| 1. |
- Forsberg, Fredrik, et al.
(författare)
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3D deformation and strain analysis in compacted sugar using x-ray microtomography and digital volume correlation
- 2009
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Ingår i: Measurement science and technology. - : IOP Publishing. - 0957-0233 .- 1361-6501. ; 20:9
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the displacement of granular beds under compaction is important for a range of industrial, geological and civil engineering applications. Such materials exhibit inhomogeneous internal displacements including strain localization, which mean that a method for the in situ evaluation of internal 3D displacement fields at high spatial resolutions would be a major development. This paper presents results from the compaction of a cylindrical bed of sugar, with diameter 7.0 mm and height 8.2 mm, using x-ray microtomography to evaluate the internal structure and digital volume correlation to calculate 3D displacement information from these data. In contrast to previous studies, which generally track a small number of marker particles, the research here uses the natural structure of the sugar to provide a random pattern for 3D image correlation, allowing full-field information to be captured. The results show good agreement when compared with a well-established 2D image correlation technique; moreover, they indicate structural features associated with deformation of granular materials that would not necessarily be observed in a 2D slice.
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| 2. |
- Sjödahl, Mikael, et al.
(författare)
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Digital volume correlation applied to compaction of granular materials
- 2012
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Ingår i: Procedia IUTAM. - : Elsevier BV. - 2210-9838. ; 4, s. 179-195
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Tidskriftsartikel (refereegranskat)abstract
- Compaction of powders and granular materials is an important process used to manufacture products including pharmaceuticals, ceramics, metals and explosives. In order to ensure mechanical integrity of the final product, an understanding of the compaction process, with particular reference to the homogeneity of the compacted bed, is required. In particular, it is necessary to have an improved understanding of the physics of the process, which can only be achieved through appropriate experimental measurements. X-ray tomography offers the opportunity to make full-field measurements of displacements in-situ: without removing the specimens from the die. This allows researchers to better understand the processes that take place at different stages in the compaction, and to more rigorously test numerical models.In this paper, we present data obtained using Digital Volume Correlation (DVC) to measure displacements in a compacted bed of sugar, with data obtained using X-ray microtomograpy. Instead of adding tracer particles, the natural, random, microstructure of the bed is used as the pattern for the volume correlation. The displacement data obtained are then used to calculate strain fields in the bed. A novel Finite Element (FE) based smoothing technique is applied to robustly smooth the data, allowing accurate and continuous strains to be calculated. These strains are compared to those calculated from the unsmoothed data. The paper presents details of both the DVC and FE smoothing routines
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