Analysis on Fatigue Crack Growth Rates Under a Wide Range of Stress Ratios

Kurihara, Masayoshi; Katoh, Akihiko; Kawahara, Mutsuto

doi:10.1115/1.3264771

Cited by 28 publications

(16 citation statements)

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“…It is clear from that with an increase in stress ratio R , Δ K th decreases increasing the fatigue crack growth rate but the influence is more pronounce in stage I (near threshold region of d a /d N versus Δ K plot) where Δ K and Δ K th are comparable than other region of the plot. This is consistent with the experimental results 20 , 45–49 . The fatigue crack growth relation derived here requires mechanical and fatigue properties E , σ′ f , ɛ′ f and n ′.…”

Section: Propagation Of Cracksupporting

confidence: 91%

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Fatigue crack growth model for constant amplitude loading

Pandey¹,

Chand

2004

Fatigue Fract Eng Mat Struct

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A B S T R A C TA fatigue crack growth model under constant amplitude loading has been developed considering energy balance during growth of the crack. The plastic energy dissipated during growth of a crack within cyclic plastic zone and area below cyclic stress-strain curve was used in the energy balance. The near crack tip elastic-plastic stress and strain were calculated on the basis of Hutchinson, Rice and Rosengren (HRR) formulations. Fatigue crack growth rate in linear and near threshold region of da/dN versus K curve can be determined on the basis of the proposed model in terms of low cycle fatigue (LCF) properties determined on smooth specimen. The predictions of the model have been compared with the experimental and theoretical results available in the literature using mechanical and fatigue properties. The model compares well in the threshold and intermediate region of the da/dN versus K curve for wide range of material tested.W c = specific energy till fracture (J m −3 ) k = cyclic strength coefficient (Pa) n = cyclic strain hardening exponent ε/2 = strain amplitude σ /2 = stress amplitude (Pa) E = modulus of elasticity (Pa) ε e = elastic part of the strain amplitude ε/2 ε p = plastic part of the strain amplitude ε/2 2N f = number of reversal to failure σ f = cyclic fatigue strength coefficient (Pa) ε f = fatigue ductility coefficient b = fatigue strength exponent c = fatigue ductility exponent K I = K max − K min = range of stress intensity factor under mode I loading (Pa √ m) K th = fatigue threshold stress intensity factor (Pa √ m) R = σmin σmax = Kmin Kmax = stress ratio σ y = cyclic yield stress ( σ y ∼ 2σ y ) (Pa) r, θ = radial and angular position of any point within the cyclic plastic zone as shown in Fig. 1 σ ij = range of stress (Pa) ahead of crack tip, i, j = r, θ σ ij (θ; n ) andε ij (θ; n ) = non-dimensional angular distribution functions of HRR stress singularities, they are function of n and θ I n = non-dimensional parameter of exponent n σ eq , ε eq = equivalent stress and strain ahead of the crack

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Section: Propagation Of Cracksupporting

confidence: 91%

“…This is consistent with the experimental results. 20,[45][46][47][48][49] The fatigue crack growth relation derived here requires mechanical and fatigue properties E, σ f , ε f and n . The FCG model expressed by Eq.…”

Section: F At I G U E C R a C K G R O W T H M O D E L D E V E L O P Mmentioning

confidence: 99%

Fatigue crack growth model for constant amplitude loading

Pandey¹,

Chand

2004

Fatigue Fract Eng Mat Struct

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“…Based on the numerically evaluated residual stress condition, a procedure based on investigations in [27] involving an effective stress ratio R eff [28] at the crack tip, is applied, see Eq. 4.…”

Section: Weight-function Approachmentioning

confidence: 99%

Crack propagation analysis and rehabilitation by HFMI of pre-fatigued welded structures

