摘要:

Abstract—A modification to Brown and Miller's critical plane approach is proposed to predict multiaxial fatigue life under both in‐phase and out‐of‐phase loading conditions. The components of this modified parameter consist of the maximum shear strain amplitude and the maximum normal stress on the maximum shear strain amplitude plane. Additional cyclic hardening developed during out‐of‐phase loading is included in the normal stress term. Also, the mathematical formulation of this new parameter is such that variable amplitude loading can be accommodated. Experimental results from tubular specimens made of 1045 HR steel under in‐phase and 90° out‐of‐phase axial‐torsional straining using both sinusoidal and trapezoidal wave forms were correlated within a factor of about two employing this approach. Available Inconel 718 axial‐torsional data including mean strain histories were also satisfactorily correlated using the af

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1988.tb01169.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract—A model predicting the magnitude of frictional effects from fracture surface roughness on mode III fatigue crack growth is presened. Analysis of published data indicates that fracture surface roughness of the order of micrometers or less is enough to account for mode III fatigue crack growth retardation observation for increasing crack lengths for growth at constant ΔK. The model suggests that high strength materials will exhibit a greater resistance to shear crack growth than low strength materials. It also suggests that the resistance to shear crack growth will be more prominent at low nominal applied shear stress. The results of the analysis suggest that the concept of similitude does apply to mode III fatigue crack growth when the effects of friction on the stress intensity factor are includ

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1988.tb01170.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract—The crack tip cyclic heat generation rate, fatigue crack growth rate, and the crack closure stress were measured in a β‐annealed Ti‐6Al‐4V forRratios of ‐0.1, 0.1 and 0.2. TheR= ‐0.1 and 0.1 cases exhibited macroscopic crack closure and theR =0.2 case exhibited no macroscopic crack closure as measured by strain gage techniques. There was a transition in the slope of the da/dN vs ΔKcurve for the closure cases and no transition for the no‐closure case. The crack tip heat generation rate above the transition for the closure cases was an order of magnitude greater than for the no‐closure case. Also the crack tip heat generation rate below the transition was greater for the closure cases than for the no‐closure case. The transition in the heat generation rate and the crack growth rate was attributed to a transition from static frictional locking of shear branch cracks to sliding of the branch crack surfaces. Below the transition the crack faces are locked open creating a large roughness‐induced closure component. When the branch cracks are allowed to undergo reverse shear, the amount of roughness‐induced closure markedly decreases and the fracture surface becomes less tortuous. The relative sliding gener

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1988.tb01171.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract—A first‐generation fatigue crack growth model has been developed which realistically models the patterns of subsurface shells and detail fracture crack growth that are commonly observed in railroad rails. (These types of defects are further described in the Introduction.) The key assumptions upon which the model is based are reviewed and the input data on railroad rail residual stresses and wheel‐induced stresses are described. Examples of the predicted growth patterns for shells and detail fractures are shown and compared to actually observed growth patterns. Apparent deficiencies in the model are discussed and probable avenues for improvement in the accuracy of the crack growth life estimates are ident

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1988.tb01172.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract—Investigations into tearing‐fatigue have been performed using three point bend specimens made of mild steel. A computer controlled testing machine was used which could maintain constant cyclic displacement ranges, or constant cyclic energy input ranges, and hence provide a range of crack tip driving force conditions. Fatigue crack growth rates were measured and compared with the predictions of a model based on the linear summation and non‐interaction of fatigue and ductile tearing growth rates. The effects of fatigue crack growth on monotonic crack growth resistance properties were investigated. It is concluded that there is no significant interaction between these two crack propagation mechanisms in this steel. Crack growth rate equations governing propagation in the tearing‐fatigue regime ar

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1988.tb01173.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract—An experimental study has been carried out to evaluate the fatigue strength and life of externally welded box girders used in gantry cranes and bridge structures. In this study, a reduced scale model was fabricated and tested under conditions similar to those of the prototype. Model analysis was used to select the model dimensions and loads. The test model was subjected to bending, shear and torsional stresses under load control conditions. After test completion, the critical sections were visually and microscopically inspected. No fatigue crack initiation was found. The results of this investigation is expected to help in establishing a fatigue design criteria for externally welded box girder

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1988.tb01174.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract—Having previously been subjected to cyclic loading below the elastic limit, wire specimens of aluminium and copper were subjected to uniaxial tension tests. The results obtained are presented with a view to studying the accumulated changes in stress‐strain behaviour during fatigue. The data obtained for virgin as well as for cyclic preloaded specimens were fitted to the Ramberg‐Osgood relation and useful empirical relationships were developed between its parameters and the prior cyclic stress amplitude as well as the number of prior fatigue cycles. Using these relations, progressive changes in the width and the area of hysteresis loops have been computed and the results obtained have been compared with the experi

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1988.tb01175.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1988.tb01168.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY