bluuebunny/crossref_metadata_2025 huggingface dataset:
Relation of Through-Thickness Ductility to Inclusion Prevalence, Matrix Toughness, and Matrix Strength
Authors: Ludwigson DC
Published: March 2009

Through-thickness ductility is used as a measure of the resistance of steel plate to lamellar tearing during and after welding. Lamellar tearing is initiated by delamination at inclusion/matrix interfaces in response to weld thermal-contraction strain, and this behavior is simulated in the through-thickness tension test. Although initiated at inclusions, lamellar tearing proceeds by microvoid growth and coalescense into terraces and, finally, by shear between terraces. These latter stages of lamellar tearing are thought to be sensitive to matrix strength and toughness. Accordingly, an attempt was made to investigate the influence of changes in strength and toughness on through-thickness reduction of area (TTRA).

Six high-strength low-alloy steel plates with a range of inclusion fractions were selected and heat-treated to develop ranges of strength and toughness. Measurements of inclusion fraction, longitudinal tensile properties, longitudinal Charpy impact properties, and TTRA were made. Analyses of these results indicated the following associations: 1. Doubling the inclusion concentration (for example, from 0.1 to 0.2 percent) resulted in a decrease in TTRA of about 12 percentage points. 2. Increasing the transition temperature (decreasing the toughness) by 56°C (100°F) resulted in a decrease in TTRA of about 4 to 12 percentage points and an average of about 7 percentage points. 3. Increasing the yield strength by 68.9 MPa (10 ksi) resulted in a decrease in TTRA of 1 to 8 percentage points and an average of about 4 percentage points.

These findings indicate that inclusions are the principal factors in restricting through-thickness ductility, but that high strength or low toughness may also be appreciably associated with reduced TTRA.
Drop-Weight NDT Temperature Test Results for Five Heats of ASTM A517 Steel
Authors: Hartbower CE
Published: March 2009

This paper describes the results of drop-weight (DW) nil-ductility transition (NDT) temperature testing (according to the ASTM Method for Conducting Drop-Weight Test to Determine Nil-Ductility Transition Temperature of Ferritic Steels [E 208-69(1975)]) of “as fabricated” surfaces as well as quarter-point (subsurface) material from five plates of ASTM A517 steel, each plate from a different heat of steel. The steel was from two California bridges, one of which developed brittle fracture of a main-load-carrying flange during erection of the bridge. The five plates were characterized by Charpy V-notch impact, precracked Charpy impact, dynamic tear, and plane-strain fracture toughness testing; these results were compared with the results obtained from the drop-weight test. One plate showed 66.7°C (120°F) difference between the NDT temperatures for surface and subsurface material. Heat tinting “unbroken” drop-weight specimens revealed further complications in using ASTM Method E 208, including cracked tension surfaces not revealed in evaluation by the ASTM test and specimens with uncracked corners (and therefore rated “unbroken” by the ASTM test) but with virtually completely fractured cross sections. Both the dynamic tear and precracked Charpy impact tests were evaluated for usefulness in estimating the drop-weight NDT temperature; the correlation of test results was made uncertain, if not precluded, by through-thickness inhomogeneity and complications in the ASTM DW test method. Recommendations are made to improve ASTM Method E 208 by heat tinting. The five heats of ASTM A517 steel were shown to have widely variable fracture characteristics.
Eddy-Current Scanning of Graphite-Reinforced Aluminum Panels
Authors: Anderson CW
Published: March 2009

The application of an eddy-current test technique for the detection of material flaws in graphite-reinforced aluminum panels is discussed. This particular technique involves scanning the specimen and recording both real and imaginary impedance components of the test coil using a format similar to that of an ultrasonic C-scan. The benefits of this approach are discussed and the results are compared with those of X-radiography and ultrasonics.
Transient Eddy Current in Magnet Structure Members
Authors: Yeh HT
Published: March 2009

A computer program was developed to model transient eddy current in thin connected plates. Eddy current is deduced from the solution of an equivalent-network problem. Loop currents are introduced by a transformation as the unknown variables of the network equations (Kirchoff's laws). The network equations are solved numerically by the Runge-Kutta method. This program is quite efficient, allows for holes and multiple materials, and has built-in rotational symmetry options. In cases with known solutions, the model has been checked for both spatial and temporal profiles of the eddy current. Results are given for eddy-current profile and eddy-current loss in the magnet case, support plate, and several other magnet structure members.
Design of a Pulsed Eddy-Current Test Equipment with Digital Signal Analysis
Authors: Wittig G , Thomas H-M
Published: March 2009

Test equipment was designed for investigations on the application of the pulsed eddy-current method on the detection of subsurface defects in thicker components or layers. The evaluation of the signals delivered by the coil system is performed in four single channels with different sampling delays or by plotting the signal time shape. The measured values are digitized and stored within the memory of a minicomputer for data processing. The coil systems are dimensioned in such a manner that the desired sensitivity was obtained for a defect depth range of about 10 mm in austenitic materials. The determination of the time of the signal zero crossing gives information concerning the defect distance from the surface.
Detection and Analysis of Electric-Current Perturbation Caused by Defects
Authors: Beissner RE , Teller CM , Burkhardt GL , Smith RT , Barton JR
Published: March 2009

The electric-current perturbation technique consists of establishing an electric-current flow in the material to be examined and then detecting localized perturbations of this current flow at inhomogeneities such as inclusions or cracks. The current perturbation is sensed by using a small noncontacting probe to detect the associated magnetic-flux perturbation at the surface of the specimen. In the work reported here, analysis of the electric-current perturbation signals was based on an analytic solution for the change in current density caused by a slot of infinite length and finite depth. Comparisons were made with experimental data for electric-discharge machining (EDM) slots of various depths in Incology 901 where the electric current was introduced by ohmic contact. Excellent agreement between theory and experiment was obtained for deep slots, although the model predicts a more rapid decrease in signal amplitude with decreasing slot depth than is experimentally observed. Additional measurements made with fatigue cracks show that cracks as small as 0.45 mm in length are easily detected. It was concluded that the technique is not only a sensitive method for flaw detection, but also offers the possibility of determining flaw characteristics through analysis of signal shapes and amplitudes.
Eddy-Current Testing of Thin Nonferromagnetic Plate and Sheet Materials Using a Facsimile-Recording Data Display Method
Authors: Feil JM
Published: March 2009

The wide-spread use of eddy-current testing of thin flat plates or sheet materials has been hampered by the difficulty of test signal interpretation and the problem of locating the discontinuity when the test has been completed. These drawbacks could be reduced by a simple facsimile-recording system that displays the test-signal amplitude changes as changes in the darkness of the facsimile recording. The interpretation of the facsimile recording is very similar to the interpretation of standard radiographic films or ultrasonic C-scan data. The location of the discontinuity on the specimen is directly related to the discontinuity indication on the facsimile recording, again analogous both to radiography and ultrasonic C-scan. This technique of data presentation also allows for the differentiation between discontinuities that extend through the full thickness of the specimen and the discontinuities that extend only partially through the full thickness. Small-diameter discontinuities can be also detected and displayed by this system.
Effect of Ply Constraint on Fatigue Damage Development in Composite Material Laminates
Authors: Stinchcomb WW , Reifsnider KL , Yeung P , Masters J
Published: March 2009

Laminae of composite materials are bonded together to form a laminate for the purpose of achieving strength and stiffness in certain desired directions. Although a direct use of laminae strength and stiffness properties can be used to determine the properties of an undamaged laminate, it is well known that the manner in which local damage initiates, grows, and combines is not the same in an unconstrained lamina as it is when the same lamina is constrained by other laminae in a laminate. This paper addresses the question of constraint effects directly and discusses the consequences of such effects on the development of fatigue damage in graphite epoxy laminates. Results of monotonic tension tests, tension-tension fatigue tests, and nondestructive investigations are reported for several constraint situations and are compared with the results of several analyses.
Damage Initiation in a Three-Dimensional Carbon-Carbon Composite Material
Authors: Robinson CT , Francis PH
Published: March 2009

Small coupons of a three-dimensionally woven, carbon-carbon composite were axially loaded in a specially-designed SEM load stage. Notched and unnotched specimens were fatigue cycled at room temperature. Crack initiation was found to be in a sliding mode, most often near a fiber-matrix interface. The cracks would immediately turn 90 degrees to an opening mode and propagate through a matrix pocket until encountering a longitudinal fiber bundle. In most cases, the crack would then propagate along the fiber bundles, again in a sliding mode. Yarn bundle failures were not limited to the immediate region of an approaching crack, leading to the conclusion that this material is not notch sensitive. Acoustic emission was found very useful in characterizing the different stages of microstructural damage.
Mechanism of Fatigue in Boron-Aluminum Composites
Authors: Gouda M , Prewo KM , McEvily AJ
Published: March 2009

A fatigue model for unidirectionally reinforced composites that are loaded parallel to the fibers is proposed that is based upon the growth of interfacial fatigue cracks. Certain predictions of the model are verified by experimental results, namely, that the rate of crack growth is independent of crack length and that the fatigue life at >106 cycles is relatively insensitive to the mean stress. Depending upon whether the matrix is elastic or elastic-plastic, a different dependency of the rate of crack growth on stress results, but the data available are insufficient to make a precise distinction between the two cases. In addition, at higher stress amplitudes the tensile rupture mode of separation becomes increasingly important, a fact dealt with only empirically by the model. It is concluded that for loading parallel to the fibers the most fatigue resistant composites will consist of strong, uniform, and defect-free fibers in a relatively soft matrix.
Statistical Techniques for Evaluating Procedures and Results for Periphyton Sampling
Authors: Sullivan JH , Putnam HD , McClave JT , Swift DR
Published: March 2009

Statistical procedures for evaluating periphyton sampling techniques and results are described. The sampling technique utilized was glass slides incubated at various locations in a reservoir receiving industrial effluent. The density, diversity, and dominance of organisms were utilized as dependent variables. Initially, the sampling and processing technique was evaluated to determine the variability at each step. From this information, decisions were made regarding where in the process replication would be most important. Further, statistical procedures are demonstrated for relating sampling replication to the ability to detect differences between results obtained at different sampling locations. Techniques for relating processing or counting effort to the reliability of estimates of dominant species are discussed. The statistical techniques illustrated can be used to relate overall sampling or processing effort or costs to the reliability of the final results.
Impact of Trinitrotoluene Wastewaters on Aquatic Biota in Lake Chickamauga, Tennessee
Authors: Putnam HD , Sullivan JH , Pruitt BC , Nichols JC , Keirn MA , Swift DR
Published: March 2009

Field surveys were conducted in Lake Chickamauga, Tenn., to determine the effects from wastewater discharge from the Volunteer Army Ammunition Plan. Trinitrotoluene (TNT) is the principal munitions component manufactured at this facility, and process wastes contain a complex mixture of compounds associated with the production of this explosive. Effects from the waste stream via selected components were established in periphyton and the macroinvertebrate communities, utilizing the Pinkham-Pearson Biotic Similarity Analysis. Less success was achieved in assessing impact by employing the Shannon-Weaver diversity theory. The utility of standard artificial substrates in periphyton studies was realized by comparing effects between community structures on natural substrates and glass slides. The results of the investigation show that effects on fixed biological communities from wastewater components of TNT manufacture can be detected at concentrations in the microgram per litre range.
Annual Macroinvertebrate Sampling—A Low-Cost Tool for Ecological Assessment of Effluent Impact
Authors: Tesmer MG , Wefring DR
Published: March 2009

Annual macroinvertebrate sampling is viewed as a low-cost tool for effluent impact assessment. The specific objectives for such studies are discussed, and the necessary restrictions required to provide meaningful results are presented. An example study is provided for demonstrating the data analysis and interpretation. The effluent discharge from the Champion International Corp. pulp and paper mill into the Tennessee River at Courtland, Ala., was monitored annually between 1970 and 1978. The study revealed that annual sampling effectively identified the causes of major fluctuations in the macroinvertebrate community structure. The effluent discharge studied was found to have a negligible effect upon the macroinvertebrate community, while the major fluctuations were attributed to natural variations in physical and hydrological conditions. The net impact of the effluent discharge upon the receiving stream was considered to be minimal over the entire study period.
Use of Asiatic Clam Larvae in Aquatic Hazard Evaluations
Authors: Foster RB
Published: March 2009

Investigative efforts to predict the potential impact of single chemical species or mixed effluents on natural waterways emphasize laboratory studies of sensitive nonindigenous aquatic organisms reared under controlled laboratory conditions. Integrated aquatic hazard evaluations appropriately require species representative of a number of trophic levels—algae, invertebrates, and fish—and of different ecological niches—benthic versus pelagic, sessile versus mobile. The oyster embryo toxicity test is often applied in hazard evaluations and is a useful measure of water quality in marine and estuarine environments. Parallel methods have been developed in which freshwater Asiatic clam larvae are used to measure the relative toxicity of industrial chemicals. Two applications, the benthic acute lethality test and the larval transformation toxicity test, are presented. The results compared with other representative aquatic species of fish and invertebrates show that these applications are appropriately sensitive to industrial chemicals. Based on the simplicity and utility of these methods, the author recommends that these and other Asiatic clam monitoring techniques be adopted as tools for assessing the impact of effluents on freshwater aquatic environments.
Role of Electrofishing in Assessing Environmental Quality of the Wabash River
Authors: Gammon JR , Spacie A , Hamelink JL , Kaesler RL
Published: March 2009

The fish community of the middle Wabash River has been studied since 1973 from the standpoint of its capacity for measuring the biological impact of various kinds of point influences, such as thermal, municipal, and industrial effluents. Of particular interest has been the potential value of various community parameters as indicators of environmental quality, since individual species populations tend to vary markedly from year to year.

The primary sampling method consisted of repeated direct-current electrofishing through a series of 0.5-km-long zones located strategically throughout 274 km (170 miles) of river, divided into twelve reaches. The use of cluster analysis and community indexes, including a composite index, has been of value in isolating problem areas prior to the development of lethal environmental conditions and in gaging the degree of environmental benefit resulting from improved waste treatment.
Emerging Concepts in Security Design
Authors: Reppetto TA
Published: March 2009

In the past decade people from a variety of backgrounds have worked together in the field of security design. Out of this outpouring of research has come many useful ideas and experiments. However, there have also been problems connected with this. There is, for example, no clear terminology that can be used across various fields. It is necessary that we begin to develop some common terminology, including standard definitions for certain concepts. The field could benefit from a comprehensive text. Such a text would begin with a discussion of crime and its relationship to urban design. It would then consider the techniques of target hardening, social factors, the relationship of law enforcement and private security, and various environmental design measures. In essence, it would proceed from an analysis of the problem to the various design solutions ranging from the simple to the complex and the consequences of those solutions. The present symposium, as a review of the state of the art in building security, is a step in that direction.
Conflicting Requirements of Exit Doors
Authors: Johnson BM
Published: March 2009

The design of exit doors to meet the requirements of security, fire safety, and building operations necessitates analysis based on building occupancy. Recent Canadian research has led to clearer understanding of building operations for specific occupancies such as spectator, educational, and correctional facilities. The result is a strategy designed to resolve conflicting requirements, but it depends on the availability of appropriate hardware and management procedures.
Perimeter Lighting for Security
Authors: Morgan JH
Published: March 2009

It is generally accepted by security managers in both government and the private sector, that the contributions of perimeter lighting to a physical security system are based on a triad consisting of: (a) psychological deterrence, (b) detection and identification, and (c) incapacitation. In theory it is difficult to question the validity of this concept. In practice, however, this triad is supported by a rather weak analytical and experimental base. The deterrent effects of lighting are inferred from limited, and often uncontrolled, studies of urban crime patterns together with a plethora of subjective opinion. A variety of innovative experimental approaches have been applied to the problem of detection and identification but verification in the field is lacking. The incapacitating effects of lighting rests on a relatively firm experimental foundation but the various techniques are on the one hand subject to countermeasures, and on the other nondiscriminating, affecting both intruder and security force equally.

This investigation identifies what are, in the author's view, experimental shortfalls in the area of security lighting effectiveness and summarizes U.S. Army Mobility Equipment Research and Development Command's plan to fill these experimental voids by a systematic series of testing.
Correlation of Long-Term Storage and Accelerated Stability Tests
Authors: Garner MQ , White EW
Published: March 2009

Three-year outdoor bottle and column storage tests described in ASTM STP 531 have been completed on four Navy distillate fuels. The total insolubles were linear functions of the time in storage in both the bottle tests and in the accelerated 43.3°C (110°F) beaker tests. About the same amount of new total insolubles formed in one week of beaker storage as formed in one month of bottle storage at an effective temperature of 19°C (67°F). The stability ranking of the four fuels was essentially the same regardless of which test was used and regardless of whether total insolubles or the rate at which additional insolubles were formed was used as the basis of the ranking. The geographic location for outdoor bottle tests was an important factor and was probably related to the average annual temperature at the location.
A Fuel Oil Distributor's Experience with Contaminated No. 2 Fuel Oil
Authors: Stieber A , Kallio NN
Published: March 2009

This presentation is largely a documentation of events that took place in Montreal when a major fuel oil distribution company inadvertently received contaminated fuel oil from a refinery and delivered it to a large number of customers, many of whom experienced operational problems. The contaminants were mostly salt (sodium chloride), sediment, and moisture, and the operational problems revolved around damage to the customer's fuel systems, principally corrosion of fuel pumps, leading to malfunction and failure. Many fuel line filters were also plugged by sediment, principally rust. Steps were then taken to repair the customer's contaminated and damaged fuel systems; to remove all traces of contaminants from the company distribution system; and, in future, to monitor on a daily basis by laboratory tests the quality of fuel received from the refinery. In particular, a simple conductivity device was built and used to test newly delivered fuel for the presence of conducting contaminants, such as salt and water.
Stability of Diesel Fuels Made from Shale Oil
Authors: Irish GE , Richardson RL
Published: March 2009

A study was carried out to determine the type and degree of processing which will be needed to produce a diesel fuel from shale oil which is sufficiently stable to be used as an alternative to petroleum-derived diesel fuels. Several test methods were used to evaluate the stabilities of shale oil products which had been refined in various ways. There is an apparent need for an accelerated stability test method which will correlate with long-term storage of diesel made from shale oil.
Use of Captive Starlings to Determine Effects of Pollutants on Passerine Reproduction
Authors: Grue CE , Christian CL
Published: March 2009

Three reproductive trials were conducted to develop techniques for propagation of captive starlings (Sturnus vulgaris) which could determine the effects of environmental contaminants on passerine reproduction. Trials were conducted during the spring of 1979 in five adjacent 2.4 by 3 by 12-m outdoor wire pens containing four or ten pairs of starlings, a similar number of nest boxes, perches, water, commercial turkey starter, and alfalfa hay as nesting material. Nestling diets consisted of combinations of Nebraska Brand bird of prey diet, live or frozen mealworms (Tenebrio molitor) and crickets (Acheta domestica), or live earthworms (Pheretima sp.). Starlings reproduced successfully when the number of breeding pairs per pen was reduced from ten to four. The average clutch sizes for each pen (4.3 to 4.9) were similar to those reported for wild starlings. Hatching (60 to 90.4 percent) and fledging (0 to 100 percent) success varied among pens. The fledging success was greatest in the pens which received the most diverse nestling diets: Nebraska Brand diet plus frozen or live mealworms and crickets. Whether the insects were presented alive or frozen appeared to have little effect on the reproductive success. The starlings did not consume or carry earthworms to their young. The body weights of 20-day-old nestlings raised in captivity (¯X = 73.9 g) were similar to those of starlings in the wild. The use of single pairs per pen may eliminate problems in presentation of nestling diets due to asynchrony in breeding between pairs and excessive interactions among individuals, which may interfere with parental care. The starling appears to be an excellent model for examining the effects of environmental contaminants on the reproduction of songbirds in captivity.
Development of an Avian Dietary LC50 Toxicity Test for Potential Use Under the Toxic Substances Control Act
Authors: Turner LW
Published: March 2009

The Toxic Substances Control Act (PL 94-469) directs the U.S. Environmental Protection Agency (EPA) to produce standards for the development of adequate data regarding the effect of chemical substances and mixtures on health and the environment. The agency is developing test standards to satisfy this charge. This paper describes part of the process by which a test standard is developed, using the avian dietary median lethal concentration (LC50) toxicity test as an example. The history of avian dietary toxicity test methods is briefly described, along with the kinds of modifications in methods made by various users. The rationale for the selection of specific test conditions and procedures is discussed with respect to the use of the test results by a regulatory agency. Selection criteria for several controversial test parameters are presented as examples.
Comparison of Various Methods for Determining K0
Authors: Al-Hussaini M
Published: March 2009

A series of tests were conducted on sands to determine the value of the coefficient of earth pressure at rest (K0) and the factors which influence its magnitude. Four laboratory techniques were used to determine the value of K0 and the stress-strain relationship for Reid-Bedford sand at dense, medium, and loose states. Test results indicated that the value of K0 for the sand tested is not significantly influenced by the testing equipment or the technique used. Results show that K0 increases with decreasing relative density, increasing stress level, and number of loading cycles. On the first loading cycle, the value of K0 agreed well with Jaky equation K0 = 1 - sin φ. The constrained modulus D increased with increasing relative density, increasing stress level, and increasing number of loading cycles, but remained almost the same for all unloading cycles.
Effect of Residual Stress on Fatigue Crack Growth Rate Measurement
Authors: Bucci RJ
Published: March 2009

Examples are given where influence of residual stress leads to erroneous interpretation of fatigue crack growth rate measurements made in accordance with ASTM Method E 647-78T. The experimental data presented form a basis for modification of applicable ASTM documents to give recognition to problems caused by residual stress, and to suggest guidelines for minimization of their effect on fracture property measurement.
Benefits of Overload for Fatigue Cracking at a Notch
Authors: Underwood JH , Kapp JA
Published: March 2009

Tests are described which measure the effect of compression overload on fatigue crack initiation and growth from a 0.1-mm-radius notch in alloy steel KIc specimens.

Other tests are described which measure the effect of tension overload on fatigue crack initiation and growth from a 3.4-mm-root-radius notch in similar specimens.

The effect of overload on the number of cycles required for crack growth is described for both types of tests in relation to a residual stress model.
A Model for Representing and Predicting the Influence of Hold Time on Fatigue Crack Growth Behavior at Elevated Temperature
Authors: Saxena A , Williams RS , Shih TT
Published: March 2009

An analytical model is developed to represent and predict the influence of hold time on fatigue crack growth behavior at elevated temperature where creep deformation is significant. This model was formulated by considering the relaxation of stress in the crack-tip region due to creep deformation and its influence on the crack-growth behavior during the hold time.

Fatigue crack growth rate data at various hold times were obtained for ASTM A470 Class 8 (chromium-molybdenum-vanadium) steel at 538°C (1000°F) to evaluate the model. Based on these results and the data taken from the literature on Inconel alloy 718, it was concluded that the proposed model is capable of accurately representing and predicting the effect of hold time on the fatigue crack growth behavior at elevated temperature. This model represents a significant improvement over the linear damage summation model used previously. Some limitations of the model are also discussed.
Stress-Intensity Factors for Complete Circumferential Interior Surface Cracks in Hollow Cylinders
Authors: Harris DO , Lim EY
Published: March 2009

An approximate expression is developed for the stress-intensity factor due to concentrated point loads applied to the surfaces of a complete circumferential interior surface crack in a hollow circular cylinder. This expression is derived from existing results for a point load on an embedded penny-shaped crack and a concentrated “ring” load on a complete circumferential interior surface crack in a hollow cylinder. Results for a particular loading case were obtained using the approximate solution and comparing with three-dimensional results obtained using boundary integral equation techniques. Since the agreement was good, it is concluded that the approximate expression provides a sufficiently accurate means of estimating K for an arbitrary loading on an interior complete circumferential surface crack. Results for bending of a cracked cylinder are then presented as an example of the use of the approximate K solution. Convenient curve fits of relevant results are included in the Appendix.
Short Rod and Short Bar Fracture Toughness Specimen Geometries and Test Methods for Metallic Materials
Authors: Barker LM
Published: March 2009

There is an increasing interest in using short rod and short bar fracture toughness specimens to measure the plane-strain critical stress-intensity factor of metallic materials. In this paper, short rod and short bar specimen design considerations are discussed, and various specimen geometries with essentially equivalent test behavior and calibration are presented. A recent experimental study was conducted on three steels and two aluminum alloys to determine the sensitivity of the test result to variations in the chevron slot thickness and the sharpness of the slot bottoms. The results give strong indications that plane-strain constraint along the crack front is enhanced by thinness of the chevron slots and sharpness of the slot bottoms. The desirable aspects of loading configurations for short rod testing are discussed, and a successful loading mechanism is described.
A More Basic Approach to the Analysis of Multiple-Specimen R-Curves for Determination of Jc
Authors: Carlson KW , Williams JA
Published: March 2009

Multiple specimen J-R curves were developed for groups of 25.4-mm-thick (1T) compact specimens with different a/W values and depth of side grooving. The purpose of this investigation was to determine Jc (J at the onset of crack extension) for each group. Judicious selection of points on the load versus load-line deflection record at which to unload and heat-tint specimens permitted direct observation of approximate onset of crack extension. It was found that the present recommended procedure for determining Jc from multiple-specimen R-curves, which is being considered for standardization, consistently yielded nonconservative Jc-values. A more basic approach to analyzing multiple-specimen R-curves is presented, applied, and discussed. This analysis determined Jc-values that closely corresponded to actual observed onset of crack extension.
Developing Design Allowables for Composite Helicopter Structures
Authors: Rich MJ , Maass DP
Published: March 2009

The overall procedures for developing composite material static and fatigue design allowables are presented. The allowables are established at the material lamina level accounting for a range of environmental conditions. Design values are derived from an interpolation method, which was confirmed by screening tests. Static test results are presented as a percentage of mean room temperature dry strength and show that the environmental effects are more pronounced for the matrix modes than for the fiber modes of fracture. Kevlar/epoxy is more sensitive to the environmental design conditions than graphite/epoxy. Fatigue test results are presented in a constant-life diagram as a percentage of room temperature wet static tensile strength. The constant-life fatigue diagram shows that the tension-compression and compression-compression range may be the governing aspect for fatigue design. Statistical evaluations are made and indicate normal distribution, and relatively small sample sizes are sufficient to establish reliable design allowables.
A Caustic Stress-Corrosion Cracking Evaluation of Thermally Treated Inconel Alloy 600 Steam Generator Tubing
Authors: Airey GP , Vaia AR
Published: March 2009

The stress-corrosion cracking (SCC) resistance of commercially fabricated mill-annealed and thermally treated Inconel Alloy 600 steam generator tubing was evaluated over a range of sodium hydroxide concentrations (10 to 50 percent), test temperatures [316 to 343 °C (600 to 650 °F)] and applied stresses (50 to 150 percent yield stress). The grain boundary microstructure was compared with that previously observed in laboratory-treated material. The SCC resistance of thermally treated tubing was superior to that of the mill-annealed product for all test conditions. It was confirmed that the improvement in caustic SCC resistance correlated with the presence of a semicontinuous grain-boundary chromium carbide precipitate. Grain boundary segregation (phosphorus, boron) and chromium depletion do not adversely affect SCC performance. The presence of copper oxide reduced SCC resistance, whereas the presence of silica inhibited SCC. These observations were rationalized by reference to the anodic polarization curve.
A Mechanistic Interpretation of the Relationship Between Temper Embrittlement and the Stress-Corrosion Cracking Susceptibility of Nickel-Chromium Steels
Authors: Bandyopadhyay N , Briant CL , Emigh P , Ford FP
Published: March 2009

The relationship between temper embrittlement and caustic embrittlement is confirmed for a 3.5Ni-Cr steel at a specific operating temperature, pH, and potential. The increased cracking susceptibility, associated with phosphorus segregation to the prior austenite grain boundary, is explained by the formation of an inhibiting environment in the crack enclave which ensures the maintenance of a sharp crack. Detemper embrittlement leads to crack blunting due to dissolution on the crack sides and the subsequent lowering of effective crack-tip stress and cracking susceptibility.
Development of Low-Cost Polymers for Solar Energy Applications
Authors: Gupta A , Liang RH , Hong SD , Di Stefano S , Coulter DR , Chung SY , Oda KL , Clayton AK , Laue E
Published: March 2009

Polymers for solar energy applications have to meet rigorous cost goals in terms of material and fabrication costs, as well as stringent criteria for performance over long periods (>10 to 30 years) of outdoor deployment. Hence, the development of reliable models for life prediction of polymeric components is essential if projections of the life cycle cost of solar energy conversion devices are to be meaningful. These models are based on a mechanistic understanding of failure and degradation mechanisms in polymeric materials and on a correlation between failure rates and degradation rates. At the Jet Propulsion Laboratory, Pasadena, Calif., we have developed a solar polymer research and development program which has the following components: (a) study of degradation mechanisms, including those induced photochemically; (b) development of accelerated test procedures, including test chambers, test parameters, and test conditions; and (c) development of diagnostic techniques that can detect small changes in chemical properties in real-time abbreviated tests as well as predict incipient failures in accelerated tests.

In this report, we describe the rationale for development of low-cost ultraviolet-absorbing transparent polymer films for solar applications. Developmental efforts have emphasized modification of existing polymers, rather than synthesis of new structures. In order to ensure long life, development of new polymers has to be integrated with the study of photothermal degradation mechanisms. This comprehensive effort has been utilized in the development of a stable polycarbonate and modified methacrylate polymers.
West German Research Programs on Irradiation Effects on Reactor Pressure Vessels
Authors: Kussmaul K
Published: March 2009

Reactor pressure vessels of nuclear installations are subjected to operating parameters that lead to a change in material and flaw state. The safety margin of both the material for older vessels and the optimized material has to be quantified with reference to extremely long-term effects. Research programs in West Germany are focused on assessing criteria for the applicability of small-scale specimen testing to component behavior under all realistic and postulated loading conditions. The problem will be treated theoretically and experimentally for a wide range of materials, including the worst-case material state at the end of life.
Effect of Irradiation on Elastic-Plastic Toughness of Pressure Vessel Steels
Authors: Soulat P , Petrequin P , Houssin B
Published: March 2009

Irradiation experiments were conducted in order to determine the effect of radiation damage on the elastic-plastic ductile fracture toughness of pressure vessel steels. Curves for the J-integral versus crack growth resistance (Δa) were established on specimens taken out of two nuclear reactor pressure vessel steels before and after neutron irradiation at 290°C to a fluence of 3.1019 n/cm2 (work function energy E > 1 MeV). The J-Δa tests were performed at room temperature (25°C) and service temperature (290°C). The main results obtained are as follows:

• For J-Δa testing the tearing modulus appears to be the most sensitive parameter.

• The two steels have significant differences in toughness, depending on their sulfur content.

• The testing temperature strongly affects the J-Δa resistance curve.

• Irradiation affects J-Δa curves only slightly for one steel but more significantly for the other at 290°C.

• Changes in the J-Δa curves with irradiation and temperature seem difficult to predict from Charpy V results.
Irradiation Experiments in the Testing Nuclear Power Plant VAK
Authors: Föhl J , Leitz CH , Anders D
Published: March 2009

Within the German research program “Integrity of Components” the first two capsules were irradiated in the Testing Nuclear Power Reactor VAK. The materials are of the 22 NiMoCr 37 and 20 MnMoNi 55 types and represent the lower bound of the base material regarding upper shelf energy and chemical composition (Cu, S, P) as well as a state of material which does not meet both chemical and toughness requirements (low upper shelf test melt). Tension, Charpy, drop-weight, and fracture mechanics specimens were irradiated up to a range of 1 · 5 to 2 · 1019 cm−2 (>1 MeV). Despite the materials being at or beyond the specification limits, the results show irradiation sensitivity which can be predicted from the U.S. Reg. Guide Trend Curves (1.99) and KWU Trend Curves in a conservative manner. The procedure to determine the adjusted reference temperature RTNDT (adj.) on the basis of ΔT41J (following ASTM E 185) could also be confirmed as conservative by comparing the different criteria derived from Charpy and drop weight tests in the unirradiated and irradiated condition.

The results of fracture mechanics testing in the linear elastic range show a remarkable temperature margin to the KIc-curve of ASME XI [6].

Prestrained 40-mm compact tension (CT) specimens made of 22 NiMoCr 3 7 material with an upper-shelf energy of approximately 100 J were wedge loaded in a range up to 30 MPa √m and exposed to the water environment during irradiation. Macroscopic examination gave no indications of stress corrosion cracking.

From tests of these specimens in the linear elastic range, a fracture toughness KIc, which was not affected by the prestrain and environment history, was found dependent only on the overload applied during the prestraining procedure.
Selection of Specimen Types for Irradiation Surveillance Programs
Authors: Varga T , Njo D-H
Published: March 2009

Recent trends in coping with embrittlement problems in reactor pressure vessels (RPVs) show two main directions of development: (1) improvement of the vessel materials and (2) limitations of fluence over the design life of the RPV. For several reasons, however, adequate irradiation surveillance programs are still considered to be necessary in the future, despite possible improvements resulting from such research activities.