Leitner

Barsoum

Schäfers³

2016

Weld World

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This paper deals with a crack propagation analysis of welded structures and rehabilitation after pre-fatigue loading by the high-frequency mechanical impact (HFMI) posttreatment technique. The investigated specimen type is a thinwalled longitudinal stiffener made of mild steel S355. Fracture mechanical calculations are primarily performed on the basis of the weight-function approach. Thereby, the local residual stress condition at the weld toe is considered by the aid of a structural weld simulation, whereas the numerically evaluated residual stress distribution in depth agrees well to X-ray measurement results. The fracture mechanical analysis illustrates that by incorporating the residual stress state, the calculated lifetime is in good accordance to the conducted fatigue test results. By application of the HFMI-treatment as rehabilitation method, it is found that the beneficial post-treatment effect increases especially by a reduction of the applied load-level. Hence, particularly for minor nominal stress ranges near the high-cycle fatigue region, the mechanical post-treatment as repair method is utmost effective leading to almost equal fatigue strength as for the HFMI-treated specimens without pre-cycling. Finally, proposals for the crack growth assessment of welded structures and a conservative application of HFMI as rehabilitation method for mild steel joints are provided.

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“…The following approximation formulas for the determination of effective ranges have been used: Crack opening at K=0, Newman's formula [13], Ibrahim's formula [14], and Kurihara's formula [15]. The results are shown in figures 13 and 14.…”

Section: Approach 2: 3d-weight Functionsmentioning

confidence: 98%

Variable amplitude fatigue of autofrettaged diesel injection parts

Thumser¹,

Bergmann

Herz

et al. 2008

Materialwissenschaft Werkst

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Experimental and analytical investigations of constant and variable amplitude fatigue life of not autofrettaged and autofrettaged components have been performed. In variable amplitude loading the new standardised COmmon-RAil-Load sequence CORAL has been used as well as two-level-tests with small cycles at high mean stresses interrupted by large cycles for the evaluation of load sequence effects. The results of the two level tests show that small cycles with amplitudes far below the fatigue limit cause fatigue damage. Life calculations have been performed according to the nominal stress approach with S-N-curves and improved Miner's Rule, linear-elastic fracture mechanics with 3D-weight functions, elastic-plastic fracture mechanics applying an extended strip yield-model, and explicit 3D-FE-simulation of fatigue crack growth with predefined crack fronts.All approaches are appropriate for predicting realistic variable amplitude lives. From a practical point of view the explicit 3D-FE-simulation of fatigue crack growth is too time-consuming. However, such simulations show that the approaches based on linear-elastic fracture mechanics and elastic-plastic fracture mechanics with extended strip yield-model capture the essential physics of fatigue crack growth in a realistic way.Key words: Autofrettage, variable amplitude, residual stress, fatigue crack growth Die Lebensdauer nicht autofrettierter und autofrettierter Bauteile unter einstufiger und betriebsähnlicher Innendruckbelastung wurde experimentell und analytisch untersucht. Als betriebsähnliche Belastung wurde die COmmon-RAil-Load sequence CORAL entwickelt. Zur weiteren Klärung von Lastfolgeeinflüssen wurden Zweistufenversuche durchgeführt mit dem Ergebnis, dass kleine Schwingspiele noch bei mitteldruckbewerteten Amplituden weit unterhalb der halben Dauerfestigkeit schädigen.Die folgenden Lebensdauervorhersagemethoden wurden über-prüft:Nennspannungskonzept mit Varianten der Miner-Regel linear-elastische Bruchmechanik mit 3D-Gewichtsfunktionen elasto-plastische Bruchmechanik mit erweitertem Fließstreifen-Modell explizite 3D-FE-Simulation des Rissfortschritts mit vorgegebener Rissfront Alle Methoden eignen sich ähnlich gut. Für die praktische Anwendung erscheint die explizite 3D-FE-Simulation zu aufwändig, sie zeigen jedoch deutlich, dass die linear-elastische Bruchmechanik mit 3D-Gewichtsfunktionen und die elasto-plastische Bruchmechanik mit erweitertem Fließstreifen-Modell die wesentlichen physikalischen Phänomene des Rissfortschritts realistisch abbilden.

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Analysis on Fatigue Crack Growth Rates Under a Wide Range of Stress Ratios

Cited by 28 publications

References 0 publications

Fatigue crack growth model for constant amplitude loading

Fatigue crack growth model for constant amplitude loading

Crack propagation analysis and rehabilitation by HFMI of pre-fatigued welded structures

Variable amplitude fatigue of autofrettaged diesel injection parts

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