bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of Residual Stress Effects on Brittle Fracture Strength Based on Weibull Stress Criterion
Authors: Yamashita Yoichi , Minami Fumiyoshi
Published: March 2010

This paper studies the method for estimating the residual stress effects on brittle fracture of structural steel based on the Weibull stress criterion. First, brittle fracture tests were conducted for four-point bend notched specimens with and without compressive preloading. It is shown that the compressive preloading apparently decreases the critical crack tip opening displacement (CTOD). The critical CTOD of the preloaded specimen can be predicted from monotonically loaded test results based on the Weibull stress criterion. It has been found that the Weibull stress is an effective fracture parameter for brittle fracture initiation under tensile residual stress. Second, using wide plate specimens with and without welding residual stress subjected to uniform tension and three-point bend fracture toughness specimens, welding residual stresses effect on the brittle fracture strength is investigated. Experiments show that the critical CTOD of wide plate with welding residual stress is significantly smaller than that without residual stress. Constraint loss effect on CTOD of wide plate can be assessed by the equivalent CTOD ratio β. β is defined as β=δ3PB∕δWP, where δ3PB and δWP are CTODs of the standard fracture toughness specimen and wide plate, respectively, at the same level of the Weibull stress. Fracture assessment result using β is shown within the context of failure assessment diagram. An excessive conservatism observed in the conventional procedure (β=1) is reasonably reduced by applying the equivalent CTOD ratio β.
Statistical Analysis of Fatigue Related Microstructural Parameters for Airframe Aluminum Alloys
Authors: Liao Min , Chisholm Kyle , Mahendran Mario
Published: March 2010

This paper presents the results of statistical analysis of the fatigue related microstructural parameters, mainly on constituent particles and pores, in 7050-T7452 aluminum forging materials. The statistical distributions of the particle and pore area data, which were obtained from the metallographic measurements on polished surfaces, were fitted well with three-parameter lognormal functions. Comparative studies were carried out for the particle and pore size distributions between the core and periphery materials, and between the hand and die forging materials. An extreme value theory-based model was investigated to correlate the overall material particle distribution with the fatigue crack-nucleating particle distribution. The results indicated that the particle size is not the only parameter affecting the fatigue process; other parameters, such as grain size and grain orientation, are also important parameters for microstructure-based fatigue modeling. Therefore, orientation image microscopy (OIM) analyses were carried out on pristine 7050 samples, on different planes, to determine the grain orientation distributions. Finally, a preliminary OIM analysis was performed on a fractured sample to measure the misorientation angles between the grains near the crack nucleation and short crack regions. It is expected that the test observations and quantitative microstructural data could help to understand the effects of microstructure on the fatigue process and develop a microstructure-based fatigue modeling.
Multi-Scale Approach to the Fatigue Crack Propagation in High-Strength Pearlitic Steel Wires
Authors: Toribio J. , González B. , Matos J. C. , Ayaso F. J.
Published: March 2010

This paper deals with the influence of the manufacturing process on the fatigue behavior of pearlitic steels with different degrees of cold drawing. The fatigue crack growth rate (da∕dN) is related to the stress intensity range (ΔK) by means a compliance method to evaluate the crack depth a in the samples at any instant during the tests. The analysis is focused on the Region II (Paris) of the fatigue behavior in which da∕dN=C(ΔK)m, measuring the constants (C and m) for the different degrees of drawing. From the engineering point of view, the manufacturing process by cold drawing improves the fatigue behavior of the steels, since the fatigue crack growth rate decreases as the strain hardening level in the material increases. In particular, the coefficient m (slope of the Paris Law) remains almost constant and independent of the drawing degree, whereas the constant C decreases as the drawing degree rises. The paper focuses on the relationship between the pearlitic microstructure of the steels (progressively oriented as a consequence of the manufacturing process by cold drawing) and the macroscopic fatigue behavior. To this end, a detailed metallographic analysis was performed on the fatigue crack propagation path after cutting and polishing on a plane perpendicular to the crack front. It is seen that the fatigue crack growth path presents certain roughness at the microscopic level, such a roughness being related to the pearlitic colony boundaries more than to the ferrite∕cementite lamellae interfaces.
Effect of Inhomogeneity in Aligned Grains on Creep-Fatigue Crack Opening and Propagation Behavior of Directionally Solidified Superalloy
Authors: Yamamoto Masato , Kitamura Takayuki , Ogata Takashi
Published: March 2010

