bluuebunny/crossref_metadata_2025 huggingface dataset:
Prediction of Crack Growth Under Variable-Amplitude and Spectrum Loading in a Titanium Alloy
Authors: Newman JC , Phillips EP
Published: April 2008

The present paper is concerned with the application of a plasticity-induced crack-closure model, FASTRAN, to predict fatigue-crack growth under various load histories in a thin-sheet Ti-62222 STA titanium alloy. This alloy was a leading candidate for a metallic High-Speed-Civil-Transport (HSCT) aircraft in the United States. The crack-growth model was based on the Dugdale strip-yield model but modified to leave plastically deformed material in the wake of the advancing crack. The model includes the influence of “constraint” on the development of plasticity and closure during constant- and variable-amplitude load histories. The model was used to correlate crack-growth-rate data under constant-amplitude loading over a wide range in crack-growth rates and stress ratios at two service temperatures (room temperature and 175°C). Tests on repeated spike overloads were used to help establish the constraint variations in the model. The model was then used to predict crack growth under two simulated aircraft spectrum load histories at the two temperatures. The spectra were a commercial HSCT wing spectrum and the Mini-TWIST (transport wing spectrum). This paper will demonstrate how constraint plays a leading role in the retardation and acceleration effects that occur under variable- amplitude and spectrum loading. The model was able to calculate the effects of repeated spike overloads on crack growth at the two temperatures, generally within about ± 30 %. Also, the predicted crack-growth behavior under the HSCT spectrum agreed well with test data (within 30 %). However, the model under-predicted the fatigue-crack-growth behavior under the Mini-TWIST spectrum by about a factor-of-two. Some of the differences may be due to fretting-product-debris-induced closure or three-dimensional effects, such as free-surface closure, not included in the model. Further study is needed on life predictions under the Mini-TWIST flight spectrum.
Crack Growth and Closure Behavior of Short and Long Fatigue Cracks under Random Loading
Authors: Song J-H , Kim C-Y , Lee S-Y
Published: April 2008

Crack growth and closure behavior of physically short and conventionally long cracks under random loading are extensively investigated, utilizing test results of 2024-T351 aluminum alloy obtained by performing narrow- and wide-band random loading tests for various stress ratios and random loading block lengths. A noise reduction method is developed to determine the crack opening load under random loading more easily, precisely, and economically. Crack growth rates are analyzed mainly in terms of the stress intensity factor range estimated by 2/PI correction proposed by Donald and Paris. The long and short cracks are very different in characteristics of closure behavior under random loading. Crack growth of short and long cracks under random loading can be well described by the crack closure concept. The effects of random spectrum or random block length on crack opening load and crack growth are not significant.
Calculation of Stress Intensity Factors for Cracks in Structural and Mechanical Components Subjected to Complex Stress Fields
Authors: Wu Z , Glinka G , Jakubczak H , Nilsson L
Published: April 2008

One of the difficulties in using fracture mechanics is in determining stress intensity factors of cracked structural and mechanical components. The cracks are often subjected to complex stress fields induced by external loads and residual stresses resulting from the surface treatment. Both stress fields are characterized by non-uniform distributions, and handbook stress intensity factor solutions are seldom available in such cases. The method presented below is based on the generalized weight function technique enabling the stress intensity factors to be calculated for any Mode I loading applied to a planar semi-elliptical surface crack. The stress intensity factor can be determined at any point on the crack tip contour by using the general weight function. The calculation is carried out by integrating the product of the stress field and the weight function over the crack area.

Several examples of point-load weight functions and resulting stress intensity factors are presented in the paper. The method is particularly suitable for modeling fatigue crack growth in the presence of complex stress fields.
Fatigue Life Modelling and Accelerated Tests for Components under Variable Amplitude Loads
Authors: El-Ratal W , Bennebach M , Lin X , Plaskitt R
Published: April 2008

This paper focuses on computer-based techniques used for optimizing and accelerating laboratory fatigue tests. After a short review of the available methodologies, a practical application is presented on a real automotive component undergoing complex loadings. Using a multi-axial non-proportional fatigue damage model to identify damaging sections of loading histories, combined with advanced joining functions of retained time windows, allows accelerating the full test from 34 days to 11 days. Applying the edited signals enables testing 3 suspension modules for the same duration needed to test one system using the original time histories. This reduces costs, time to market and increases design confidence.
High Cycle Fatigue Testing and Analysis Using Car Standard Sequence
Authors: Morel F , Ranganathan N
Published: April 2008

An original computer software package for controlling a servo-hydraulic machine was used to carry out uniaxial and biaxial variable amplitude loading tests on a high strength steel. Tension-compression and torsion uniaxial tests, as well as combined proportional tension-torsion tests were performed under the car loading sequence CARLOS used for fatigue strength investigations of car wheel suspension components. The number of sequences to crack nucleation was estimated by means of a crack front marking technique using very small amplitude cycles to generate marker bands on the fracture surface. The experimental data obtained from these tests were compared to the predictions of the fatigue life prediction method proposed by Morel and based on a microplasticity analysis. It was shown that all the predictions, though non-conservative, were within an acceptable scatter band.
Periodic Overloads in the Near Threshold Regime
Authors: Tabernig B , Pippan R , Foulquier J , Rapaport A , Sereni S
Published: April 2008

The effect of periodic overloads on the crack propagation behavior in the near threshold regime of long cracks and physically (extrinsically) short cracks is investigated. A 20 Vol. % SiC particle reinforced 359 cast aluminum alloy and a 17 Vol. % SiC particle reinforced 2129 aluminum alloy are examined. In the Paris regime the two alloys exhibit a different behavior. In the 2124 reinforced alloy a reduction of the mean crack propagation rate, which is typical for ductile metals, is observed. On the other hand the mean crack propagation rate accelerates in the 359 reinforced cast alloy, which is caused by generation of micro-cracks during the overload.

In the near threshold regime and at smaller stress intensity ranges in the physical short crack regime the behavior of both alloys is very similar. The effective threshold is not affected by the overload, i.e., if the constant amplitudes are smaller than the effective threshold they do not contribute to crack propagation. If both, the constant amplitudes and the overload amplitudes contribute to crack propagation, the build up of crack closure is affected by the load history.
Fatigue Reliability Analysis of an Overload Effect in Welded Joints Including Crack Initiation and Plastic Zone as Random Variables
Authors: Darcis P , Recho N
Published: April 2008

This paper deals with the reliability analysis of the influence of an overload on the fatigue design of welded joints. The modeling of the fatigue life is presented as the sum of four parts: the first one concerns the fatigue life initiation, the second one involves the fatigue life between the initiation period and the overload application, the third one deals with the fatigue life behavior from the overload to the total restoration of the crack growth rate, and the fourth is related to the fatigue life between the end of the retardation zone until the failure. Concerning the modeling of the retardation effect, particular attention is given to the calculation of the effective stress intensity factor. Finally, the developed methodology is applied to the case of welded joints in order to evaluate the importance of considering the overload effect in the reliability analysis.
Probabilistic and Semi-Probabilistic Format in Fatigue Ship Classification Rules
Authors: Huther M , Mahérault S , Parmentier G , Césarine G
Published: April 2008

Following a short review of the ship classification principle, of the cyclic fatigue in ship structures, the deterministic format based on S-N curves is reviewed. First, the probabilistic format for fatigue verification using S-N curves is presented with emphasis on the uncertainties and limits of use versus ship structures design. Then the semi-probabilistic format, as used in the new Bureau Veritas BV2000 rules for steel ships is presented. Particular attention is given to the selected partial safety factors versus the other failure modes. The calculation of those partial safety factors is also analysed, based on practical cases. As a conclusion, the interest of the probabilistic approach versus the deterministic one is outlined. Then the limits of practical applications, semi-probabilistic for design and drawing approval, probabilistic for rule developers and RBI are discussed. To end, the research and development needs for future are pointed out.
Fatigue Life of a SG Cast Iron under Real Loading Spectra: Effect of the Correlation Factor Between Bending and Torsion
Authors: Banvillet A , Palin-Luc T , Vittori JF
Published: April 2008

This paper deals with the effect on life of the desynchronism between two variable amplitude load sequences in combined bending and torsion. Experiments were carried out on smooth specimens made of the EN-GJS800-2 cast iron. The comparison between experimental lives and predicted ones with the following fatigue life calculation methods is presented: Smith-Watson-Topper, Fatemi and Socie (method proposed by Bannantine), Wang and Brown, Socie's proposal for high cycle fatigue, and Morel. If the scatter of experiments is considered, these experiments show a low effect of the correlation factor on life. All the simulated fatigue life calculation methods give good results for proportional loads, but their predictions are not good for non-proportional loads. Morel's proposal seems to be the best to predict life of the tested material with our non-proportional fatigue test conditions.
Modelling of Hysteresis Loops During Thermomechanical Fatigue
Authors: Sandström R , Andersson HCM
Published: April 2008

The hysteresis loops obtained during thermomechanical fatigue testing of the stainless steel 253 MA and the ODS alloy PM2000 have been analysed using a model taking elastic, plastic, and creep deformation into account. Data from previously performed creep and tensile tests were used to determine the constants in the model. Hysteresis loops both from in-phase and out-of-phase cycling were successfully reproduced. By integrating the fatigue and creep damage along the hysteresis loops, the cyclic lifetimes of 253 MA were predicted.
Damage and Failure Mechanisms of Thermal Barrier Coatings under Thermomechanical Fatigue Loadings
Authors: Tzimas E , Hähner P , Moretto P , Peteves SD , Bressers J
Published: April 2008

The mechanical behavior of thermal barrier coated (TBC) systems under the influence of combined thermal and mechanical cyclic loading has been studied using a prototype experimental configuration that simulates realistically the operational conditions within a gas turbine. This study has demonstrated that the failure mechanisms of TBC systems under thermomechanical fatigue (TMF) conditions depend on the range of applied mechanical strain and on the phase angle between thermal and mechanical loading. The results highlight the importance of proper design of TMF experiments so that the failure mechanisms activated and studied during the experiments are the mechanisms responsible for the failure of TBC systems under service conditions.
Using Fracture Mechanics Concepts for a Mechanism-Based Prediction of Thermomechanical Fatigue Life
Authors: Christ H-J , Teteruk R , Jung A , Maier HJ
Published: April 2008

An extensive database on the isothermal and thermomechanical fatigue behavior of high-temperature titanium alloy IMI 834 and dispersoid-strengthened aluminum alloy X8019 in SiC particle-reinforced as well as non-reinforced condition was used to evaluate both the adaptability of fracture mechanics approaches to TMF and the resulting predictive capabilities of determining material life by crack propagation consideration. Emphasis was put on the selection of the correct microstructural concepts, then adjusting them using data from independent experiments in order to avoid any sort of fitting. It is shown that the cyclic J-integral (ΔJeff concept) is suitable to predict the cyclic lifetime for conditions where the total crack propagation rate is approximately identical to plain fatigue crack growth velocity. In the case that crack propagation is strongly affected by creep, the creep-fatigue damage parameter DCF introduced by Riedel can successfully be applied. If environmental effects are very pronounced the accelerating influence of corrosion on fatigue crack propagation can no longer implicitly be taken into account in the fatigue crack growth law. Instead, a linear combination of the crack growth rate contributions from plain fatigue (determined in vacuum) and from environmental attack was assumed and found to yield a satisfactory prediction, if the relevant corrosion process is taken into account.
Thermomechanical Fatigue Behavior of an Aluminide-Coated Monocrystalline Ni-Base Superalloy
Authors: Grube F , Affeldt EE , Mughrabi H
Published: April 2008

This study is part of a project concerned with the effect of diffusional aluminide coatings on the stress response and life of a coated monocrystalline nickel-base superalloy (CMSX-6) during thermomechanical fatigue (TMF) testing.

In this project, the effects of different platinum-modified aluminide coatings are studied. To separate the effects induced by the coatings from other effects with respect to the TMF life, uncoated specimens are investigated as reference specimens.

In this paper, TMF studies on specimens coated with a two-phase platinum-modified aluminide coating are reported. The TMF tests were performed with a particular type of asymmetric counterclockwise diamond cycle (lower and upper temperatures: 400 °C and 1100 °C, respectively) representing typical loads experienced by turbine blades under conditions of service during start-up and shut-down operation. The life of the specimen is determined by crack initiation and propagation. Crack initiation is observed to occur early during TMF life at the surface of the coating as a consequence of its brittleness at low temperatures. Thus, the coating shortens the life of the substrate-coating system. In this context, the characteristics of the two-phase platinum-aluminide coating studied here and its influence on the mechanisms of crack initiation and propagation during TMF are of special interest.
The Fatigue Behavior of NiCr22Co12Mo9 Under Low-Frequency Thermal-Mechanical Loading and Superimposed Higher-Frequency Mechanical Loading
Authors: Moalla M , Lang K-H , Löhe D
Published: April 2008

The repeated start-ups and shut-downs experienced by gas turbines cause complex thermal-mechanical loading, which may result in the low-cycle fatigue failure of components such as the walls of the combustion chambers. In addition, a higher frequency high cycle fatigue loading (HCF) is often superimposed due to mechanical vibrations and unsteady combustion processes. It is known that such a superimposed HCF loading may not only change the cyclic deformation behavior, but also reduce the lifetime considerably. In the present study, the cyclic response of a combustion chamber material, NiCr22Co12Mo9 (Inconel 617), was investigated under combined TMF/HCF loading in total strain controlled out-of-phase (OP) and in-phase (IP) TMF tests with and without superimposed HCF loading. The minimum temperature of the TMF tests was 200 °C, and the maximum temperature was varied from 750 to 1200 °C. For each maximum temperature condition, the superimposed HCF amplitude was varied between 0 and 0.2%. Cyclic hardening was observed, but it became less pronounced the higher the maximum temperature, and at the highest Tmax the material was cyclically neutral. With increasing superimposed HCF amplitude the cyclic deformation behavior was more and more determined by the HCF. Further, as a result of the superimposed HCF loading the TMF lifetimes decreased significantly. In general, the lifetimes decreased with increase in HCF amplitude and approached only 10% of the fatigue lifetime obtained in the pure TMF experiments. The relation between the applied total strain amplitude, εa,tme,and the number of cycles to failure, Nf, could be expressed as εa,tme = A ∙ Nf-b for each Tmax and type of TMF-test. With the use of this empirically determined relationship it was possible to estimate the lifetime reduction caused by a superposition of a higher frequency HCF loading on the OP- as well as IP-TMF loading.
Thermomechanical Fatigue Behavior of Stainless Steel Grades for Automotive Exhaust Manifold Applications
Authors: Santacreu P-O , Simon C , Coleman A
Published: April 2008

This paper describes a study performed on the thermomechanical fatigue behavior of stainless steel grades for exhaust systems, especially for exhaust manifolds. A testing rig has been developed to characterize the thermomechanical fatigue resistance of bent stainless steel sheets. In particular, the behaviors of ferritic and austenitic stainless steels are compared. After the identification of the elasto-viscoplastic constitutive law of the materials, the numerical simulation of the test is performed, enabling the computation of the viscoplastic strain accumulated during each cycle. Examination of the failed specimens indicated that cracks could be mainly attributed to out-of-phase thermomechanical fatigue in the case of ferritic grades and to in-phase thermomechanical fatigue in the case of austenitic grades. A Taira type damage criterion is proposed, which correlates the amplitude of the viscoplastic strain and the number of cycles to failure. But due to a coupling with oxidation and creep during in-phase thermomechanical fatigue, the phasing between the thermal and the mechanical loads has to be taken into account in the criteria. The hydrostatic pressure at maximum temperature is proposed as such a phasing factor.
Analysis of Thermal Gradients during Cyclic Thermal Loading under High Heating Rates
Authors: Affeldt EE , Hammer J , Huber U , Lundblad H
Published: April 2008

The magnitude of temperature gradients and their variation with temperature and time was investigated for a thermomechanical fatigue (TMF) cycle between 400°C and 1100°C under a heating rate of 10°C/s. The measurements of the temperature distribution in the gauge section of a flat rectangular specimen of the Nickel base superalloy CMSX-6 were carried out by means of thermocouples located at various positions on the surface and in the volume, respectively. As a reference the temperature distribution was calculated by finite element analysis based on the temperature signal of the control thermocouple. Additionally, the surface temperature distribution was studied by thermographic measurements.

The results reveal that thermal gradients establish in longitudinal and in transverse direction of the gauge section. Although the temperatures in the bulk material exceed the reference given by the control signal during the entire cycle, this effect is most pronounced (+40°C) during cooling by forced air. In comparison, the predictive results of the finite element calculation lead to slightly enhanced surface temperatures during heating (+8°C) and to reduced surface temperatures during cooling (-5°C). Therefore, it is concluded that heat transport in the bulk material is sufficiently fast to guarantee almost homogeneous temperature distribution. The significantly enhanced volume temperatures in the experiment were found to result from influences of the experimental set-up, and from superimposed effects due to forced air cooling and heat flow through the wires of the spot welded thermocouple.
Measuring Uplift Resistance of Asphalt Shingles
Authors: Shiao ML , Snyder RA , Livsey RD , Kalkanoglu HM
Published: April 2008

The uplift resistance of asphalt shingles with self-sealing adhesives is studied by applying mechanical forces to examine the effects of loading geometry, shingle rigidity, and the rate of load application. Three distinct test methods for simulating the wind-induced uplift effects of peeling, pulling, and its combination are used to study the sealant performance as a function of shingle rigidity and the rate of loading. The results show that the measured sealant strength is significantly influenced by the test and loading configurations, as well as by the loading rate. The current ASTM D 6381 test, which measures the uplift resistance under mechanical peeling action, is found to yield relatively low measured sealant strength as compared to the other test method intended to simulate wind uplift effects according to current wind-uplift force model. Fracture analysis and fractography conducted on test specimens reveal that the measured shingle uplift resistance is significantly increased under high deformation rate due to a transition from failure inside the asphalt coating to adhesive fracture in the sealant by cavitation mechanism.
On the Kinetics of Thermal Loads for Accelerated Aging
Authors: Shiao ML , Nester DA , Terrenzio LA
Published: April 2008

A mathematical model based upon the theory of total cumulative damage has been developed to describe the kinetics of thermal aging in roofing material subjected to changing temperatures and durations. The new model employs a degradation rate function that is derived from a chemical model using a diffusion theory coupled with Arrhenius rate function to describe the temperature dependency of asphalt chemical composition under transient conditions. Such a model enables the construction of master curves in asphalt composition as aged at various temperatures, and may be used to predict the change in property due to heat aging using known roof temperature profile and materials parameters obtained from lab accelerated testing. Examples of the model are demonstrated by using the real-time roof temperature data collected from test houses located in a cold climate of Minnesota and in a hot climate of Florida. The calculations suggest that the high thermal history in a hot climate has a strong effect in accelerating aging of asphalt, particularly during the winter months. Furthermore, the effect of attic ventilation is found to reduce the uneven distribution of total cumulative damage across the roof deck due to unbalanced thermal history found in an unventilated deck. The potential application of the model and its advantage in predicting field properties by simulation are also discussed.
The Weathering Behaviour of Contaminated Industrial Sediments After Their Exposure to Atmospheric Oxygen
Authors: Schubert M , Morgenstern P , Wennrich R , Freyer K , Paschke A , Weiss H
Published: April 2008

Mining and ore processing of “copper shale” in the Mansfeld region, Germany, were stopped in 1990 as a consequence of the obsolete level of the applied technology. One of the residues of the former pyrometallurgical activities is a flue dust, which was scrubbed out of the process gases. The scrubbing resulted in an extremely fine-grained sludge, which was stored in “ponds” where it settled down as sediment. The need to assess the risk of heavy metal emissions posed by such sludge deposits when they dry up and become exposed to weathering prompted the question over the depth to which heavy metals can possibly be mobilized. A drill hole was bored into the dried-up sediment of such a “pond” and the sediment material was analysed. The results show a substantial influence of weathering in the upper 0.5 m of the material, In particular the oxidation of the heavy metal sulphides abundant in the sediment and the subsequent dissolution of the sulphates is nowadays a major problem for the quality of the nearby ground- and surface waters.
Deep-Freeze Sampling Methods for Soft Sediments
Authors: Ricking M , Schulze T
Published: April 2008

Freeze coring systems were applied for sampling high-water-content sediments or very coarse sediments for a couple of years. At the Free University within the last 20 years different systems were developed and applied for sampling the upper 1.5–2.5 m in an undisturbed stratified way. The difficulty in controlling the depth penetration has been overcome by applying a small echo sounding system onboard. The LINDE-LANCE device runs on liquid nitrogen pressurized through a copper pipe, where the sediment freezes in concentric layers onto the lance at -193°C. A low weight system with a closed aluminium lance (CO2-LANCE) running on a eutectic mixture of dry ice and alcohol that freezes the concentric sediment layers onto the lance at -90°C was developed for a much easier sampling by means of a Zodiac. Advantages and limits are addressed.
Quality Evaluation of Eutrophic Sediments at St. Augustin Lake, Quebec, Canada
Authors: Galvez-Cloutier R , Brin M-E , Dominguez G , Leroueil S , Arsenault S
Published: April 2008

St. Augustin Lake is located 20 kilometers west from Quebec City in the territory of Quebec's Provincial Capital. The whole basin land is largely urbanized with some agricultural and wetland zones, some forest spots and surrounded by an important network of highways. The lake neighbors an industrial park that includes airport installations and storage facilities for chemical products. In 1993, a first quality study revealed the presence of some toxic metals in lake sediments. Although, lower levels were found, these analyses were performed at a time where neither standards methods nor quality guidelines were available in Canada. Recently launched, a major City project aims to open the lake to public recreational activities and involves the cleaning of water. St. Augustin Lake is in a eutrophic state most of the year, and all usages have been limited. However, a recent paleo-limnologic study showed that the lake used to be in the past (60 years ago) rather mesotrophic. The water clean-up program cannot succeed without the evaluation and restoration (if needed) of the bottom sediments. Indeed, bottom sediments may constitute important reservoirs for contaminants such as phosphorus, nitrogen, heavy metals and hydrocarbons. These contaminants may be strongly attached to organic colloids, clay and carbonates that are usually present in sediments. This study shows metal profiles and their distribution and correlations between metals and some sediment constituents.
Reclamation Using Waste Sediment by Sand Capping Technique
Authors: Tan TS , Karunaratne GP , Choa V , Bo MW
Published: April 2008

Disposal of unwanted seabed sediment arising from dredging activities is an increasingly intractable problem. One solution is to use the sediment as fill material for land reclamation, as a replacement for sand, the traditional fill. As the water content of sediment is high, even a small fill will ensure rapid consolidation. The underlying philosophy is to place a layer of sand on top of the slurry to accelerate consolidation. This paper summarizes the research carried out in Singapore. A pilot test and a large-scale project will be described and the results from monitoring discussed. A physical framework will then be provided to explain the sand capping of the sediment, followed by the introduction of a simplified model to connect the two key aspects of the mechanics of sand capping, namely the accumulation of sand on the sediment and the way the slurry gained shear strength to resist this load. This simple model was able to produce results consistent with that observed in the field.
Steps for Restoration of a Polluted Egyptian Closed Lagoon on the Alexandria Mediterranean Coast
Authors: El-Rayis OA
Published: April 2008

Lagoon (or Lake) Maryout Main Basin is one of the lagoon's four sub-basins, polluted with organic and metals contaminants from untreated sewage and industrial effluents from Alexandria City. Since 1993, these effluents have become primary treated before discharging into this basin through two point sources; one source is at a new site, as a step in rehabilitating the lagoon. Surface sediment samples were collected 3 years later, from the Main Basin as well as from the other three basins of the lagoon to determine the level of nine priority metal pollutants as well as organic carbon (Org-C). The data reveal that the sediments of the Lagoon Main Basin, particularly that in vicinity of the new point source, became spoiled and remarkably enriched with all the studied contaminants. In addition, some of the studied metals are at levels comparable to those of the median effect-range of Long and Morgan recommended by the EPA. This means that either diversion or advanced treatment is necessary to eliminate these effluents.
A Reactive Geocomposite to Remediate Contaminated, Subaqueous Sediments
Authors: Sheahan TC , Alshawabkeh A , Fernandez LA , Henry KS
Published: April 2008

This paper describes a new geocomposite overlay, consisting of filter fabric layers surrounding a chemically reactive core, that is being developed to contain and remediate contaminated, subaqueous sediments. This geosynthetic-based reactive material will provide the same isolation as that of traditional soil caps, but will have the added advantages of: providing a remediation layer to adsorb and neutralize target contaminants; block resuspension of fine sediment particles; and serve as a foundation material during remediation. In addition, the geocomposite could be used in a tube configuration to simultaneously store and remediate dredged sediments. The paper describes the results of a two-phase, bench-top experimental program to assess the feasibility of this idea and to help model its scalability for sediment remediation in the field. This testing consisted of two parts: one-dimensional consolidation testing on layered systems of very soft soils and geotextiles, both woven and non-woven; and sorption isotherm testing of lead ions (Pb+2), in solutions of various pH and salt concentration, for both soil and zeolite. Results show the effects of the two geotextile types on the soil-geotextile system during consolidation, including changes in coefficients of consolidation and hydraulic conductivity. The adsorption tests show the effectiveness of the zeolite in binding the lead ions, and the soil's potential for lead adsorption under a variety of pH and salt concentrations.
Issues Related to the Flammability Assessment of Polymers for Hazard Analyses of Oxygen Systems
Authors: Hirsch D , Motto S , Porter A , Beeson H , Pedley MD
Published: April 2008

During hazard analyses of oxygen-enriched systems, the flammability of polymers is commonly assessed by reviewing standard limiting oxygen index (LOI) data available in the literature and summarized in ASTM Standard Guide for Evaluating Nonmetallic Materials for Oxygen Service (ASTM G 63). The data provided by this standard may not correlate with many real-life fire scenarios. Two of the most common issues relate to the direction of flame propagation recommended by the method and the test environment temperature. Modifications of these two parameters could render most polymers flammable, which under standard testing conditions set forth by ASTM G 63 would be considered nonflammable. Modified LOI tests were conducted on 16 polymers to determine the magnitude of these effects. The results indicate that the existing data presented in ASTM G 63 should be used with caution. Furthermore, modified oxygen index data should be included in standard guides for oxygen systems design.
Upward Flammability Testing — A Probabilistic Measurement
Authors: Engel CD , Davis SE , Richardson EH
Published: April 2008

Examination of NASA-STD-6001 Test 1 data suggests burn length outcome for a given environment has a large statistical variation from run to run. Large data sets show that burn length data form cumulative probability distribution curves, which describe a material's characteristic to burn in a specific environment, suggesting that the current practice of testing three samples at specific conditions is inadequate. Sufficient testing can establish material characteristics probability curves to provide the probability that a material will sustain a burn length of at least 15.24 cm (6.0 in.) or will sustain burning until all material is consumed. A simple pass/fail criterion may not be possible or practical. Future application of flammability data for some material classes may require the engineer to assess risk based on the probability of an occurrence and the probable outcome with different materials as characterized with cumulative burn length distributions for specific use conditions.
Filters for Use in High Pressure Oxygen Service—Qualification and Test Methods
Authors: Barthélémy H , Roy D , Schaaff JP
Published: April 2008

Filters are very often used for oxygen equipment. Their role is normally to prevent downstream contamination of components by particles and dust, and thus may help to prevent ignition caused by particle impact or static electricity buildup. They also create a pressure drop upstream from internal components, which may help decrease the risk of ignition by adiabatic compression. However, filters are sometimes the cause of ignition. Lack of maintenance or poor design can lead to the creation of local restrictions or dead ends and thus increase the risk of ignition at the filter level due to adiabatic compression. They can also fail and suddenly release blocked contamination that can possibly cause ignition by particle impact. In this paper, we are proposing a test method to qualify some type of filters for oxygen service equipments. It is particularly important to check that they are able to resist particle impacts.
Promoted Ignition and Burning Tests of Stainless Steel in Flowing and Nonflowing Oxygen
Authors: Forsyth ET , Maes M , Stoltzfus JM , Bachelier F
Published: April 2008

The Industry-Sponsored Metals Combustion Test Program 96-1 was coordinated through Wendell Hull & Associates, Inc., on behalf of several contributing companies, and all design and testing was performed at the NASA White Sands Test Facility. Phase I of this test program studied the threshold pressure for self-sustained burning of various types and sizes of stainless steel rods in nonflowing oxygen, as observed in Standard Test Method for Determining the Combustion Behavior of Metallic Materials in Oxygen-Enriched Atmospheres (ASTM G 124-95). Phase II studied the ignition and propagation of burning of 316L stainless steel rods and pipe in flowing gaseous oxygen. The test sample configurations were chosen to replicate previous promoted ignition and burning tests as well as to represent geometries and cross-sectional thicknesses common in industrial piping applications. The gas pressures and velocities for the test matrix were selected to generally compare with CGA G-4.4 guidelines for the use of stainless steel in oxygen service. This paper summarizes the results from the Phase I nonflowing oxygen tests and presents in detail the results of the Phase II flowing oxygen tests. The maximum sample burn-length is shown as a function of test pressure in Phase I and also as a function of gas velocity in Phase II. These results indicate that flowing oxygen, under the given test conditions, significantly affects maximum sample burn length as compared to nonflowing oxygen. Supplementary flowing oxygen test data on stainless steel rods from a follow-up test program are consistent with these results and are presented herein.
Thickness Effects on the Promoted Ignition-Combustion Behavior of Engineering Alloys
Authors: Samant AV , Zawierucha R , Million JF
Published: April 2008

For several years the ASTM G-4 committee has been actively publishing ocuments pertaining to the suitability of using various engineering alloys in oxygen-enriched atmospheres. These publications have resulted in a better understanding of the behavior of materials and have helped industry-wide consciousness of the safety and ntegrity requirements of equipment utilized in the generation, transportation and use of oxygen. However, the majority of promoted ignition-combustion data are based on testing conducted on 3.2-mm-diameter specimens and data on other specimen geometries are limited.

In practice, oxygen systems often use materials in a variety of thicknesses. Hence, here is a need for determining the suitability of using materials of cross sections other than 3.2 mm to represent the various components typically encountered in such systems.

This paper is dedicated to the discussion of thickness effects on the promoted ignition-combustion behavior of a few commonly used austenitic alloys in oxygen-enriched atmospheres. Effects of oxygen gas pressure and material thickness on the combustion behavior of the alloys tested will be discussed.
Australia's Contribution to Advancing the State of Knowledge of Oxygen Systems—the Hard Way: A Review of 30 Years' Incident Experience Down Under, 1965–1995
Authors: McMahon B , Nguyen H
Published: April 2008

Details are given of incidents, known to the authors, involving xygen. They occurred in Australia and might have escaped northern attention. The fuel and sources of ignition are identified for each incident (with oxygen the given third side of the fire triangle). The lessons learned (or to be learned) are recorded.
A Database for Performing and Archiving Oxygen Hazards Analyses
Authors: Peralta SF , Stoltzfus JM
Published: April 2008

ASTM Committee G-04 published several guides and a manual that outline a process for identifying and analyzing fire hazards in oxygen systems. Many companies and government agencies have accepted this process and require hazards analyses to be performed on oxygen systems. When an oxygen hazards analysis is performed, the results are usually documented to identify the hazards associated with the system and its components.

The information needed to perform an oxygen hazards analysis include details on system components, configuration, and operating conditions. Material flammability, ignitability, and potential damage data are also used when analyzing oxygen hazards. In the past, word processing and spreadsheet tools have been used to document results. However, the wide variety of numerical data, explanatory text, and pictures or graphics makes it difficult to retrievably catalog hazards data using word processing and spreadsheet tools.

Recently, the NASA White Sands Test Facility (WSTF) was requested to do an increased number of oxygen hazards analyses. In doing so, it became apparent that many oxygen systems use the same components with slight variations. However, with the existing tools, all data had to be re-entered for each analysis. To increase efficiency and precision of analysis, an electronic database for performing oxygen hazards analyses was developed.

The database provides a repository of all information used in hazards analyses, including drawings, materials data, and environmental information that can be used for future analyses. Furthermore, the analyses of both systems and components remain available for future reference, allowing users to quickly access all data and past analyses as a reference for performing current analyses and answering questions that arise during the process. This paper presents the design, layout, advantages, and potential uses of this database.
A Parametric Modeling Study of the Temperature Dynamics of Contaminated or Damaged Softgoods in Compressed Oxygen
Authors: Wilson DB , Barragan M , Beeson HD
Published: April 2008

The continuing occurrence of fires in systems processing oxidizing gases necessitates further analysis into likely causes. Oil contamination and damaged softgoods have been identified as burning components, while adiabatic compression and particle impact have been identified as ignition sources. This work reports experimental observations on a simulated primary pressure control module in the presence of oil contamination under repeated compression of oxygen. This system is mathematically modeled and studied for the effects of parameter variation. Model parameters are ullage volume, pressure ratio, oil film thickness, softgoods thickness, drop size, and heat transfer. Model analysis is validated by the experimental results.

A generic, lumped parameter heat transfer model of combinations of oil film, softgoods, and metal heat transfer surfaces is developed. This model allows for consideration of damaged softgoods under these previous conditions, and demonstrates the greater susceptibility for fires such a system presents.
Optical Techniques for Viewing Oxygen System Fires
Authors: Gallus TD , Smith SR , Stoltzfus JM
Published: April 2008

White Sands Test Facility has developed several techniques for viewing events inside oxygen systems. In addition, several existing techniques have been refined and customized for this application. Successive refinements and layering of techniques are described. The use of high-speed video is discussed. Techniques for laser illumination and laser bandpass filtering are described. In addition, a still photography method for recording external fire events is described. Finally, a method for temperature mapping in a flowing gas system is described. Applications of all techniques are described.
Preliminary Results of ASTM G175 Interlaboratory Studies
Authors: Smith SR , Stoltzfus JM
Published: April 2008

ASTM G175 is a standard test method for evaluating the ignition sensitivity and fault tolerance of oxygen regulators used for medical and emergency applications. During its development, interlaboratory testing was conducted to assess whether the standard could be performed reproducibly and repeatably. Specifically, this testing examined ignition pill production and the performance of different test systems using test articles manufactured specifically for this testing. Five laboratories used materials provided from single batch lots to manufacture ignition pills, and their heat of combustion was determined and compared to G175 requirements. To determine whether the performance of different test systems would affect upcoming interlaboratory testing, four laboratories tested CGA 870-style test articles manufactured to examine the flame jet resulting from pill ignition. Still photography was used to capture the ignition events; these photos were used to compare test system performance. This paper discusses these results in relation to the repeatability and reproducibility of G175 and the possible effect on future interlaboratory testing, which will involve actual off-the-shelf regulators.
Injuries in Women's Recreational Ice Hockey: Outcome and Follow-up
Authors: Voaklander DC , Dryden DM , Francescutti LH , Spence JC , Rowe BH
Published: April 2008

Participation in ice hockey by women is increasing in many parts of North America; however, research into injuries and the patterns of injury among females associated with this activity is limited. The purpose of this research was to examine the nature and sequelae of injuries suffered by female recreational ice hockey players. This prospective study followed 314 female players from 33 teams in Edmonton, Canada during an entire hockey season. Injury and game attendance data were collected using monthly telephone interviews throughout the season. Six-months-post-injury players were contacted to determine if injuries had modified their desire to continue playing ice hockey. One hundred and two players reported a total of 125 injuries. The anatomic region most often injured was the lower extremity (31.2%), and the most common diagnosis was sprain/strain (52.0%). The predominant injury mechanism was player contact, either as a result of collision with another player or a body check (40.0%). While less than 1% of injuries resulted in hospitalization, 17.6% of injuries resulted in an absence from hockey of eight or more days. Of the 102 players who were injured, 86 (84.3%) responded to the follow-up questionnaire. Seventy-six (88.4%) players indicated that they intended to continue to play hockey. While a number of players acknowledged the possibility and consequences of injury, these were not sufficient to keep them from playing the sport.
Coaches' Perceptions of Aggression in Elite Women's Ice Hockey
Authors: Bloom GA , Vanier JL
Published: April 2008

In the past three decades, there has been a substantial amount of research and public debate regarding aggression and violence in sport, particularly in men's ice hockey. Up to this point, there exists a paucity of research on aggression and violence in women's ice hockey, despite the rapid increase of participants in this sport. The purpose of this study was to address this gap in the literature by summarizing the perceptions of expert coaches of women's ice hockey. A qualitative research methodology was employed in the current study. Four elite ice hockey coaches participated in an in-depth open-ended interview. The results of the study revealed that aggressive techniques were being used in elite women's ice hockey. This paper discusses the causes and ramifications of aggression on women's ice hockey, as well as the impact that the increase of size and strength of the modern female hockey player has had on the sport.
Epidemiology of NCAA Men's Ice Hockey Injuries
Authors: LaPrade RF , Dick RN , Kiff TA , Wentorf FA
Published: April 2008

The purpose of this project was to demonstrate the epidemiology of NCAA ice hockey injuries and to determine any trends in injury occurrence.

The NCAA injury surveillance system for men's intercollegiate ice hockey, which as been prospectively collected in Divisions I, II, and III since the 1986–87 season, was reviewed. Injury rates were expressed as injuries per 1000 athlete exposures (A/E). Practice injury rates in Division I were 2.1/1000 A/E and for Division III were 2.5/1000 A/E from 1986–87 to 2000–01. The game injury rates for both divisions were the same at 17.5/1000 A/E. The rest of the injury data were collated among all three divisions for injury timing (preseason or regular season), injuries requiring surgery, and body part injured.

In conclusion, men's NCAA ice hockey has a low incidence of practice injuries with the highest incidence of these injuries occurring in the preseason. It also has a low rate of surgery compared with all other sports and has a higher than average incidence of injury in games. While shoulder and knee injuries have the highest incidence over time, the incidence of reported concussions has been increasing since 1986–87.
A Review of Ice Hockey Injuries: Location, Diagnosis, Mechanism
Authors: Azuelos YH , Pearsall DJ , Turcotte R , Montgomery DL
Published: April 2008

This review summarizes the published reports of ice hockey injuries sustained by junior level or higher players dating between 1952 and 2000. North American and European results were compared wherever possible. Considerable changes in the general injury profile distribution (i.e., injury location, diagnosis or type, and mechanism) have taken place particularly since the introduction of helmets, facemasks, and the high sticking rule. In brief, the percentages of head and face injuries, lacerations, and injuries caused by the stick have decreased substantially. Conversely, shoulder and knee injuries, contusions, as well as injuries caused through player-player contacts (i.e., checking, being checked, accidental, or intentional) have substantially increased.