Multiaxial fatigue limit criterion for defective materials

Nadot, Y.; Thomas, Benedict

doi:10.1016/j.engfracmech.2005.06.005

Cited by 82 publications

(50 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Critical Distance Method (CDM) based on the stress field around a defect proposed by Susmel and Taylor [17]; and 4. Gradient approach based on the stress gradient surrounding the defect proposed by Nadot [19,20] In the case of the CDM and gradient approaches, a multiaxial fatigue criterion and a description of the stress distribution around a defect is necessary. For the multiaxial fatigue criterion, the equivalent stress criterion recently proposed by Vu [23] will be used.…”

Section: Simulation Of Multiaxial Kitagawa Relationshipsmentioning

confidence: 99%

“…Based on the initial work of Nadot [19], Gadouini et al [20] described the impact of a defect on fatigue resilience by amplifying the equivalent stress by a function of the surrounding stress gradient. This criterion is expressed as:…”

Section: Gradient Criterionmentioning

confidence: 99%

“…Most recently, Critical Distance Theory [17] has been shown to successfully correlate fatigue behavior with a critical distance from a defect that is material dependent. Other studies have shown that the stress gradient around a defect is a more practical indicator of fatigue resilience [18,19,20].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Multiaxial Kitagawa analysis of A356-T6

Roy

Nadot

Nadot-Martin

et al. 2011

International Journal of Fatigue

Self Cite

View full text Add to dashboard Cite

Experimental Kitagawa analysis has been performed on A356-T6 containing natural and artificial defects. Results are obtained with a load ratio of R = −1 for three different loadings: tension, torsion and combined tensiontorsion. The critical defect size determined is 400 ±100 µm in A356-T6 under multiaxial loading. Below this value, the microstructure governs the endurance limit mainly through Secondary Dendrite Arm Spacing (SDAS). . It is shown that the CDM and gradient methods are accurate; however fatigue data for three loading conditions is necessary to allow accurate identification of an endurance limit.

show abstract

Section: Simulation Of Multiaxial Kitagawa Relationshipsmentioning

confidence: 99%

Section: Gradient Criterionmentioning

confidence: 99%

See 1 more Smart Citation

Multiaxial Kitagawa analysis of A356-T6

Roy

Nadot

Nadot-Martin

et al. 2011

International Journal of Fatigue

Self Cite

View full text Add to dashboard Cite

show abstract

“…Then equivalent stress around defect σ* eqv taking into account the multiaxial stress fields as well as the gradient effect was determined using multiaxial fatigue criterion for surface defective materials [1] (Fig. 2 (a)) .As a result a couple (σ* eqv, N r ) was identified instead of (σ, N r ) and then an equivalent S-N curve (σ* eqv , N r ) was drawn up.…”

Section: Prediction Of the Residual Lifetimementioning

confidence: 99%

“…Several approaches have been proposed to determine fatigue behavior of material with introduced defect [1]. But the effect of these defects on fatigue behavior has usually been evaluated by constant amplitude stress-life fatigue tests.…”

Section: Introductionmentioning

confidence: 99%

Fatigue damage accumulation and lifetime prediction of defective C35 steel subjected to block loading

Sallem

Nadot

Bouraoui

2014

MATEC Web of Conferences

View full text Add to dashboard Cite

Abstract. This paper deals with the influence of both defect and loading sequence on fatigue damage accumulation of C35 steel containing artificial defects. Tests were carried out using fatigue samples with artificial spherical defects introduced at the surface. Tests were performed using two blocks loading under increasing and decreasing magnitude. The experimental results were compared to the damage calculated by the Miner rule. In the case of defective material; it is shown in both cases a minor influence of sequence's effect. A lifetime prediction method is then developed to assess the residual lifetime of damaged defective material. The method is based on a multiaxial endurance criterion used to calculate the equivalent local stress distribution around the defect and to inject it in an uniaxial damage cumulative rule. Finally a comparison between experimental and theoretical results is performed. It is observed that the Mesmacque sequential law gives the most accurate lifetime prediction of defective specimens.

show abstract

Pockmark formation and evolution in deep water Nigeria: Rapid hydrate growth versus slow hydrate dissolution

et al. 2014

View full text Add to dashboard Cite

In previous works, it has been suggested that dissolution of gas hydrate can be responsible for pockmark formation and evolution in deep water Nigeria. It was shown that those pockmarks which are at different stages of maturation are characterized by a common internal architecture associated to gas hydrate dynamics. New results obtained by drilling into gas hydrate-bearing sediments with the MeBo seafloor drill rig in concert with geotechnical in situ measurements and pore water analyses indicate that pockmark formation and evolution in the study area are mainly controlled by rapid hydrate growth opposed to slow hydrate dissolution. On one hand, positive temperature anomalies, free gas trapped in shallow microfractures near the seafloor and coexistence of free gas and gas hydrate indicate rapid hydrate growth. On the other hand, slow hydrate dissolution is evident by low methane concentrations and almost constant sulfate values 2 m above the Gas Hydrate Occurrence Zone. Study Area and Main ObjectiveThe investigated area is located in deep water of Nigeria. Bathymetry in the area ranges from 1100 to 1250 m ( Figure 1). This area was previously shown to host a field of (sub) circular pockmarks [Georges and Cauquil, 2007]. These range in shape from a slightly depressed, hummocky seafloor to a much more pronounced depression and each of them is several tens to a few hundreds of meters wide (Figure 1). The various morphologies of the pockmarks suggest either distinct modes of formation or different evolutionary stages [Sultan et al., 2010]. Most of the pockmarks are located in an area bounded by two NW-SE trending deeprooted normal faults, which delineate a graben linked to the axis of anticline in the subsurface. Several deep and shallow faults and three N-S trending buried channels were recognized with high-resolution 3-D seismic data (Figure 1). The buried channels, which are situated between 80 ms and 180 ms (two-way travel time, TWTT) below the seabed, may have the potential of accumulating amounts of free gas and play therefore an important role for the gas hydrate distributions.Based on geophysical and sedimentological data, and in situ piezocone measurements, Sultan et al. [2007] have shown that pockmark-associated gas hydrate accumulated within a few meters thick sediment layers at shallow depth. In addition, Sultan et al. [2010] proposed that the formation of a circular depression around the gas hydrate occurrence zone (GHOZ) is related to multiple steps in the pockmark evolution. The sequence is starting with hydrate formation induced by upward migration of fluids oversaturated in gas through fracture systems followed by decrease of fluid flow resulting in gas undersaturation, hydrate dissolution, generation of excess pore pressure, and by concurrent collapse of the gas hydrate-bearing sediment structures. Respective analyses were mainly based on subseabed approaches, using piston cores and in situ piezocone geotechnical measurements with a maximum penetration of 30 m below seafloor (mbsf). Howe...

show abstract

Multiaxial fatigue limit criterion for defective materials

Cited by 82 publications

References 18 publications

Multiaxial Kitagawa analysis of A356-T6

Multiaxial Kitagawa analysis of A356-T6

Fatigue damage accumulation and lifetime prediction of defective C35 steel subjected to block loading

Pockmark formation and evolution in deep water Nigeria: Rapid hydrate growth versus slow hydrate dissolution

Contact Info

Product

Resources

About