Directionally solidified superalloy, which has elongated large grains, is used for gas-turbine blade application because of its high creep strength. Since the grain size is not small enough in comparison with the component size or the crack size, the inhomogeneous microstructure strongly affects the crack propagation behavior in such a structure. The authors investigate the effect of microstructural inhomogeneity on crack propagation morphology and crack propagation rate (da∕dN) under a creep-fatigue condition. The macroscopic direction of the main crack is perpendicular to the loading axis, though the path is microscopically bumpy due to the effect of inhomogeneous multi-grains. Several subcracks are found around the main crack, and they occasionally coalesce with each other. In order to understand the local fluctuation of (da∕dN) due to the inhomogeneous multi-grains, the grain shape and its crystallographic orientation are identified by means of a scanning electron microscope (SEM) and an electron back scattering diffraction (EBSD). The subcracks tend to initiate at the high angle grain boundaries oriented nearly perpendicular to the loading axis. The local fluctuation of da∕dN is influenced by two factors. One is the cracking path; the intergranular crack shows higher da∕dN. The other factor is the magnitude of Young's modulus of the grain (in loading direction) at the crack tip. The higher Young's modulus leads to a lower da∕dN in transgranular cracking. The detailed observation of local displacement near the crack tip clarified that the magnitude of cyclic displacement inversely related to the Young's modulus of the grain in the loading axis, and results in the high strain concentration at the crack tip in the grain with low Young's modulus. The experiment result suggests that the strain around the crack tip governs the crack propagation rate though it is affected by the inhomogeneous microstructure.
Introducing Heterogeneity into Brittle Fracture Modeling of a 22NiMoCr37 Ferritic Steel Ring Forging
Authors: Zhao Xinglong , Lidbury David , Quinta da Fonseca João , Sherry Andrew
Published: March 2010

Microstructural observations of the 22NiMoCr37 “EURO” reactor pressure vessel (RPV) steel ring forging reveal that there is a banded structure along the radial direction, composed of alternate layers rich in bainite and ferrite of wavelength ∼1.5 ±0.75 mm. Heterogeneity at this meso (millimetre)-scale as well as at the micro (micrometre)-scale is currently not considered by conventional fracture mechanics. This paper describes the development of two numerical approaches aimed at incorporating such heterogeneity into the Beremin local approach model of cleavage failure, a model that has been used extensively for predicting the brittle fracture of ferritic RPV steels. The approaches developed combine the crystal plasticity finite element method (CPFEM) with continuum finite element analysis (FEA). CPFEM is applied to predict stress distributions at the microscale and to obtain phase-specific yield and flow properties for continuum FEA that derives stresses at the mesoscale. The results confirm that deformation heterogeneity on the micro- and mesoscales influences the local development of stress. At the microscale, the stress distribution within a representative volume of material located within the crack-tip plastic zone is shown to follow a normal distribution with a ratio of mean stress to standard deviation tending towards 0.1. These results indicate local stress levels that are within approximately ±20 % of those derived using continuum FEA. At the mesoscale, a periodic variation of stress is predicted within the larger representative volume. This variation is less dramatic than that observed at the microscale, though it still gives a spatial variation in maximum principal stress of approximately ±7 % between bainite- and ferrite-rich microstructural regions. These results suggest a significant influence of deformation heterogeneity on local stress levels, particularly at the microscale. However, the conventional Beremin cleavage fracture model, modified to account for microscale stress distribution, predicts only a modest influence of deformation heterogeneity on cleavage fracture probability, increasing Pf by just 5 %. This highlights the need to account for both the spatial variation in cleavage initiation sites as well as the distribution in stress throughout the microstructure. The paper describes one approach for this development.
Stress-Triaxiality in Zr-2.5Nb Pressure Tube Materials
Authors: Leitch B. W. , Lawrence S. St.
Published: March 2010

The crack growth resistance of irradiated Zr-2.5Nb pressure tubes is controlled by the initiation of voids and their subsequent growth and coalescence. The presence of particles that contribute to void nucleation is determined by the operating conditions∕history of the pressure tube and by the concentration of pre-existing species, which is a function of the manufacturing process. The susceptibility of the pressure tubes to void nucleation is determined by the number and distribution of particles, the deformation properties of the matrix, and the stress state at the crack tip. The effect of irradiation on zirconium material is to increase the yield stress but to reduce the work hardening ability of the matrix and to promote strain localization, which, in turn, leads to void nucleation. Void nucleation is also enhanced by high values of stress triaxiality at or near the crack tip. For irradiated pressure tube material, both small-scale curved compact tension specimens and large-scale burst test sections are used to characterize the crack growth resistance. However, the measured fracture toughness can depend on the specimen geometry due to differences in constraint. The present investigation uses three-dimensional finite element analyses to characterize stress triaxiality at the crack tip in these different specimen geometries. Results of the numerical analyses are compared to the experimental evidence that provide qualitative evidence of differences in stress triaxiality at the crack tip for different specimen geometries.
Laser Generated Crack-Like Features Developed for Assessment of Fatigue Threshold Behavior
Authors: Nardi Aaron T. , Smith Stephen L.
Published: March 2010

Developing methods to evaluate damage tolerance in high cycle fatigue is an important issue for the propeller industry. Traditional methods to establish threshold stress intensity factors for aluminum and martensitic steel have relied mainly on load shedding through-crack test specimens resulting in a pre-cracking history and the associated closure effects. For threshold determination of real life defects, a surface-crack test method, devoid of pre-cracking and closure issues, is needed. To this end, laser generated crack-like features (LGCLFs) were created and have been used successfully to evaluate the threshold crack growth properties of cracks in 7075-T651 with and without shot peening in axial R = 0.1 loading. For this work, a laser part marking system was used to generate a LGCLF semi-circular in shape, and measuring ∼0.015 in. (0.381 mm) deep by ∼0.030 in. (0.762 mm) long, with a notch height of 0.0007–0.001 in. (17.8–25.4 μm) with a tip radius of 0.000 14 in. (3.5 μm). When evaluated metallographically, these laser notches exhibited a very thin recast layer and a negligible heat affected zone. Specimens produced with these flaws were tested in R=0.1 tension-tension fatigue to produce a stress versus life plot of the data. A NASGRO crack growth model was used to generate stress versus cycle data points for the same geometry over the same stress range with a 7075-T651 material model and a crack growth threshold of 1.35 ksi ·(in.)0.5 resulting in very good agreement with the test data. This threshold compares favorably with the small crack threshold of 1.27–1.33 ksi·(in.)0.5 produced by da∕dN testing performed by NASA at R=0.1 using a compressive pre-cracking method. Testing with samples shot peened prior to generating a LGCLF exhibited significantly higher endurance stresses and failure initiations were not from the LGCLF.
Comparison of the Temperature and Pre-Aging Influences on the Low Cycle Fatigue and Thermo-Mechanical Fatigue Behavior of Copper Alloys (CuCoBe∕CuCo2Be)
Authors: Koeberl H. , Winter G. , Leitner H. , Eichlseder W.
Published: March 2010

Typically thermo-mechanical fatigue (TMF) loaded components in power plants and steel works are made of copper alloys and are used in different applications (e.g. cooling systems in continuous casting, transformers). So a careful analysis and comparison of the experimental results and microstructure of thermo-mechanical loaded copper components, which are based on a systematic variation of the relevant influence factors, have been conducted to develop empirical models for computing the fatigue life. At specific low cycle fatigue (LCF) and thermo-mechanical fatigue test series on the copper alloys CuCoBe and CuCo2Be, the influence of pre-aging and temperature were investigated by means of the cyclic deformation and lifetime behavior. Based on stress-strain loops from LCF tests at different temperatures and aging conditions a non-linear combined material model was adopted to describe the cyclic deformation behavior. The simulated loading parameters of stress and strain were the basis for the subsequent lifetime simulation. A new energy based damage parameter for copper alloys has been developed to fulfill the requirements of lifetime simulation.
Carrying Capacity Prediction of Steam Turbine Rotors with Operation Damage
Authors: Shlyannikov V. N. , Ilchenko B. V. , Yarullin R. R.
Published: March 2010

This study is concerned with assessing the integrity of cracked steam turbine rotor which operates under creep conditions. Damage accumulation and growth for turbine rotor took place on the inner surface of hole in a shaft. In this case the crack front was nearly half-elliptical shape. The model based on the critical distance concept is presented for expressing crack growth rate in terms of creep damage accumulation in a process zone ahead of the crack tip. An engineering approach to the prediction of residual lifetime of a turbine rotor which is sensitive to the loading history at maintenance is proposed. Full-size stress-strain state analysis of turbine rotor is represented for different stages of lifetime under considering loading conditions. As a result accumulated creep strain in critical zones of turbine rotor depending on time of loading is defined. The creep fracture mechanics parameters that are found numerically are used to characterize the local strain rate and stress fields at any instant around the crack tip in a turbine rotor subjected extensive creep conditions. The meaning of the critical creep ductility appropriate to the stress state at the crack tip is defined as the difference between permissible and accumulated creep strains at different times of loading. Approximate estimations of carrying capacity are presented for the different stress-strain state of a steam turbine rotor at the operation. It is found that the individual mean lifetime of a turbine rotor can be predicted with reasonable accuracy from knowledge of the stress-strain distributives and the material uniaxial creep ductility and creep rupture strength.
In-situ Fatigue Damage Investigations in Welded Metallic Components by Infrared Techniques
Authors: Medgenberg Justus , Ummenhofer Thomas
Published: March 2010

The paper reviews the state of the art of thermal damage assessment in metals and proposes a specialized form of lock-in thermography as an efficient tool for the quantification of early fatigue damage phenomena in welded steel structures in the regime of mid- to high-cycle fatigue. It can be proved that advanced thermographic techniques are sensitive to early damage phenomena in the weld toe. They provide a new experimental mean for in-situ investigation of early inhomogeneous fatigue damage phenomena as mesoplasticity and fatigue cracks. The results demonstrate that noncontacting full field temperature measurements using highly sensitive infrared technology can be applied successfully to detect localized fatigue damage at around 10 % to 20 % of the total fatigue lifetime of the tested specimens. The applied method is based on the separation of thermoelastic and thermoplastic temperature effects which cause characteristic local temperature signatures. In contrast to other well-known approaches—as, e.g., measuring the rise of mean temperature during fatigue loading—the applied method offers a very high spatial resolution and resolves extremely localized phenomena. The methodology can be applied to monitor the fatigue process during conventional fatigue testing. The additional effort for the specimen preparation and the installation of the testing setup is minimal.
Fatigue Crack Growth in Integrally Stiffened Panels Joined Using Friction Stir Welding and Swept Friction Stir Spot Welding
Authors: Burford Dwight A. , Tweedy Bryan M. , Widener Christian A.
Published: March 2010

Fatigue crack growth rates in AA2024-T3 sheet joined to AA7075-T6 stiffeners by friction stir welding have been compared with rates measured in panels joined with rivets and in unstiffened parent material panels. Friction stir panels were prepared with both continuous friction stir welding (FSW) and swept friction stir spot welding (FSSW). Fatigue cracks in edge crack panels with continuous FSW joints tended to grow into the parent material away from the stiffeners. This behavior was attributed to the reduced stress levels corresponding to the increased thickness of continuous FSW joints and the support of the attached stiffener. Fatigue cracks in edge crack panels were found to follow the joint line in panels made with discrete fasteners (both rivets and swept FSSW joints). The measured crack growth rates in riveted panels increased at an increasing rate as the crack approached the riveted joints. In contrast, crack growth rates in panels joined with FSSW decreased at a decreasing rate as the crack approached the swept spot joints. Test results indicate that the swept FSSW process produced favorable residual stresses that inhibited fatigue crack growth along the joint line.
Evaluation of the EPA Drift Reduction Technology (DRT) Low-Speed Wind Tunnel Protocol
Authors: Fritz Bradley K. , Hoffmann W. Clint , Lan Yubin
Published: March 2010

The EPA's proposed Drift Reduction Technology (DRT) low-speed wind tunnel evaluation protocol was tested across a series of modified ASAE reference nozzles. Both droplet size and deposition and flux volume measurements were made downwind from the nozzles operating in the tunnel at airspeeds of 1 m∕s and 2.5 m∕s, following the prescribed protocol. Overall, the data followed anticipated trends with a few unanticipated results observed, which could be addressed in future iterations of the protocol. There were some difficulties meeting the proposed protocol data quality requirements. Refined quality requirements would address this with no detrimental effect to the overall data set. Major concerns, at this point, are the feasibility of the overall protocol as well as the applicability of the final collected data. The protocol was tailored such that the collected data would directly input into a dispersion model (most likely WTDISP). However, not having access to such a model puts into question the validity and practicality of the protocol in its present form. Given the time requirements, which require approximately nine times that of the high speed protocol (90 min versus 10 min, unpublished data), there is a definite need to modify the existing protocol to insure equitable implementation of the overall DRT program.
Keynote—Materials Selection for Oxidizer Service—Successes and Challenges
Authors: Slusser Joseph W.
Published: March 2010

Improper selection of materials of construction for oxygen and other strong oxidizer applications can result in sudden catastrophic failure. Many available materials are flammable and will burn in oxidizer systems if sufficient ignition energy is provided. Because these combustion events occur suddenly, they cannot be monitored by periodic inspection. Also, a definitive cause after such an event is often difficult to determine because much of the evidence is destroyed. Materials selection and system design must be correct from the beginning. The key is to ensure the ignition energies imposed on the materials during operation of the system do not challenge the materials. Or, to state it differently, a designer must ensure that the materials selected have adequate compatibility to withstand the operating conditions (including transient conditions such as startups) without igniting. This paper will provide an overview of the science of oxygen compatibility and how Committee G04 efforts have helped improve safety. It will also comment on the technical issues the Committee may address in the future and a concern, shared with many similar organizations, of declining industry participation.
Defining the Flammability of Cylindrical Metal Rods through Characterization of the Thermal Effects of the Ignition Promoter
Authors: Lynn David , Steinberg Ted , Sparks Kyle , Stoltzfus Joel M.
Published: March 2010

All relevant international standards for determining if a metallic rod is flammable in oxygen utilize some form of “promoted ignition” test. In this test, for a given pressure, an overwhelming ignition source is coupled to the end of the test sample and the designation flammable or nonflammable is based upon the amount burned, that is, a burn criteria. It is documented that (1) the initial temperature of the test sample affects the burning of the test sample both (a) in regards to the pressure at which the sample will support burning (threshold pressure) and (b) the rate at which the sample is melted (regression rate of the melting interface); and, (2) the igniter used affects the test sample by heating it adjacent to the igniter as ignition occurs. Together, these facts make it necessary to ensure, if a metallic material is to be considered flammable at the conditions tested, that the burn criteria will exclude any region of the test sample that may have undergone preheating during the ignition process. A two-dimensional theoretical model was developed to describe the transient heat transfer occurring and resultant temperatures produced within this system. Several metals (copper, aluminum, iron, and stainless steel) and ignition promoters (magnesium, aluminum, and Pyrofuze®) were evaluated for a range of oxygen pressures between 0.69 MPa (100 psia) and 34.5 MPa (5,000 psia). A MATLAB® program was utilized to solve the developed model that was validated against (1) a published solution for a similar system and (2) against experimental data obtained during actual tests at the National Aeronautics and Space Administration White Sands Test Facility. The validated model successfully predicts temperatures within the test samples with agreement between model and experiment increasing as test pressure increases and∕or distance from the promoter increases. Oxygen pressure and test sample thermal diffusivity were shown to have the largest effect on the results. In all cases evaluated, there is no significant preheating (above about 38°C∕100°F) occurring at distances greater than 30 mm (1.18 in.) during the time the ignition source is attached to the test sample. This validates a distance of 30 mm (1.18 in.) above the ignition promoter as a burn length upon which a definition of flammable can be based for inclusion in relevant international standards (that is, burning past this length will always be independent of the ignition event for the ignition promoters considered here).
Determination of Time Required for Materials Exposed to Oxygen to Return to Reduced Flammability
Authors: Harper Susana , Hirsch David , Smith Sarah
Published: March 2010

Increased material flammability due to exposure to high oxygen concentrations is a concern from both safety and operational perspectives. Localized high oxygen concentrations can occur when exiting a higher oxygen concentration environment due to material saturation as well as oxygen entrapment between barrier materials. Understanding of oxygen diffusion and its correlation to flammability risks can reduce the likelihood of fires while improving procedures as NASA moves to longer missions with increased extravehicular activities in both spacecraft and off-Earth habitats. This paper examines the time required for common spacecraft materials exposed to oxygen to return to reduced flammability after removal from the increased oxygen concentration environment. Specifically, NASA-STD-6001A maximum oxygen concentration testing and ASTM Standard F1927 diffusion testing were performed on Nomex® HT90-40, Tiburon® surgical drape, cotton, Extravehicular Mobility Unit (EMU) Liquid-Cooled Ventilation Garment, EMU Thermal Comfort Undergarment, EMU Mosite foam with spandex covering, Advanced Crew Escape Suit (ACES) outer cross-section, ACES Liquid-Cooled Garment, ACES O2 hose material, Minicel® polyethylene foam, Minicel® polyethylene foam with Nomex® covering, Pyrell polyurethane foam, and Zotek® F-30 foam.
Good Practices for Avoiding Fires in Steel Mill Oxygen Systems
Authors: Forsyth Elliot T. , Newton Barry E. , Chiffoleau Gwenael J. A. , Brophy Brendan
Published: March 2010

Over time, oxygen has been used with increasing frequency in the steel industry. Applications include basic oxygen furnaces, electric arc furnaces, scrap melting, lancing operations, and slab-cutting operations. Because of the inherently “dirty” environment of most steel mills, avoiding contaminants in the oxygen systems can be challenging and numerous fires have occurred due to contaminant-promoted ignition sources. This paper presents many good practices that can be practically implemented to reduce the risk of oxygen fires in typical steel mill oxygen system installations.
Sealed Aluminum Cavity Reactions When Submerged in Pure O2 Reboiler Sump
Authors: Schmidt William P. , Cawthra Michael , Houghton Patrick A. , McDonald Ralph H. , Sherwood Robert J. , Wieder Stephen J.
Published: March 2010

Aluminum has a long history of safe service in cryogenic air separation units; however, there have been some rare instances of aluminum∕O2 reactions. Aluminum ignition and propagation depends strongly on the oxygen purity, oxygen pressure, aluminum geometry, and type and energy of igniter. Over the years, the industry has experienced a particular type of aluminum∕O2 reaction: cavity incidents. These incidents are characterized by the presence of a sealed cavity that is created when welding two metal items together. Such a sealed cavity can lead to aluminum ignition under certain specific conditions: (1) The sealed cavity is submerged in a bath of liquid oxygen. Over a long period of time, liquid cryogen can enter the sealed cavity through slight imperfections in the weld. (2) The sealed cavity is warmed over a short period of time, typically a few hours. (3) The liquid oxygen vaporizes, and the pressure inside the cavity builds to very high levels (potentially over 50 bars). (4) Ignition occurs in the high pressure, high purity oxygen environment, and the resulting aluminum∕oxygen reaction burns through the relatively thick cavity walls. (5) The oxygen and reaction products exit the cavity through the hole, lowering the pressure and extinguishing the reaction. This paper discusses two such incidents, which have occurred since 2001. Both incidents took place in brazed aluminum heat exchanger (BAHX) reboiler support beam systems. In both cases, the BAHX reboiler was damaged, leading to a process leak, which required that the plant be repaired. In one case, the damage occurred while warming a plant. In the second case, the damage occurred during normal operation. This second case does not appear to follow the sequence of events outlined above; however, evidence is presented to support the scenario that the cavity incident occurred during a previous warming of the plant. This initial damage then impaired the normal operation of the reboiler, leading to a second hydrocarbon related reaction during normal operation. The paper discusses the potential ignition mechanisms, probable causes of the incidents, and methods to prevent future re-occurrences.
Analysis of the Impact Performance of Ice Hockey Helmets Using Two Different Test Methodologies
Authors: Giacomazzi Amber , Smith Terry , Kersey Robert
Published: March 2010

This paper reports on the results of a study to determine the protective characteristics of ice hockey helmets when tested using two different methodologies. The first methodology involved a traditional monorail drop impact test commonly used in North American ice hockey helmet standards (i.e., ASTM F1045, CSA Z262.1). This involves a guided freefall test onto a flat anvil using an ISO headform fitted with a uniaxial accelerometer at its center of gravity. The second methodology involved striking a Hybrid III head and neck mounted to a linear bearing track with a pendulum impactor. The use of a linear bearing track permitted the Hybrid III headform to move freely following the initial impact. At the distal end of the pendulum, a flat steel anvil was used to represent the impacting object. This configuration was felt to represent a head check from an opposing player, believed to be one of the mechanisms of head injury in ice hockey. Linear and angular acceleration measurements were recorded for all pendulum tests. High speed video was used to capture all headform motion. A total of six different helmet models were evaluated using both test methodologies. Peak linear headform accelerations were compared between helmet models tested using the monorail drop system and the identical helmet model tested using the impact pendulum. The results showed significant differences between helmet models as well as between the two different test methodologies. The implications of these results relative to current ice hockey standards and relative to head injury in ice hockey are discussed.
Translational and Rotational Accelerations Generated during Reconstructed Ice Hockey Impacts on a Hybrid III Head Form
Authors: Coulson N. R. , Foreman S. G. , Hoshizaki T. B.
Published: March 2010

In this study, the relationship between flagrant impacts to the head and peak translational and rotational accelerations in reconstructed ice hockey impacts was examined. A Hybrid III head-neck complex attached to a sliding table and equipped with nine accelerometers was fitted with an ice hockey helmet and impacted under various striking conditions through the head form's center of mass. Eight right-hand-dominant male ice hockey players carried out three maximal impacts for each of the striking techniques, and peak translational and rotational accelerations were measured. It was found that the highest mean translational and rotational accelerations were generated during the slashing trials to a static head form (138 g and 14, 100 rad∕s2, respectively), while the lowest mean translational and rotational accelerations were produced in the static crosschecking (26.5 g) and moving crosschecking trials (2,260 rad∕s2), respectively. The reconstruction of illegal impacts reflecting flagrant fouls in ice hockey can generate peak translational and rotational accelerations great enough to cause concussive injuries. Accordingly, these types of injurious infractions must be prevented.
A Comparison of Peak Linear and Angular Headform Accelerations Using Ice Hockey Helmets
Authors: Rousseau P. , Post A. , Hoshizaki T. B.
Published: March 2010

The objective of this study was to quantify the ability of hockey helmets to manage peak angular and linear acceleration of the center of gravity of a Hybrid III headform at six impact locations and three velocities (5, 7, and 9 m∕s). The method was intended to represent a reconstruction of helmet, shoulder, and elbow strikes to the head. Six different ice hockey helmets were impacted using a pneumatic linear impactor at velocities similar to those encountered in ice hockey. The results were then compared to impacts to an unhelmeted headform. The data demonstrated that under certain conditions, peak angular accelerations were above estimated injury thresholds, while peak linear accelerations remained below. This confirmed the importance of measuring peak angular acceleration and peak linear acceleration in order to better predict minor traumatic brain injuries.
Preliminary Evaluation of Selected Hockey Equipment Tested according to EN TS15256: Protective Clothing—Hand, Arm, Leg, Genital, and Neck Protectors for Use in Ice Hockey—Protectors for Players Other than Goalkeepers—Requirements and Test Methods
Authors: Bishop Patrick J.
Published: March 2010

Several randomly selected models of three types of protective equipment for ice hockey, protective cups, shoulder pads, and shin pads, were tested according to CEN∕TS 15256. Three of the nine models of genital protectors, three of the four models of shoulder pads, and four of the fifteen models of shin pads exceeded the threshold limits defined in the Technical Specification. However, these results were not well correlated with injury data to these regions of the body as provided by Hockey Canada. It would appear that the test protocols stated in TS 15256 are not reflective of the reality of the game of ice hockey and if used are likely to drive very adequately functioning equipment from the hockey market. Substantial changes to the test methods must be considered as standards and technical specifications, or both, for personal protective equipment for ice hockey are developed.
In situ Measures of Head Impact Acceleration in NCAA Division I Men's Ice Hockey: Implications for ASTM F1045 and Other Ice Hockey Helmet Standards
Authors: Gwin Joseph T. , Chu Jeffery J. , McAllister Thomas A. , Greenwald Richard M.
Published: March 2010

A pilot study was performed to measure head impact accelerations in collegiate men's ice hockey during the 2005–2007 seasons using helmets instrumented with Head Impact Telemetry System technology to monitor and record linear head accelerations and impact locations in situ. The objectives of this study were (1) to quantify the relationship between resultant peak linear head acceleration and impact location for in situ head impacts in collegiate men's ice hockey, (2) to quantify the frequency and severity of impacts to the facemask, and (3) to determine if in situ impacts occurred such that the peak resultant linear head acceleration was higher than the peak resultant linear headform acceleration from a 40-in. linear drop (as in ASTM F1045-99) on the same helmet at a similar impact location. Voluntary participants (n=5 and 7 for years 1 and 2, respectively) wore instrumented helmets which monitored head impact accelerations sustained by each player during all games and practices. Head impact data were grouped by impact location into five bins representing top, back, side, forehead, and facemask. Forehead impacts represented impacts to the helmet shell as distinguished from facemask impacts. Additionally, a sample instrumented helmet was impacted in the laboratory at forehead, side, rear, and top impact locations (40-in. drop, three trials per location, test setup as specified in ASTM F1045-99). The mean peak resultant linear headform acceleration for each impact location was determined for analysis. Of the 4,393 recorded head impacts, 33.2 % were to the back of the helmet. This percentage increased to 59.2 % for impacts above 70 g. Facemask impacts accounted for 12.2 % of all impacts but only 2.4 % of impacts above 70 g. Over two seasons, five in situ impacts occurred such that the peak resultant linear head acceleration was greater than the mean peak resultant linear headform acceleration for a corresponding impact location in the laboratory. This study found that the most common impact location in ice hockey, particularly for impacts with higher peak linear accelerations, was the back of the head and demonstrated that facemask impacts were typically of a lower magnitude. The five impacts or ∼0.4 per player∕season that exceeded the peak linear acceleration associated with 40-in. laboratory drops suggested that the impact energy specified in ASTM F1045 may not reflect the highest energy impacts seen in situ.
Measuring Athlete Exposure and Body Contact Using Time-on-Task Technology in Ice Hockey
Authors: Faught Brent E. , Baker Joseph , Cairney John , Corey Paul N. , Montelpare William J. , Nystrom Murray
Published: March 2010

It is common for athlete exposure (AE) and body contact (BC) to be incorrectly estimated in epidemiologic research due to the technical challenges associated with field-based research in ice hockey. Time-on-task technology has shown promise in accurately quantifying AE and BC using computer technology through direct measurement during real time games. The purpose of this prospective cohort study was to adopt time-on-task technology to monitor AE and BC in Atom hockey players who were permitted body checking versus those not allowed to body check. We evaluated 579 boys (age 9–10 year olds) from 42 representative Atom hockey teams over 107 games during the 2003–2004 regular season from five hockey associations using a time-on-task computing program running on a tablet computer. Body checking was allowed in four associations [Northern Ontario Hockey Association (NOHA), Minor Hockey Alliance of Ontario, Ontario Minor Hockey Association, Greater Toronto Hockey League], while one association was non-body checking (HNO). Body contact was 4.5 times greater in the body checking associations versus the non-body checking association per game. No significant difference in mean AE per game was found between body checking and non-body checking associations. However, greater AE was reported in NOHA games compared to the remaining four associations. Conversely, BC in the NOHA was significantly less compared to the remaining body checking associations, but not the HNO. Time-on-task technology was valuable in monitoring AE and BC, accounting for variability in individual players. Expected AE and BC was observed between checking and non-body checking associations. Unexpectedly larger AE in NOHA is attributed to smaller team roster size and longer duration games. Furthermore, decreased BC in NOHA players may be due to smaller roster size intrinsic factors contributing to the inverse relationship between AE and BC. Time-on-task technology is valuable in monitoring AE and BC in Atom ice hockey. This is a practical method of monitoring important aspects of the game.
Warnings and Instructions: One of Three Legs on Ice Hockey's Safety Stool
Authors: Granger Mark S. , Miosek Ryan W.
Published: March 2010

Ice hockey is a fast-moving, action-packed contact sport. With any high-action sport there is a risk of serious personal injury and possibly even death. The combination of fast play, substantial contact, and high speed with good-size force, hard ice, and unyielding boards creates potential for injury. The sport has responded to these factors by controlling and setting rules for play, designing protective equipment to reduce the risk of serious personal injury or death, and providing warnings and instructions both on protective gear and through the amateur leagues and school coaching. This paper will primarily deal with this third leg of the safety stool with a primary emphasis on the warnings and instructions provided on the actual equipment and with accompany materials.
Pals1 Is a Major Regulator of the Epithelial-Like Polarization and the Extension of the Myelin Sheath in Peripheral Nerves
Authors: Özçelik Murat , Cotter Laurent , Jacob Claire , Pereira Jorge A. , Relvas João B. , Suter Ueli , Tricaud Nicolas
Published: March 2010

Diameter, organization, and length of the myelin sheath are important determinants of the nerve conduction velocity, but the basic molecular mechanisms that control these parameters are only partially understood. Cell polarization is an essential feature of differentiated cells, and relies on a set of evolutionarily conserved cell polarity proteins. We investigated the molecular nature of myelin sheath polarization in connection with the functional role of the cell polarity protein pals1 (Protein Associated with Lin Seven 1) during peripheral nerve myelin sheath extension. We found that, in regard to epithelial polarity, the Schwann cell outer abaxonal domain represents a basolateral-like domain, while the inner adaxonal domain and Schmidt–Lanterman incisures form an apical-like domain. Silencing of pals1 in myelinating Schwann cellsin vivoresulted in a severe reduction of myelin sheath thickness and length. Except for some infoldings, the structure of compact myelin was not fundamentally affected, but cells produced less myelin turns. In addition, pals1 is required for the normal polarized localization of the vesicular markers sec8 and syntaxin4, and for the distribution of E-cadherin and myelin proteins PMP22 and MAG at the plasma membrane. Our data show that the polarity protein pals1 plays an essential role in the radial and longitudinal extension of the myelin sheath, likely involving a functional role in membrane protein trafficking. We conclude that regulation of epithelial-like polarization is a critical determinant of myelin sheath structure and function.
Searching for Autocoherence in the Cortical Network with a Time-Frequency Analysis of the Local Field Potential
Authors: Burns Samuel P. , Xing Dajun , Shelley Michael J. , Shapley Robert M.
Published: March 2010

Gamma-band peaks in the power spectrum of local field potentials (LFP) are found in multiple brain regions. It has been theorized that gamma oscillations may serve as a ‘clock’ signal for the purposes of precise temporal encoding of information and ‘binding’ of stimulus features across regions of the brain. Neurons in model networks may exhibit periodic spike firing or synchronized membrane potentials that give rise to a gamma-band oscillation that could operate as a ‘clock’. The phase of the oscillation in such models is conserved over the length of the stimulus. We define these types of oscillations to be ‘autocoherent’. We investigated the hypothesis that autocoherent oscillations are the basis of the experimentally observed gamma-band peaks: the autocoherent oscillator (ACO) hypothesis. To test the ACO hypothesis, we developed a new technique to analyze the autocoherence of a time-varying signal. This analysis used the continuous Gabor transform to examine the time evolution of the phase of each frequency component in the power spectrum. Using this analysis method, we formulated a statistical test to compare the ACO hypothesis with measurements of the LFP in macaque primary visual cortex, V1. The experimental data were not consistent with the ACO hypothesis. Gamma-band activity recorded in V1 did not have the properties of a ‘clock’ signal during visual stimulation. We propose instead that the source of the gamma-band spectral peak is the resonant V1 network driven by random inputs.
Wavering Sonorities and the Nascent Film Noir Musical Style
Authors: Hickman Roger
Published: March 2010

Film noir emerged in the early 1940s and remained a potent force in Hollywood filmmaking for nearly two decades. In the groundbreaking article “Notes on Film Noir,” Paul Schrader observes, “Most every dramatic Hollywood film from 1941 to 1953 contains some noir elements.”1 Because of this pervasive influence, film noir has received extensive coverage in both scholarly and popular press. Yet a precise definition of the movement is elusive. Cinema studies offers no consensus as to whether film noir is a genre or just a style, what the defining characteristics are, when the movement began, and which films should be included in its canon. The situation remains much as Schrader described in 1972, “Almost every critic has his own definition of film noir.”2 Unfortunately, most of these definitions do not consider music. Relatively little has been written about music for film noir. Cinema scholars have concentrated on its visual and dramatic qualities,3 and musical scholars have treated the topic within larger contexts or have focused on the singular aspect of jazz.4 Further research into the music of film noir bears significance both to cinema studies, where it can clarify further the notion of “noirness,” and to musicology, where it can illuminate the expanding roles of both popular and modern musical styles in Hollywood films during the 1940s and 50s.
PCR-RFLP of 16S ribosomal DNA to confirm the identification of Enterococcus gallinarum and Enterococcus casseliflavus isolated from clinical and food samples
Authors: Medeiros Aline Weber , d'Azevedo Pedro , Pereira Rebeca Inhoque , Cassenego Ana Paula , Van Der Sand Sueli , Frazzon Jeverson , Frazzon Ana Paula Guedes
Published: March 2010

INTRODUCTION: This study aimed to confirm the identification of Enterococcus gallinarum and Enterococcus casseliflavus isolated from clinical and food samples by PCR-RFLP. METHODS: Fifty-two strains identified by conventional biochemical exams were submitted to PCR amplification and digested with HinfI. Only 20 (38.5%) of the 52 strains showed a DNA pattern expected for E. gallinarum and E. casseliflavus. RESULTS: Analysis of the results of this study showed that E. gallinarum and E. casseliflavus are occasionally erroneously identified and confirmed the potential application of 16S rDNA analysis for accurate identification of these species. CONCLUSIONS: A correct identification is important to distinguish between intrinsic and acquired vancomycin resistance.
Produção científica publicada pelas enfermeiras de hospitais públicos e privados do município de São Paulo
Authors: Salzano Sonia Della Torre , Stefanelli Maguida Costa , Adami Nilce Piva , Jorge Ana Lúcia Silva , Castro Rosa Aparecida Pimenta de , Silva Isília Aparecida
Published: March 2010

Estudo realizado em sete hospitais públicos e seis privados do Município de São Paulo, relacionado à publicação da produção científica realizada pelas enfermeiras, assistenciais, no período de janeiro de 1989 a junho de 1995. Foram apontadas 486 publicações, sendo 242 sob a forma de resumos, 124 em anais, 92 em periódicos nacionais e internacionais, 21 capítulos de livros e 7 livros na área de enfermagem. Aparecem também, as facilidades e dificuldades encontradas para a publicação dos trabalhos científicos, manifestadas pelas enfermeiras.