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A dual-energy approach for improvement of the measurement consistency in computed tomography
Örebro University, School of Science and Technology.ORCID iD: 0000-0002-9362-8328
Örebro University, School of Science and Technology.ORCID iD: 0000-0003-1408-2249
2016 (English)In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 27, no 11, article id 115013Article in journal (Refereed) Published
Abstract [en]

Computed tomography is increasingly adopted by industries for metrological and material evaluation. The technology enables new measurement possibilities, while also challenging old measurement methods in their established territories. There are, however, uncertainties related with the computed tomography method. Investigation of multi-material components with, in particular, varying material thickness can result in unreliable measurements. In this paper the effects of multi-materials, and differing material thickness, on computed tomography measurement consistency has been studied. The aim of the study was to identify measurement inconsistencies and attempt to correct these with a dual-energy computed tomography approach. In this pursuit, a multi-material phantom was developed, containing reliable measurement points and custom-ability with regards to material combinations. A dual-energy method was developed and implemented using sequential acquisition and pre-reconstruction fusing of projections. It was found that measurements made on the multi-material phantom with a single computed tomography scan were highly inconsistent. It was also found that the dual-energy approach was able to reduce the measurement inconsistencies. However, more work is required with the automation of the dual-energy approach presented in this paper since it is highly operator dependant.

Place, publisher, year, edition, pages
Bristol, United Kingdom: Institute of Physics (IOP), 2016. Vol. 27, no 11, article id 115013
Keywords [en]
Multi-materials, computed tomography, dual-energy, metrology, measurement consistency, varying material thickness
National Category
Mechanical Engineering
Research subject
Mechanical Engineering
Identifiers
URN: urn:nbn:se:oru:diva-52976DOI: 10.1088/0957-0233/27/11/115013ISI: 000385929400008Scopus ID: 2-s2.0-84992365816OAI: oai:DiVA.org:oru-52976DiVA, id: diva2:1037335
Available from: 2016-10-14 Created: 2016-10-14 Last updated: 2020-01-31Bibliographically approved
In thesis
1. Only a Shadow: Industrial computed tomography investigation, and method development, concerning complex material systems
Open this publication in new window or tab >>Only a Shadow: Industrial computed tomography investigation, and method development, concerning complex material systems
2016 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The complexity of components fabricated in today's industry is ever increasing. This increase is partly due to market pressure but it is also a result from progress in fabrication technologies that opens up new possibilities. The increased use of additive manufacturing and multi-material systems, especially, has driven the complexity of parts to new heights. The new complex material systems brings benefits in many areas such as; mechanical properties, weight optimisation, and sustainability. However, the increased complexity also makes material integrity investigations and dimensional control more difficult. In additive manufacturing, for example, internal features can be fabricated which cannot be seen or measured with conventional tools. There is thus a need for non-destructive inspection methods that can measure these geometries. Such a method is X-ray computed tomography. Computed tomography utilizes the X-rays ability to penetrate material to create 3D digital volumes of components. Measurements and material investigations can be performed in these volumes without any damage to the investigated component. However, computed tomography in material science is still not a fully mature method and there are many uncertainties associated with the investigation technique. In the work presented in this thesis geometries fabricated by various additive manufacturing processes have been investigated using computed tomography. Also in this work, a dual-energy computed tomography tool has been developed with the aim to increase the measurement consistency of computed tomography when investigating complex geometries and material combinations.

Place, publisher, year, edition, pages
Örebro: Örebro University, 2016. p. 61
Series
Örebro Studies in Technology, ISSN 1650-8580 ; 73
Keywords
Computed tomography, Dual-energy, Material investigation, Additive manufacturing, Measurement consistency
National Category
Other Mechanical Engineering
Research subject
Mechanical Engineering
Identifiers
urn:nbn:se:oru:diva-54880 (URN)978-91-87789-10-6 (ISBN)
Presentation
2017-01-19, HSM, Örebro universitet, Örebro, 13:15 (English)
Opponent
Supervisors
Projects
MultiMatCT
Available from: 2017-02-03 Created: 2017-01-20 Last updated: 2017-10-18Bibliographically approved
2. More Than a Shadow: Computed Tomography Method Development and Applications Concerning Complex Material Systems
Open this publication in new window or tab >>More Than a Shadow: Computed Tomography Method Development and Applications Concerning Complex Material Systems
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The complexity of the components fabricated in today's industry is ever increasing. This is partly due to market pressure, but it is also a result from recent progress in fabrication technologies that open up new design possibilities. The increased use of additive manufacturing and multi-material systems, especially, has driven the complexity of parts to new heights. The new complex material systems bring benets in many areas such as; mechanical properties, weight reduction, and multifunctions. However, the increased complexity also makes inspection and dimensional control more dicult. In additive manufacturing, for example, internal features can be fabricated which cannot be seen or measured with conventional tools. There is thus a need for non-destructive inspection methods that can measure these geometries. Such a method is X-ray computed tomography. Computed tomography utilizes the X-rays ability to penetrate material to create 3D digital volumes of components. Measurements and material investigations can be performed in these volumes without any damage to the investigated component. However, industrial computed tomography is still not a fully mature method and there are many uncertainties associated with the investigation technique. In this work, a dual-energy computed tomography tool has been developed with the aim to increase the performance of computed tomography when investigating complex geometries and material combinations. This method has been applied to various phantoms and an industrial case. Also, in this work, complex lattice structures fabricated with additive manufacturing have been investigated and analysed using computed tomography. The results show that the new DECT method improves measurement results and can be utilized to inspect multi-material components. The results also show that computed tomography can be used successfully to gain knowledge about complex lattices.

Place, publisher, year, edition, pages
Örebro: Örebro University, 2019. p. 139
Series
Örebro Studies in Technology, ISSN 1650-8580 ; 84
National Category
Other Mechanical Engineering
Identifiers
urn:nbn:se:oru:diva-73739 (URN)978-91-7529-286-1 (ISBN)
Public defence
2019-06-12, Örebro universitet, Teknikhuset, Hörsal T, Fakultetsgatan 1, Örebro, 13:15 (English)
Opponent
Supervisors
Available from: 2019-04-15 Created: 2019-04-15 Last updated: 2020-01-31Bibliographically approved

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Jansson, AntonPejryd, Lars

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