摘要:

AbstractThe fatigue crack growth behaviour, the length of the arrested cracks and the shape of the crack front were investigated for cyclic compression. Specimens with deep sharp notches were used. The experiments were performed for different load amplitudes and load ratios under conditions of small scale yielding. The material used was ARMCO‐iron. The growth rate and length of the arrested cracks were estimated and compared with the experimental results. The crack growth rate of very short cracks is determined by the stress intensity and is independent of the stress ratio. The length of the arrested cracks depends on the stress ratio and is bounded by the size of the cyclic and the monotonic plastic zone

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1987.tb00459.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractStress intensity factors are calculated in weighted average at the surface and the deepest point of a circular‐fronted surface crack in a cylindrical bar by use of the weight function method. A wide range of various crack shapes are studied, from a nearly straight‐fronted edge crack to a semi‐circular crack front. Use of the weight function method requires that the crack opening displacement field of a reference load has to be known. It was obtained by 3‐D finite element analysis. Results are presented for the cracked cylinder subjected to a constant stress (tension) and a linear stress distribution acting perpendicular to the crack faces and they are compared with values found by other invest

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1987.tb00460.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractStarting with the basic fatigue life formulaΔε/ΔεT= (Nf/NT)b+ (Nf/NT)can inversion formula is derived in the formNf/NT= [(Δε/ΔεT)z/b+ (Δε/ΔεT)z/c]1/zwherezis a function of strain range and the ratioc/b.The inversion formula is valid over the entire life range of engineering interest for all materials examined. Conformity between the two equations is extremely close, suitable for all engineering problems. The approach used to invert the life relation is also suitable for the inversion of other formulas involving the sum of two powe

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1987.tb00461.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractBending fatigue in the low cyclic life range differs from axial fatigue due to the plastic flow which alters the linear stress‐strain relation normally used to determine the nominal stresses. An approach is presented in this report to take into account the plastic flow in calculating nominal bending stressSbendingbased on true surface stress. For a given surface strain εS, hence the surface life (NS), an equation is derived to expressSbendingin terms of axial fatigue stress (Saxial), involving material constantsc, b, NTwhich are obtained from axial fatigue information andf1andf2which are functions of strain hardening exponent and depend on the geometry of cross‐section. These functions are derived in closed form for rectangular and circular cross‐sections. The nominal bending stress and the axial fatigue stress are plotted as a function of life (NS) and these curves are shown for some materials of engineering in

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1987.tb00462.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractDimensional analysis has been applied to the fatigue failure of a material. The growth rate of cracks propagating within the limitations of LEFM can be described unequivocably by ΔK, as for example, in the Paris law. However, in the more general case, when LEFM conditions are violated or when the crack is short, an extra term, relating plastic zone size to crack length, is needed to preserve the physical similarity

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1987.tb00463.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractThe mechanisms causing crack growth retardation after an overload were examined for BS4360 50B steel. It was found that plasticity‐induced crack closure is the main cause of retardation when the pre‐overload growth rate is in the mid‐regime of the growth rate versus stress intensity range plot. When the pre‐overload growth rate is near threshold it is argued that retardation at the surface of the specimen is primarily due to strain hardening and to the build‐up of a favourable residual stress distribution in the material ahead of the crack tip. Supporting evidence for this argument is provided by a preliminary test on 2014A‐T4 aluminium alloy. Plasticity‐induced crack closure may be a further cause of retardation in the bulk, plane strain regions of the specimens made from BS4360 50B steel and 2014A‐T4 aluminium alloy, when the pre‐overload growth rate

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1987.tb00464.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Editor's Note:The following Software Descriptions have been submitted by our readers in response to our call for an open exchange of information on software programs. They are offered without review or comment to provide a rapidly published, easily accessible avenue of communication. Other readers with relevant software packages are invited to complete and submit a Software Description Form (found at the end of this section).

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1987.tb00458.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY