A normalized area-compliance method for monitoring surface crack development in a cylindrical rod

Cai, Chen; Shin, C.S.

doi:10.1016/j.ijfatigue.2005.01.005

Cited by 26 publications

(13 citation statements)

References 24 publications

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“…As the crack propagates through a round specimen bar, the crack shape factor β increases, mainly because the ligament area reduces. The round bar crack through stress intensity factor problem has been widely investigated, even recently, through Finite Element (FE) [39][40][41][42][43]24]. In these papers particular attention was devoted to the crack shape evolution, when the crack propagates inside the round bar, for different initial elliptical crack aspect ratios.…”

Section: Fatigue Crack Initiation From S-n Curvesmentioning

confidence: 99%

Physically short crack propagation in metals during high cycle fatigue

Santus

Taylor

2009

International Journal of Fatigue

124

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In metals, during high cycle fatigue on plain specimens, almost the entire fatigue life is spent as short crack initiation and propagation. The fatigue short crack life can be schematically divided into two subsequent phases: microstructurally short crack and physically short crack. Recently, Chapetti proposed a physically short crack threshold and propagation driving force model [1]. In his model the physically short crack behavior is obtained from the long crack propagation, just introducing the reduced threshold due to unsaturated closure. In the present paper the physically short crack propagation is similarly modeled by means of a driving force equation, but independent from the long crack propagation. In this way, a better description of the short crack behavior is provided, however short crack propagation data is required. Physically short crack propagation model parameters were obtained, by fitting experimental data drawn from the literature, for two Aluminum alloys and a Titanium alloy at two different heat treatment conditions and load ratios. By calculating the physically short crack plus long crack propagation, and assuming microstructurally short crack as part of the initiation stage, a purer information about crack initiation can be drawn from the S − N curves, and it is shown in the paper for the investigated materials. A precise crack initiation size and the number of cycles just for initiation are then provided. This information is useful to accurately predict fatigue life for blunt notched and for thick components, where the propagation is much higher than in the small plain specimen. A validation of the model was obtained by predicting the fatigue life of a notched specimen. An accurate prediction was obtained both when the initiation was much smaller than propagation and when almost the entire fatigue life was initiation.

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Section: Fatigue Crack Initiation From S-n Curvesmentioning

confidence: 99%

Physically short crack propagation in metals during high cycle fatigue

Santus

Taylor

2009

International Journal of Fatigue

124

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“…It is possible to relate the crack front geometry with compliance, one of the few characteristics which can be measured during the crack propagation [14]. If tensile load is applied, it is obtained that the local displacement u is related to the applied force F through compliance λ as follows:…”

Section: Dimensionless Compliancementioning

confidence: 99%

“…(21) in Eq. (14), which allows calculating compliance in a cracked round bar subjected to bending loading, it is obtained:…”

Section: Dimensionless Compliancementioning

confidence: 99%

Evolution of crack paths and compliance in round bars under cyclic tension and bending

Toribio

Matos

González

et al. 2014

Frattura Ed Integrità Strutturale

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The aim of this paper is to calculate how the surface crack front and the dimensionless compliance evolve in cracked cylindrical bars subjected to cyclic tension or bending with different initial crack geometries (crack depths and aspect ratios). To this end, a computer application (in the Java programming language) that calculates the crack front's geometric evolution and the dimensionless compliance was made by discretizing the crack front (characterized with elliptical shape) and assuming that every point advances perpendicularly to the crack front according to the Paris law, and using a three-parameter stress intensity factor (SIF). The results show that in fatigue crack propagation, relative crack depth influences more on dimensionless compliance than the aspect ratio, because the crack front tends to converge when the crack propagates from different initial geometries, showing greater values for tension than for bending. Furthermore, during fatigue crack growth, materials with higher values of the exponent of the Paris law produce slightly greater dimensionless compliance and a better convergence between the results for straight-fronted and circular initial cracks.

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“…A number of authors [1][2][3][4][5][6] have agreed on the fact that the generation of a residual compressive stress field in the superficial layer of the metal structural components considerably enhances their fatigue life. In this aspect, the methods of mechanical surface treatment whose basic concept is a localized nearsurface plastic deformation are very promising.…”

Section: Introductionmentioning

confidence: 99%

Modelling the power parameters of the spherical motion burnishing

Maximov

Duncheva

Amudjev

et al. 2011

Proceedings of the Institution of Mechanical Engineers, Part C:

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This article presents the outcomes from analytical and experimental modelling, the power parameters of new burnishing of external cylindrical surfaces called spherical motion burnishing. The axes of the workpiece and the ring-shaped tool having toroidal acting surface intersect at an angle of 2 . The tool motion is superposition from a spherical motion and a rectilinear translation with respect to the workpiece. The method is implemented on lathes. The tool transfer angular velocity is assigned by the lathe spindle, and the relative one is a consequence from unknown manufacturing resistance. Analytical models of the power parameters of the new burnishing process have been obtained. The unknown manufacturing intensities in these models have been determined experimentally. For proving the authenticity of the proposed semi-analytical models a comparison of the results obtained for the axial force with the experimental ones has been made. For that purpose, the axial force has been measured by means of a strain gauge system. The comparison shows a good agreement.

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A normalized area-compliance method for monitoring surface crack development in a cylindrical rod

Cited by 26 publications

References 24 publications

Physically short crack propagation in metals during high cycle fatigue

Physically short crack propagation in metals during high cycle fatigue

Evolution of crack paths and compliance in round bars under cyclic tension and bending

Modelling the power parameters of the spherical motion burnishing

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