bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Fabrication Variables on Irradiation Response of Crack Growth Resistance of Zr-2.5Nb
Authors: Coleman CE , Theaker JR , Kidd KV 
Published: September 2004

Abstract
Specimens of pressure tubes made from Zr-2.5Nb by various fabrication routes were irradiated in research reactors to evaluate the response of their fracture toughness (represented by crack growth resistance, dJ/da) at 250°C to irradiation by fast neutrons (E &gt; 1 MeV). The reference route consists of melting Kroll sponge and some recycled material, primary hot-working, extrusion at 815°C, and cold-working 27 %. Tubes made from ingots that were melted four times (quadruple melting) are initially tougher than tubes made from ingots that have been melted twice (double melting), and after irradiation the former retain close to 50 % of their original crack growth resistance while the latter retain less than 30 % of theirs. The high toughness and its retention in the quadruple melted material are attributed to low concentrations of chlorine. Tubes made from electrolytic powder contain fluorine rather than chlorine. Fluorine is less damaging than chlorine. Crack growth resistance and its retention with irradiation of tubes made from electrolytic powder are intermediate between those of tubes made from quadruple and double melted sponge. Lowering the amount of cold-work is beneficial, and the toughness of tubes made with less than 27 % cold-work correlates well with strength, both before and after irradiation. Lowering the extrusion temperature produces strong, tough tubes, but these tubes lose much of their crack growth resistance with irradiation. This loss in toughness is not associated with material chemistry but with a high sensitivity to strength.
High Cycle Variable Amplitude Fatigue of a Nodular Cast Iron
Authors: Marquis GB , Rabb BR , Karjalainen-Roikonen P 
Published: September 2004

AbstractThis paper provides a brief summary of life prediction methods for variable amplitude fatigue. Special attention is given to cracks propagating from nominally defect free components in the high cycle regime where a significant portion of the fatigue damage can be attributed to cycles with amplitude less than the fatigue limit observed under constant amplitude loading. Constant and variable amplitude fatigue data for a nodular cast iron are presented. An effective stress method for variable amplitude loaded similar to the Topper model is developed. Most model parameters are derived from constant amplitude S-N curves and the Haigh diagram, but two sets of long life variable amplitude tests are needed to derive the variable amplitude interaction parameters.
Effect of Transient Loads on Fatigue Crack Growth in Solution Treated and Aged Ti-62222 at −54, 25, and 175°C
Authors: Stephens RR , Stephens RI , Berge SC , Lemm DE , Glancey CD 
Published: September 2004

Abstract
Transient loads consisting of single tensile overloads and single tensile overloads followed by single compressive underloads were applied to Ti-62222 solution treated and aged titanium alloy at −54, 25, and 175°C. Tensile overload ratios were 2.0 and 2.5, and the compressive underload ratio was −0.5. Four reference steady state ΔKss values, using constant δK testing at R = 0.1, were investigated at each temperature. Cycles of delay, fatigue crack growth during delay, and minimum fatigue crack growth rate during a transient load were obtained for all tests. Cycles of delay ranged from zero to crack arrest. Higher tensile overloads caused greater delay cycles, and underloads were often detrimental. Low and high temperatures were primarily beneficial to delay cycles relative to those at room temperature. Crack growth delay distance was always greater than the pertinent reversed plastic zone size. Fatigue crack growth life predictions were made using FASTRAN III and AFGROW computer programs and produced both conservative and non-conservative results with more than half the predictions being within ±2 of the experimental results. Macro- and microfractography revealed surface crack closure, Mode II displacements, crack tip blunting, branching, and tunneling contributed to the transient fatigue crack growth behavior.
Prediction of Crack Growth Under Variable-Amplitude and Spectrum Loading in a Titanium Alloy
Authors: Newman JC , Phillips EP 
Published: September 2004

