bluuebunny/crossref_metadata_2025_split huggingface dataset:
VALIDATION OF THE FRACTURE MECHANICS TEST METHOD EGF P1–87D (ESIS P1–90/ESIS P1–92): ANALYSIS OF AN EXPERIMENTAL ROUND ROBIN
Authors: Schwalbe K.‐H. , Hayes B. , Baustian K. , Cornec A. , Gordon R. , Homayun M. , Voss B. 
Published: April 2007

Abstract— The elastic—plastic fracture mechanics test method EGF P1–87 D: EGF Recommendations for Determining the Fracture Resistance of Ductile Materials has been validated by an extensive round robin, covering fracture tests and their evaluation as well as scanning electron fractography. The results confirmed the suitability of the procedure, but suggested some modifications. The resulting procedure ESIS P1–90 was then further modified and its actual designation is ESIS P1–92.The present report provides comprehensive information on the determination of crack growth resistance curves and initiation values. Particular emphasis is on single specimen techniques and on determining the stretch zone width. Beyond the validation of the ESIS procedure the information given is pertinent to elastic‐plastic fracture testing in general.
THE EFFECT OF MEAN STRESS ON MIXED MODE (I + III) FATIGUE THRESHOLDS
Authors: Yates J. R. , Mohammed R. A. 
Published: April 2007

Abstract— Mode I, mode III and mixed mode (I + III) fatigue crack growth threshold tests have been performed on a 3.5% NiCrMoV steel at a range of mean stresses corresponding to load ratios R = 0.06 to 0.5. Angled slit three point bend specimens were used for mixed mode (I + III) tests, circumferentially slit round bars for mode III tests and conventional three point bend specimens for mode I tests.Test results were divided into those specimens which had failed and those in which no extension of the initial slit had occurred. The results were compared with the response predicted by two existing mixed‐mode threshold models. It was found that a model based on the magnitude and direction of mode I crack opening gave results which were in better agreement with the experimental results than a model based on branch crack formation.
SHORT FATIGUE CRACK GROWTH UNDER MEAN STRESS, UNIAXIAL LOADING
Authors: Wang C. H. , Miller K. J. 
Published: April 2007

AbstractAn investigation of the effects of mean and alternating stresses on short fatigue crack growth under uniaxial loading is reported. Tests under stress‐controlled conditions with different combinations of mean and alternating stresses were conducted at room temperature using a 1.99% NiCrMo steel. The fatigue process was divided into three phases: Plasticity Localization, Microstructural Short Crack (MSC) growth, and Physically Short Crack (PSC) growth. The effect of mean stress on the above three phases is studied and a set of equations is obtained which can predict the early stage and growth behaviour of short cracks under various mean and alternating stresses. Satisfactory predictions of fatigue endurance curves at different mean stresses have been achieved. This approach provides an alternative method, based on the physics of the fatigue process, for use by designers who currently rely on conventional Goodman‐type diagrams.
FATIGUE RESISTANCE OF A MEDIUM CARBON STEEL WITH A WEAR RESISTANT THERMAL SPRAY COATING
Authors: Rakitsky A. A. , de los Rios E. R. , Miller K. J. 
Published: April 2007

Abstract— The fatigue behaviour of a Ni‐Cr‐base powder flame‐spray coating on a 0.4% C steel is investigated. Fatigue tests were carried out using mild hour‐glass profile specimens. Cracks were detected and measured using plastic replicas and an image analysis system. Coated specimens showed a slightly lower fatigue endurance than plain specimens under torsion loading, while the opposite was observed for push‐pull loading. Microcracks in coated specimens invariably form at pores.Contrary to the usual case of stage I shear growth for a plain 0.4% C steel in tension or torsion loading, the coated specimens show initial crack growth from pores along directions perpendicular to the maximum tensile stress. The crucial behaviour of short cracks, and their growth rates, relative to the thickness of the coating, are discussed in some detail.
FRACTURE AND LIFE PREDICTION UNDER THERMAL‐MECHANICAL STRAIN CYCLING
Authors: Ellison E. G. , Al‐Zamily A. 
Published: April 2007

Abstract— Thermal‐mechanical cyclic strain tests were carried out under in‐phase and out‐of‐phase conditions on a ferritic 1 CrMoV steel in the temperature range 315 to 565°C and two different batches of a 316 stainless steel in the temperature range 400 to 625°C. The results were compared with isothermal data.In general, lives for in‐phase thermal‐mechanical tests were lower than for equivalent isothermal tests. This was substantiated by metallographic examination which indicated greater intergranular damage for the in‐phase specimens. The addition of a tensile dwell to the in‐phase condition caused even greater differences.Three life prediction methods were used: the ductility exhaustion and a modified strain range partitioning approach gave reasonable estimates of life, whilst the linear life fraction method produced poor prediction.
UNSTABLE FATIGUE CRACK PROPAGATION AND FATIGUE FRACTURE TOUGHNESS OF STEELS
Authors: TROSHCHENKO V. T. , POKROVSKY V. V. , YASNIY P. V. 
Published: April 2007

AbstractThis paper presents the results of fatigue crack growth and fatigue fracture toughness studies of a high‐pressure vessel steel with particular emphasis on the influence of heat treatment, low temperatures, plastic prestraining, the stress ratio and specimen dimensions.It has been shown that steels in an embrittled state, caused primarily by thermal treatment and low‐temperatures, exhibit unstable fatigue crack growth which is characterized by alternate crack jumps (cleavage zones) and zones of fatigue crack growth. The fatigue fracture toughness, which corresponds to the first crack jump, and final fracture can be appreciably lower (i.e. up to 50%) than the static fracture toughness under plane strain conditions at the corresponding temperature.An analysis has been performed of unstable and stable fatigue crack growth and a model of unstable crack propagation is proposed which accounts for the observed experimental behaviour.
ACCELERATION OF FATIGUE CRACK GROWTH UNDER INTERMITTENT OVERSTRESSING WITH DIFFERENT MEAN STRESS LEVELS
Authors: KOTERAZAWA R. , MUDJIJANA  , QINSHENG Y. , TIAN‐JIAN W. , NOSH T. 
Published: April 2007

Abstract—Fatigue crack growth behaviour under intermittent overstressing was investigated in dry air with a low carbon steel under tension‐compression and tension‐tension loading with different mean stress levels. A very small number of cycles of overstress applied intermittently during a very large number of cycles of understress below threshold caused, in all cases, a significant acceleration in crack growth rate as compared to the case of steady cyclic stress. The acceleration for the case with tensile mean stresses was a little smaller than in the case without mean stress and it was related to a little higher crack closure level in the former case. Stress history in the precracking process had some effect on crack closure and, consequently, on the acceleration. A fairly good correlation was obtained between the acceleration and the effective stress intensity range. The acceleration under multi‐level intermittent overstresses with different mean stresses could be predicted by linear summation from two‐level intermittent overstress test data. No difference was recognized in the fracture surface morphology between the cases with different mean stress level including the cases of multi‐level stresses, indicating that the micromechanism of crack growth acceleration would be the same in all cases.
EVALUATION OF FATIGUE DAMAGE ACCUMULATION BY ACOUSTIC EMISSION
Authors: FANG D. , BERKOVITS A. 
Published: April 2007

Abstract—Improvements in acoustic emission (AE) test techniques have lead to developments whereby reliable acoustic emission measurements as a fatigue damage indicator were made at room temperature on Incoloy 901 smooth specimens, over a stress‐ratio range of −1.0≤R≤0.2. Fatigue damage accumulation was evaluated in terms of an AE damage definition and a damage function was developed. Thus, various damage phases in the cumulative damage process were identified by their AE signature, and then formulated and analyzed in terms of cumulative AE ringdown counts.
FINITE ELEMENT ANALYSIS OF CLOSURE BEHAVIOUR OF FATIGUE CRACKS IN RESIDUAL STRESS FIELDS
Authors: CHOI H.‐C. , SONG J.‐H. 
Published: April 2007

AbstractAn elastic‐plastic finite element analysis with high order elements is performed to examine closure behaviour of fatigue. cracks in residua1 stress fieids and the numerical results are then compared with experimental results. The finite element analysis, performed under plane stress using 8‐node isoparametric elements, can predict fatigue crack closure behaviour through residual stress fields very well. The crack opening and closing behaviour through a compressive residual stress field is found to be complicated and influenced by the applied load magnitude and the location of the crack tip. Three different types of crack opening behaviour, namely, normal, unsymmetric partial and symmetric partial crack opening behaviour are observed through a compressive residual stress field. The partial crack opening stress intensity factor including the partial crack opening effect is recommended for the prediction of fatigue crack growth through a compressive residual stress field.
THE EFFECT OF SAMPLE SIZE ON THE CONFIDENCE OF ENDURANCE FATIGUE TESTS
Authors: Beretta S. , Clerici P. , Matteazzi S. 
Published: April 2007

AbstractExperimental determination of the fatigue endurance (S‐N) curve of either a given material or a machine element imposes the choices of sample size and of stress levels to be tested. Since referenced recommendations do not apply when the data include run‐outs or have variable scatter, this paper studies the confidence of fatigue tests, taking into account the effect of sample size and of a statistical model. In this research, a great number of rotary bending fatigue tests were carried out, using a heat treated carbon steel with relevant scatter of fatigue lives. The statistical analysis allowed one to obtain confidence limits of the S‐N diagram estimates and to propose some criteria for a better formulation of test schedules.
DYNAMIC FRACTURE TOUGHNESS MEASUREMENTS AND LOCAL APPROACH MODELLING OF TITANIUM ALLOYS
Authors: Roudier Ph. , François D. 
Published: April 2007

AbstractTwo titanium alloys TA6V and TD5AC were tested. Tensile tests were performed, under static and dynamic loadings, on cylindrical notched and fatigue precracked specimens. The visco‐plastic constitutive equations of the alloy were found by fitting finite element computations with the experimental results. The dynamic fracture toughness was obtained by applying the convolution method of Bui and Maigre. Results for the TA6V alloy did not display significant variations of fracture toughness with loading rate, whereas for the TD5AC alloy an increase was measured. The critical void growth was found to be independent of the strain rate. Fair predictions of the fracture toughness under static as well as under dynamic conditions could be achieved by finite element computations using these experimental critical void growth values.
A MICRO‐MECHANICS MODEL OF CORROSION‐FATIGUE CRACK GROWTH IN STEELS
Authors: de los Rios E. R. , Wu X. D. , Miller K. J. 
Published: April 2007

AbstractPrinciples of Microstructural Fracture Mechanics (MFM) are used to develop a model for the characterization of environment‐assisted short fatigue crack growth.Fatigue cracks are invariably initiated at corrosion pits formed at inclusions, hence the analysis includes stress concentration effects at pits that lead to the propagation of fatigue cracks the rates of which are considered to be proportional to the crack tip plastic displacement. This plasticity is constrained by microstructural barriers which are overcome in a non‐aggressive environment at critical crack lengths only when the applied stress is higher than the fatigue limit. However, the superposition of an aggressive environment assists fatigue damage via crack tip dissolution, enhancement of crack tip plastic deformation, the introduction of stress concentrations at pits and a reduction of the strength of the microstructural barrier. These environment effects are manifested in a drastic reduction of the fatigue limit and higher crack propagation rates.The model is compared with fatigue crack propagation data of a BS251A58 steel tested in reversed torsion when submerged in a 0.6M NaCl solution.
VARIABLE AMPLITUDE LOADING IN En8 (080M40) STEEL: A DETAILED EXPERIMENTAL STUDY OF CRACK GROWTH
Authors: Ng'ang'a S. P. , James M. N. 
Published: April 2007

Abstract —The load interaction effects that occur under variable amplitude loading conditions following single peak overloads, low‐high blocks and high‐low blocks have been investigated on a commonly used structural steel. A detailed investigation has been carried out on long cracks which aims at developing and assessing the efficacy of a simple predictive model based on closure and plastic zone effects.The material was tested in a quenched and tempered condition. All the tests were carried out in the four point bending mode, in both the Paris regime and near the threshold, with overloads ranging from 10% to 100%.An attempt to relate crack closure to crack growth rates in the transient growth rate region (which follows a load change) was made.The trends observed for a wide range of loading parameters are presented.
CYCLIC STRESS‐STRAIN RESPONSE AND MICROSTRUCTURE UNDER VARIABLE AMPLITUDE LOADING
Authors: Christ H.‐J. , Mughrabi H. 
Published: April 2007

