require...

  19. 14 CFR 121.141 - Airplane flight manual.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Airplane flight manual. 121.141 Section 121... REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Manual Requirements § 121.141 Airplane flight manual. (a) Each certificate holder shall keep a current approved airplane flight manual for each type...

  20. 14 CFR 121.570 - Airplane evacuation capability.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Airplane evacuation capability. 121.570... REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Flight Operations § 121.570 Airplane evacuation capability. (a) No person may cause an airplane carrying passengers to be moved on the surface, take off,...

  1. 14 CFR 121.159 - Single-engine airplanes prohibited.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Single-engine airplanes prohibited. 121.159 Section 121.159 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... airplanes prohibited. No certificate holder may operate a single-engine airplane under this part....

  2. 14 CFR 23.71 - Glide: Single-engine airplanes.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Glide: Single-engine airplanes. 23.71... AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Flight Performance § 23.71 Glide: Single-engine airplanes. The maximum horizontal distance traveled in still air, in nautical...

  3. 14 CFR 121.141 - Airplane flight manual.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Airplane flight manual. 121.141 Section 121... REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Manual Requirements § 121.141 Airplane flight manual. (a) Each certificate holder shall keep a current approved airplane flight manual for each type...

  4. 14 CFR 121.161 - Airplane limitations: Type of route.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Airplane limitations: Type of route. 121... OPERATING REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Aircraft Requirements § 121.161 Airplane... specifications, no certificate holder may operate a turbine-engine-powered airplane over a route that contains...

  5. 14 CFR 125.205 - Equipment requirements: Airplanes under IFR.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Equipment requirements: Airplanes under IFR... CERTIFICATION AND OPERATIONS: AIRPLANES HAVING A SEATING CAPACITY OF 20 OR MORE PASSENGERS OR A MAXIMUM PAYLOAD... Equipment Requirements § 125.205 Equipment requirements: Airplanes under IFR. No person may operate...

  6. 14 CFR 125.407 - Maintenance log: Airplanes.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Maintenance log: Airplanes. 125.407 Section... OPERATIONS: AIRPLANES HAVING A SEATING CAPACITY OF 20 OR MORE PASSENGERS OR A MAXIMUM PAYLOAD CAPACITY OF 6... Maintenance log: Airplanes. (a) Each person who takes corrective action or defers action concerning a...

  7. 14 CFR 23.1437 - Accessories for multiengine airplanes.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Accessories for multiengine airplanes. 23... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Equipment Miscellaneous Equipment § 23.1437 Accessories for multiengine airplanes. For multiengine...

  8. 14 CFR 121.159 - Single-engine airplanes prohibited.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Single-engine airplanes prohibited. 121.159 Section 121.159 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... airplanes prohibited. No certificate holder may operate a single-engine airplane under this part....

  9. 14 CFR 121.303 - Airplane instruments and equipment.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Airplane instruments and equipment. 121.303... Airplane instruments and equipment. (a) Unless otherwise specified, the instrument and equipment... airspeed limitation and item of related information in the Airplane Flight Manual and pertinent...

  10. 14 CFR 121.199 - Nontransport category airplanes: Takeoff limitations.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Nontransport category airplanes: Takeoff... OPERATING REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Airplane Performance Operating Limitations § 121.199 Nontransport category airplanes: Takeoff limitations. (a) No person operating...

  11. 14 CFR 121.303 - Airplane instruments and equipment.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Airplane instruments and equipment. 121.303... Airplane instruments and equipment. (a) Unless otherwise specified, the instrument and equipment... airspeed limitation and item of related information in the Airplane Flight Manual and pertinent...

  12. 14 CFR 121.199 - Nontransport category airplanes: Takeoff limitations.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Nontransport category airplanes: Takeoff... OPERATING REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Airplane Performance Operating Limitations § 121.199 Nontransport category airplanes: Takeoff limitations. (a) No person operating...

  13. 14 CFR 125.91 - Airplane requirements: General.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Airplane requirements: General. 125.91... AND OPERATIONS: AIRPLANES HAVING A SEATING CAPACITY OF 20 OR MORE PASSENGERS OR A MAXIMUM PAYLOAD CAPACITY OF 6,000 POUNDS OR MORE; AND RULES GOVERNING PERSONS ON BOARD SUCH AIRCRAFT Airplane...

  14. 14 CFR 23.71 - Glide: Single-engine airplanes.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Glide: Single-engine airplanes. 23.71... AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Flight Performance § 23.71 Glide: Single-engine airplanes. The maximum horizontal distance traveled in still air, in nautical...

  15. 14 CFR 125.205 - Equipment requirements: Airplanes under IFR.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Equipment requirements: Airplanes under IFR... CERTIFICATION AND OPERATIONS: AIRPLANES HAVING A SEATING CAPACITY OF 20 OR MORE PASSENGERS OR A MAXIMUM PAYLOAD... Equipment Requirements § 125.205 Equipment requirements: Airplanes under IFR. No person may operate...

  16. 14 CFR 121.161 - Airplane limitations: Type of route.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Airplane limitations: Type of route. 121... OPERATING REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Aircraft Requirements § 121.161 Airplane... specifications, no certificate holder may operate a turbine-engine-powered airplane over a route that contains...

  17. 14 CFR 23.1437 - Accessories for multiengine airplanes.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Accessories for multiengine airplanes. 23... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Equipment Miscellaneous Equipment § 23.1437 Accessories for multiengine airplanes. For multiengine...

  18. 14 CFR 23.1437 - Accessories for multiengine airplanes.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Accessories for multiengine airplanes. 23... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Equipment Miscellaneous Equipment § 23.1437 Accessories for multiengine airplanes. For multiengine...

  19. 14 CFR 125.407 - Maintenance log: Airplanes.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Maintenance log: Airplanes. 125.407 Section... OPERATIONS: AIRPLANES HAVING A SEATING CAPACITY OF 20 OR MORE PASSENGERS OR A MAXIMUM PAYLOAD CAPACITY OF 6... Maintenance log: Airplanes. (a) Each person who takes corrective action or defers action concerning a...

  20. 14 CFR 125.91 - Airplane requirements: General.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Airplane requirements: General. 125.91... AND OPERATIONS: AIRPLANES HAVING A SEATING CAPACITY OF 20 OR MORE PASSENGERS OR A MAXIMUM PAYLOAD CAPACITY OF 6,000 POUNDS OR MORE; AND RULES GOVERNING PERSONS ON BOARD SUCH AIRCRAFT Airplane...

  1. 14 CFR 125.205 - Equipment requirements: Airplanes under IFR.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Equipment requirements: Airplanes under IFR... CERTIFICATION AND OPERATIONS: AIRPLANES HAVING A SEATING CAPACITY OF 20 OR MORE PASSENGERS OR A MAXIMUM PAYLOAD... Equipment Requirements § 125.205 Equipment requirements: Airplanes under IFR. No person may operate...

  2. 14 CFR 121.161 - Airplane limitations: Type of route.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Airplane limitations: Type of route. 121... OPERATING REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Aircraft Requirements § 121.161 Airplane... specifications, no certificate holder may operate a turbine-engine-powered airplane over a route that contains...

  3. 14 CFR 125.91 - Airplane requirements: General.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Airplane requirements: General. 125.91... AND OPERATIONS: AIRPLANES HAVING A SEATING CAPACITY OF 20 OR MORE PASSENGERS OR A MAXIMUM PAYLOAD CAPACITY OF 6,000 POUNDS OR MORE; AND RULES GOVERNING PERSONS ON BOARD SUCH AIRCRAFT Airplane...

  4. 14 CFR 125.407 - Maintenance log: Airplanes.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Maintenance log: Airplanes. 125.407 Section... OPERATIONS: AIRPLANES HAVING A SEATING CAPACITY OF 20 OR MORE PASSENGERS OR A MAXIMUM PAYLOAD CAPACITY OF 6... Maintenance log: Airplanes. (a) Each person who takes corrective action or defers action concerning a...

  5. 14 CFR 121.199 - Nontransport category airplanes: Takeoff limitations.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Nontransport category airplanes: Takeoff... OPERATING REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Airplane Performance Operating Limitations § 121.199 Nontransport category airplanes: Takeoff limitations. (a) No person operating...

  6. 14 CFR 121.303 - Airplane instruments and equipment.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Airplane instruments and equipment. 121.303... Airplane instruments and equipment. (a) Unless otherwise specified, the instrument and equipment... airspeed limitation and item of related information in the Airplane Flight Manual and pertinent...

  7. 14 CFR 121.570 - Airplane evacuation capability.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Airplane evacuation capability. 121.570... REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Flight Operations § 121.570 Airplane evacuation capability. (a) No person may cause an airplane carrying passengers to be moved on the surface, take off,...

  8. 14 CFR 121.570 - Airplane evacuation capability.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Airplane evacuation capability. 121.570... REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Flight Operations § 121.570 Airplane evacuation capability. (a) No person may cause an airplane carrying passengers to be moved on the surface, take off,...

  9. Quantifying and scaling airplane performance in turbulence

    NASA Astrophysics Data System (ADS)

    Richardson, Johnhenri R.

    This dissertation studies the effects of turbulent wind on airplane airspeed and normal load factor, determining how these effects scale with airplane size and developing envelopes to account for them. The results have applications in design and control of aircraft, especially small scale aircraft, for robustness with respect to turbulence. Using linearized airplane dynamics and the Dryden gust model, this dissertation presents analytical and numerical scaling laws for airplane performance in gusts, safety margins that guarantee, with specified probability, that steady flight can be maintained when stochastic wind gusts act upon an airplane, and envelopes to visualize these safety margins. Presented here for the first time are scaling laws for the phugoid natural frequency, phugoid damping ratio, airspeed variance in turbulence, and flight path angle variance in turbulence. The results show that small aircraft are more susceptible to high frequency gusts, that the phugoid damping ratio does not depend directly on airplane size, that the airspeed and flight path angle variances can be parameterized by the ratio of the phugoid natural frequency to a characteristic turbulence frequency, and that the coefficient of variation of the airspeed decreases with increasing airplane size. Accompanying numerical examples validate the results using eleven different airplanes models, focusing on NASA's hypothetical Boeing 757 analog the Generic Transport Model and its operational 5.5% scale model, the NASA T2. Also presented here for the first time are stationary flight, where the flight state is a stationary random process, and the stationary flight envelope, an adjusted steady flight envelope to visualize safety margins for stationary flight. The dissertation shows that driving the linearized airplane equations of motion with stationary, stochastic gusts results in stationary flight. It also shows how feedback control can enlarge the stationary flight envelope by alleviating

  10. Rotor acoustic monitoring system (RAMS): a fatigue crack detection system

    NASA Astrophysics Data System (ADS)

    Schoess, Jeffrey N.

    1996-05-01

    The Rotor Acoustic Monitoring System (RAMS) is an embedded structural health monitoring system to demonstrate the ability to detect rotor head fatigue cracks and provide early warning of propagating fatigue cracks in rotor components of Navy helicopters. The concept definition effort was performed to assess the feasibility of detecting rotor head fatigue cracks using bulk- wave wide-bandwidth acoustic emission technology. A wireless piezo-based transducer system is being designed to capture rotor fatigue data in real time and perform acoustic emission (AE) event detection, feature extraction, and classification. A flight test effort will be performed to characterize rotor acoustic background noise and flight environment characteristics. The long- term payoff of the RAMS technology includes structural integrity verification and leak detection for large industrial tanks, and nuclear plant cooling towers could be performed using the RAMS AE technology. A summary of the RAMS concept, bench-level AE fatigue testing, and results are presented.

  11. Nonlinear ultrasonic fatigue crack detection using a single piezoelectric transducer

    NASA Astrophysics Data System (ADS)

    An, Yun-Kyu; Lee, Dong Jun

    2016-04-01

    This paper proposes a new nonlinear ultrasonic technique for fatigue crack detection using a single piezoelectric transducer (PZT). The proposed technique identifies a fatigue crack using linear (α) and nonlinear (β) parameters obtained from only a single PZT mounted on a target structure. Based on the different physical characteristics of α and β, a fatigue crack-induced feature is able to be effectively isolated from the inherent nonlinearity of a target structure and data acquisition system. The proposed technique requires much simpler test setup and less processing costs than the existing nonlinear ultrasonic techniques, but fast and powerful. To validate the proposed technique, a real fatigue crack is created in an aluminum plate, and then false positive and negative tests are carried out under varying temperature conditions. The experimental results reveal that the fatigue crack is successfully detected, and no positive false alarm is indicated.

  12. Fatigue reliability assessment of correlated welded web-frame joints

    NASA Astrophysics Data System (ADS)

    Huang, W.; Garbatov, Y.; Guedes Soares, C.

    2014-03-01

    The objective of this work is to analyze the fatigue reliability of complex welded structures composed of multiple web-frame joints, accounting for correlation effects. A three-dimensional finite element model using the 20-node solid elements is generated. A linear elastic finite element analysis was performed, hotspot stresses in a web-frame joint were analyzed and fatigue damage was quantified employing the S-N approach. The statistical descriptors of the fatigue life of a non-correlated web-frame joint containing several critical hotspots were estimated. The fatigue reliability of a web-frame joint wasmodeled as a series system of correlated components using the Ditlevsen bounds. The fatigue reliability of the entire welded structure with multiple web-frame joints, modeled as a parallel system of non-correlated web-frame joints was also calculated.

  13. Precision controllability of the YF-17 airplane

    NASA Technical Reports Server (NTRS)

    Sisk, T. R.; Mataeny, N. W.

    1980-01-01

    A flying qualities evaluation conducted on the YF-17 airplane permitted assessment of its precision controllability in the transonic flight regime over the allowable angle of attack range. The precision controllability (tailchase tracking) study was conducted in constant-g and windup turn tracking maneuvers with the command augmentation system (CAS) on, automatic maneuver flaps, and the caged pipper gunsight depressed 70 mils. This study showed that the YF-17 airplane tracks essentially as well at 7 g's to 8 g's as earlier fighters did at 4 g's to 5 g's before they encountered wing rock. The pilots considered the YF-17 airplane one of the best tracking airplanes they had flown. Wing rock at the higher angles of attack degraded tracking precision, and lack of control harmony made precision controllability more difficult. The revised automatic maneuver flap schedule incorporated in the airplane at the time of the tests did not appear to be optimum. The largest tracking errors and greatest pilot workload occurred at high normal load factors at low angles of attack. The pilots reported that the high-g maneuvers caused some tunnel vision and that they found it difficult to think clearly after repeated maneuvers.

  14. Airplane takeoff and landing performance monitoring system

    NASA Technical Reports Server (NTRS)

    Middleton, David B. (Inventor); Srivatsan, Raghavachari (Inventor); Person, Lee H., Jr. (Inventor)

    1994-01-01

    The invention is a real-time takeoff and landing performance monitoring system for an aircraft which provides a pilot with graphic and metric information to assist in decisions related to achieving rotation speed (VR) within the safe zone of a runway, or stopping the aircraft on the runway after landing or take-off abort. The system processes information in two segments: a pretakeoff segment and a real-time segment. One-time inputs of ambient conditions and airplane configuration information are used in the pretakeoff segment to generate scheduled performance data. The real-time segment uses the scheduled performance data, runway length data and transducer measured parameters to monitor the performance of the airplane throughout the takeoff roll. Airplane acceleration and engine-performance anomalies are detected and annunciated. A novel and important feature of this segment is that it updates the estimated runway rolling friction coefficient. Airplane performance predictions also reflect changes in head wind occurring as the takeoff roll progresses. The system provides a head-down display and a head-up display. The head-up display is projected onto a partially reflective transparent surface through which the pilot views the runway. By comparing the present performance of the airplane with a continually predicted nominal performance based upon given conditions, performance deficiencies are detected by the system and conveyed to pilot in form of both elemental information and integrated information.

  15. Airplane takeoff and landing performance monitoring system

    NASA Technical Reports Server (NTRS)

    Middleton, David B. (Inventor); Srivatsan, Raghavachari (Inventor); Person, Jr., Lee H. (Inventor)

    1996-01-01

    The invention is a real-time takeoff and landing performance monitoring system for an aircraft which provides a pilot with graphic and metric information to assist in decisions related to achieving rotation speed (V.sub.R) within the safe zone of a runway, or stopping the aircraft on the runway after landing or take-off abort. The system processes information in two segments: a pretakeoff segment and a real-time segment. One-time inputs of ambient conditions and airplane configuration information are used in the pretakeoff segment to generate scheduled performance data. The real-time segment uses the scheduled performance data, runway length data and transducer measured parameters to monitor the performance of the airplane throughout the takeoff roll. Airplane acceleration and engine-performance anomalies are detected and annunciated. A novel and important feature of this segment is that it updates the estimated runway rolling friction coefficient. Airplane performance predictions also reflect changes in head wind occurring as the takeoff roll progresses. The system provides a head-down display and a head-up display. The head-up display is projected onto a partially reflective transparent surface through which the pilot views the runway. By comparing the present performance of the airplane with a continually predicted nominal performance based upon given conditions, performance deficiencies are detected by the system and conveyed to pilot in form of both elemental information and integrated information.

  16. 14 CFR 135.422 - Aging airplane inspections and records reviews for multiengine airplanes certificated with nine...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Aging airplane inspections and records... Maintenance, and Alterations § 135.422 Aging airplane inspections and records reviews for multiengine... aging airplane inspection and records review required by this section. During the inspection and...

  17. 14 CFR 135.422 - Aging airplane inspections and records reviews for multiengine airplanes certificated with nine...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Aging airplane inspections and records... Maintenance, and Alterations § 135.422 Aging airplane inspections and records reviews for multiengine... aging airplane inspection and records review required by this section. During the inspection and...

  18. 14 CFR 135.422 - Aging airplane inspections and records reviews for multiengine airplanes certificated with nine...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Aging airplane inspections and records... Maintenance, and Alterations § 135.422 Aging airplane inspections and records reviews for multiengine... aging airplane inspection and records review required by this section. During the inspection and...

  19. 14 CFR 135.422 - Aging airplane inspections and records reviews for multiengine airplanes certificated with nine...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Aging airplane inspections and records... Maintenance, and Alterations § 135.422 Aging airplane inspections and records reviews for multiengine... aging airplane inspection and records review required by this section. During the inspection and...

  20. 14 CFR 135.422 - Aging airplane inspections and records reviews for multiengine airplanes certificated with nine...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Aging airplane inspections and records... Maintenance, and Alterations § 135.422 Aging airplane inspections and records reviews for multiengine... aging airplane inspection and records review required by this section. During the inspection and...