摘要:

AbstractA fatigue crack is often initiated by a localized cyclic plastic deformation in a crystal where the active slip plane coincides with the plane of maximum shear stress. Once a crack is initiated, the crack will propagate on the maximum shear plane for a while and, in the majority of the cases, will eventually change to the plane of the applied tensile stress. The “shear” and “tensile” modes of fatigue crack propagation are termed stage I and stage II fatigue crack growth. They are also known as mode II and mode I fatigue crack growth. However, the mechanism of the tensile mode fatigue crack propagation is shear in nature.Considerable progress has been made recently in the understanding of mode II fatigue crack growth. This paper reviews the various test methods and related data analyses.The combined mode I and mode II elastic crack tip stress field is reviewed. The development and the design of the compact shear specimen are described and the results of fatigue crack growth tests using the compact shear specimens are reviewed. The fatigue crack growth tests and the results of inclined cracks in tensile panels, center cracks in plates under biaxial loading, cracked beam specimens with combined bending and shear loading, center cracked panels and the double edge cracked plates under cyclic shear loading are reviewed and analyzed in

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1985.tb00429.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractFatigue crack growth behaviour under mixed modes I and II was studied by applying in‐phase alternating tensile and torsional loading to a thin‐walled hollow cylindrical specimen with an initial crack.In the linear region of a log‐log plot where da/dN=A(ΔK)m, da/dNat first decreases with increasing ΔK110component and then approaches a minimum close to the value of ΔK110/ΔK10∼ 0.58; here ΔK110/ΔK10is the ratio of the initial ΔKIIto the initial ΔK1., When ΔK110/ΔK10increases further, da/dNincreases. Under shear mode, da/dNbecomes higher than that under mode I. The ΔK1, and ΔK11components during fatigue crack growth under mixed mode loading increase and decrease, respectively, with an increase in da/dNIn the low crack growth rate region the fatigue crack growth rates accelerate with an increase of the initial ΔK11component, ΔK110. Fatigue life increases with increase of ΔK110/ΔK10under the test condition of equivalent stress range being kept constant and the pre‐cr

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1985.tb00430.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractSurface fatigue crack studies were carried out and statistically analysed from rotating bend fatigue tests in the high cycle region for three metals, copper, stainless steel and mild steel with four ferrite grain sizes. Quantitative observations of the initiation and growth behavior, including coalescence of closely spaced cracks, are discussed and a limiting condition for coalescence is proposed. Statistical properties of initiation, propagation and propagation rate of surface cracks are examined and the effect of different metals and grain sizes is discussed.

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1985.tb00431.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractFatigue propagation tests on artificial short cracks (initial length ˜ 0.15 mm) were performed in vacuum and in nitrogen containing small traces of water vapour (˜ 3 ppm) on a high strength aluminium alloy type 7075 in two aged conditions (T651 and T7351) at a load ratio of 0.1 and a frequency of 35 Hz. A predominant influence of environment was determined for short crack growth. This behaviour has been discussed in terms of crack growth rate versus the effective stress intensity factor range relationship previously determined for long cracks. The results obtained suggest the absence of closure at the early stage of short crack growth with an enhanced environmental influence as compared to long crack behaviour at the same load ratio. As the crack grows the effect of closure increases progressively and the short crack effect disappears after a crack growth of the order of 1 m

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1985.tb00432.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractStress intensity factors were calculated, based on Bueckner's principle for cracks in both infinite and finite plates with notches subjected to biaxial loading. Approximate Green's functions have been obtained by modifying two existing Green's functions, originally for unnotched plates. Values of stress intensity factors calculated using Bueckner's principle with the approximate Green's functions are in good agreement with published stress intensity factors for cracks in both infinite and finite plates containing a circular notch or an elliptical notch, previously found by the method of boundary collocation.

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1985.tb00433.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractHigh strain fatigue properties of Alloy 800H have been investigated at 600°C in strain control. The behaviour of solution heat treated material was compared with that of material aged at 550 and 600°C. It was found that both aging treatments extended the fatigue life significantly, the longest fatigue life being observed for fine‐grained material aged at 550°C. The results are explicable in terms of partially reversible plastic flow occurring when the γ′ particles are by‐passed by

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1985.tb00434.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY