bluuebunny/crossref_metadata_2025_split huggingface dataset:
A SIMPLIFIED RESIDUAL STRESS MODEL FOR PREDICTING FATIGUE CRACK GROWTH BEHAVIOR AT COLDWORKED FASTENER HOLES
Authors: Su X. , Gu M. , Yan M. 
Published: April 2007

AbstractThis paper presents an investigation of the fatigue crack growth (FCG) behavior at fastener holes in a high strength steel, 30CrMnSiNi2A, before and after a cold‐expansion process. The fatigue life of coldworked specimens was significantly increased compared to non‐coldworked ones and increased the lower applied stress level.From a study of the residual stress distribution near the edge of the hole, it was found that the experimental residual compressive stresses in absolute values were much less than the calculated values derived by previous analytical methods. Thus, a simplified residual stress model for describing the FCG behavior at coldworked fastener holes is proposed, from which, the δKeff and fatigue lives of specimens after cold‐expansion can be predicted satisfactorily for engineering applications.
THE EFFECTS OF CATHODIC POTENTIAL AND CALCAREOUS DEPOSITS ON CORROSION FATIGUE CRACK GROWTH RATE IN SEA WATER FOR TWO OFFSHORE STRUCTURAL STEELS
Authors: Murakami R. , Ferguson W. G. 
Published: April 2007

AbstractThe effects of cathodic protection potential, corrosion products and stress ratio on corrosion fatigue crack growth rate have been studied on offshore structural steels. These materials were cathodically polarised in seawater and 3% sodium chloride solution at three potentials of ‐0.8, ‐1.0 and ‐1.1 V(SCE). The corrosion fatigue crack growth rate in seawater was greater than that in air and increased with more negative potentials. The maximum acceleration of crack growth rate in seawater was observed at the crack growth plateau which was independent of ΔK.Calcareous deposits precipitated within the cracks resulted in an increase of crack opening level and contributed to a reduction of the corrosion fatigue crack growth rate. Such a corrosion‐product‐wedging effect could be evaluated by using an effective stress intensity range, ΔKeff. The estimation of corrosion fatigue crack growth rate in terms of ΔKeffclarified the effect of hydrogen embrittlement under a cathodic potential. Thus the processes of cracking in seawater at cathodic potentials resulted from mechanical fatigue and hydrogen embrittlement with calcareous deposits reducing the crack growth rate. All these three mechanisms were mutually competitive.
EFFECT OF FATIGUE CRACK CLOSURE ON NEAR‐THRESHOLD CRACK RESISTANCE OF STRUCTURAL STEELS
Authors: Romaniv O. N. , Tkach A. N. , Lenets Yu N. 
Published: April 2007

Abstract— The present paper is an attempt to clarify conditions for plasticity‐induced and oxide‐induced crack closure as well as to evaluate the effect of crack closure on near‐threshold fatigue crack behaviour.The autocatalytic character of oxide formation at the crack tip has been elucidated in this study. An increase of plastic constraint at the crack tip is shown to intensify the fretting oxide formation process on the fracture surface and thus to cause an increase of the stress intensity factor range controlling the fatigue crack propagation rate. The proposed concept of stress state influence on crack closure allows us to explain the effect of specimen thickness on ΔKth.
THE USE OF A NEW LINE‐SPRING SHELL ELEMENT FOR ELASTIC SURFACE CRACK ANALYSIS
Authors: Langre E. de , Ebersolt L. 
Published: April 2007

AbstractIn this paper, the Line‐Spring concept developed by Rice and Levy[l] is used to build a new elastic surface cracked shell element in the general purpose Finite Element code CASTEM 2000. The implementation is described and an energy release rate technique is proposed to arrive at more accurate Stress Intensity Factor values at the crack front‐free surface intersection. A comparison with existing accepted numerical solutions is made on various plane and cylindrical configurations and a discussion on the applicability of the model is presented.
FATIGUE STRENGTH OF BUTT WELDED Al–Mg ALUMINIUM ALLOY: TESTS WITH MAXIMUM STRESS AT YIELD STRENGTH
Authors: Ohta Akihiko , Mawari Toshio 
Published: April 2007

