Accuracy of XCT to Perform Dimensional Measurements on Different Measurands | Chapter 2 | Science and Technology: Developments and Applications Vol. 1

As additive manufacturing is increasingly used in industry to manufacture complex shapes with internal features, x-ray computed tomography (XCT) has become an essential tool for performing dimensional measurements. Thus, an x-ray computed tomography (XCT) interlaboratory comparison campaign, involving an aluminium-machined object, whose dimensions (92 × 78 × 63 mm³) are significant for a 225 kV XCT system, was performed for the purpose of investigating the performances of industrial XCT systems for dimensional measurements in terms of accuracy, i.e. precision and trueness, and to evaluate the influence of the measurement protocol (i.e. measurement strategy), of the operator and of the software on the results by comparison to reference measurements. The campaign involved seven French XCT users and system suppliers. Seven measurands were selected for the comparison campaign, including one distance, three diameters, one cylindricity, one coaxiality and one true position. The results of the comparison campaign were analysed to evaluate the performance of XCT systems implementing ISO 5725-2 related to accuracy, and more specifically to one of the two components of accuracy: precision, and ISO 5725-4 related to the other component of accuracy: trueness. In this campaign, we came to the conclusion that the measurement strategy is predominant, except for distance; that the measurement process is affected by the operator only for cylindricity and coaxiality; that there is no or little influence of the software except for coaxiality and position; and that a volumetric Gaussian filter allows improving the measurements only for some participants’ measurements. Furthermore, different behaviours, in terms of precision and trueness, are observed depending on the type of measurands when performed by different operators. The diameter measurements are reproducible with XCT, lower than 30 μm which corresponds to a subvoxelic factor of 2.5 and the trueness is lower than 22 μm. The distance measurement is also reproducible with XCT, 15 μm which corresponds to a subvoxelique factor of 4.9 and the trueness is 8 μm. For these measurands, their measurements do not depend on the used XCT system. However, the XCT reproducibility for cylindricity, coaxiality and position is worse as well as the trueness except for the position which has a trueness of 1 μm. The process measurement should be revised regarding cylindricity and coaxiality measurements which have been done (see addendum). Finally, overall, the ability of the participants to perform measurements with XCT, whatever their system, is statistically comparable except for a few measurements. In this article, the results of an interlaboratory comparison campaign on XCT dimensional measurements have been presented.

 

Author (s) Details

 

Anne-Françoise Obaton
Laboratoire National de Métrologie et D’essais (LNE), 1 Rue Gaston Boissier, 75015 Paris, France.

 

Anis Tanich
Laboratoire National de Métrologie et D’essais (LNE), 1 Rue Gaston Boissier, 75015 Paris, France.

 

Nicolas Fischer
Laboratoire National de Métrologie et D’essais (LNE), 1 Rue Gaston Boissier, 75015 Paris, France.

 

Sophie Antona
SARL 3D Casting, Z.I. Genève Océan, 71520 Dompierre-Les-Ormes, France.

 

Florian Montagner
Baker Hughes Digital Solutions France, 68 Chemin Des Ormeaux, 69760 Limonest, France.

 

Sylvain Genot
Nikon Metrology, 39 rue du Bois Chaland, 91090 Lisses, France.

 

Sébastien Brzuchacz
Cetim, 52 Av. Félix Louat, 60300 Senlis, France.

 

Patrick De Soete
COMET Yxlon GmbH, Essener Bogen, 22419 Hamburg, Germany.

 

Kevin Duboeuf
Carl Zeiss SAS, 25 Rue Saint-Blaise, 72300 Sablé-sur-Sarthe, France.

 

Thomas Beuvier
Carl Zeiss SAS, 25 Rue Saint-Blaise, 72300 Sablé-sur-Sarthe, France.

 

Rakesh Nanjareddy
Volume Graphics GmbH (VG), Speyerer Straße 4-6, 69115 Heidelberg, Germany.

 

Nicolas Coutant
Volume Graphics GmbH (VG), Speyerer Straße 4-6, 69115 Heidelberg, Germany.

 

Nicolas Cochennec
Safran Composites, 33 Avenue de la Gare, 91760 Itteville, France.

Lionel Gay
Safran Composites, 33 Avenue de la Gare, 91760 Itteville, France.

 

Please see the book here:- https://doi.org/10.9734/bpi/stda/v1/2480

Interrelationship between Breakthrough Curves and X-ray Computed Tomography Analyzed Macropore Characteristics: An Update | Chapter 12 | Research Advances and Challenges in Agricultural Sciences Vol. 7

The present study aimed to study the role of pore contact of micro-lysimeters in the soil column on tracer transport in relation to the structure, as assessed by X-ray CT under different initial conditions and irrigation. As it is not possible to carry out these investigations under field conditions, non-destructive CT data were used, making it possible for 3-D reconstruction of the structure of the investigated soil columns. Quantitative relationships between soil structure (especially macropore characteristics, namely their size, number, type, distribution and continuity) and soil hydraulic properties are essential for improving our ability to model flow and transport in structured soils. Ten undisturbed soil monoliths of clayey Pelosol at Gottingen, Germany covering the horizons Ah and P were collected. Some columns were left at natural humidity, some were oven-dried to simulate drought situations in forest soils in consequence of climate change. In seven columns, four micro-lysimeters, each, were installed at half height in order to obtain data for analysis of single solute pathways. A fixed amount of KBr tracer was applied to the humus layer. The columns were irrigated with CaCl2. Column output and lysimeter output were collected and analyzed to record breakthrough curves. Bimodal analytical convection dispersion equation (CDE) solutions were fitted for the column outputs using a non-linear least square fit. A simple CDE solution did not fit well. This supports the model of two overlaying transport phenomena. After breakthrough recording was complete, all columns were scanned using X-ray computed tomography (CT). From the CT data 3-D reconstructions of the porous system were created for visual inspection, and the exact pathways for macropores along the micro-lysimeters were determined. Additionally, indices of the pore structure were computed to compare with the slow and fast dispersivity values from the bimodal CDE fit.  The three-dimensional reconstruction could be used to explain the difference in micro-lysimeter performance. Following the conclusion of irrigation, no statistically significant variations were found in the pore structure of the wet and dried columns. In general, there is a positive linear relationship between the pore index and slow dispersivity and a negative linear relationship with rapid dispersivity. In topsoil, these relationships are more robust. The CT images and 3-D reconstructions offer a fascinating look into the soil pore system and could be useful in understanding drought issues caused by climate change that are caused by humans.

Author(s) Details:

A. Spangenberg,
University of Göttingen, Institute for Soil Science and Forest Nutrition, Büsgenweg 2, 37077 Göttingen, Germany.

Y. Nagarajarao,
University of Göttingen, Institute for Soil Science and Forest Nutrition, Büsgenweg 2, 37077 Göttingen, Germany.

C. Hinz,
University of Göttingen, Institute for Soil Science and Forest Nutrition, Büsgenweg 2, 37077 Göttingen, Germany.

Please see the link here: https://stm.bookpi.org/RACAS-V7/article/view/14270