摘要:

Abstract—Non‐propagating cracks have been observed at notch roots by several workers. A simple linear elastic fracture mechanics model based on the Kitagawa‐Takahashi diagram is presented in this paper to predict the occurrence and length of non‐propagating cracks. Predicted crack lengths are compared with experimental data taken from the lit

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1987.tb00477.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract—The present paper is an attempt to clarify conditions for plasticity‐induced and oxide‐induced crack closure as well as to evaluate the effect of crack closure on near‐threshold fatigue crack behaviour.The autocatalytic character of oxide formation at the crack tip has been elucidated in this study. An increase of plastic constraint at the crack tip is shown to intensify the fretting oxide formation process on the fracture surface and thus to cause an increase of the stress intensity factor range controlling the fatigue crack propagation rate. The proposed concept of stress state influence on crack closure allows us to explain the effect of specimen thickness

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1987.tb00478.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract—A fatigue analysis was conducted on a rail that was placed in the Facility for Accelerated Service Testing (FAST) after a detail fracture was detected in service. The initial detail crack produced in service was grown to failure under controlled FAST conditions simulating service. Knowledge of the FAST wheel/rail load history for this rail made it an ideal candidate for quantitative fatigue crack growth analysis.The investigation revealed that undulations in the detail fracture surface were caused by changes in the direction of traffic. The angle of the facture surface, with respect to the running surface of the rail, was measured for each direction change. These results showed that the angles did not change significantly as the depth of the crack increased, relative to the running surface.The change in the direction of traffic and the associated change in the angle of the detail fracture provided benchmarks on the surface that were used to estimate the crack growth rate between each train reversal. The results showed that the rate of detail crack growth remained relatively constant from its initial size, until it broke out on the gage side of the rail. After gage‐side break out, the crack growth rate increased until failure of the rail occurred.This paper provides documentation on the process of detail fracture development in this specific rail. A discussion is also included which addresses the question of why detail fractures develop, and what the probable driving forces are for their gro

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1987.tb00479.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract—The paper deals with the fracture toughness of nodular cast irons of differing microstructure and manganese content. Fracture toughness was determined for static and impact loading in the temperature range from 77 to 523 K. The dependences of fracture toughness on manganese content and microstructure were obtained.Fatigue crack growth rate curves were obtained at room temperature and a correlation between the parameters characterizing fatigue crack growth rate was found.Fractographic studies revealed an important role of graphite inclusions in the process of fracture. On the one hand, as stress raisers they favour the nucleation of microcracks while on the other hand, they cause local retardation of fatigue crack growth probably due to the residual compressive stress surrounding them. In the mid‐range of the fatigue crack growth rate curve a correlation was found between fatigue striation (or blocks of striations) spacings and the crack growth r

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1987.tb00480.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract—The objective of this paper is to report fatigue crack growth and closure behavior for corner cracked holes. An optical interference technique is employed with transparent polymer specimens to determine the three‐dimensional crack surface displacement field. The local crack closure behavior is examined along the crack front under remote tension and pure bending conditions. It was observed that the crack opening loads along the hole and the free surface were significantly higher than the opening values at interior crack locati

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1987.tb00481.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract—We present a new and simple definition of the Rain Flow Cycle count method for the analysis of a random load process. It is combined with the Palmgren‐Miner damage rule, and a stochastic model for the fatigue life and fatigue limit variability. Algorithms are presented which make it possible to calculate the RFC‐amplitude distribution, based on a Markov Chain approximation of local maxima and minima. The method derived would apply to structures subjected to random fatigue loads such as acoustic noise, random vibration or sea waves

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1987.tb00482.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

ISSN:8756-758X    

DOI:10.1111/j.1460-2695.1987.tb00475.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY