| Mechanism-Based Modeling of Hydrogen Environment Assisted Cracking (HEAC) in High Strength Alloys for Marine Applications: Prediction of Monel K-500 HEAC for Select Environmental and Mechanical Conditions |
15 Oct 2012 |
142 pages |
| Authors:
John R Scully; Richard P Gangloff; Francisco P Moreno; VIRGINIA UNIV CHARLOTTESVILLE DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
 | The objective of this interdisciplinary research program was to implement quantitative predictive models of hydrogen environment assisted cracking (HEAC) of Monel K-500 in a pseudo-application specific situation. Here the crack growth behavior and component lifetime will be predicted as a function of applied stress, surface condition component geometry (summed into stress intensity variation), as well as metallurgical and environmental conditions (applied cathodic potential in seawater with local pH and potential ... |
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| Fluid Structure Interaction Effects on Composites Under Low Velocity Impact |
Jun 2012 |
77 pages |
| Authors:
Ryan P Conner; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| In this study composite materials were tested in different fluid environments to determine the role of Fluid Structure Interaction with these composites under a lower velocity impact. The purpose of this research is to develop a better understanding of possible marine applications of composite materials. This was done using a low velocity impact machine and two composite types. The first composite is made from a multi-ply symmetrical plain weave 6 ... |
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| Practical Application of Residual Stress Measurements on Maritime Vessels |
Jun 2012 |
99 pages |
| Authors:
Dixon T Whitley; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
|
| This thesis examines the practical application of portable X-ray diffraction to measure residual stresses on board active maritime platforms. These measurements will provide better understanding of structural failures in aluminum hulls and superstructures. The feasibility of this process was analyzed by comparing data from welded aluminum test samples using portable X-ray diffractometers from three different sources. The effects on residual stress from ultrasonic impact treatments were measured using laboratory X-ray ... |
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| Navy Littoral Combat Ship (LCS) Program: Background, Issues, and Options for Congress |
06 Apr 2012 |
87 pages |
| Authors:
Ronald O'Rourke; LIBRARY OF CONGRESS WASHINGTON DC CONGRESSIONAL RESEARCH SERVICE
|
| The Littoral Combat Ship (LCS) is a relatively inexpensive Navy surface combatant equipped with modular plug-and-fight mission packages. The Navy wants to field a force of 55 LCSs. Twelve LCSs have been funded through FY2012, and the FY2013-FY2017 Future Years Defense Plan (FYDP) calls for procuring 16 more, in annual quantities of 4-4-4-2-2. The Navy's proposed FY2013 budget requests $1,785.0 million in procurement funding for the four LCSs requested for ... |
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| Oxidation Behavior of a Refractory NbCrMo0.5Ta0.5TiZr Alloy (Preprint) |
Mar 2012 |
41 pages |
| Authors:
D M Dimiduk; C Woodward; D B Miracle; O N Senkov; S V Senkova; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIR METALS CERAMICS AND NONDESTRUCTIVE EVALUATION DIV/METALS BRANCH
|
| Isothermal oxidation behavior of a refractory high entropy NbCrMo0.5Ta0.5TiZr alloy was studied during heating at 1273 K for 100 hours in flowing air. Continuous weight gain occurred during oxidation and the time dependence of the weight gain per unit surface area was described by a parabolic dependence with the time exponent n = 0.6. X-ray diffraction and scanning electron microscopy (SEM) accompanied by energy dispersive X-ray spectroscopy (EDS) showed that ... |
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| Wavelet Spectral Finite Elements for Wave Propagation in Composite Plates |
21 Feb 2012 |
17 pages |
| Authors:
Ratneshwar Jha; CLARKSON UNIV POTSDAM NY DEPT OF MECHANICAL AND AERONAUTICAL ENGINEERING
|
| The principal goal of this research is to advance the technology of structural health management (SHM) for composite structures. Wave propagation based methods have shown promise for SHM of composite structures. The spectral finite elements (SFE) method is highly suitable for wave propagation analysis due to its frequency domain approach which yields models that are many orders smaller than conventional FEM. Wavelet spectral finite element (WSFE) method overcomes the wrap ... |
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| Probabilistic and Reliability-Based Health Monitoring Strategies for High-Speed Naval Vessels |
01 Jan 2012 |
31 pages |
| Authors:
Jerome P Lynch; Kincho H Law; Sean O'Connor; MICHIGAN UNIV ANN ARBOR DEPT OF ELECTRICAL ENGINEERING AND COMPUTER SCIENCE
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| In this project, a strategy is proposed for fatigue life estimation of a ship hull using a wireless sensor network installed in the hull for autonomous health monitoring. First, a rainflow counting algorithm is implemented as a continuous time-domain approach to fatigue estimation. Cycles are defined by a rainflow counting procedure and are kept on-board the wireless sensing unit in a histogram structure for long-term storage. Fatigue damage is accumulated ... |
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| Strain Compatible Oxidation and Corrosion Protection Coatings for Enhanced Thermo-Mechanical Durability of Turbine Airfoils |
05 Dec 2011 |
20 pages |
| Authors:
Tresa M Pollock; CALIFORNIA UNIV SANTA BARBARA
|
| As critical components of advanced aircraft engines, turbine airfoils require coatings for the enhancement of oxidation, corrosion, and thermal capabilities. Airfoil coatings often constitute a significant fraction of the overall airfoil wall thickness and may therefore strongly influence the overall thermo-mechanical response of the turbine blade. However, to date, coatings have not been designed to enhance system performance, since the coating-substrate degradation mechanisms under relevant mechanical cycling conditions are not ... |
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| Study of the Progressive Failure of Composites under Axial Loading with Varying Strain Rates |
Dec 2011 |
79 pages |
| Authors:
Yew K Boey; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| This study investigated the progressive damage/failure of composite panels with open circular holes under progressive axial loading. A series of experiments was carried out to determine the failure in laminated specimens with and without circular holes under tensile and compressive loads, respectively. Different strain rate loading was applied to observe the rate effect on the damage initiation and propagation. Both uniform and non-uniform strain rate loads were applied to the ... |
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| Air Vehicle Integration and Technology Research (AVIATR). Delivery Order 0013: Nonlinear, Low-Order/Reduced-Order Modeling Applications and Demonstration |
Dec 2011 |
269 pages |
| Authors:
Salvatore L Liguore; Dale M Pitt; Michael J Thomas; Nicholas Gurtowski; BOEING CO ST LOUIS MO
|
| Dynamic response analysis tools used by the aerospace industry rely heavily on linear modal frequency response finite element methods. These linear methods are straight forward to use even in the analysis of a complex structural component that require a large number of degrees-of-freedom to model. However, this approach is not suitable for predicting the response of highly loaded thermal/acoustic aircraft structures that may respond in a nonlinear geometric manner. This ... |
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| Model-Based Structural Health Monitoring of Fatigue Damage Test-Bed Specimens |
15 Nov 2011 |
26 pages |
| Authors:
Kincho H Law; Jerome P Lynch; Masahiro Kurata; MICHIGAN UNIV ANN ARBOR DEPT OF ELECTRICAL ENGINEERING AND COMPUTER SCIENCE
|
| This research project represents a preliminary investigation into a comprehensive analytical, numerical, and experimental framework for the monitoring and life-cycle assessment of the structural integrity and performance of aluminum hull structures. Aluminum plate specimens were designed and fabricated to facilitate the investigation of system identification and damage detection methodologies, both of which are key components of future life-cycle analyses. The design of the plate specimens was intended to include the ... |
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| Modeling Turbine Blade Crack Detection in Sonic IR Imaging with a Method of Creating Flat Crack Surface in FEA (Preprint) |
Nov 2011 |
9 pages |
| Authors:
Xiaoyan Han; Ding Zhang; Golam Newaz; Lawrence D Favro; Robert L Thomas; UNIVERSAL TECHNOLOGY CORP DAYTON OH
|
| Sonic Infrared (IR) Imaging Nondestructive Evaluation (NDE) technology has shown inherent advantages for defect detection in aircraft structures. It can image a wide area within a second or two for metal material targets. Due to high stresses aircraft engine turbine blades bear during their operation, fatigue cracks can form after a number of hours of service. Sonic IR imaging shows great potential for this application. However, interaction of the sonic ... |
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| A Framework for Probabilistic Assessment of Fracture Mechanics Life (Preprint) |
Nov 2011 |
19 pages |
| Authors:
Srikanth Akkaram; Adrian Loghin; Genghis Khan; GE GLOBAL RESEARCH CENTER NISKAYUNA NY
|
| This report was developed under a SBIR contract for topic AF103-157. The paper develops a framework for application of probabilistic methods to assess the variability in fracture mechanics life for components. The probability of failure for a component at a specific failure location is typically defined by a crack size exceeding a threshold crack size (e.g. as defined by repair or bore-scope inspection limits). The computation of the probability of ... |
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| Corrosion and Maintenance Data Sharing (Partage des Donnees de Corrosion et de Maintenance) |
Nov 2011 |
88 pages |
| Authors:
NATO RESEARCH AND TECHNOLOGY ORGANIZATION NEUILLY-SUR-SEINE (FRANCE)
|
| The increasing average age of military platforms and greater legislative restriction of maintenance materials that has occurred in the past decade has heavily exacerbated the detrimental effects of corrosion on worthiness and maintenance costs. In order to identify the efficacy of different anticorrosion policies and procedures adopted among the NATO countries, a number of Nations - namely Canada, Germany, Italy, Netherlands, the United Kingdom and the United States - have ... |
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| Determination of Small Crack Stress Intensity Factors for an American Society for Testing Materials (ASTM) Middle Tension Test Specimen by Finite Element Method |
Nov 2011 |
95 pages |
| Authors:
Callum Wright; DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION VICTORIA (AUSTRALIA) AIR OPERATIONS DIV
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| Improved small-crack stress intensity factors are important for accurate fatigue crack growth prediction. This report presents accurate small-crack stress intensity factor distributions for the American Society for Testing Materials middle tension test specimen, derived in three dimensions utilising the advanced finite element method code StressCheck for a parametric study of a range of small crack sizes and shapes. This information was not readily available in reference books. The results have ... |
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| Phenomenological Studies of the Response of Granular and Geological Media to High-Speed (Mach 1-5) Projectiles |
06 Oct 2011 |
15 pages |
| Authors:
Koichi Tanaka; Kazuyoshi Takayama; Keiko Watanabe; Kiyonobu Ohtani; Hiroaki Yamamoto; CHUBU UNIV (JAPAN) DEPT OF MECHANICAL ENGINEERING
|
| The objective of this research was to elucidate the response of geological media such as sand and soil to high-speed and high-pressure loading of projectiles. Particularly, penetration mechanics of high-speed projectiles into granular materials and response of granular media to shock waves were our substantial concern. One of unique the approaches we proposed was to collect numerical data and imaging data in laboratory scale experiments on high-speed projectile impacts using ... |
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| The Hierarchy of Fatigue Mechanisms in the Long Lifetime Regime (Preprint) |
Oct 2011 |
8 pages |
| Authors:
C J Szczepanski; C P Przybyla; J M Larsen; S K Jha; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIR METALS CERAMICS AND NONDESTRUCTIVE EVALUATION DIV/METALS BRANCH
|
| The primary factors governing the behavior in the long lifetime regime of turbine engine materials are discussed. These factors are based on a study of fatigue lifetime distributions and underlying mechanisms in a number of materials, including titanium alloys, nickel-base superalloys, and gamma TiAl based alloys. A hypothesis of fatigue variability is described, and appears to explain the various features of fatigue behavior seen in the HCF and VHCF regimes. ... |
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| The Influence on Microstructure and Microtexture on Fatigue Crack Initiation and Growth in Alpha + Beta Titanium |
Oct 2011 |
6 pages |
| Authors:
Adam L Pilchak; Kazuo Nakase; Ikuhiro Inagaki; Yoshihisa Shirai; Andrew H Rosenberger; James C Williams; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIR METALS CERAMICS AND NONDESTRUCTIVE EVALUATION DIV/METALS BRANCH
|
| The strain paths and thermal cycles utilized during thermomechanical processing of two-phase alloys have a pronounced influence on the resulting distribution of grain orientations present and their spatial distribution. For example, large regions of similarly oriented alpha grains, commonly referred to as microtextured regions or macrozones, may persist despite the imposition of large macroscopic strains. The detrimental effect of microtexture on dwell fatigue life of high temperature alloys is well ... |
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| The Role of Microstructure on Various Stages of the Very High Cycle Fatigue Behavior of an a + Beta Titanium Alloy, Ti-6Al-2Sn-4Zr-6Mo (Preprint) |
Oct 2011 |
8 pages |
| Authors:
C J Szczepanski; S K Jha; J M Larsen; J W Jones; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
|
| The very high cycle fatigue behavior (105-109 cycles) of Ti-6246 has been investigated using ultrasonic fatigue techniques. In this regime of fatigue (0.4-0.6deltaYS), only certain microstructural regions are susceptible to fatigue damage accumulation, and lifetimes are related to the distribution of fatigue critical microstructural neighborhoods. Three distinct categories of crystallographic crack initiation sites have been identified. Fatigue crack initiation and early growth is typified by a crystallographic facet formation process ... |
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| The Role of Microtexture on Fatigue Lifetime Variability and Crack Initiation Mechanisms (Preprint) |
Oct 2011 |
6 pages |
| Authors:
Christopher J Szczepanski; S L Semiatin; James M Larsen; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
|
| Commercial titanium alloys have demonstrated a fatigue lifetime debit in material that contains microtextured regions, as compared to material that has been processed to reduce microtexture. This result has generated commercial incentive to identify the effectiveness of various thermomechanical processing steps to remove microtexture and to determine the fatigue crack initiation mechanism in these microtextured regions. To quantify the efficacy of microtexture reduction on the fatigue behavior of alpha + ... |
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| Characterization of Fatigue Crack-Inititation Facets in Relation to Lifetime Variablility in Ti-6Al-4V (Preprint) |
Jul 2011 |
|
| Authors:
Patrick Golden; Reji John; Sushant Jha; Christopher Szczepanski; III Porter William; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
|
| An analysis of fatigue crack-initiation facets from the perspective of variability in lifetime of a duplex microstructure of Ti-6Al-4V is presented. Fatigue variability behavior of this alloy was marked by an increase in the lifetime variability to almost three orders in magnitude as the stress level was decreased. Crack initiation was found to occur primarily from the specimen surface with only a few exceptions where subsurface initiation was recorded. In ... |
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| Stress Corrosion Cracking Facet Crystallography of Ti-8Al-1Mo-1V (Preprint) |
May 2011 |
36 pages |
| Authors:
Adam L Pilchak; A H Young; J C Williams; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIR METALS CERAMICS AND NONDESTRUCTIVE EVALUATION DIV/METALS BRANCH
|
| The spatial and crystallographic orientations of facets formed during stress corrosion cracking of Ti-8Al-1Mo-1V have been characterized using quantitative fractography and electron backscatter diffraction. The results indicate that most facets are formed nearly perpendicular to the loading direction on irrational {hkil} planes. The facets were imaged with high resolution scanning electron microscopy and were found to contain evidence of localized plastic flow despite their brittle appearance at moderate magnification. Some ... |
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| Navy Littoral Combat Ship (LCS) Program: Background, Issues, and Options for Congress |
18 Mar 2011 |
69 pages |
| Authors:
Ronald O'Rourke; LIBRARY OF CONGRESS WASHINGTON DC CONGRESSIONAL RESEARCH SERVICE
|
| The Littoral Combat Ship (LCS) is a relatively inexpensive Navy surface combatant equipped with modular plug-and-fight mission packages. The Navy wants to field a force of 55 LCSs. The first two LCSs (LCS-1 and LCS-2) were procured in FY2005 and FY2006 and were commissioned into service on Nov 8, 2008, and Jan 16, 2010. Another two (LCS-3 and LCS-4) were procured in FY2009 and are under construction. Two more (LCS-5 ... |
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| Corrosion Fatigue and Environmentally Assisted Cracking in Aging Military Vehicles (La fatigue-corrosion et la fissuration en milieu ambiant des vehicules militaires vieillissants) |
MAR 2011 |
434 pages |
| Authors:
NATO RESEARCH AND TECHNOLOGY ORGANIZATION NEUILLY-SUR-SEINE (FRANCE)
|
| This AGARDograph provides a comprehensive and updated state-of-the-art on corrosion fatigue and environmentally assisted cracking. The interest of the NATO community in this specific subject can be dated back some decades ago, as shown by the publication of the AGARDograph AG-278 issued in 1985, the AGARD Corrosion Handbook Vol. 1 -- Aircraft Corrosion: Causes and Case Histories, where this issue was also jointly covered with the many other aspects of ... |
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| The Role of Microtexture on the Fatigue Behavior of an alpha + beta Titanium Alloy, Ti-6Al-2Sn-4Zr-6Mo (Preprint) |
MAR 2011 |
|
| Authors:
J. M. Larsen; C. J. Szczepanski; S. K. Jha; J. W. Jones; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIR METALS CERAMICS AND NONDESTRUCTIVE EVALUATION DIV/METALS BRANCH
|
| The effect of microstructural heterogeneity, specifically regions of grains with similar crystallographic orientations, or microtexture, on the initiation and early growth of fatigue cracks from multiple micro-notches has been investigated in Ti-6246. Experiments were performed using ultrasonic fatigue techniques for two different microstructural conditions. Local texture surrounding micro-notches was found to influence micro-notch fatigue crack initiation in one of the microstructures. Fatigue crack initiation was least likely to occur from ... |
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| Navy Littoral Combat Ship (LCS) Program: Background, Issues, and Options for Congress |
20 Jan 2011 |
66 pages |
| Authors:
Ronald O'Rourke; LIBRARY OF CONGRESS WASHINGTON DC CONGRESSIONAL RESEARCH SERVICE
|
| The Littoral Combat Ship (LCS) is a relatively inexpensive Navy surface combatant equipped with modular plug-and-fight mission packages. The Navy wants to field a force of 55 LCSs. The first two (LCS-1 and LCS-2) were procured in FY2005 and FY2006 and were commissioned into service on Nov 8, 2008, and Jan 16, 2010. Another two (LCS-3 and LCS-4) were procured in FY2009 and are under construction. Two more were procured ... |
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| Effectiveness of Empirical Mode Decomposition Based Features Compared to Kurtosis Based Features for Diagnosis of Pinion Crack Detection in a Helicopter |
Oct 2010 |
9 pages |
| Authors:
Canh Ly; Kenneth Ranney; Kwok Tom; Hiralal Khatri; Harry Decker; ARMY RESEARCH LAB ADELPHI MD
|
| Features based on empirical mode decomposition (EMD) of measured vibration data were developed for a Bell OH-58 helicopter main rotor gearbox. A tooth on the input pinion of the gearbox was notched and run for an extended period at several over-torque conditions to induce a tooth fracture. Vibration data were recorded at regular intervals until a tooth fractured. The EMD features were found to be more sensitive to the gearbox ... |
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| Impact Experiments into Borosilicate Glass at Three Scale Sizes |
Nov 2009 |
78 pages |
| Authors:
Jr Anderson Charles E; Carl E Weiss; Sidney Chocron; SOUTHWEST RESEARCH INST SAN ANTONIO TX
|
| Glass impact experiments were designed at three different scales--0.22-cal, 0.375-cal, and 0.50-cal--named after the diameter of the bullets. Four experimental series were conducted at the three scale sizes: 1) Lexan-only experiments; 2) monoblock glass experiments; 3) single impact bonded glass experiments, and 4) multi-hit experiments. The experiments were conducted to obtain residual velocity as a function of impact (striking) velocity, including sufficient partial penetrations to calculate a V50. The Vs ... |
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| Test and Material Specifications for Dynamic Delamination Studies of Z-Pinned Laminates |
AUG 2007 |
7 pages |
| Authors:
Brian Cox; Christian Lundsgaard-Larsen; Roberta Massabo; TELEDYNE SCIENTIFIC AND IMAGING LLC THOUSAND OAKS CA
|
| We specify tests by which we expect to demonstrate inference from test data of a mixed mode dynamic cohesive law that represents the crack-shielding effects of through-thickness reinforcement (e.g., z-pins) in a laminate. |
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| High Strength and Impact Damage Tolerant Syntactic Foam for High Performance Sandwich Structures |
25 JUL 2006 |
|
| Authors:
Guoqiang Li; SOUTHERN UNIV AND A AND M COLL BATON ROUGE LA DEPT OF MECHANICAL ENGINEERING
|
 | This study explored a novel higher strength and higher impact tolerant syntactic foam for composite sandwich structures. A unique microstructure was designed and realized through a unique manufacturing technology. The foam was fabricated by dispersing rubber latex coated microballoons into a nanoclay and milled microfiber reinforced epoxy matrix. Each component was designed to contribute to a desired property of the foam. The nanoparticle and microfiber served to increase the strength ... |
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| Controlling Hydrogen Embrittlement in Ultra-High Strength Steels |
JUN 2006 |
21 pages |
| Authors:
John R. Scully; Hakan Dogan; Daoming Li; Richard Gangloff; VIRGINIA UNIV CHARLOTTESVILLE DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| A Fe-13Co-11Ni-3Cr- 1Mo-0.2C steel alloy, processed for ultra-high strength and fracture toughness, exhibits three distinct hydrogen trap states in a complex precipitation hardened martensitic microstructure and is susceptible to severe hydrogen embrittlement (HE) at threshold stress intensity levels as low as 20 MPa square root of m. The causes of HE susceptibility include very high crack-tip tensile stresses and a reservoir of diffusible hydrogen that is trapped reversibly with a ... |
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| Mechanical Behavior of Cracked Panels Repaired with Bonded Composite Patch |
JUN 2005 |
113 pages |
| Authors:
Michael A. Hansen; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| This research focuses on investigating the mechanical behavior of cracked aluminum panels repaired with bonded boron/epoxy composite patches. The effects of crack initiation and growth on the residual strength of the repaired panels are characterized. This research establishes a correlation between damage modes, residual strength and evolution of strain within as well as outside the patch. Monotonic tensile tests on specimens with a perfectly bonded patch were used to determine ... |
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| Nonlinear Characterizing of the Crack Growth Behavior in a Filled Elastomer |
2004 |
9 pages |
| Authors:
C. T. Liu; M. Yen; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
|
| In this study, the crack growth behavior in a filled elastomer containing hard particles embedded in a rubbery matrix was investigated. The specimen was tested at a constant strain rate of 0.067 cm/cm/min at room temperature. Two initial crack lengths, 2.54 mm and 12.7 mm, were considered. A hybrid experimental-numerical method was used to calculate the J-integral value. The results show that the initial crack length had a significant effect ... |
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| Spiral Bevel Pinion Crack Detection in a Helicopter Gearbox |
JUN 2003 |
16 pages |
| Authors:
Harry J. Decker; David G. Lewicki; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| The vibration resulting from a cracked spiral bevel pinion was recorded and analyzed using existing Health and Usage Monitoring System (HUMS) techniques. A tooth on the input pinion to a Bell OH-58 main rotor gearbox was notched and run for an extended period at severe over-torque condition to facilitate a tooth fracture. Thirteen vibration-based diagnostic metrics were calculated throughout the run. After 101.41 hours of run time, some of the ... |
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| Ex-Service F/A-18 Centre Barrel Fatigue Flaw Identification Test Plan |
MAY 2003 |
|
| Authors:
B. Dixon; L. Molent; DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION VICTORIA (AUSTRALIA) PLATFORM SCIENCES LAB
|
| This report provides a generic plan for fatigue cycling and teardown of ex-service F/A-18 centre barrels for the purpose of fatigue flaw identification. It describes the accelerated fatigue test cycling program which will be applied to each centre barrel to increase the size of existing microflaws or defects so that they can be more reliably detected. It also covers the teardown, inspection and storage requirements of the project. |
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| Recent Advances in High Cycle Fatigue |
MAY 2003 |
10 pages |
| Authors:
Ted Nicholas; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| High cycle fatigue (HCF) has been the cause of a number of turbine engine failures over the last several years within the U.S. Air Force. Extensive investigations have determined that the root cause when related to material properties, is the accumulation of damage prior to and during service which, in turn, reduces the capability of the material in terms of the fatigue limit strength. Numerous studies have been conducted over ... |
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| Fracture and Residual Characterization of Tungsten Carbide Cobalt Coatings on High Strength Steel |
MAY 2003 |
9 pages |
| Authors:
Donald S. Parker; OAK RIDGE NATIONAL LAB TN
|
| Tungsten carbide cobalt coatings applied via high velocity oxygen fuel thermal spray deposition are essentially anisotropic composite structures with aggregates of tungsten carbide particles bonded with both amorphous and crystalline cobalt phases. X-ray diffraction was used to characterize the residual stresses within the coatings to understand the crack initiation and propagation behavior of samples subjected to axial fatigue loads. Diffraction was also used to establish a baseline stress state of ... |
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| Research and Educational Activities at the FAST Center for Structural Integrity of Aerospace Systems |
03 SEP 2002 |
220 pages |
| Authors:
Roberto A. Osegueda; Carlos M. Ferregut; TEXAS UNIV AT EL PASO FAST CENTER FOR STRUCTURAL INTEGRITY OF AEROSPACE SYSTEMS
|
| This report describes the technical research activities that were carried out at the Future Aerospace Science and Technology (FAST) Center for Structural Integrity of Aerospace Systems, the University of Texas at El Paso, under findings from the US Air Force Office of Scientific Research. Also included is a brief description of the efforts to educate minority scientists and engineers. The technical mission was to conduct basic research to contribute to ... |
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| Nondestructive Inspection (NDI) Through High-Velocity Oxygen Fuel (HVOF) Thermal Spray Coatings. Delivery Order 0001: Nondestructive Evaluation Exploratory Development for Air Force Systems |
MAY 2002 |
26 pages |
| Authors:
Noel Tracy; Sandra Davis; John Brausch; UNIVERSAL TECHNOLOGY CORP DAYTON OH
|
| High Velocity Oxygen Fuel (HVOF) thermal spray coatings are the leading candidates to replace electrolytic hard chrome (EHC) coatings on critical high strength steel components such as aircraft landing gear. HVOF qualification as an acceptable replacement for hard chrome plating has not been fully demonstrated, particularly for fatigue-sensitive aircraft components. One area lacking is the ability to inspect through these coatings for substrate damage. Three nondestructive inspection (NDI) techniques were ... |
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| An Investigation on High Temperature Behavior of Laminate and Nanostructured Composite Materials |
SEP 2001 |
15 pages |
| Authors:
Horacio D. Espinosa; NORTHWESTERN UNIV EVANSTON IL DEPT OF MECHANICAL ENGINEERING
|
| A novel high-strain-rate and high temperature experimental set-up was developed to investigate failure of advanced materials. Experiments were performed on preheated Ti-6Al-4V specimens, at temperatures in the range 25-550 deg C, to determine the role of thermal activation on dynamic stress induced inelasticity and damage. Interferometric techniques were employed to record the free surface velocity of the target plates. The experimental results show that thermal activation overcomes the role of ... |
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| TARGET ACQUISITION USING CORRELATION FILTERS AND LASER RADAR DATA, |
SEP 2001 |
|
| Authors:
STEVEN D. VANSTONE; ARMY AVIATION AND MISSILE COMMAND REDSTONE ARSENAL AL
|
| (U) THIS PAPER INVESTIGATES THE RELATIVE MERIT OF USING INTENSITY IMAGE DATA VERSUS RANGE IMAGE DATA IN A CORRELATION BASED TARGET ACQUISITION SYSTEM. THE RESEARCH DIRECTLY COMPARES DETECTION AND CLASSIFICATION PERFORMANCE OF BOTH INTENSITY AND RANGE DATA, AND DEMONSTRATES A METHOD FOR GENERAL PERFORMANCE COMPARISON. THE RESEARCH PROVIDES INSIGHT INTO USING LASER RADAR DATA WITH EXISTING TARGET ACQUISITION TECHNOLOGY. CORRELATION FILTER TRADEOFF PARAMETERS ARE ADJUSTED TO EXPOSE CHARACTERISTICS UNIQUE TO ... |
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| Optimizing the Strength and SCC Resistance of Aluminum Alloys used for Refurbishing Aging Aircraft |
07 MAY 2001 |
113 pages |
| Authors:
Charles P. Ferrer; NAVAL ACADEMY ANNAPOLIS MD
|
| The focus of this report is on the mechanical end corrosion properties of high-strength aluminum alloys. Aluminum alloy 7075, a common material in the aerospace industry, is susceptible to stress-corrosion cracking (SCC) in the T6, or peak-aged temper. The susceptibility of this temper to SCC is alleviated through the use of the T73, or overaged temper. This temper exhibits significantly better SCC resistance, but at a 10-15% strength loss compared ... |
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| New Frontiers in Integrated Diagnostics and Prognostics. Proceedings of the 55th Meeting of the Society for Machinery Failure Prevention Technology. Virginia Beach, Virginia, April 2 - 5, 2001 |
05 APR 2001 |
467 pages |
| Authors:
Henry C. Pusey; Sallie C. Pusey; W. R. Hobbs; SOCIETY FOR MACHINERY FAILURE PREVENTION TECHNOLOGY WINCHESTER VA
|
| The 55th Meeting of the Society for Machinery Failure Prevention Technology (MFPT) was held April 2-5, 2001 in Virginia Beach, Virginia. MFPT sponsors include the Office of Naval Research, U.S. Army Research Laboratory, National Aeronautics and Space Administration and the Naval Surface Warfare Center. The cooperation of several professional organizations with mutual Interests is acknowledged. Mr. Carl S. Byington from the Applied Research Laboratory at Pennsylvania State University was Technical ... |
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| Life Prediction Methodologies for Aerospace Materials |
AUG 2000 |
166 pages |
| Authors:
N. E. Ashbaugh; D. J. Buchanan; A. L. Hutson; R. John; K. Li; DAYTON UNIV OH RESEARCH INST
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| The effect of microstructure, environment, and coatings on mechanisms of fatigue and fatigue crack initiation and growth in TiAl intermetallic alloys has been investigated. For a gamma titanium aluminide alloy, the coarse and refined lamellar materials with colony sizes equal to 700 and 280 m, respectively, have substantially greater crack growth resistance than does the fine duplex material with approximately 20 m grain size. The influence of laboratory air on ... |
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| The Significance of Small Cracks in Fatigue Design Concepts as Related to Rotorcraft Metallic Dynamic Components |
FEB 2000 |
14 pages |
| Authors:
R. A. Everett Jr.; W. Elber; ARMY VEHICLE TECHNOLOGY DIRECTORATE HAMPTON VA
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| In this paper the significance of the "small" crack effect as defined in fracture mechanics will he discussed as it relates to life managing rotorcraft dynamic components using the conventional safe- life, the flaw tolerant safe-life, and the damage tolerance design philosophies. These topics will be introduced starting with an explanation of the small-crack theory, then showing how small-crack theory has been used to predict the total fatigue life of ... |
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| Application of Damage Tolerance to Increase Safety of Helicopters in Service |
FEB 2000 |
8 pages |
| Authors:
Bogdan R. Krasnowski; BELL HELICOPTER TEXTRON INC FORT WORTH TX
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| In the past, all helicopters have been designed to safe-life requirements. Introduced in October 1989, FAR 29.571 at Amendment 28 requires damage tolerance substantiation for transport category helicopters. Therefore, the majority of helicopters currently in service were designed to safe-life requirements. In general, the safe-life approach has proven to be adequate. However, there have been a number of field problems with cracking components, which lend themselves to the application of ... |
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| The US Navy's Helicopter Integrated Diagnostics System (HIDS) Program: Power Drive Train Crack Detection Diagnostics and Prognostics Life Usage Monitoring and Damage Tolerance; Techniques, Methodologies, and Experiences |
FEB 2000 |
22 pages |
| Authors:
Andrew Hess; William Hardman; Harrison Chin; John Gill; NAVAL AIR WARFARE CENTER AIRCRAFT DIV PATUXENT RIVER MD
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| The evolution of automated diagnostic systems for helicopter mechanical systems has been greatly advanced by the Navy, in a program of systematic testing of drive train components having known anomalies (seeded faults) while simultaneously executing a suite of diagnostic techniques to identify and classify the mechanical anomalies. This program, called the Helicopter Integrated Diagnostic System (HIDS) was carried out using both an iron bird test stand and SH-60B/F flight vehicles. ... |
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| Flaw Tolerant Safe-Life Methodology |
FEB 2000 |
8 pages |
| Authors:
D. O. Adams; SIKORSKY AIRCRAFT CORP STRATFORD CT
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| Conventional safe-life methodology has been in general use in the helicopter industry for more than 40 years to substantiate fatigue-loaded dynamic components. However, it is seen to need improvement. One improvement is to reduce its sensitivity to the strength-reducing effects of flaws and defects that may occur in manufacturing and service use. Damage Tolerance methodology provides a means to accomplish this improvement but it is currently difficult to economically apply ... |
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| Treatment of High-Cycle Vibratory Stress in Rotorcraft Damage Tolerance Design |
FEB 2000 |
10 pages |
| Authors:
John W. Lincoln; Hsing C. Yeh; AERONAUTICAL SYSTEMS CENTER WRIGHT-PATTERSON AFB OH DIRECTORATE OF ENGINEERING
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| Fixed wing aircraft manufacturers have adopted the damage tolerance design philosophy with great success for both military and commercial aircraft. However, rotorcraft manufacturers currently still primarily use the classical safe life approach or a modification thereof. One reason for this is that, at this time, no clearly defined damage tolerance design criteria exist for rotorcraft structures because of the analysis and test problems associated with the high cycle loading environment. ... |
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| Distributed Fiber Optic Laser Ultrasonic System |
29 MAR 1999 |
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| Authors:
Ignacio Perez; NAVAL AIR WARFARE CENTER AIRCRAFT DIV PATUXENT RIVER MD
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| This invention relates to ultrasonic inspection, and particularly to an ultrasonic inspection apparatus utilizing a laser to generate acoustic waves at ultrasonic frequencies. The invention has many uses, including, for example, monitoring the structural integrity of components of aircraft, ships, submarines, land vehicles, and pressure vessels. Parameters that can be monitored include, but are not limited to, strain. temperature, crack initiation, corrosion, impact damage, delamination and bond integrity. |
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Reports by Keyword(s)
CRACKING(FRACTURING)
