Shear cracking in an Al powder compact studied by X-ray microtomography

McDonald, S.A.; Cocks, A.C.F.; Withers, Philip J.

doi:10.1016/j.msea.2009.02.009

Cited by 12 publications

(7 citation statements)

References 17 publications

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“…Therefore, the Elliptical Cap yield criteria is more suitable in describing a shear (mode II) crack during the densification process based upon a lower θ value in comparison to those obtained using the Mohr-Coulomd yield criteria. The simulated shear (mode II) crack during the densification stage of the powder compaction process has already been verified by a recently published experimental work [9]. In addition, the crack starts at the end of step 21 and propagates at step 25, which is much later compared to the previous case where crack starts at step 9 when Mohr-Coulomb yield criteria is used.…”

Section: Crack Propagationsupporting

confidence: 58%

“…Even though it is believed that failure in metal powder compaction is due to shear fracture [9], the fracture criterion in need must not neglect the possibility of fracture due to the opening mode (mode I). Classical mixed mode fracture criteria have always been used to find the crack initiation angle (or direction) where crack extension depends on a specific fracture parameter.…”

Section: Fracture Criteriamentioning

confidence: 99%

“…Recent numerical and experimental works present evidences of the presence of a shear crack (Mode II) occurring during the densification stage of the powder compaction process [5,9]. Hence, it is the purpose of this paper to assess the suitability of two common yield criteria for powder compaction; the Elliptical Cap and Mohr-Coulomb yield criteria in simulating a shear crack (Mode II) during the densification stage of the powder compaction process.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Finite element modelling of crack propagation in metal powder compaction using Mohr–Coulomb and Elliptical Cap yield criteria

2010

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In the modelling of the compaction process of particulate materials into a coherent green body, an appropriate yield criterion for the deformation process has to be selected. In this paper, two commonly used yield criteria for powder compaction, namely Mohr-Coulomb and Elliptical Cap are utilized in the finite element modelling of iron powder compaction process, which incorporates a fracture criterion of granular materials in compression. The simulated crack growth patterns obtained by using these two yield criteria were compared in terms of the influence of shear stress and relative density distributions. This work has shown that the application of the Elliptical Cap yield model gives a more realistic simulated Mode II crack propagation during the densification stage of the metal powder compaction process in comparison to the Mohr-Coulomb yield model.

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Section: Crack Propagationsupporting

confidence: 58%

Section: Fracture Criteriamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Finite element modelling of crack propagation in metal powder compaction using Mohr–Coulomb and Elliptical Cap yield criteria

2010

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“…Amongst the full‐field displacement measurement methods, the Digital Volume Correlation (DVC) (which is a 3D extension of the Digital Image Correlation (DIC) technique ) has been applied to many materials over the last years, such as trabecular bone , wood , granular materials , cast iron and stone wool , for instance. Since it is a non‐contact technique, DVC is very attractive in experimental conditions where classical instrumentation techniques may be unsuccessful.…”

Section: Introductionmentioning

confidence: 99%

A Multigrid PGD‐based Algorithm for Volumetric Displacement Fields Measurements

Perini

Passieux

Périé

2014

Strain

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The use of a finite elements-based Digital Volume Correlation (FE-DVC) leads to lower measurement uncertainties in comparison to subset-based approaches. However, the associated computing time may become prohibitive when dealing with highresolution measurements. To overcome this limitation, a Proper Generalised Decomposition solver was recently applied to 2D digital image correlation. In this paper, this method is extended to measure volumetric displacements from 3D digital images. In addition, a multigrid Proper Generalised Decomposition algorithm is developed, which allows to use different discretisations in each term of the decomposition. Associated to a coarse graining of the digital images, this allows to avoid local minima, especially in presence of large displacements. Synthetic and practical cases are analysed with the present approach, and measurement uncertainties are compared with standard FE-DVC. Results show that such an approach reduces the computational cost (when compared to FE-DVC) whilst maintaining lower measurement uncertainties than standard subset-based DVC.

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“…The XCT machine used was the 225/320 kV Nikon XTEK custom bay, located at the Manchester X-ray Imaging Facility. The progressive loading was applied by a DEBEN mechanical testing rig [22,23] with a load capacity of 25 kN, placed on the rotation stage of the CT machine. Table 1.…”

Section: In Situ Xct Experimentsmentioning

confidence: 99%

Three‐Dimensional In Situ XCT Characterisation and FE Modelling of Cracking in Concrete

et al. 2018

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Three-dimensional (3D) characterisation and modelling of cracking in concrete have been always of great importance and interest in civil engineering. In this study, an in situ microscale X-ray computed tomography (XCT) test was carried out to characterise the 3D microscale structure and cracking behaviour under progressive uniaxial compressive loading. The 3D cracking and fracture behaviour including internal crack opening, closing, and bridging were observed through both 2D tomography slices and 3D CT images. Spatial distributions of voids and cracks were obtained to understand the overall cracking process within the specimen. Furthermore, the XCT images of the original configuration of the specimen were processed and used to build microscale realistic 3D finite element (FE) models. Cohesive interface elements were inserted into the FE mesh to capture complicated discrete crack initiation and propagation. An FE simulation of uniaxial compression was conducted and validated by the in situ XCT compression test results, followed by a tension simulation using the same image-based model to investigate the cracking behaviour. The quantitative agreement between the FE simulation and experiment demonstrates that it is a very promising and effective technique to investigate the internal damage and fracture behaviour in multiphasic composites by combining the in situ micro XCT experiment and image-based FE modelling.

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Shear cracking in an Al powder compact studied by X-ray microtomography

Cited by 12 publications

References 17 publications

Finite element modelling of crack propagation in metal powder compaction using Mohr–Coulomb and Elliptical Cap yield criteria

Finite element modelling of crack propagation in metal powder compaction using Mohr–Coulomb and Elliptical Cap yield criteria

A Multigrid PGD‐based Algorithm for Volumetric Displacement Fields Measurements

Three‐Dimensional In Situ XCT Characterisation and FE Modelling of Cracking in Concrete

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