摘要:

Abstract—A study has been made of the role of Prior Austenite Grains (PAG) in fatigue crack initiation and propagation in low carbon martensite.The occurrence of ferrite precipitation along prior austenite grain boundaries during rapid cooling will lead to the formation of intergranular cracking. This intergranular cracking has a close relationship with the reduction of the endurance limit for fine grained low carbon martensit

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1979.tb01083.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Abstract—During the last few years there has been an intensification of interest in the fatigue performance of steel reinforcement bars in concrete structures. Although fatigue has not proved to be a problem to date, loading cycles are becoming increasingly severe so that the margin of reserve strength is progressively being reduced.In this paper the main parameters associated with fatigue of reinforcement are reviewed with particular attention given to conditions related to highway bridges. Fatigue testing can be either axial in air or by bending of reinforced concrete beams. The latter is experimentally less convenient but simulates more closely the service environment. Endurances can be influenced by type of steel, geometry and size of the bars, nature of the loading cycle, welding and presence of corrosion. The relative behaviour of butt welded joints is considered and it is shown that the reduction in fatigue strength commonly attributed to flaws and to the stress concentrations associated with welds does not always occur for bending fatigue of reinforced concrete beam

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1979.tb01084.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1979.tb01085.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Abstract—Residual stress distribution in the vicinity of fatigue cracks was determined experimentally by means of the X‐ray method and theoretically calculated by finite element analysis. Both the intensity and the extent of residual stress increase with the increasing stress intensity factor amplitude. There is good agreement between experimental and theoretical resu

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1979.tb01086.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1979.tb01087.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Abstract—In this study, in‐phase and out‐of‐phase thermal fatigue tests at the temperature ranges of 473–823 and 573–873 K were carried out on three kinds of 304 stainless steel as well as isothermal low‐cycle fatigue tests at 823 and 873 K, in order to investigate the properties of thermal fatigue strength under creep‐fatigue interaction. Based on the relation between the fatigue life and the failure mode, the time‐dependent effect on the fatigue life was discussed. Also, an attempt was made to apply the strain range partitioning method to the thermal fatigue life prediction.It is difficult to evaluate the thermal fatigue life at high temperatures simply from the isothermal fatigue life under the same strain condition. It was also found that an unbalanced creep strain during tensile loading, which increased the number of intergranular cracks, gave the largest damage to the material.By the strain range partitioning method, it was possible to predict the isothermal fatigue life and the thermal fatigue life at the low temperature range within a factor of 1·5. On the other hand, the thermal fatigue life at the high temperature range could only be predicted within a factor of 3. However, further detailed investigations are required on the technique of partitioning the inelastic strain range and predicting the effects of dynamic strain ageing and recovery d

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1979.tb01088.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Abstract—A method of calculating crack growth rates in high strain fatigue from total endurance data is presented. Endurances are known to be affected by dwell periods and environment and the expression derived takes these into account. The basic argument is that crack propagation may be regarded as increments of successive reinitiation and so the deeper a crack grows, with an accompanying increase in strain concentration at the tip, the fewer fatigue cycles are required for the next step. Previously derived expressions for strain concentration are employed which require a knowledge of the cyclic strain hardening properties of the material. These are produced in detail for a cast 1/2 Cr‐Mo‐V steel at 550°C. Two constants in the resulting propagation expression are semi‐empirical, but if the surface (plastic or total) strain range is known then cyclic crack growth rates may be calculated for any crack depth. It is also shown that in the limiting case of zero surface plastic strain, the expression reduces to that observed for crack growth under linear elastic co

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1979.tb01089.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Abstract—Flight simulation fatigue crack propagation tests with gust spectrum loading were carried out on laminates of (i) aluminium alloy 2024‐T3/carbon epoxy, (ii) aluminium alloy 7475‐T761/carbon‐epoxy and (iii) titanium alloy Ti–6Al–4V/carbon‐epoxy, each with a nominal weight saving of 30% as compared to equivalent 2024‐T3 panels. The performance of the 2024‐T3/carbon‐epoxy laminates was much superior to those of the other material combinations. Overall, there was a fairly strong effect of changing from an environment of normal air to an air plus water spray environment. Probable reasons for this strong e

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1979.tb01090.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Abstract—The fatigue crack propagation rate is related to the cyclic flow stress and the cyclic ductility of materials by means of a ductility exhaustion mechanism. The da/dNvs. ΔKrelationship is derived from the assumption that an elemental crack extension occurs when the sum of the fractional fatigue life of an element at various cycles equals unity. A comparison of predicted crack growth curves with those obtained experimentally for representative alloys shows good agreement. The threshold ΔKbehavior has been explained in terms of the existence of a threshold plastic strain amplit

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1979.tb01091.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY