Fracture toughness of a constrained metal layer

Lin, Guoyu; Kim, Yun Jae; Cornec, A.; Schwalbe, K.‐H.

doi:10.1016/s0927-0256(97)00056-6

Cited by 20 publications

(12 citation statements)

References 16 publications

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“…Extreme effects of undermatching, with high values of the normalized load parameter, were observed by Varias et al 15 . and Lin et al 28 ,. 30 They analysed joints with very small weld widths and assumed the base material to be a ceramic with an infinite yield stress ( m = 0).…”

Section: Introductionmentioning

confidence: 84%

“…The value of the peak stress attained and its distance from the crack tip increase as the normalized load parameter is increased (corresponding to either smaller weld thicknesses or applying higher loads), and can occur at several weld thicknesses ahead of the crack tip 15 ,. 28 Such behaviour far from the crack tip cannot be quantified using constraint parameters such as Q M , which is defined near the crack tip.…”

Section: Introductionmentioning

confidence: 99%

“…The resulting crack growth resistance curves were very flat, and they also observed a large elevation in the stress fields ahead of the crack. Using a cohesive zone model, Lin et al 28 ,. 30 showed that the peak stress could develop far enough ahead of the crack tip that cavitation occurred remote from the crack tip, forming a new crack which itself caused the formation of further new cracks.…”

Section: Introductionmentioning

confidence: 99%

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Damage mechanics models of ductile crack growth in welded specimens

Burstow

Howard

2000

Fatigue Fract Eng Mat Struct

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Two‐dimensional, plane strain, finite element analyses of strength‐mismatched welded joints have been performed using the modified boundary layer formulation. The welds were idealized as two‐material joints with the material interface running parallel to the crack, which was embedded in the weld material. The Rousselier ductile damage model was employed within the weld material to simulate crack extension due to the growth and coalescence of microvoids. By analysing models with different levels of material mismatching, weld dimensions and applied T‐stress levels, it was possible to analyse the effects of crack tip constraint due to both material mismatching and specimen geometry on the fracture resistance of the weld material. The results show that material strength overmatching (where the weld material is stronger than the base material) reduces the level of constraint ahead of the crack, which can increase the resistance to fracture of the weld material. Conversely, material strength undermatching increases crack tip constraint, reducing the fracture resistance of the joint. By employing estimates for the crack tip constraint levels, QM , based on the applied load, level of material mismatching and weld region thickness, it has been possible to ‘order’ the J–resistance curves of overmatched joints by generating a family of J–QM loci which describe the effects of constraint on the fracture resistance of the weld material. However, it is shown that the QM‐stress parameter is not capable of describing the effect of material strength undermatching on the fracture resistance of a joint, which can be much lower than that obtained from a high‐constraint homogeneous specimen of weld material.

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Section: Introductionmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Damage mechanics models of ductile crack growth in welded specimens

Burstow

Howard

2000

Fatigue Fract Eng Mat Struct

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“…A review on the application of the CZM approach to studies of crack growth under monotonic loading can be found in Hutchinson and Evans (2000). Specifically, applications of the CZM approach to studies of crack growth in multi-layer structures under monotonic loading were presented in Tvergaard and Hutchinson (1994Hutchinson ( , 1996, Lin et al (1997), Lane et al (2000). There, the crack growth behavior of a crack lying along one of the interfaces of a thin ductile layer joining two elastic solids was computed.…”

Section: Introductionmentioning

confidence: 99%

A numerical analysis of constraint effects in fatigue crack growth by use of an irreversible cohesive zone model

Wang

Siegmund

2005

Int J Fract

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The analysis of constraint effects in fatigue crack growth in multi-layer structures is discussed. The process of material separation under cyclic loading is described by a cohesive zone model (CZM) with an irreversible constitutive relationship. The traction-separation behavior does not follow a predefined path, but is dependent on the evolution of the damage dependent cohesive zone properties. A modified boundary layer model is used in simulations of fatigue crack growth along the centerline crack of the metal layer sandwiched between two elastic substrates. Fatigue crack growth is computed for a series of values of metal layer thickness under constant and variable amplitude loading conditions. The results of the computations demonstrate that certain combinations of load magnitude, layer thickness and material properties results in significant constrain effects in fatigue crack growth. The influence of these constraint effects on fatigue crack growth rates and on crack closure processes is determined. The evolutions of the traction-separation law, the accumulated and current plastic zones, as well as the stress fields during the crack propagation are discussed.

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“…For increased plastic contributions they observed crack arrest accompanied by the formation of secondary loading zones around the crack tip. The formation of secondary cracks has been observed for cohesive zone models within constraint metal layers by Lin et al (1997). The decrease of the loading capacity due to a priori existent secondary cracks has been extensively studied in the literature, e.g.…”

Section: Main Crack Secondary Crackmentioning

confidence: 99%

Simulation of local instabilities during crack propagation in the ductile–brittle transition region

Hütter

Mühlich

Kuna

2011

European Journal of Mechanics - A/Solids

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The crack propagation for a cohesive zone model within an elastic-plastic material under small-scale yielding conditions is simulated numerically. The resulting crack growth resistance curves show local instabilities, so-called pop-ins even for homogeneous cohesive properties if the cohesive strength lies sufficiently close to the maximum stress of the corresponding blunting solution. The formation of secondary cracks and unloading zones in front of the actual crack tip is identified as the underlying mechanism. It is found that the shape of the cohesive law has a considerable influence on the crack arrest behavior. Furthermore, requirements to the mesh resolution are derived.

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Fracture toughness of a constrained metal layer

Cited by 20 publications

References 16 publications

Damage mechanics models of ductile crack growth in welded specimens

Damage mechanics models of ductile crack growth in welded specimens

A numerical analysis of constraint effects in fatigue crack growth by use of an irreversible cohesive zone model

Simulation of local instabilities during crack propagation in the ductile–brittle transition region

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