J-integral analysis of the elastic strain fields of ferrite deformation twins using electron backscatter diffraction

Koko, Abdalrhaman; Elmukashfi, Elsiddig; Dragnevski, Kalin I.; Wilkinson, Angus J.; Marrow, James

doi:10.1016/j.actamat.2021.117203

Cited by 15 publications

(2 citation statements)

References 117 publications

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“…Microstructural information and local strain measurements can be used to identify individual slip system activities and relate them to the initiation and growth of fatigue cracks. 155 Recent work by Koko et al 156,157 used high-(angular) resolution electron backscatter diffraction (HR-EBSD), as opposed to DIC, to extract local deformation measurements to associate mixed mode SIFs quantitatively in age-hardened duplex stainless-steel.…”

Section: Applicationsmentioning

confidence: 99%

Extracting fracture properties from digital image and volume correlation displacement data: A review

Becker

2023

Strain

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The advent of digital image and volume correlation has attracted wide use in fracture mechanics. The full‐field nature of digital image and volume correlation allows for the integration of computational fracture mechanics to analyse cracked samples quantitatively. This review provides a comprehensive overview of current methods used to extract fracture properties from full‐field displacement data. The term full‐field fracture mechanics is introduced to highlight the uniqueness of using inherently noisy experiential data to extract fracture properties. The review focuses on post‐processing‐based approaches rather than integrated approaches, as these have less limitations and are more commonly employed. There are four approaches that are discussed in extracting fracture properties from experimentally computed displacement data: field‐fitting, integral, crack‐opening and cohesive zone modelling approaches. This is further developed to discuss problems associated with using digital image and volume correlation to extract properties, including application examples.

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Section: Applicationsmentioning

confidence: 99%

Extracting fracture properties from digital image and volume correlation displacement data: A review

Becker

2023

Strain

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“…Evaluating the accuracy and uncertainty of the measured results is vital for any measurement. The accuracy of orientation indexation directly impacts the advanced applications of EBSD, such as in the lattice tetragonality measurement [25,26], elastic stress estimation from strain level [27,28], crystal lattice determination [29]. The accuracy problem frequently arises in the EBSD community (see, for example, the discussion webpage [30]).…”

Section: Introductionmentioning

confidence: 99%

Accuracy assessment of crystal orientation indexations by EBSD

Shi,

Loisnard,

et al. 2024

Meas. Sci. Technol.

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Accuracy and uncertainty analyses are essential for every measurement technology. In crystal orientation indexation by electron backscatter diffraction (EBSD), a series of accuracy estimations have been made for the Hough transform and dictionary indexation methods. The mean angular deviation is a standard parameter to indicate orientation accuracy, but this criterion is indirect and closely related to the accuracy of the projection center coordinates. Precise known orientation relationships are necessary to evaluate orientation accuracy without the ground truth. The current work uses the natural crystal twins and hardware orientation relationships to assess the orientation accuracy directly. The accuracy level for different EBSD analysis methods is compared through four experimental data sets of varying pattern definitions and noise levels. It is found that the full pattern match (FPM) algorithms improve the accuracy as compared to Hough indexation, and the gain varies greatly between 14% for fast acquisitions and 20 times for high-quality patterns. Depending on the resolution and quality of diffraction patterns, FPM results in an accuracy of crystal orientation between 0.04° and 0.9°. Comparing the two FPM variants, matching the gradients of diffraction patterns performs better in the case of high-to-median quality acquisitions while matching the pattern itself is more accurate for more noisy and low-definition patterns.

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Modelling the nucleation and propagation of cracks at twin boundaries

Grilli

Cocks

2021

Int J Fract

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Fracture arising from cracks nucleating and propagating along twin boundaries is commonly observed in metals that exhibit twinning as a plastic deformation mechanism. This phenomenon affects the failure of macroscopic mechanical components, but it is not fully understood. We present simulations in which a continuum model for discrete twins and a cohesive zone model are coupled to aid the understanding of fracture at twin boundaries. The interaction between different twin systems is modelled using a local term that depends on the continuum twin variables. Simulations reveal that the resolved shear stress necessary for an incident twin to propagate through a barrier twin can be up to eight times the resolved shear stress for twin nucleation. Interface elements are used at the interfaces between all bulk elements to simulate arbitrary intragranular cracks. An algorithm to detect twin interfaces is developed and their strength has been calibrated to give good agreement with the experimentally observed fracture path. The elasto-plastic deformation induced by discrete twins is modelled using the crystal plasticity finite element method and the stress induced by twin tips is captured. The tensile stress caused by the tip of an incident twin on a barrier twin is sufficient to nucleate a crack. A typical staircase fracture path, with cracks propagating along the twin interfaces, is reproduced only if the strength of the twin interfaces is decreased to about one-third of the strength of the bulk material. This model can be used to help understand fracture caused by the activation of multiple twin systems in different materials.

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J-integral analysis of the elastic strain fields of ferrite deformation twins using electron backscatter diffraction

Cited by 15 publications

References 117 publications

Extracting fracture properties from digital image and volume correlation displacement data: A review

Extracting fracture properties from digital image and volume correlation displacement data: A review

Accuracy assessment of crystal orientation indexations by EBSD

Modelling the nucleation and propagation of cracks at twin boundaries

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