摘要:

Abstract—Elastic‐plastic finite element analysis is used to study fatigue crack closure at three different crack length to width ratios for three plane stress specimen geometries: center‐cracked plate, single‐edge‐cracked plate (tension), and single‐edge‐cracked plate (bend). The maximum stress to flow stress ratio, Smax/σO, which successfully describes closure results in many center‐cracked plate configurations, does not correlate the effect of different geometries on the normalized opening stress,Sopen/Smax. Crack opening stresses for different geometries and crack lengths are successfully correlated by a normalized stress intensity parameter,Kmax/K0, whereK0=σ0φa. The quality of the correlation is very high at smallKmax/K0, and gradually deteriorates asKmax/K0increases beyond the small‐s

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1994.tb00816.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract—The present study is to investigate the fatigue crack propagation behaviour of surface cracks subjected to combined tension and bending stress. An estimation of fatigue crack growth behaviour employed the Newman‐Raju formula before penetration, and aKsolution, proposed by the authors, after penetration. Crack length aLat penetration increases with an increase in bending stress. The calculated fatigue crack shape was in good agreement with the experimental shape. It was also found that the crack growth behaviour and the crack shape after penetration can be satisfactorily evaluated using theKsolution proposed by the auth

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1994.tb00817.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract—Two methods are employed, namely the Charpy impact test and a strain gauge technique, for the determination of the dynamic fracture toughnesses of CrNiMoV27 and CrNiMoV45 alloy steels under various impact loading rates and heat treatments. The results show that the dynamic fracture toughnessKIdis significantly affected by impact velocity and that tempering has a greater influence onKIdthan quenching. It is also shown that the alloy containing a greater amount of vanadium yields consistently a higher value ofKi

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1994.tb00818.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract—Fatigue crack propagation threshold values have been determined with two experimental methods, it., the constantRmethod and the constantKmaxmethod. Three materials, namely A17075‐T7351 and Ti6A14V STA in the LT‐ and TL‐orientations, and a Ti‐turbine disk material (IMI 685) in the CR‐orientation, were investigated.The paper is divided into 3 parts. In the first part the test conditions, the experimental results and the conclusions drawn from the experimental results are presented, namely that the three different functional dependencies of ΔKthonRcannot be reconciled with present continuum mechanics concepts. In the second part, some facts used in conjunction with the da/dN–ΔKeffmethodology are applied to the non‐propagation condition ΔKth. Parameters such as KOp, the threshold ΔKT, and a parameter “KLL” are investigated by numerical modelling of their individual influence on the ΔKthversusRcurves. This modelling work shows that the individual ΔKthversusRcurves are primarily dependent on theKopbehavior of the respective material. Further, it is shown that the threshold ΔKTis a constant value, independent of any particular cyclic loading condition. In the third part of the paper, the ΔKeffconcept is applied to the experimental results obtained in the first part. Using either experimentally or semi‐empirically determinedKopfunctions and the measured ΔKTvalues, the ΔKthversusRcurves of the three materials investigated were accurately reconstructed. It follows that the ΔKthversusRcurves of the individual materials are the natural consequence of the driving force for fatigu

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1994.tb00819.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract—The stress field in front of a crack tip lying in a plane bimaterial interface is always of a complex nature. The stress intensity factor characterising its asymptotic variation is therefore a complex number and its assessment from a numerical calculation requires the separation of the particular loading modes by an appropriate method. A suitable method is provided by the combination of curve integrals and an auxiliary singular field, enabling this separation by means of simple post‐processing. This method can also be applied to the separation of load modes in front of the crack tip in a homogeneous specimen exposed to a mixed‐mode

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1994.tb00820.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract—The paper deals with the analytical representation of the cyclic stressstrain curve, the hysteresis loop and the hysteresis energy for a single‐phase α‐brass. The one‐ and two‐parameter elastic‐plastic models that were used were so chosen as to produce compatible representation of both the stress‐strain relationship and the hysteresis loop. The models were checked with experimental data. The specimens were tested in uniaxial tension‐compression (Rε=−1) under total strain amplitude control. The experiments covered a broad spectrum of lives from the low‐cycle region through to the high‐cycle regime, i.e. up to lives ofN= 1 × 106cycles. The adopted measurement method enabled the cyclic deformation curve, hysteresis loop and hysteresis energy to be determined independently. It was shown that the modifed Ramberg‐Osgood model is a good approximation to actual c

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1994.tb00821.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract—Anderson and Dodds have recently introduced a test specimen size requirement in the transition regime which they suggest must be satisfied for the cleavage fracture resistance to be size independent. This paper assesses the implications of imposing the size requirement in fracture toughness testing standards. It is shown that imposing the size requirement can lead to a size dependence in fracture toughness data. This observation raises the general question of whether even existing size requirements for the lower shelf and upper shelf regimes are capable of giving size independent dat

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1994.tb00822.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract—Fretting induced cracking is commonly observed in industrial components that are in contact and are subjected to small oscillatory movements between them. Fretting causes a considerable reduction in fatigue strength. In this paper recent knowledge on the short and long crack growth behaviour is applied to estimate crack propagation and fatigue life in fretting. The model is based on mode I stress intensity factors with a threshold modified for short cracks. The predicted results are compared with experiments and the influence of the contact pressure is examined. A good correlation between predictions and experimental results are obtained for crack growth rates as well as fatigue lives in terms of number of cycles to failure. It is seen that the increase of fatigue life observed for contact pressures above a certain level can be predicted by the crack growth mode

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1994.tb00823.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract—Fretting fatigue tests of an austenitic stainless steel used for a propeller tail shaft were carried out in seawater and in air. In seawater, fretting significantly reduced the fatigue strength, however, the fretting fatigue lives at higher levels of stress were longer than those in air. The tangential force coefficient (defined as the ratio of the frictional force amplitude and the contact load) in seawater was much lower than that in air and varied in the range from 0.3 to 0.5 during the fretting fatigue tests. The lower tangential force coefficient in seawater seems to be the main reason for the longer fretting fatigue life in seawater. The prediction of fretting fatigue life was made on the basis of elastic‐plastic fracture mechanics, where the frictional force between the specimen and the contact pad was taken into consideration. The predicted fatigue lives agreed well with the experimental results in both air and seawa

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1994.tb00824.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract—This paper reports on a three‐dimensional numerical prediction that involves continuum damage theory for the deformation of centre cracked panels under uniaxial and biaxial tensile loading. The predicted differences of crack tip blunting movement, crack tunnelling behaviour and the changing shape of the plane ahead of the crack tip for the two loadings are close to those observed in tests. The material parameters that encapsulate the damage response of the A533 B class 1 steel tested, were selected from a detailed parametric study on laboratory crack‐growth resistance tests on the mat

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1994.tb00825.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY