bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Atrazine on Aquatic Ecosystems: A Physical and Mathematical Modeling Assessment
Authors: Malanchuk JL , Kollig HP
Published: December 2008

Physical and mathematical models were employed to determine the effects of atrazine on pH, dissolved oxygen, and dissolved nutrients in aquatic systems. The data show that changes in measured variables are observed in the presence of toxicant but that systems recover rapidly when toxicant input ceases. Simple linear donor-controlled mathematical models of nutrient cycles are capable of simulating the effect, although sufficient model detail should be incorporated to account for direct and indirect effects and to improve verification. System measurements are responsive in terms of disruption and recovery. Changes in nutrient cycling patterns should be incorporated into the hazard evaluation process.
A Review of U.S. Marine Fuel Oil Availability and Quality—Present and Future
Authors: Wilkison JL
Published: December 2008

A study of crude availability indicates that enough crude will be available to meet the expected demand well into the twenty-first century. Energy conservation coupled with world crude production capacity indicates stable crude oil prices for the future. Marine Fuel Oil (MFO) will continue to be available in sufficient quantity to meet demand. MFO quality in the United States has not declined since 1980 and is expected to decline but little in the future. Diesel engine developments and improvements in fuel handling equipment are expected to keep pace with any decline in MFO quality. Shell Research has advanced a procedure for ranking the ignition quality of fuels by estimating their aromaticity with an equation based on the fuel's density and viscosity.
Fuel Qualities, On-Board Treatment, and Responsive Design of Two-Stroke Low-Speed Diesel Engines
Authors: Grøne O
Published: December 2008

It has been a basic design criterion that two-stroke low-speed diesel engines should be able to burn the lowest and cheapest qualities of fuel oils that are commercially available. For this reason, extreme fuel qualities, right from their appearance on the market, always have been used in such engines. Developments in the mineral oil industry, well described in numerous articles, have caused an increasing volume of fuel oil to be used in the lower end of the quality scale. Also, a more diversified market pattern has led to the frequent occurrence of such extreme fuels in an increasing number of bunkering ports of the world.

In consequence, it was only natural that a comprehensive test program was initiated a few years ago by the engine industry to meet the challenge raised by this forecasted development. Several samples of fuels were secured from various oil companies. These samples, which came from all over the world for testing, were evaluated by the supplying oil companies as representative of the qualities predicted by the forecasts and, as such, were representative for the fuels on the market in the eighties.

Simultaneously, the engine industry established an increased contact with the manufacturers of equipment for on-board fuel treatment, that is, makers of fuel oil centrifuges, filters, and homogenizers as well as makers of pumps, heat exchangers, etc. Also, the systematic accumulation of service results from these ships in service, which according to experience were originally expected to use larger volumes of such marginal fuel qualities, was intensified. The conclusion of the combustion research was that all these so-called extreme fuel qualities could be used in most larger marine diesel engines as has been the case with the traditional heavy fuels.

The same result was concluded by the plants in service that were especially followed in the fuel research program. However, for the ships in service, it also could be concluded that it was of extreme importance that the on-board fuel treatment was adequate. This paper will describe further the just mentioned tests and service results as well as engine design steps taken dictated by, among other reasons, the fuel quality development. Also, tests with coal derivatives, fuel-water emulsions, as well as fuel oil specification tendencies will be discussed. The practical aspects of using extremely heavy and poor fuel qualities in plants in service will be discussed, especially such issues as fuel oil pretreatment, that is, preheating and cleaning. In particular, installation and service aspects will be enlarged upon, with a look forward to a further decline of fuel qualities.
Shipboard Fuel Handling and Treatment for Diesel Engines
Authors: Winkler MF
Published: December 2008

It is well accepted that, on the average, marine fuel quality has begun to significantly degrade and is beginning to cause increased problems for the operators. Besides representing the largest single voyage expense, marine fuel oils significantly influence the performance, operation, and maintenance of marine power plants. The impact of the fuels' characteristics upon the marine power plant is largely determined by the effectiveness and efficiency of the shipboard fuel conditioning system.

Future marine fuels will continue to degrade in quality and will become more contaminated. The price of these fuel oils will increase as well, with a premium to be paid for blended, spec controlled, and distillate fuels. As the fuel quality purchased tends toward the heavier and more contaminated, maintenance costs in terms of spare parts and labor increase significantly; therefore, the requirements become more comprehensive for associated support systems such as fuel conditioning systems for all types of diesel systems, lube oil purification, waste heat boilers, turbocharges, and diesel turbocharger washing systems.

This paper is intended to provide practical, real world systems design solutions intended to permit the ship operator to cope with degrading fuel quality. It is important that the ship operator accept the primary responsibility to protect the welfare and operation of his fleet. Years ago, the major suppliers provided a good deal of protection by controlling the quality of the fuel that went to the ship. Times have changed! Generally, the major oil suppliers no longer provide this service. Much of the market is served by independents and brokers today, and this trend likely will continue in the future. The oil company refineries are still the major source of marine fuel oils.

The techniques to handle fuel presented represent refinements to known methodology as opposed to representing breakthroughs and are suitable not only for new design but for retrofit as well.
A Separation System for High Density Fuels
Authors: Stepanovich MG
Published: December 2008

Due to the changing quality of heavy fuel oils, especially with respect to density, traditional purifier and clarifier cleaning plants are being operated near their limits to ensure sufficient cleaning of these fuels. The ALCAP separation system was developed specifically to operate on high density fuels, thereby guaranteeing optimum cleaning efficiency for the fuels of today and tomorrow.
A Portable Test Kit for Naval Distillate Fuel
Authors: Stavinoha LL , Westbrook SR , Strandell PA
Published: December 2008

The Navy diesel fuel specification (MIL-F-16884H) controls filterable materials (dust, dirt, organic sediment, etc.) by ASTM Method for Water and Sediment in Distillate Fuels by Centrifuge (D 2709-82) with a limit set at 0.01 volume %. If an assumption is made that organic fuel-derived sediment/microparticulates have an average density close to 1.7 times that of diesel fuel (having a density of approximately 0.85 g/mL), then 0.01 volume % sediment in fuel is equivalent to 0.017 mass %. Micro-particulate analysis by ASTM Methods for Particulate Contaminant in Aviation Turbine Fuels [D 2276-73 (1978)] would potentially then measure up to 145 mg/L of filterable particulate. This amount of particulate material is intolerable and would rapidly plug filter separators and diesel/turbine engine fuel filters. Currently, Navy field guidance is for filterable fuel insolubles not to exceed 15 mg/L by ASTM D 2276 for acceptable filter separator performance. A portable diesel fuel microparticulate analyzer utilizing glass fiber fuel filters and light transmittance has been developed for testing marine diesel fuel aboard ships of the U.S. Navy. This analyzer (tester) is one of four different testers in a portable diesel fuel test kit developed for Navy use aboard ship or ashore. The test kit includes testers for color, flash point, free water, and microparticulates. This paper describes the design, development, and demonstration of this test kit with major emphasis being placed on the design and use of the filterable microparticulate tester. Comparison of this tester to other similar devices is also provided.
The Potential of Scientifically Based Fire Protection Engineering?
Authors: Nelson HE
Published: December 2008

Fire science advances of recent years are now creating a state of knowledge that permits the emergence of a scientifically based fire protection engineering technology. It is proposed that a clear overview of an effective engineering approach is apparent and to at least an initial degree supported by engineering capabilities. A conceptual model of the elements of an analytical method is provided along with a list of references that present procedures for calculating the impact of each element. Test methods need to provide the data required to execute the calculation procedure.
Fire Risk Assessment: Integrating Fire Testing and Fire Codes
Authors: Beyreis JR , Castino GT
Published: December 2008

Fire risk assessment, using experience as a basis, has led to the development of fire test methods and building codes and standards. Fire risk is composed of the multiple elements of potential for harm, probability of occurrence, and probability for exposure. The integration of fire test methods and building codes and standards is part of a multiple-element response to fire risk.
Effect of Fire Exposure on Structural Response and Fireproofing Requirements of Structural Steel Frame Assemblies
Authors: Bresler B , Iding RH
Published: December 2008

Fire endurance ratings of structural steel frame assemblies are based on limiting temperature rise and on preventing structural collapse during a specified fire. Currently, a single standard fire, ASTM Method for Fire Tests of Building Construction and Materials E 119-83, is specified as the fire exposure. Thermal and structural responses can be determined either by a standard test or by calculations using computer programs such as FIRES-T3 and FASBUS II. Use of analytical methods in predicting thermal and structural responses of steel frame assemblies, with or without fireproofing, permits evaluation of the effect of different fire exposures. In this paper, a general approach for the evaluation of structural responses and fireproofing requirements of steel assemblies under different fire exposures is described and the results of three case studies are presented.

Data required for and procedures used in evaluating the response to fire, as well as the response acceptance criteria for the desired level of fire protection, are discussed. Two fire exposures, short duration high intensity (SDHI) and long duration low intensity (LDLI), are described. These fire exposures together with the ASTM E 119 standard fire, are used in the evaluation of fire responses of a typical steel deck floor assembly specimen. Response of this assembly with different thicknesses of fireproofing is determined analytically, and the results are summarized.
Computer Modeling the Fire Endurance of Floor Systems in Steel-Framed Buildings
Authors: Jeanes DC
Published: December 2008

The rational approach for the design of building structures to resist the effects of fire has advanced significantly over the past decade. Part of this advancement has been the development of a computer model, FASBUS II, which predicts the structural response of steel-framed floor systems exposed to fire. An evaluation of this model using large-scale test data has demonstrated its ability to accurately predict the influence of heating on the overall performance of these floor assemblies. The approach represented by the traditional test method, Method for Fire Tests of Building Construction and Materials (ASTM E 119-83), contrasts markedly with the engineering-based solution utilized in the FASBUS II model. In order to evaluate this difference, the performance associated with each approach has been characterized and a comparison made. As a result, a relationship between thermal restraint in the test and restraint due to predicted structural interaction has been suggested.