Since the introduction of linear elastic fracture mechanics (LEFM) and elastic-plastic fracture mechanics, (EPFM), irradiation surveillance programs show a trend towards direct measurement of fracture toughness, in addition to relying on the conventional nil-ductility transition temperature (NDTT) shift as a relative measure of embrittlement. Some basic considerations concerning the selection of specimen types for irradiation surveillance programs and some technical aspects of currently used specimen types are discussed.
A Service Laboratory's View of the Status and Direction of Reactor Vessel Surveillance
Authors: Norris EB
Published: March 2009

Advances in testing techniques and analysis procedures have had a minor impact to date on the conduct of reactor vessel material surveillance programs. However, major thrusts in the near future will be associated with the development of elastic-plastic fracture toughness data on irradiated materials and improvements in analysis techniques for projecting surveillance results to the pressure vessel wall. In this regard, increased emphasis will be placed on the development of R-curves from the results of J-integral tests. Also, efforts will be increased to develop a better understanding of neutron irradiation embrittlement mechanisms, to determine if a time dependency of damage can lead to saturation and to evaluate the significance of small variations in irradiation temperature on the embrittlement response.
Application of Scanning Electron Microscopy for Correlating Fracture Topography and Microstructure
Authors: Nenonen P , Törrönen K , Kemppainen M , Kotilainen H
Published: March 2009

A new method for correlating fracture topography and microstructure has been developed. The details of the method, which utilizes scanning electron microscopy, are described. The method is applied in a microstructural analysis of cleavage crack propagation in a bainitic pressure-vessel steel.
Characterization of the Fracture Behavior of Fine-Grained High-Strength Low-Alloy (HSLA) Steels and Iron-Base Alloys Under Low-Temperature and Mechanical Environments
Authors: Krishnadev MR , Cutler LR , Sojka GJ , Gauvin P , Hamel G
Published: March 2009

This paper discusses the use of different fractographic techniques to characterize the fracture morphology of high-strength low-alloy (HSLA) steels with a variety of fine-grained microstructures and iron-base alloys strengthened by intermetallic precipitates in order to understand the various fracture mechanisms controlling their fracture resistance under low-temperature and mechanical environments. The fractographic techniques that have been used are conventional techniques, scanning electron fractography, sectioning techniques, and a newly developed chemical polishing method in conjunction with the Nomarski interphase contrast technique. The mechanical tests that have been used are tensile, notched-tensile, instrumented impact testing with precracked Charpy V-notch specimens, low-cycle fatigue, and high-cycle fatigue. A comprehensive characterization of the fracture morphology of the HSLA steels developed for arctic applications has resulted. Important features of the fracture (such as “splitting,” striations, ductile tearing, quasi-cleavage, microvoid coalescence, unit fracture path, persistent slip bands) have been identified and related to the mechanical behavior of the materials.
Estimating the Environmental Concentrations of Consumer Product Components
Authors: Holman WF
Published: March 2009

Procedures are developed for estimating the environmental concentrations of chemical components contained in consumer products and disposed down the drain. The concentrations are estimated by considering the quantities of the chemical used in consumer products, reported values of per capita wastewater flow, the extent of removal and degradation in wastewater treatment systems, and estimates of the factors by which wastewater sludge is amended in soil and effluent is diluted in receiving streams. The stream dilution factor (the ratio of river flow rate to the effluent discharge rate) is calculated for each of 161 major river basins in the United States. The median of these values is about 100, with 91 percent of them being greater than 10. The use of these estimates in environmental risk assessments is discussed, as well as assumptions and limitations.
Environmental Carcinogenesis Studies in the Western New York Great Lakes Aquatic Environment
Authors: Black JJ , Dymerski PP , Zapisek WF
Published: March 2009

A localized portion of the western New York Great Lakes aquatic environment is being examined for the presence of carcinogenic and mutagenic substances. Several approaches are being utilized, including a survey of tumors and contaminant analysis of tissue in fish collected from a heavily industrialized freshwater estuary.

Chemical characterization studies of contaminants present in bottom sediments were carried out using reversed-phase high-pressure liquid chromatography (HPLC) applied to fractions derived by routine organic extraction and separation methods. Correlations between the polynuclear aromatic hydrocarbon (PAH) composition of the contaminated sediments and that found in the biota were sought. The HPLC analysis of fractions isolated from sediments, tubifex worms, aquatic snails, and fish tissues indicated the presence of a PAH “fingerprint” in all segments of the aquatic food chain. Of the limited biota analyzed, only the annelids accumulated relatively high levels of PAH compounds.

Selected ion monitoring (MS) of the HPLC eluate was used to confirm the results of the HPLC analysis of fractions derived from fish and sediments. These data indicate the presence of a series of compounds having mass units consistent with empirical HPLC identifications of PAH compounds.