AbstractThe present paper is concerned with the application of a plasticity-induced crack-closure model, FASTRAN, to predict fatigue-crack growth under various load histories in a thin-sheet Ti-62222 STA titanium alloy. This alloy was a leading candidate for a metallic High-Speed-Civil-Transport (HSCT) aircraft in the United States. The crack-growth model was based on the Dugdale strip-yield model but modified to leave plastically deformed material in the wake of the advancing crack. The model includes the influence of “constraint” on the development of plasticity and closure during constant- and variable-amplitude load histories. The model was used to correlate crack-growth-rate data under constant-amplitude loading over a wide range in crack-growth rates and stress ratios at two service temperatures (room temperature and 175°C). Tests on repeated spike overloads were used to help establish the constraint variations in the model. The model was then used to predict crack growth under two simulated aircraft spectrum load histories at the two temperatures. The spectra were a commercial HSCT wing spectrum and the Mini-TWIST (transport wing spectrum). This paper will demonstrate how constraint plays a leading role in the retardation and acceleration effects that occur under variable-amplitude and spectrum loading. The model was able to calculate the effects of repeated spike overloads on crack growth at the two temperatures, generally within about ± 30%. Also, the predicted crack-growth behavior under the HSCT spectrum agreed well with test data (within 30%). However, the model under-predicted the fatigue-crack-growth behavior under the Mini-TWIST spectrum by about a factor-of-two. Some of the differences may be due to fretting-product-debris-induced closure or three-dimensional effects, such as free-surface closure, not included in the model. Further study is needed on life predictions under the Mini-TWIST flight spectrum.
Crack Growth and Closure Behavior of Short and Long Fatigue Cracks under Random Loading
Authors: Song JH , Kim C-Y , Lee S-Y 
Published: September 2004

AbstractCrack growth and closure behavior of physically short and conventionally long cracks under random loading are extensively investigated, utilizing test results of 2024-T351 aluminum alloy obtained by performing narrow- and wide-band random loading tests for various stress ratios and random loading block lengths. A noise reduction method is developed to determine the crack opening load under random loading more easily, precisely, and economically. Crack growth rates are analyzed mainly in terms of the stress intensity factor range estimated by 2/PI correction proposed by Donald and Paris. The long and short cracks are very different in characteristics of closure behavior under random loading. Crack growth of short and long cracks under random loading can be well described by the crack closure concept. The effects of random spectrum or random block length on crack opening load and crack growth are not significant.
Comparison of the Rain Flow Algorithm and the Spectral Method for Fatigue Life Determination Under Uniaxial and Multiaxial Random Loading
Authors: Łagoda T , Macha E , Niesłony A 
Published: September 2004

AbstractThis paper presents the strain energy density parameter used for fatigue life calculation under random loading by two methods. The first method is based on schematization of energy parameter histories with the rain flow algorithm. The other one is based on moments of the power spectral density function of the energy parameter. The experimental data of fatigue tests of 10HNAP steel under constant amplitude and random uniaxial loading with non-gaussion probability distribution, zero mean value, and wide-band frequency spectrum used for comparison of the rain flow algorithm and the spectral method gave satisfactory results. Next, histories of the random stress tensor with normal probability distribution, wide-band frequency, and zero mean values corresponding to biaxial tension-compression, combined tension with torsion and triaxial loading with various correlation coefficients were generated, and the lifetime was calculated. It has been observed that both methods of fatigue life determination give almost the same results.
Spectrum Fatigue Testing and Small-Crack Life Prediction Analysis on a Coupon Similar to a Critical Design Detail of a CF188 Hornet Component
Authors: Yanishevsky M , Everett RA 
Published: September 2004

Abstract
Numerous studies have shown that small-crack methodology can be used to predict the total fatigue life of laboratory type (KT = 1 and 3) specimens under variable amplitude loading. Prior to investigating how well this fatigue life prediction capability could be extended to “real” aircraft structures, an intermediary step was taken where total fatigue life was predicted for a laboratory type specimen similar to a critical design detail in a fighter aircraft fuselage bulkhead. Using the small-crack analysis in the computer code called FASTRAN and assuming an initial crack size of 20 microns, the time to catastrophic failure of the test coupons was predicted to within 10% of the average test times.
Variable Amplitude Fatigue Crack Growth Using Digital Signal Processing Technology
Authors: Donald JK , George K 
Published: September 2004

AbstractAn automated variable amplitude fatigue crack growth system has been developed using digital signal processing (DSP) technology to provide waveform generation, command-feedback verification, and crack growth monitoring. The system is designed to interface with existing analog or digital closed-loop servo-hydraulic mechanical test systems. An important parameter in the control of variable amplitude testing is the effect of loading errors on the fatigue crack growth rate response. A damage parameter (Γ) has been incorporated to quantify the magnitude and effect of loading errors. In this paper, a FALSTAFF, Mini-TWIST, and truncated Mini-TWIST aircraft spectrum were applied to an M(T) crack growth sample to demonstrate the correlation between the damage parameter and fatigue life.
A Model for the Inclusion of Notch Plasticity Effects in Fatigue Crack Growth Analysis
Authors: Ball DL 
Published: September 2004

Abstract
Notches or other stress concentrations are by far the most common sites for the initiation and growth of fatigue cracks in aircraft structures. The growth of these cracks is directly influenced by the material stress-strain response in the vicinity of the notch. Specifically, when the applied (remote) stress is sufficient to cause local plastic deformation at the notch, the response (local) stresses can no longer be found using elastic stress concentration factors, and they become dependent on the prior loading history. This is to say that the response stresses can no longer be treated as state variables. The occurrence of fatigue crack growth at notches which experience local yielding one or more times during their design lifetime is, in fact, quite common in many cyclically loaded structures. Some of the assumptions inherent in “traditional” Linear Elastic Fracture Mechanics (LEFM) based fatigue crack growth analysis may be inappropriate for such problems. In particular, the assumption that the stress distribution on a critical plane remains proportional to the elastic distribution throughout the loading history becomes incorrect when one or more of the applied loads causes plastic deformation and introduces or alters a residual stress field in this region. This paper first describes an elastic-plastic stress-strain response algorithm which may be used to estimate response stress distributions on a critical plane on a cycle-by-cycle basis. This is followed by a discussion of the manner by which stress intensity factors may be calculated based on these response stress distributions using Green's functions. Finally, the use of these stress intensity factors for the calculation of crack growth rate and, ultimately, crack growth life, is demonstrated.
Study on Fatigue Design Loads for Ships Based on Crack Growth Analysis
Authors: Tomita Y , Hashimoto K , Osawa N , Terai K , Wang Y 
Published: September 2004

Abstract
Although ship structural members are designed to survive 20 years, fatigue crack damage still occurs, often starting very early in the ship's life, with some cracks growing quickly to considerable size. The primary factor causing variability is the sequence of the variable amplitude load cycle, and the others are welding irregularities on the weld toe and variations in mechanical properties in the material. In this paper, the load sequence effect on fatigue life variability is examined by the use of a fatigue design procedure proposed by the authors. It is found that the fatigue lives of ship structural members vary from several months to 20 years, strongly dependent on the sequence of sea state which ships encounter during ocean-going service. The worst possible loading sequence is elucidated for the fatigue life of the ship's hull. Sensitivity study of fatigue life is discussed.
High Cycle Fatigue Testing and Analysis Using Car Standard Sequence
Authors: Morel F , Ranganathan N 
Published: September 2004

Abstract
An original computer software package for controlling a servo-hydraulic machine was used to carry out uniaxial and biaxial variable amplitude loading tests on a high strength steel. Tension-compression and torsion uniaxial tests, as well as combined proportional tension-torsion tests were performed under the car loading sequence CARLOS used for fatigue strength investigations of car wheel suspension components. The number of sequences to crack nucleation was estimated by means of a crack front marking technique using very small amplitude cycles to generate marker bands on the fracture surface. The experimental data obtained from these tests were compared to the predictions of the fatigue life prediction method proposed by Morel and based on a microplasticity analysis. It was shown that all the predictions, though non-conservative, were within an acceptable scatter band.
Effect of Overloads and Underloads on Fatigue Crack Growth and Interaction Effects
Authors: Romeiro F , de Freitas M , Pommier S 
Published: September 2004

Abstract
Under constant amplitude loading a single variable (ΔK) is required in crack growth relationships. The transferability of fatigue laws, determined under constant amplitude loading, to variable amplitude fatigue requires at least an additional variable, whose evolution with crack length accounts for the interaction effects between cycles of different types. The crack opening level (Kop) is usually employed for this purpose because it can be determined from the experiments and compared with predictions from models or FEM analyses. This paper presents an analysis of fatigue crack growth on M(T) specimens of medium carbon steel specimens and using FEM analyses. The specimens are subjected to repeated blocks of cycles made up of one or several overloads separated by a variable number of baseline cycles. The experiments are simulated by FEM analyses, taking into account the cyclic plastic behavior of the low carbon steel. The main objective of this study is to better understand the mechanisms at the origin of interactions effects due to the presence of overloads (or underloads) at different locations of the block loading. It is concluded that the interaction effects are closely related to the cyclic plastic behavior of the material and namely to the Bauschinger effect.
Crack Initiation at a Notch under Constant and Selected Variable Amplitude Loading Conditions
Authors: Gérard N , Leroy R , Girard O , Ranganathan N 
Published: September 2004

Abstract
In a previous study, we showed that crack initiation life at a notch tip can be modeled as the micro crack propagation life from an initial microstructural defect up to a crack size of about 500 µm. This model is based upon the assumption that short cracks at a notch propagate without any significant closure effects. In our present experimental study, the results of fatigue tests to verify this hypothesis are presented and discussed.
The fatigue tests were conducted in ambient air on single edge notched specimens with a theoretical stress concentration factor of 3.14 on thin sheets of 1.2 mm thick Aluminum alloy 2024 T351. The test conditions studied are: constant amplitude tests at stress ratios of 0.1, 0.3, and 0.5 and variable amplitude tests using an extract from the TWIST spectrum. The tests were carried out at a nominal frequency of 10 Hz. At selected intervals, micro crack advance (if any) was determined using replicas. The measurements were made at the maximum stress for constant amplitude tests and at a chosen positive stress for variable amplitude tests (avoiding any overload). The smallest crack size detected is about 10 µm.
Time-Resolved ESCA: a Novel Probe for Chemical Dynamics
Authors: Drescher Markus 
Published: September 2004

Abstract
Electron spectroscopy for chemical analysis (ESCA) is a well established tool for quantitative studies of the composition and the chemical environment of molecular systems. Recent developments in the generation and utilization of ultrashort X-ray pulses now add the dimension of time to this technique and will expand the possibilities of femtochemistry in terms of chemical selectivity, quality of information, and temporal resolution. The properties and capabilities of various X-ray pulse sources are discussed, along with their prospects for dynamical studies. Examples of time-resolved electron spectroscopy are presented in the femtosecond (1 fs = 10−15 s) as well as the attosecond (1 as = 10−18 s) regime, the latter marking the current ultimate limit for the time-resolution in pump-probe experiments.
Contributions of Multipolar Polarizabilities to the Isotropic and Anisotropic Light Scattering Induced by Molecular Interactions in Gaseous Sulfur Hexafluoride
Authors: El-Kader M.S.A. , El-Sheikh S.M. , Omran M. 
Published: September 2004

Abstract
The binary isotropic and anisotropic collision-induced light scattering spectra of the gaseous sulfur hexafluoride at room temperature are analyzed in terms of recent intermolecular potential and interaction-induced pair polarizability models, using quantum line-shapes computations. The spectra at relatively low frequencies are determined largely by the effect of bound and free transitions. At intermediate frequencies the spectra are sensitive to both the attractive part of the potential and the short-range part of the polarizability trace and anisotropy. The high frequency wings are discussed in terms of the collision-induced rotational Raman effect and estimates for the dipole–octopole polarizability E, is obtained and checked with recent ab initio theoretical value. Absolute zeroth moment of both spectra have been measured and compared with theoretical calculations using different models of the intermolecular potentials. Also, the temperature dependence of the pressure second virial coefficient, viscosity and thermal conductivity are also discussed for the proposed potentials. The results show that (M3SV) is the most accurate potential yet reported for this system.
The Dissolution of FeO and FeF3 in Cryolite
Authors: Šimko F. , Proks I. , Daněk V. , Boča M. , Chrenková M. 
Published: September 2004

Abstract
Theoretical derivation of relations valid for cryoscopic measurements in solvents with dystectic mode of melting (solvents, which undergo at melting a more or less extended thermal dissociation), when also chemical reaction between solvent and solute takes place, is presented. When one of the products of this chemical reaction is identical with the product of thermal dissociation of the solvent, arise the problem of defining the number of “foreign” substances, originating in the reaction. The presented approach shows that the partially dissociated solvent cannot distinguish as foreign substance between the own dissociation product and the originating one and made it easier to determine the nature of the probable chemical reaction.
The presented approach is applied in the systems Na3AlF6–FeO and Na3AlF6–FeF3, which are of great importance in the fundamentals of aluminium electrolysis.
In the system Na3AlF6–FeO for the dependence of the temperature of primary crystallization of cryolite on x(Na3AlF6) the equation

T
pc/K = 1014.4 + 267.86x(Na3AlF6)
was obtained, which yields for the Stortenberker’s correction factor the value k
St = 2.09. This means that dissolving FeO in cryolite two new particles are formed. This can be interpreted by the chemical reaction
2Na3AlF6 + FeO ⇔ Na2FeF4 + Na2Al2OF6 + 2NaF.
In the system Na3AlF6–FeF3 for the dependence of the temperature of primary crystallization of cryolite on x(Na3AlF6) the equation

T
pc/K = 1547.2 − 659.88x(Na3AlF6) + 394.99x
2 (Na3AlF6)
was obtained. For the Stortenbeker’s correction factor the value k
St = 1.02 was then calculated, which means that one new particle is created when FeF3 is dissolved in cryolite. The most probable reaction is
1.5Na3AlF6 + FeF3 ⇔ Na3FeF6 + 1.5NaAlF4.
Middle school victims of bullying: Who reports being bullied?
Authors: Unnever James D. , Cornell Dewey G. 
Published: September 2004

AbstractThis study examined factors that influence a student's decision to report being bullied at school. An anonymous survey of 2,437 students in six middle schools identified 898 students who had been bullied, including 25% who had not told anyone that they were bullied and 40% who had not told an adult about their victimization. We investigated chronicity and type of bullying, school climate, familial, demographic, and attitudinal factors that influenced victim reporting to anyone versus no one, to adults versus no one, and to adults versus peers. Logistic regression analyses indicated that reporting increased with the chronicity of victimization. Reporting was generally more frequent among girls than boys, and among lower grade levels. Students who perceived the school climate to be tolerant of bullying, and students who described their parents as using coercive discipline were less likely to report being bullied. Implications for improving victim reporting of bullying are discussed. Aggr. Behav. 30:373–388, 2004. © 2004 Wiley‐Liss, Inc.
Urinary testosterone metabolite levels and aggressive behaviors in male and female bonobos (Pan paniscus)
Authors: Sannen Adinda , Van Elsacker Linda , Heistermann Michael , Eens Marcel 
Published: September 2004

AbstractThis study presents the first data on the relationship between testosterone (T) and aggression in both sexes of the bonobo (Pan paniscus). Morning urinary concentrations of T metabolites (measured by immunoreactive 5α–androstane–17α–ol–3–one) were used to reflect T status. Results show that first, no correlation of T metabolite levels with any of the aggressive behaviors was found between individuals. Within an individual, T metabolite levels only correlated with a minority of aggressive behaviors. Hence, social factors are likely of major importance for the occurrence of aggression in this highly gregarious species, but certain intraindividual aspects of aggressive behavior are nevertheless related to T. A more detailed discussion of the results follows. Secondly, all correlations with T were similar for every individual, males and females, suggesting an analogous relationship in both sexes. Thirdly, our study confirms for bonobos that the measure of aggression used, the time scale at which the correlation is studied, and whether this is done on an inter‐ or intraindividual level, considerably affect results. Aggr. Behav. 30:425–434, 2004. © 2004 Wiley‐Liss, Inc.