Results 321 to 330 of about 19,892 (363)

Initiation of fatigue cracks in 4340 steel

Metallurgical Transactions, 1973
Electron microscopy of surface replicas has been employed to determine the metallurgical micromechanics of fatigue crack initiation at surface and shallow subsurface inclusions in 4340 steel. The experimental results are considered in terms of current theoretical analyses of elastic stress distributions around hard inclusions imbedded in soft matrices.
J. Lankford, F. N. Kusenberger
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Fatigue-crack initiation at corrosion pits

Metals Technology, 1982
Abstract The initiation of fatigue cracks at corrosion pits has been responsible for the failure of a wide range of engineering components. The present work demonstrates the effects ofcorrosion pits up to 250μm deep on the initiation offatigue cracking in both plain and notched specimens of a low-alloy steel.
T. C. Lindley, P. Mcintyre, P. J. Trant
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A fatigue crack initiation map for polycarbonate

Journal of Applied Polymer Science, 1993
AbstractThe mechanisms of fatigue crack initiation for various stress levels and thicknesses have been determined for single‐edge notched specimens of polycarbonate and used to assemble a map. Three basic fatigue crack initiation mechanisms were identified and named as cooperative ductile (the damage zone formed ahead of crack consisting of yielded ...
T.‐J. Chen, C. P. Bosnyak, C.‐I. Kao, A. Chudnovsky   +3 more
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Initiation and propagation of fretting fatigue cracks

Wear, 1976
Abstract Fretting fatigue tests of a carbon steel were carried out. Fatigue cracks were measured by means of electrical resistance and observed with a scanning electron microscope. The mechanism of fretting fatigue failure is discussed from the experimental results.
K. Endo, H. Goto
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Initiation of Fatigue Cracks Around Inclusions in Rolling Fatigue

1983
The cyclic behavior of E52 100 quenched and tempered rolling bearing steel displayed strain-hardening according to the law Δσ/2 = 5790 (Δϵp/2)0.137. The fatigue life was found to be given by the formula Δϵ/2 = 0.0073 (2Nf)-0.36 + 0.0145 (2Nf)-0.062. The cyclic strain-hardening law was used in a finite-element bidimensional incremental ...
M Freitas, D Francois
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Computer simulation of fatigue crack initiation

Engineering Fracture Mechanics, 1980
Abstract Results of a Monte Carlo simulation of the initiation stage of fatigue failure of aluminum alloys are described. Initiation processes simulated are: (1) nucleation of cracks at particles at or near the alloy surface; (2) early growth of microcracks with lengths on the order of the grain size; and (3) microcrack coalescence.
W.L. Morris, M.R. James, O. Buck
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The Micromechanics of Fatigue Crack Initiation

1984
Over the last few years there has been an increasing interest in assessing the reliability of involved and expensive engineering structures and components being subjected to fatigue loading situations. The approach being taken in these studies has been and still is to describe, in a statistical manner, the microstructural material degradation processes
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Micromechanics of Crack Initiation in High-Cycle Fatigue

1991
The author presents some previous theories of fatigue crack, gating mechanism and the quantitative effects of mean stress, grain size, strain hardening, overload and creep on fatigue crack initiation. The paper is divided into seven sections entitled: (1) Introduction; (2) Dislocations and plastic strain; (3) Slip bands under monotonic loadings; (4) A ...
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Nonarbitrary Crack Size Concept for Fatigue Crack Initiation

2005
Abstract This appendix presents an analytical model that estimates damage rates for both crack initiation and propagation mechanisms. The model provides a nonarbitrary definition of fatigue crack initiation length, which serves as an analytical link between initiation and propagation analyses and appears to have considerable merit in ...
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Dislocation substructures and the initiation of cracks by fatigue

Metal Science, 1977
AbstractRecent work on the fundamental dislocation mechanisms by which cyclic straining leads to crack nucleation has suggested an empirical model relating various measures of fatigue strength, such as fatigue limit and saturation stress. The model is briefly described in this short review.
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