AbstractFatigue tests were carried out on type A5083P‐O Al–Mg aluminium alloy butt welded specimens by a test method which simulates the behaviour of large size welded structures having high tensile residual stresses by means of ordinary narrow specimens, containing low level residual stresses. In the tests, specimens were cycled down from a constant maximum stress of the yield strength of the material. The S–N data obtained in these tests were compared with corrected lines from S–N data for narrow specimens tested at R= 0 considering the presence of high tensile residual stresses and the proposed design curve in the draft British Standard BS 8118. It was found that the discrepancy between corrected lines and the data plots was not small and that the proposed design curve was over conservative in the high cycle region.
FATIGUE MICROCRACKS IN TYPE 304 STAINLESS STEEL AT ELEVATED TEMPERATURE
Authors: Suh C. M. , Lee J. J. , Kang Y. G. 
Published: April 2007

AbstractMicrocracking of type 304 stainless steel at 538°C has been studied, in particular, the initiation, growth and coalescence, of fatigue microcracks on smooth specimens via surface replicas and photomicrographs. Quantitative information, such as, initiation period, growth and coalescence behaviour, statistical distributions of crack length, density of cracks, distribution patterns and crack growth properties, were obtained. Knowledge of these parameters is critical for the application of fracture mechanics to fatigue life assessment and the damage evaluation of structures at elevated temperature.
SHORT AND LONG FATIGUE CRACK GROWTH IN A SiC REINFORCED ALUMINIUM ALLOY
Authors: Kumai Shinji , King Julia E. , Knott John F. 
Published: April 2007

AbstractFatigue crack growth behaviour in a 15 wt% SiC particulate reinforced 6061 aluminium alloy has been examined using pre‐cracked specimens. Crack initiation and early growth of fatigue cracks in smooth specimens has also been investigated using the technique of periodic replication. The composite contained a bimodal distribution of SiC particle sizes, and detailed attention was paid to interactions between the SiC particles and the growing fatigue‐crack tip. At low stress intensity levels, the proportion of coarse SiC particles on the fatigue surfaces was much smaller than that on the metallographic sections, indicating that the fatigue crack tends to run through the matrix avoiding SiC particles. As the stress intensity level increases, the SiC particles ahead of the growing fatigue crack tip are fractured and the fatigue crack then links the fractured particles. The contribution of this monotonic fracture mode resulted in a higher growth rate for the composite than for the unreinforced alloy. An increase in the proportion of cracked, coarse SiC particles on the fatigue surface was observed for specimens tested at a higher stress ratio.
DESIGN AND GROWTH RULES FOR BIOLOGICAL STRUCTURES AND THEIR APPLICATION TO ENGINEERING
Authors: Mattheck C. 
Published: April 2007

AbstractStarting from the well‐accepted but not proved hypothesis that biological load carrying structures are highly optimized by growth, some examples are given and their degrees of optimization are demonstrated. Especially branch joints, deer antlers, branch holes in trees and modelling growth of trees loaded by contact stresses are discussed. On the basis of the knowledge that biological structures always try to avoid localized stress peaks (notch stresses), and that they try to grow into a locally homogeneous surface stress state, a new method of CAO (computer aided shape‐optimization) is proposed which relies on biological growth. Its efficiency and success are demonstrated for two‐ and three‐dimensional structures with very homogenous stress states after optimization.
A COMPARISON OF SMALL FATIGUE CRACK GROWTH, LOW CYCLE FATIGUE AND LONG FATIGUE CRACK GROWTH IN A1‐Li ALLOYS
Authors: Nicholls D. J. , Martin J. W. 
Published: April 2007

AbstractThe behaviour of small fatigue cracks in the A1‐Li‐Cu‐Mg‐Zr alloy 8090 has been studied. Growth rates of small fatigue cracks in these alloys were found to be proportional to ΔK2. This relationship is compared to that suggested by Murakami where crack growth rate was proportional to ε2pa. The difference between the equations is attributed to the relative importance of plastic strain for the two sets of data. It is suggested that the two equations are equivalent if crack growth rate is related to total strain. The common observation of a Paris law exponent of two in different alloys suggests that there is a single common mechanism for small fatigue crack growth. This contrasts with long fatigue crack growth, where a variety of Paris law exponents are observed. Other characteristics of this fatigue mechanism include crack propagation on {111} slip bands, insensitivity of crack propagation rate to precipitate distribution and a plastic zone comparable in size to the crack itself.
COMPLEX STRESS FUNCTIONS AND PLASTIC ZONE SIZES FOR NOTCH CRACKS SUBJECTED TO VARIOUS LOADING CONDITIONS
Authors: Youshi Hong , Miller K. J. , Brown M. W. 
Published: April 2007

AbstractIn this paper, the conformal mapping method is used to solve the plane problem of an infinite plate containing a central lip‐shaped notch subjected to biaxial loading at a remote boundary or a surface uniform pressure on the notch. The stress intensity factors KI and KII are obtained by the derived complex stress functions. The simple analytical expressions can be applied to the situation of cracks originating from a circular or an elliptical notch. The plastic zone sizes for such notch cracks are subsequently evaluated in light of the Dugdale strip yield concept. The results are consistent with available numerical data.
DYNAMIC MEASUREMENT OF CRACK CLOSURE BEHAVIOUR OF SMALL FATIGUE CRACKS BY AN INTERFEROMETRIC STRAIN/DISPLACEMENT GAUGE WITH A LASER DIODE
Authors: Akiniwa Yoshiaki , Harada Shoji , Fukushima Yoshihiro 
Published: April 2007

AbstractAn interferometric strain/displacement gauge (ISDG) system with a laser diode was developed to measure dynamically the crack closure behaviour of a small surface crack. Two Vickers indentations, about 100 μ apart, were illuminated with the laser pulse synchronized with the load signal. The interference fringe patterns moved as the indentation moved apart. The 95% confidence limit, obtained on the basis of the difference between the strain measured by the ISDG and that by the resistance strain gauge (RSG), was ±6.0 × 10−4μ for stepwise loading. The standard deviations of the relation between stress and displacement under elastic conditions were 1.7 for stepwise loading at 0.067 Hz and 2.6, 2.6, 2.3 for dynamic loading at 5, 10 and 20 Hz respectively. The crack mouth opening displacement was measured dynamically as well as statically with the system. The crack opening stress was determined using the unloading elastic compliance method. The measuring frequency hardly affected the crack opening stress. Smooth specimens of a type 304 austenitic stainless steel were fatigue tested. The crack propagation behavior was observed and crack closure measurements monitored for crack lengths ranging from 0.12 to 0.75 mm. The aspect ratio of the surface crack was determined on the basis of the relation between the surface crack length and the elastic compliance. The relation between the crack propagation rate and the J integral range was unique, and agreed well with that calculated by the effective stress intensity range for long cracks.
A REVIEW OF FRACTURE MECHANICS MODELS OF TUBULAR JOINTS
Authors: Haswell J. , Hopkins P. 
Published: April 2007

AbstractFracture mechanics methods are used to assess the significance of cracking in any structure, but a tubular joint is very complex to analyse. However the improvements in numerical methods, such as stress analysis using finite elements, and extensive full‐scale laboratory testing (UKOSRP, ECSC, etc.) have allowed various workers to propose fracture mechanics models of tubular joints.This paper presents a critical review and comparison of these models. It concludes that simple plate models can provide upper and lower bound stress intensity factor solutions for cracked tubular joints. Stress intensity factors from three dimensional finite element analysis of a tubular joint are in reasonable agreement with semi‐empirical data. However, in the absence of a validated database the paper concludes that any analytical assessment of a crack in a joint should be viewed as tentative.
EFFECT OF PARTIAL‐COVERAGE UPON THE FATIGUE FRACTURE BEHAVIOUR OF PEENED COMPONENTS
Authors: Meguid S. A. 
Published: April 2007

AbstractThe achievement of full‐coverage during the application of shot‐peening to critical components represents a major concern in the aerospace and power generation industries. It has been accepted, for many years, that full‐coverage of such components is needed to attain the beneficial fatigue‐life effects of the treatment. It has also been proposed, by a number of industrialists, that partial‐coverage may apparently shorten the fatigue‐life of the component because of the presumed presence of tensile residual stresses in the uncovered areas. Three aspects of the investigation were accordingly examined. The first deals with the accurate measurement of peening coverage using a three‐dimensional surface profilometer arrangement. The second deals with the development of fatigue crack growth data for fully‐ and partially‐peened components using an instrumented rotating‐bend fatigue rig. The third deals with monitoring the residual stress field associated with different peening‐coverage using the dissection method. In order to highlight the effect of the treatment upon the fatigue behaviour of the tested components, both theoretical and experimental techniques were considered. In the theoretical work, three‐dimensional finite element analysis of circumferentially cracked notched and un‐notched cylindrical components was considered in the development of the corresponding stress‐intensity factor (KK1) under bending loads. The stress‐intensity factor vs crack length relationship was subsequently used in the experimental determination of fatigue crack growth rate data at the different stress levels examined. Accordingly, room temperature rotating‐bend fatigue tests were conducted on specimens made from medium carbon steel 080 M40 (En 8) and aluminium alloy (7075‐T6). Surprisingly, the results of both materials reveal that a life improvement of up to 50% can be attained at 35% coverage level.
BEHAVIOUR OF A 1Cr‐1Mo‐0.25V STEEL AFTER LONG‐TERM EXPOSURE–I. CHARPY IMPACT TOUGHNESS AND CREEP PROPERTIES
Authors: Moliniéa E. , Piques R. , Pineau A. 
Published: April 2007

AbstractThis paper deals with the effect of casting conditions and long‐term in‐service exposure on the Charpy‐V notch and creep properties of a 1Cr‐1Mo‐0.25V steel. The material is investigated under two conditions: (i) as‐cast in a thick part which produces a mixed ferrite‐bainite microstructure and (ii) as‐cast as a small ingot which produces a fully bainitic microstructure. The material from the thick part was taken from either the cold part (∽200°C) or the hot part (∽540°C) of a steam power casing which operated for about 150,000 h. A small shift in the ductile‐brittle transition temperature is shown after the long exposure time. This shift is related to segregation of phosphorus impurities along the grain boundaries as shown by Auger electron spectrometry. The bainitic microstructure exhibits a much better creep resistance compared to the thick part component material. Moreover, in the latter case, it is shown that long‐term in‐service exposure induces an increase in creep strain rate and a decrease in creep ductility at least for relatively short times to failure (≲1000 h). These variations in mechanical properties are briefly discussed in terms of microstructural changes. Scanning electron microscopy confirmed that grain boundary cavitation was responsible for decreasing the creep ductility at large times to failure (≳ 10,000 h).
ANALYSIS OF FATIGUE LIFE DATA USING THE BOX‐COX TRANSFORMATION
Authors: Hinkle A. J. , Emptage M. R. 
Published: April 2007

AbstractFatigue life data customarily analyzed using the logarithmic transformation may be better analyzed using the Box‐Cox transformation. This transformation has the advantages of stabilizing the variance, simplifying the model and transforming to approximate normality. In addition, simple schemes for imputing run‐outs can be constructed and the endurance limit can be easily calculated.This paper considers in detail the use of the transformation on fatigue life data from a thick plate Al‐Zn‐Cu‐Mg alloy. It presents a simplified method for determining the transformation, and then uses the transformation to determine distinctions in quality between different lots and confidence intervals on the lifetime.
THE VIRTUAL CRACK EXTENSION METHOD FOR CREEP FRACTURE
Authors: Hellen T. K. 
Published: April 2007

AbstractKnowledge of the creep behaviour of materials used in structures which operate for many years is of fundamental importance when assessing the integrity of such structures. The additional consideration of cracks which may occur in metals is also important. For discrete cracks, characterising parameters associated with the creep conditions at the crack tip may be evaluated to determine whether the crack will grow slowly, rapidly, or remain stationary. For arbitrary structures containing such defects, the finite element method is particularly effective for calculating the time‐dependent stress analysis. The particular fracture parameters can then be evaluated using algorithms based on existing technology for contour integration, and a new virtual crack extension technique. These features are described and compared in application to a laboratory compact tension specimen.
THE EFFECTS OF MICROSTRUCTURE AND FRACTURE SURFACE ROUGHNESS ON NEAR THRESHOLD FATIGUE CRACK PROPAGATION CHARACTERISTICS OF A TWO‐PHASE CAST STAINLESS STEEL
Authors: Murakami Ri‐ichi , Kim Yun‐Hae , Ferguson W. G. 
Published: April 2007

AbstractIn this study, the effects of stress ratio, microstructure and fracture surface roughness on the fatigue properties of a two‐phase cast stainless steel were investigated. This behaviour was examined by means of the fracture mechanics approach and fractography. The fatigue crack growth rate decreased with decreasing stress ratio. The stress ratio markedly influenced the fatigue crack growth rate as ΔK approached the ΔKth value. The roughness of the fracture surface was greater in the as‐cast material than in the heat‐treated material. Analysis of the crack growth data using ΔKeff showed that the effect of R ratio could be explained but that the effect of microstructure on crack growth rate could not.
OXIDATION‐ASSISTED FATIGUE CRACK GROWTH BEHAVIOR IN ALLOY 718‐PART I. QUANTITATIVE MODELING
Authors: Ghonem H. , Zheng D. 
Published: April 2007

AbstractThis paper presents a new model to predict the high temperature, intergranular crack growth rate behavior in alloy 718 at 650°C. The model is based on the concept that the crack tip oxidation‐fatigue damage is a nonlinear process governed by the chemical‐mechanical interaction along the grain boundary fracture path at the crack tip. A concept of two‐stage oxidation mechanism was used here. This mechanism depends on the rate of formation of the chromia layer in relation to the build‐up of other oxide types at the crack tip. The saturation of the Cr2O3 build‐up signifies the occurrence of the oxide passivation effect. The determination of the amount of Cr2O3 depends on the amount of both oxygen diffused along the affected grain boundary and chromium transported via a mobile dislocation network. Here, both the grain boundary and effective dislocation pipe are treated as short‐circuit diffusion paths along which the diffusion process can be described using Whipple's solution. The model yields sufficient information to correlate the amount of Cr2O3 with the reduction in the grain boundary ductility within the affected oxide zone. The grain boundary ductility is balanced by the effective strain at the crack tip resulting from the external loading. This balance defines the fracture criterion of the model and permits the calculation of the crack advance per cycle which is the ultimate goal of this work.
ELEVATED TEMPERATURE FATIGUE CRACK PROPAGATION IN HOT WORK TOOL STEEL
Authors: Tang N.‐Y. , Plumtree A. 
Published: April 2007

AbstractCyclic tests have been carried out on a hot work tool steel (H13) over a range of temperatures using different waveforms. At a temperature of 125°C, a slow‐fast wave resulted in lower crack propagation rates than those with a balanced (or symmetrical) waveform. However, at 500°C normal fatigue crack propagation behaviour was observed in which the slow‐fast wave was more damaging than a balanced waveform at the same frequency. Dynamic strain aging is attributed to the reversed crack propagation effect at 125°C.
CORROSION FATIGUE FRACTURE‐MODE MAPS OF LOW ALLOY STEELS
Authors: Xing Zhiqiang , Song Yujiu , Tu Mingjing 
Published: April 2007

AbstractThe fatigue fracture features of low alloy steels in aqueous environments are investigated. It is revealed that microstructures, compositions and mechanical variables will affect the fracture mode. A series of fracture‐mode maps of structural steels are established and a corrosion‐fatigue‐mechanism map of 15 Mn dual‐phase steel is developed. The importance of fractography and fracture‐mode is emphasized.
RAINFLOW CYCLES IN GAUSSIAN LOADS†
Authors: Rychlik Igor 
Published: April 2007

AbstractWe present a new approximation of the expected damage for Gaussian loads. The approximation is based on an exact relationship between the rainflow cycle count and the range‐pair exceedances count. This relationship links the intensity of rainflow amplitudes to expectations of marked crossings of the random load. The method is best suited for the fatigue life prediction for locally stationary Gaussian loads with slowly varying means and covariance functions. These results are illustrated with numerical examples.
FATIGUE BEHAVIOUR OF Al2O3 SHORT FIBRE REINFORCED ALUMINIUM ALLOY
Authors: Liu Xi Cong , Bathias Claude 
Published: April 2007

AbstractThe room temperature fatigue strengths of A1‐7Si‐0.6Mg and A1‐SSi‐3Cu‐1Mg composites randomly reinforced with A12O3 short fibres were determined using a stress ratio of 0.1, a frequency of 50 Hz. The fatigue strength of the composites under these testing conditions can be expressed by a single curve‐fitting equation. The effect of surface roughness on fatigue strength was also studied and the results show that these composites are not sensitive to surface roughness. The orthogonal growth of cracks is an important fatigue fracture mechanism in these composites. The residual strength decreased as the fatigue load increased.