Abstract— In order to study the cyclic stress‐strain behaviour under variable amplitude loading in terms of dislocation glide character and microstructure, various metals and alloys were cyclically loaded in single‐step tests and in an incremental step test (IST). The cyclic stress‐strain curves (CSS curves) which correspond to the different loading conditions were compared and the shapes of the hysteresis loops were analysed with respect to Masing or non‐Masing behaviour.As expected, cyclic loading with constant amplitude leads to the formation of a characteristic dislocation arrangement that depends on the amplitude applied. The amplitude‐related microstructure corresponds to the observation that Masing behaviour was not found in single‐step tests. However, in the IST a state of saturation, or at least approximate saturation, is attained after some or many loading blocks. In the case of single‐phase polycrystalline materials, wavy slip behaviour was found to be a prerequisite for the fulfilment of Masing behaviour. Then, the CSS curve, obtained by means of IST, intersects that of the single‐step tests at an intermediate amplitude. Planar‐slip materials show very similar CSS curves in spite of considerable differences in the dislocation arrangements for different testing modes. The behaviour of particle‐hardened alloys depends very strongly on the relative effectiveness of the precipitates as obstacles for dislocation motion and can be understood analogously to single‐phase materials on the basis of the resulting dislocation glide character.
J‐INTEGRAL APPROACH TO MODE III FATIGUE CRACK PROPAGATION IN STEEL UNDER TORSIONAL LOADING
Authors: Tanaka K. , Akiniwa Y. , Nakamura H. 
Published: April 2007

Abstract—Mode III fatigue crack propagation tests were conducted on circumferentially cracked bars of a medium carbon steel under a constant value of the J‐integral range. The ΔJ value was evaluated from the loading part of the hysteresis loop of the applied torque and the angle of twist. The fracture surface was macroscopically flat for all cases examined in the present study. The crack propagation rate decreased with crack extension, because of the shear contact of the crack faces. The crack propagation rate, without contact shielding, obtained by extrapolating the relation between the crack propagation rate and the crack length to the pre‐crack length, was a power function of ΔJ irrespective of the initial notch depth.
A MICROCRACK GROWTH LAW FOR MULTIAXIAL FATIGUE
Authors: McDowell D. L. , Bennett V. P. 
Published: April 2007

Abstract—Within the past decade, critical plane approaches have gained increasing support based on correlation of experimentally observed fatigue lives and microcrack orientations under predominately low cycle fatigue (LCF) conditions for various stress states. In this paper, we further develop an engineering model for microcrack propagation consistent with critical plane concepts for correlation of both LCF and high cycle fatigue (HCF) behavior, including multiple regimes of small crack growth. The critical plane microcrack propagation approach of McDowell and Berard serves as a starting point to incorporate multiple regimes of crack nucleation, shear growth under the influence of microstructural barriers, and transition to linear crack length‐dependent growth related to elastic‐plastic fracture mechanics (EPFM) concepts. Microcrack iso‐length data from uniaxial and torsional fatigue tests of 1045 steel and IN 718 are examined and correlated by introducing a transition crack length which governs the shift from nonlinear to linear crack length dependence of da/dN. This transition is related to the shift from strong microstructural influence to weak influence on the propagation of microcracks. Simple forms are introduced for both the transition crack length and the crack length‐dependence of crack growth rate within the microcrack propagation framework (introduced previously by McDowell and Berard) and are employed to fit the 1045 steel and IN 718 microcrack iso‐length data, assuming preexisting sub‐grain size cracks. The nonlinear evolution of crack length with normalized cycles is then predicted over a range of stress amplitudes in uniaxial and torsional fatigue. The microcrack growth law is shown to have potential to correlate microcrack propagation behavior as well as damage accumulation for HCF‐LCF loading sequences and sequences of applied stress states.
APPROXIMATE EXPRESSIONS FOR THREE‐DIMENSIONAL NOTCH TIP STRESS FIELDS
Authors: Xu R. X. , Thompson J. C. , Topper T. H. 
Published: April 2007

Abstract—The analytical solution of Sadowsky and Sternberg for the stress field around an biaxial elliptical cavity in an infinite elastic body was carefully examined. For uniaxial tension, it was found that the stress concentration factor varies very slowly along the equator of the cavity, regardless of the shape of the cavity. As was found for two dimensional notch problems, the normalized stress fields around cavities with different shapes are virtually identical within the stress concentration region and differ only slightly beyond that region. This fact permits simple, yet very accurate approximate stress equations to be developed for three dimensional notch problems by modifying the previously obtained solutions for two dimensional notch problems.
THE FRACTURE MECHANISM IN 475°C EMBRITTLED FERRITIC STAINLESS STEELS
Authors: Marrow T. J. 
Published: April 2007

Abstract—The mechanism of “475°C embrittlement” in age‐hardened ferritic stainless steel, E‐Brite and A129‐4, is investigated. Experimental results for smooth tensile and notched bending fracture tests are interpreted using a finite element simulation of the stresses at fracture. Yield is characterised by profuse slip band formation. Transgranular fracture initiation is observed at slip band intersections with grain boundaries. Deformation twinning occurs during brittle fracture. Slip bands and deformation twins are identified using lattice rotations measured with electron back‐scatter diffraction patterns. Mechanisms for the ductile‐to‐brittle transition are discussed.
THE FRACTURE MECHANISM OF 475°C EMBRITTLEMENT IN A DUPLEX STAINLESS STEEL
Authors: Marrow T. J. , Harris C. 
Published: April 2007

Abstract—The mechanism of “475°C embrittlement” of a duplex stainless steel was investigated using finite element modelling of the stress distribution at brittle fracture initiation. Brittle fracture initiated at a critical shear stress, which increased with ferrite hardness. The fracture stress was affected by the duplex microstructure. Fracture was nucleated by deformation twins, which were identified using electron back‐scatter diffraction. The ductile‐to‐brittle fracture transition was sensitive to age‐hardening and could be described simply by the effect of age‐hardening and test temperature on the yield stress.
A TECHNICAL NOTE. INFLUENCE OF MEAN STRESS ON FATIGUE IN SEVERAL ALUMINIUM ALLOYS UTILIZING Kcmax THRESHOLD PROCEDURES
Authors: Clark T. R. , Herman W. A. , Hertzberg R. W. , Jaccard R. 
Published: April 2007

Abstract—Recent interest in the constant Kmax (Kcmax) threshold testing procedure has resulted in a more in‐depth study of the influence of Kmax level on fatigue response and ΔKth in aluminium alloys. Under Rc= 0.1 conditions, which cause large amounts of closure, ΔKth levels were typically 2 to 4 Mpam. However, under Kcmax test procedures, associated with no measurable closure at threshold, ΔKth was typically 1 Mpam. A slight Kcmax level effect on ΔKth was observed at high Kmax values for some of the alloys, and was deemed to be a pure mean stress effect, separate from closure arguments.
CYCLIC BEHAVIOUR AND ROOM TEMPERATURE MICROMECHANISMS OF 3Y‐TZP CERAMICS AT SUBMICRON AND NANOCRYSTALLINE LEVELS
Authors: Zheng Y. , Yan D. , Gao L. 
Published: April 2007

Abstract— The cyclic behaviour and micromechanisms of 3Y‐TZP ceramics were investigated at a stress ratio, R, of 0.1 and a frequency of 0.1 Hz at room temperature for both nanocrystalline (100nm) and submicron polycrystalline (0.35μm) 3Y‐TZP ceramics. The nanocrystalline material displayed cyclic softening, but the submicron polycrystalline material displayed cyclic hardening. The cyclic hardening resulted mainly from saturation of tetragonal to monoclinic phase transformation which induced a higher internal stress in the material; the cyclic softening resulted partly from the formation of microcracks along the grain boundary of the tetragonal phase.Superplastic deformation was first found by the Scanning Electron Microscope and the Atomic Force Microscope (AFM) in some micro‐areas of the fatigue fracture surface of the nanocrystalline material. Furthermore it was observed by AFM that there were a large number of slip lines and an early stage for the formation of an extrusion on the side edge of the fracture. From this it was deduced that the micromechanism of local superplasticity resulted from the slip motion of dislocation.
FRACTURE SURFACE DEVELOPMENT IN AN OVERLOADED D16T Al‐ALLOY SUBJECTED TO BIAXIAL LOADING. A FRACTOGRAPHIC ANALYSIS
Authors: Shanyavsky A. A. , Orlov E. F. 
Published: April 2007

Abstract— Fatigue crack growth experiments were carried out on cruciform specimens of D16T Al‐alloy, loaded under uniaxial and biaxial loads, including a sequence of various overloads. It is shown that, for biaxial cyclic loads at stress ratios λ and various R‐ratios, fracture surface development during overloads and the crack length dependences on the cyclic loads following overloads are similar to those for uniaxial loading.The aim of this investigation was to study interaction effects by analyzing the crack retardation length and associated parameters together with their relationships. These parameters’depend on the biaxial ratio (λ) and the stress ratio (R) and their uses in crack growth modelling are briefly considered.