Using the analytical solution represented by FASBUS II, an evaluation of actual details of construction can be made and the interaction between the exposed and unexposed portions of the structure can be examined. Such an analysis provides the designer with information that will contribute to a more accurate and effective means of accessing structural fire endurance.
An Evaluation of Toxic Hazards from Full-Scale Furnished Room Fire Studies
Authors: Grand AF , Kaplan HL , Beitel JJ , Switzer WG , Hartzell GE
Published: December 2008

Fully furnished and finished 3.7 by 5.5-m (12 by 18-ft) rooms, designed to simulate a typical hotel/motel arrangement, were ignited in identical scenarios and allowed to proceed past flashover. The test facility consisted of the burn room attached perpendicular to the end of a 13.7-m (45-ft) corridor with another room off the corridor 4.9 m (16 ft) from the test room. The second room contained animals for an assessment of both preflashover and flashover toxic effects. The rooms and corridor were fully instrumented with thermocouples, heat flux radiometers, smoke meters, gas sampling trains, and, in the burn room only, smoke detectors and sprinkler heads. In the few minutes prior to visual flashover, the toxic hazard of this fire scenario increased dramatically. At the 1.7-m (5 1/2-ft) level in the burn room, temperature rose to 650°C (1200°F), carbon monoxide (CO) concentration reached 70 000 ppm, oxygen concentration dropped to zero, and the hydrogen cyanide level exceeded 1000 ppm. In the remote room, the animals died from carbon monoxide poisoning around 12 min after the dramatic change in conditions (approximately 10 min after visual flashover occurred). Other factors besides CO contributed to the incapacitation of the animals.
Definition of the Concentration Gradient Above Flammable Liquids
Authors: Munoz-Candelario R , Alvares NJ
Published: December 2008

Areas where the potential for spill of flammable fluids is finite are defined as hazardous locations and are subject to code restrictions regarding location and protection from potential ignition sources. These locations require a specific separation distance between the potential spill plain and the ignition sources. This distance is universally accepted to be 18 in. for most U.S. codes. We found that acceptable separation distances have increased over the years, intuitively in the name of safety, although we found no data to support this. We surveyed the literature and performed experiments to find a quantitative basis for the increasing distances. The literature revealed a case for evaporating fluids with boundary conditions for the volatile vapor diffusing through a stagnant gas film. In containers with open tops, the calculated vapor-concentration gradients are monotonic and directly proportional to the vapor pressure of the fluid. We confirmed the validity of these calculated values by performing experiments to determine the elevations at which flammable mixtures formed above the surfaces of volatile, high-vapor-density liquids.
Changes in Asphalt Concrete Durability Resulting from Exposure to Multiple Cycles of Freezing and Thawing
Authors: Gilmore DW , Darland JB , Girdler LM , Wilson LW , Scherocman JA
Published: December 2008

Concern over water-induced damage in asphalt concrete pavements has resulted in the development of several new moisture susceptibility detection tests. This report compares two modifications of the water conditioning procedure for asphalt concrete specimens as described in the National Cooperative Highway Research Program (NCHRP) Reports 192 and 246. These modifications incorporate longer water exposure conditions for investigating the long-term durability of antistripping additives and paving mixtures.

Significant and progressive changes in tensile strength were found to occur when asphalt concrete specimens were repeatedly exposed to freeze-thaw cycles. Factors, such as aggregate source, additive type, and additive quantity, influence the rate of strength loss during cyclical conditioning, and these rates are valuable in material selection. In particular, the sensitivity of cyclical conditioning to additive effectiveness was utilized to develop and select improved additives.
Maximizing the Beneficial Effects of Lime in Asphalt Paving Mixtures
Authors: Button JW
Published: December 2008

Laboratory and field tests were conducted to evaluate the use of hydrated lime as an antistrip additive in hot mix asphalt concrete. Batch and drum mix plants were used to prepare the paving mixtures. Lime was added dry and in slurry form. Individual aggregates and the total aggregate were separately treated with lime slurry and allowed to age for different time periods from a few minutes to 30 days before mixing with asphalt. Laboratory mixed and plant mixed asphalt concrete was tested using indirect tension and resilient modulus before and after moisture conditioning. Results indicate that lime is effective in reducing moisture susceptibility and that it is most effective when applied in the presence of moisture. In addition, a time delay after application of lime to aggregate is unnecessary. There are no significant differences in mixtures produced in batch and drum plants.
Transient and Stable Deformation Behavior Under Cyclic Nonproportional Loading
Authors: McDowell DL , Socie DF
Published: December 2008

The transient hardening behavior of metals subjected to nonproportional cyclic loading, including the corresponding cyclically stable state, is dependent on plastic strain range in addition to the “degree” of nonproportionality. Experiments were performed on thin-walled tubular specimens of stainless steel 304 in combined tension-compression and torsion to investigate sequence effects, memory of prior loading, and rate changes of cyclic hardening under complex, nonproportional, strain-controlled cyclic loading. The material was observed to remember cyclic hardening achieved under the most severe nonproportional loading case. Effective stress states achieved by cycling at increasingly severe nonproportionality of loading increased correspondingly and tended to “wash out” the effects of less severe nonproportional paths. For several complex nonproportional paths, the actual intermediate cyclically stable (or near stable) effective stress states were correlated accurately using a path-dependent integral. Only uniaxial and 90° out-of-phase sinusoidal test results are required by this integral representation.
Fatigue Crack Initiation and Growth in a High-Strength Ductile Steel Subject to In-Plane Biaxial Loading
Authors: Smith EW , Pascoe KJ
Published: December 2008

Flat cruciform-shaped specimens of HY100 steel were tested in fatigue under biaxial stress states. For Mode I crack growth, a tensile component of stress parallel to the crack decreased crack growth rate; a compressive component had the opposite effect. These changes in growth rate are explained in terms of the material's differing cyclic stress-strain response under shear and equibiaxial loading.

Studies of Mode II growth were found difficult to perform, due to a critical balance between Mode II and Mode I growth. Mode II crack growth rates were much greater than for the equivalent Mode I crack. The growth rate increased with increasing ΔKII but did not follow the Paris relationship due to the occurrence of incipient or undeveloped bifurcation which prevented continued and undisturbed Mode II growth.
Effect of Local Stress Biaxiality on the Behavior of Fatigue Crack Growth Test Specimens
Authors: Rhodes D , Radon JC
Published: December 2008

Fatigue crack growth rates have been measured for aluminium alloys, using compact type (CT) specimens, and the results compared with published data from the same materials, obtained from center-cracked tension (CCT) specimens. There is a general trend for CCT specimens to exhibit higher crack growth rates, even at identical stress intensity factor ranges. This result is explained in terms of the difference in the nonsingular component of stress, parallel to the crack faces, which influences both the plastic zone size, and, in the case of very thin specimens, the buckling behavior.
Growth of Fatigue Cracks Under Combined Mode I and Mode II Loads
Authors: Hua G , Alagok N , Brown MW , Miller KJ
Published: December 2008

Although the majority of fatigue crack propagation studies have been concerned with pure Mode I loading situations, in practice many cracks in components may initially extend by fatigue under a combination of all three crack growth modes, and this initial period may predominate during the fatigue lifetime. In this paper, the threshold and growth behavior of cracks under various combinations of Mode I and Mode II crack tip displacements are studied, showing the effect of the T-stress in the biaxial specimen. Four materials (AISI 316 stainless steel, DTD 5120 aluminium alloy, Ti-6A1-4V, and 1Cr-Mo-V steel) have been tested. Two different experimental procedures, four-point bending and biaxial loading of a plate, are employed.

An expression is derived for fatigue crack growth under combined mode load conditions relating growth to crack-tip reversed plastic deformation, which depends on the Mode I and Mode II crack-tip stress-intensity factors and also the T-stress. A secondary but important factor is the fracture ductility of the material around the crack tip, which itself is a function of biaxial stress state.
Mode III Fatigue Crack Growth Under Combined Torsional and Axial Loading
Authors: Ritchie RO , McClintock FA , Tschegg EK , Nayeb-Hashemi H
Published: December 2008

An investigation has been made into the propagation of fatigue cracks in Mode III (anti-plane shear) in circumferentially notched cylindrical specimens subjected to cyclic torsion with and without small superimposed static tension loading. Studies were performed in a range of low-alloy steels of yield strengths varying from 310 to 1625 MN/m2, with the objective of characterizing both constant amplitude and variable amplitude Mode III crack growth behavior. Rates of fatigue crack propagation in Mode III were found to be characterized uniquely by the Mode III cyclic crack tip displacement (ΔCTDIII) or the plastic strain intensity range (ΔΓIII) for elastic/plastic and fully plastic conditions, only if allowance was made for friction, rubbing, and interlocking between sliding crack surfaces (crack surface interference) through superposition of small axial loads. Such Mode III crack advance is envisaged in terms of Mode II shear coalescence of microcracks initiated at inclusions in the immediate vicinity of, and parallel to, the main crack front, consistent with micromechanical modelling studies incorporating either instantaneous crack tip displacement or damage accumulation arguments. The application of such models to the prediction of Mode III fatigue crack propagation behavior under both constant amplitude and simple variable amplitude loading spectra is briefly reviewed.
Crack Initiation Under Low-Cycle Multiaxial Fatigue
Authors: Jacquelin B , Hourlier F , Pineau A
Published: December 2008

This study is devoted to the determination of a criterion for predicting crack initiation under low-cycle multiaxial fatigue. Here crack initiation, Ni, is defined as the number of cycles needed by the final microcrack to reach one grain size. The tests which were carried out at room temperature on Type 316L stainless steel and Inconel 718 alloy included (a) reversed tension-compression (b) reversed tension-compression with a superimposed steady torque, (c) pulsated tension-compression with a stress ratio Rσ such that −0.5 < Rσ < 0 and (d) reversed torsion. Scanning electron microscope (SEM) observations were used to determine the number of cycles corresponding to crack initiation and the orientation of the microcracks.

From these observations a criterion combining the plastic shear strain range for the crack initiation plane, Δγp, and the maximum of the shear stress on this plane, τ, is proposed. It is shown that the predictive capability of this criterion is satisfactory for various experimental results featuring both Types A and B crack initiation. Using the proposed criterion and the experimental relation between Ni and the number of cycles at failure, Nf, in conjunction with a double linear damage rule, it is shown that this approach accounts for previously published experimental results involving two level loadings.
Effect of Local Stress State on the Growth of Short Cracks
Authors: Leis BN , Ahmad J , Kanninen MF
Published: December 2008

This paper examines the extent to which local state stress contributes to observed short crack growth rate behavior. Local crack-tip stress state effects are explored in terms of data developed at notch roots in notched plates of various thicknesses. Experimental data and fractography coupled with the results of stress intensity solutions show that a part of the so-called short crack effect may be rationalized by three-dimensional considerations.
The Role of Fretting in the Initiation and Early Growth of Fatigue Cracks in Turbo-Generator Materials
Authors: Lindley TC , Nix KJ
Published: December 2008

The reduction in fatigue strength due to fretting has been measured for various combinations of materials used for components in turbo generators. With the range of pad contact pressures and pad spans employed, fretting fatigue strength reduction factors of up to 3.5 were found for 3.5Ni-Cr-Mo-V ferritic steel, 2.5 for 18Mn-4Cr, and 18Mn-18Cr austenitic steels and 11 for 2014A aluminum alloy. Metallography and strain gage methods (to monitor frictional forces) revealed that small cracks could develop by fretting early in fatigue life, and a fracture mechanics approach is developed to describe crack growth.
Fatigue of Steel Wire Under Combined Tensile and Shear Loading Conditions
Authors: Verpoest I , Notohardjono BD , Aernoudt E
Published: December 2008

Combined tension and torsion fatigue tests were performed on low- and high-carbon steel wires in the annealed (namely, patented) and drawn condition. It is shown how, with increasing shear to tensile stress ratio, a maximum tensile stress criterion dictates the orientation of the Mode I fatigue cracks in the annealed specimens. This is also the case in drawn wires when the tensile loading component predominates. However, when shear loading predominates and in heavily drawn material where structural and crystallographic anisotropy are well pronounced, easy paths for crack propagation parallel to the wire axis are created and correspondingly Mode II cracks occur.
A Review of the Multiaxial Fatigue Testing of Fiber Reinforced Plastics
Authors: Found MS
Published: December 2008

A number of multiaxial fatigue systems employed for the testing of fiber reinforced plastics (FRP) composites are discussed, and how they may be used to evaluate failure theories. The effects of anisotropy and end fittings are examined for different specimen geometries. A conservative failure criterion is suggested for predicting the biaxial static and fatigue strength of FRP based on limited test data.
Biaxial Fatigue of Glass Fiber Reinforced Polyester Resin
Authors: Radon JC , Wachnicki CR
Published: December 2008

Fatigue crack growth tests were carried out on chopped strand mat polyester resin under biaxial tensile stress. Center-notch specimens were used to measure the effects of the load biaxiality factor, B, defined as the ratio of the load acting normally to the crack line and that acting parallel to it. A compliance calibration technique was used to measure the crack growth so as to overcome difficulties with visual measurement when using conventional stress-intensity factors in order to present the fatigue results on a fracture mechanics basis. An adaptation of the compliance technique was also used to extend the applicability of the stress-intensity factor concept to planar composite materials by proposing a K-equation that takes into account the effects of reinforcement geometry and biaxial stress. This allows a safe life crack growth criterion to be used more effectively to assess damage tolerance, taking account of a number of detrimental intrinsic effects due to the nature of the composite reinforcement. The Paris power relationship was found to be applicable to the results, the analysis of which shows that nonsingular stresses do affect the behavior of a crack subjected to plane stress cyclic loading. Biaxial stresses were found to produce a shift in the fatigue crack propagation rates, notably a decrease in the Paris exponent with increase in the load biaxiality factor, B. Analysis of the fatigue behavior indicates the failure mechanisms are influenced by the reinforcement geometry of the composite material, together with the Poisson's ratio of the material under biaxial stress. It would seem that the fatigue behavior is governed by the fiber-resin interface at low stress levels, while at higher stresses the Poisson's ratio of the composite determines the biaxial influence.
Fatigue Behavior of Cyclically Softening and Hardening Steels Under Multiaxial Elastic-Plastic Deformation
Authors: Sonsino CM , Grubisic V
Published: December 2008

To investigate the fatigue behavior of cyclically softening and hardening steels under multiaxial elastic-plastic strains, axial strain, and shear strain controlled fatigue tests under constant amplitude loading were carried out. S-N curves under axial strain and torsional pure shear as well as under combined axial strain and shear, in and out of phase, were obtained for the cyclically softening high-strength steel 30Cr-Ni-Mo 8 (similar to AISI Type 4340) and the cyclically hardening stainless steel X 10Cr-Ni-Ti 18 9 (AISI Type 321) in the region of low-cycle fatigue.

For both steels, used for vessels, pipings, shafts, etc., the fatigue life to crack initiation (crack depth a < 1 mm) is reduced by an out-of-phase (δ = 90°) loading of the specimens in comparison to in-phase loading.

The decrease of fatigue life under out-of-phase strains is caused by the changing direction of principal strains resulting in an interaction of the deformations in all directions on the surface. This interaction is taken into account by the arithmetic mean value of shear amplitudes acting in all interference planes of the surface. The equivalent strain is then calculated according to the octahedral shear strain hypothesis. Using this equivalent strain and the S-N curve for uniaxial strain, the fatigue life under combined strain is predicted. For the multiaxial strain evaluation it is important to know if the local strains and shears are deformation or load controlled.
Fatigue Under Out-of-Phase Biaxial Stresses of Different Frequencies
Authors: McDiarmid DL
Published: December 2008

An analysis of fatigue under out-of-phase biaxial stresses of different frequencies shows that the stress conditions on the critical shear plane are of a nonconstant amplitude nature. A general expression for the allowable principal stresses to give long life fatigue is derived in terms of the uniaxial fatigue strength and the principal stress amplitude ratio, the expression being independent of both phase angle and frequency ratio. A test system to subject thin-wall cylinders to these stress conditions is described, and the results of tests under a range of out-of-phase angles and frequency ratios are given and discussed in relation to the derived theory. It is suggested that the maximum shear stress criterion of failure can be adapted for use in designing for such complex stress conditions.
Effect of Changing Principal Stress Axes on Low-Cycle Fatigue Life in Various Strain Wave Shapes at Elevated Temperature
Authors: Ohnami M , Sakane M , Hamada N
Published: December 2008

A study on the effect of changing the principal stress axes on low-cycle fatigue lives was carried out in four strain waveforms at 923 K in air using SUS 304 austenitic stainless steel. No effect of alternation of axes on fatigue lives was observed at that temperature. But comparison of this result with a former result at 823 K, in which the alternation of axes is detrimental to fatigue lives, shows that the effect of the alternation of axes is connected closely to the fracture mode, that is, transgranular at 823 K and intergranular at 923 K. When the specimen fractured transgranularly the alternation of axes decreases the fatigue life, but, when the specimen fractured intergranularly, no effect is noted. This phenomenon is not affected by the strain waveform. Detailed discussion on the fatigue life is made from crack initiation and propagation considerations.
A Metallographic Study of Multiaxial Creep-Fatigue Behavior in 316 Stainless Steel
Authors: de los Rios ER , Kandil FA , Miller KJ , Brown MW
Published: December 2008

A metallographic examination of elevated temperature multiaxial fatigue specimens of 316 stainless steel was conducted to identify the type of damage and other microstructural changes that occurred during testing. The work hardening which takes place at the beginning of the test is associated with the development of either a cell or a maze dislocation structure. Two main factors contribute to the flow stress, that is, dislocation and carbide precipitation hardening. Dislocation hardening prevails, but precipitation hardening, which increases with testing time, becomes significant for long hold-time and low-strain range tests. Fatigue cracks are predominantly transgranular. However, intergranular cracks have been observed in hold-time specimens and are related to grain-boundary sliding and grain-boundary precipitation. The fatigue fracture is a three stage process, the initial stage (Stage I) is crystallographic, extending for one to three grains. The intermediate stage (Stage II) is dominated by striations, with the exception of some featureless facets in biaxial specimens. The final stage (Stage III) is a dimple type fracture (tension fracture), beginning at shorter crack lengths in the hold-time and high-strain range specimens. Striation spacing calculations give approximate life estimates in low-cycle fatigue.
Diets for Ceriodaphnia reticulata Life-Cycle Tests
Authors: Norberg TJ , Mount DI
Published: December 2008

Two diets were compared for the cladoceran, Ceriodaphnia reticulata, for use in culturing and life-cycle toxicity tests. One diet was a suspension of dry yeast dissolved in distilled water and fed at a rate of 250 µg per animal. The other diet was prepared from frozen adult brine shrimp (Artemia salina) and distilled water, the aged supernatant of which was fed using 0.05 mL per animal. Animals were fed daily and water changed three times each week. The feeding study was conducted for ten generations using young per female and adult survival as endpoints. The young production per female of surviving adults was comparable, but the longevity of the animals fed the yeast diet was considerably greater than that of the animals fed the shrimp diet.
A New Aquatic Bioassay Technique Using Wyeomyia smithii, the Pitcher-Plant Mosquito
Authors: Strickman D
Published: December 2008

A new bioassay using larvae of the pitcher-plant mosquito, Wyeomyia smithii, was used to assess water for the presence of toxic contaminants. Procedurally, the bioassay has the advantages of simplicity, minimum equipment requirements, and low maintenance. It is well suited for bioassays of water from remote sites because of the minimal amount of water (30 mL) necessary for each replicate. The bioassay was capable of detecting 30 ppm of 1 Stroke Ves-Phene (a disinfectant detergent concentrate containing phenates), 5 ppb of heptachlor epoxide, and 100 ppb of malathion. In addition to reducing survival, toxicants caused delayed development and produced signs of intoxication unique to each substance. In another instance, the bioassay was used in the investigation of a fish kill. Persistence of toxicity, delayed development, and non-nervous signs of intoxication indicated which samples were contaminated and suggested that heavy metals were involved. Subsequent analysis revealed toxic levels of copper and elevated levels of zinc and manganese.
Method for Early Life-Stage Toxicity Tests Using Three Atherinid Fishes and Results with Chlorpyrifos
Authors: Goodman LR , Hansen DJ , Middaugh DP , Cripe GM , Moore JC
Published: December 2008

We have developed methods for obtaining embryos and conducting early life-stage toxicity tests (continuous exposure from the embryonic stage to approximately three weeks or more into the exogenous feeding stage) with three estuarine species of atherinid fishes. Early life-stage tests were conducted for 28 days with Menidia beryllina, M. menidia, and M. peninsulae and the insecticide chlorpyrifos. Responses of the three species were similar: upper chronic values (“effect” concentrations) ranged from 0.48 to 1.8 µg chlorpyrifos/L and lower chronic values (“no effect” concentrations) ranged from 0.28 to 0.75 µg/L. Chlorpyrifos exposure did not affect survival of embryos to hatching which averaged 91 to 93% for each species. In treatments in which no adverse effects were observed, combined survival of M. menidia embryos and hatched fish averaged 51% and fish weights averaged 23 mg; for M. peninsulae, 69% and 13.6 mg; and for M. beryllina, 81% and 8.7 mg. Chlorpyrifos bioconcentration factors (concentration in whole fish ÷ average measured concentration in water) averaged 220 for M. beryllina, 460 for M. peninsulae, and probably < 420 for M. menidia.

From these three species, toxicologists may select an Atlantic or Gulf Coast species that occurs in either high or low salinity.
An Approach to Sewage Sludge Bioaccumulation Potential Tests
Authors: Maciorowski AF , McCulloch WL , Fava JA
Published: December 2008

A sewage sludge bioaccumulation potential test responsive to the U.S. Environmental Protection Agency's Ocean Dumping Regulations and Criteria was developed and evaluated with sludges from twelve water pollution control plants with secondary treatment. In keeping with the regulations, the test was designed to examine if hard clams, grass shrimp, and Atlantic silversides exposed to sludge exhibited statistically elevated body burdens of cadmium, mercury, PCB, DDT and metabolites, and petroleum hydrocarbons compared against controls. Exposure consisted of ten-day renewal followed by a two-day post-exposure period in clean seawater. Five replicate aquaria per treatment per species were employed using sludge concentrations of 0.033, 0.0084, and 0.0042%. Seven hundred and eighty tissue samples were analyzed for the specified chemicals. Of 195 possible statistical evaluations (13 sludges × 3 species × 5 chemicals), significant differences between treatment group means occurred in only 31 trials. However, in 27 of these trials, the highest body burden mean was (1) at or below pretest levels for the organisms tested, (2) within the concentration range exhibited by control groups over the study period, or (3) present in controls. The inherent limitations of basing pass/fail compliance of ocean-dumped material on a single timepoint exposure are discussed.
Biological Implications of the Management of Waste Materials: The Importance of Integrating Measures of Exposure, Uptake, and Effects
Authors: Mearns AJ
Published: December 2008

Mental tools are needed to remind us of the ultimate uses of aquatic toxicology research. These tools can aid those who manage complex waste materials. A simple conceptual diagram is offered to remind researchers and managers of the need to simultaneously or sequentially acquire, or otherwise integrate, information on exposure, bioconcentration, and effects. The author urges researchers to weigh the benefits and statistical costs of acquiring these data in a multidisciplinary approach.
Implications of Waste Disposal in Coastal Waters on Fish Populations
Authors: Cross FA , Peters DS , Schaaf WE
Published: December 2008

Assessment and prediction of the impact of pollution on animal populations are required to improve waste management strategies. This information is not easy to obtain in the marine environment because of the large natural fluctuations in abundance of organisms. Use of information on commercial fishery populations in impact assessment is advised for three reasons: (1) pollution-related effects on marine fishery populations will have direct economic consequences, (2) many major fish stocks that already are overfished should be more vulnerable to additional stresses than nonexploited populations, and (3) long-term data bases that reflect population changes are available.

