Advanced analysis of crack tip plastic zone under cyclic loading

Besel, Michael; Breitbarth, Eric

doi:10.1016/j.ijfatigue.2016.08.013

Cited by 93 publications

(45 citation statements)

References 16 publications

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“…Therefore, the results of Besel et al [17] are consistent with the present EBSD results. In Figure 4c it can be observed that only a small part (<30 μm) of the plastic zone exhibits intensified KAM values corresponding to strain values higher than 1.5%.…”

Section: Discussionsupporting

confidence: 92%

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Measuring Plasticity with Orientation Contrast Microscopy in Aluminium 6061-T4

Ghodrat

Riemslag

Kestens

2017

Metals

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Orientation contrast microscopy (i.e., electron backscattered diffraction, EBSD) was employed to monitor the plastic strain in loaded tensile samples of aluminium alloy Al6061 in T4 condition. The kernel average misorientation (KAM) is known to be an appropriate parameter in orientation contrast microscopy which has the potential to characterise the plastic strain by monitoring the local misorientations. This technique was applied here to gauge the extent of the plastic zone around a fatigue crack. To establish the magnitude of strain (which can be identified by the KAM parameter), a series of tensile samples were strained in the range of 1% to 25%. KAM maps were compared, and the average misorientations were related to the tensile strain values. The KAM distribution functions for all the strained samples were derived from a large scanned area. In addition, Vickers microhardness tests were conducted for these series of samples. This allowed the comparison of the mesoscopic plastic strain measured by Vickers microhardness with the micro plastic strain locally obtained by KAM. Noise was observed in the average KAM values up to a plastic strain of 1.5%. For the plastic strain exceeding 1.5%, noise no longer dominates the KAM map, and a positive-though not linear-correspondence between plastic strain and KAM was observed. The observed plastic zone at the tip of the fatigue crack by micro-Vickers hardness measurements was about an order of magnitude higher than the plastic zone observed on the KAM maps. In view of the calibration of KAM values on the tensile samples, it could be concluded that in the larger area of the plastic zone, the strain did not exceed the critical value of 1.5%.

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Section: Discussionsupporting

confidence: 92%

“…The work of Besel et al [17], in which they determined the plastic zone size with 3D numerical finite element method (FEM) simulations and digital image correlation (DIC), shows that the main part of the plastic zone also has strain values less than 1%. Therefore, the results of Besel et al [17] are consistent with the present EBSD results.…”

Section: Discussionmentioning

confidence: 99%

Measuring Plasticity with Orientation Contrast Microscopy in Aluminium 6061-T4

Ghodrat

Riemslag

Kestens

2017

Metals

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“…One of the first applications of DIC technique in fracture mechanics studies is the estimation of SIF, K . Explicit stress and displacement fields near a crack tip may be derived from the Westergaard functions using the general Kolossov‐Muskhelishvili potentials .…”

Section: Determination Of Fracture Mechanics Parametersmentioning

confidence: 99%

“…In addition to SIFs and T stress, DIC data have also been used for the identification of other fracture mechanics parameters, such as plastic flow under mixed mode loading, crack propagation law, monitor crack growth, parameters in cohesive law, estimating plastic zone size, and crack opening displacement, the latter will be discussed in the following chapter. Digital image correlation measures total displacements/strains; hence, plastic components normally need to be separated from the total using numerical methods together with suitable materials constitutive models (Figure ) . Decreuse et al partitioned deformation under mixed mode loading conditions into elastic and plastic parts by considering unloading to be essentially elastic.…”

Section: Determination Of Fracture Mechanics Parametersmentioning

confidence: 99%

Full‐field characterisation of crack tip deformation and fatigue crack growth using digital image correlation—a review

Tong

2018

Fatigue Fract Eng Mat Struct

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In recent years, digital image correlation has been widely used in the analysis of crack problems. This review will examine digital image correlation, as a full‐field measurement technique, in the studies of crack tip mechanical behaviour under cyclic loading conditions. In particular, topics including determination of fracture mechanics parameters and evaluation of crack closure will be discussed. Micromechanical aspects of crack growth under cyclic loading will also be explored in crack driving and attenuation effects.

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“…10 Also, Besel and Breitbarth 11 showed experimentally and numerically 3 different types of the plastic zones around the crack tip under cyclic loading. In these models, the behaviour of the material is assumed as elastic-perfectly plastic.…”

Section: And Dugdalementioning

confidence: 99%

Study of hardening and cyclic plastic behaviour around the crack tip of C(T) specimen made by as‐received and annealed copper

Hosseini

Seifi

2018

Fatigue Fract Eng Mat Struct

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The purpose of this research is determining experimentally the characteristics of tension and cyclic plastic behaviours of as‐received and annealed coppers and studying distribution of stress/strain field near the crack tip. Samples made by pure copper were annealed at 420°C for 40 minutes in electric furnace. To determine the properties of the cyclic plastic behaviour, proper tests with symmetric strain‐controlled conditions were performed on standard samples. Chaboche nonlinear hardening model was used to determine the cyclic plastic behaviour of both materials. According to results, annealing process creates isotropic hardening in the copper and also changes its initial kinematic hardening behaviour. Effects of the annealing and hardening on the variations of the stresses and strains around the crack tip were investigated. Also, ratcheting and mean stress relaxations versus number of cycles, inside the plastic region, were studied.

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Advanced analysis of crack tip plastic zone under cyclic loading

Cited by 93 publications

References 16 publications

Measuring Plasticity with Orientation Contrast Microscopy in Aluminium 6061-T4

Measuring Plasticity with Orientation Contrast Microscopy in Aluminium 6061-T4

Full‐field characterisation of crack tip deformation and fatigue crack growth using digital image correlation—a review

Study of hardening and cyclic plastic behaviour around the crack tip of C(T) specimen made by as‐received and annealed copper

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