The Atlantic menhaden, Brevoortia tyrannus, an economically and ecologically important fish, inhabits coastal and estuarine waters along the mid-Atlantic coast of the United States. Within its range, we have identified a number of man-related activities that could potentially affect its population size. Adverse impacts in coastal waters could result from an increase in the ocean dumping of sewage sludge and industrial wastes and oil spilled during the development of offshore oil reserves. In estuaries, adverse impacts could result from a slow but steady decline in water quality associated with human population growth and industrialization of coastal areas.

Scenarios were developed using a density-independent Leslie matrix model and data from the Atlantic menhaden fishery to simulate population responses to both catastrophic and chronic mortalities. These simulations demonstrate that a fish population which is heavily fished may have limited compensatory reserve and thus may be particularly sensitive to pollution.

Improvement in our capacity to predict the effects of pollution on fisheries requires an understanding of the environmental factors that control variability in fish populations and the effect of multiple stresses on these stocks over their entire geographical range. Increased predictive capability can be gained most cost-effectively through closer integration of the disciplines of population dynamics and toxicology.
Are the “Guidelines for Deriving Numerical National Water Quality Criteria for the Protection of Aquatic Life and Its Uses” Based on Sound Judgments?
Authors: Stephan CE
Published: December 2008

Until recently, procedures used to derive water quality criteria for aquatic life were not well defined and few principles were identified. On 28 November 1980 the United States Environmental Protection Agency published “Guidelines for Deriving Water Quality Criteria for the Protection of Aquatic Life and Its Uses” in the Federal Register. These have been subsequently revised and renamed “Guidelines for Deriving Numerical National Water Quality Criteria for the Protection of Aquatic Life and Its Uses” and are referred to as the “National Guidelines.” In addition, guidelines have been developed for deriving site-specific criteria either by modifying national criteria or by using other appropriate information. Procedures for deriving water quality criteria and for assessing hazard to aquatic life have many similarities because both make use of information from many areas of aquatic toxicology. In addition, both assume that the science has developed sufficiently that these activities are feasible and desirable and that appropriate rationales are available for making necessary decisions concerning various technical issues.
Energy Release Rate During Delamination Crack Growth in Notched Composite Laminates
Authors: Mahishi JM , Adams DF
Published: December 2008

The elastoplastic nature of delamination crack growth in composite laminates is discussed. A simple estimation of the local elastic strain energy release rate in the presence of plasticity (IL) is made, and used as a criterion for stable delamination crack growth in notched composite laminates. A three-dimensional elastoplastic, generally orthotropic finite-element method is used for the analysis. The finite-element techniques developed for estimating IL (in Mode I, Mode II, Mode III, and mixed-mode fracture) and for crack growth simulation are described. The analysis has been used to predict the initiation and growth of delamination near through-the-thickness cracks in central and single-edge notched [±45/0]s graphite/epoxy laminates subjected to static in-plane tensile stresses normal to the notches. Delamination between +45/−45 and −45/0 interfaces and material yielding at different stages of loading are presented. Numerical results demonstrate that the proposed elastoplastic fracture criterion is very effective in predicting stable delamination crack growth in composite laminates having nonlinear matrix-dominated properties.
Evaluation of Tensile Tests for Adhesive Bonds
Authors: Anderson GP , DeVries KL , Sharon G
Published: December 2008

Tensile adhesion tests have been used for many years as a quality control tool and to quantify the strength of a bond. The quantity generally reported as the tensile strength is the breaking force per unit bond area (average axial stress at the maximum load). The stress distribution in tensile adhesion tests, as discussed in this report, depends upon many factors such as material properties of the adherend and adhesive and the ratio of bond area to adhesive thickness. Test data are presented which demonstrate that the debond initiation point changes from the bond edge to the center of the bond area as the adhesive thickness is decreased. These test data confirm a prior prediction by the authors.

The stress distribution and debond load were shown to be very sensitive to test specimen alignment during the tensile test. A test grip has been designed and used to alleviate effects of specimen misalignment. The effect of the modified test grip on tensile adhesion tests is discussed. A very large decrease in data variability as well as a 76% gain in apparent load carrying capability were observed when the modified test grip was used with brittle epoxy tensile adhesion test specimens.
A Modified Free-Edge Delamination Specimen
Authors: Whitney JM , Knight M
Published: December 2008

An experimental approach to delamination fracture is presented which utilizes a free-edge delamination tensile coupon containing starter cracks in the form of embedded strips of material. These strips are embedded along the free edges of the laminate at the midplane. The purpose of the starter cracks is to promote Mode I interlaminar fracture behavior. Energy release rates are determined for various initial crack widths in conjunction with AS-4/3502 graphite/epoxy laminates with the stacking geometry [±30/∓30/902]s. These results are compared with energy release rates determined from a standard free-edge delamination coupon. The data reduction scheme is derived from a classical laminated plate theory analysis, including thermal residual stresses, of the test specimen.