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Lindgren, Owe
Publications (10 of 28) Show all publications
Couceiro, J. & Lindgren, O. (2016). Estimation of miosture content in wood using dual x-ray energies in a medical CT-scanner. In: Process Technologies for the Forest & Biobased Products Industries: PTF BPI 2016. Paper presented at 4th International Conference on Process Technologies for the Forest and Biobased Products Industries, PTF BPI 2016, St. Simons, Georgia, USA, October 25-26 2016 (pp. 22).
Open this publication in new window or tab >>Estimation of miosture content in wood using dual x-ray energies in a medical CT-scanner
2016 (English)In: Process Technologies for the Forest & Biobased Products Industries: PTF BPI 2016, 2016, p. 22-Conference paper, Oral presentation with published abstract (Other academic)
National Category
Wood Science Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-61069 (URN)
Conference
4th International Conference on Process Technologies for the Forest and Biobased Products Industries, PTF BPI 2016, St. Simons, Georgia, USA, October 25-26 2016
Available from: 2016-12-13 Created: 2016-12-13 Last updated: 2017-11-24Bibliographically approved
Lindgren, O., Seifert, T. & Plessis, A. d. (2016). Moisture Content Measurements in Wood Using Dual Energy CT-scanning: A Feasibility Study (ed.). Wood Material Science & Engineering, 11(5), 312-317
Open this publication in new window or tab >>Moisture Content Measurements in Wood Using Dual Energy CT-scanning: A Feasibility Study
2016 (English)In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 11, no 5, p. 312-317Article in journal (Refereed) Published
Abstract [en]

Currently computed tomography (CT) scanning provides a non-destructive method to determine moisture content in wood in three dimensions. With the current methodology two measurements are needed, one with the scanned piece of wood’s moist state and one after drying. Then the difference of the images can be calculated. The drawback and challenge is that dimensional changes due to shrinkage of wood in the drying process have to be compensated for by image processing. In this study a dual-energy CT scanning method is tested based on the consecutive scanning of wood samples at different energy levels to differentiate water from wood, without the necessity to dry the sample and thus without the need for complex image correction. Not quantified but visible differentiations due to moisture content were obtained on small cubical pine samples of different densities by quick consecutives scans at 60 and 200 kV. The results suggest that given that the pixels in the CT images are representing absorption coefficients it should be possible to directly measure moisture content in wood non-destructively in small volume elements inside solid wood in three dimensions. Further applications of this technique in industrial CT scanning of wood are discussed.

National Category
Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-9443 (URN)10.1080/17480272.2016.1201863 (DOI)000385568400006 ()2-s2.0-84979608828 (Scopus ID)810749b0-572e-49a9-af9f-61036d4d955d (Local ID)810749b0-572e-49a9-af9f-61036d4d955d (Archive number)810749b0-572e-49a9-af9f-61036d4d955d (OAI)
Note

Validerad; 2016; Nivå 2; 2016-10-19 (andbra)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Fredriksson, M. & Lindgren, O. (2013). End grain water absorption and redistribution in slow-grown and fast-grown Norway spruce (Picea abies (L.) Karst.) heartwood and sapwood (ed.). Paper presented at . Wood Material Science & Engineering, 8(4), 245-252
Open this publication in new window or tab >>End grain water absorption and redistribution in slow-grown and fast-grown Norway spruce (Picea abies (L.) Karst.) heartwood and sapwood
2013 (English)In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 8, no 4, p. 245-252Article in journal (Refereed) Published
Abstract [en]

Wood is susceptible to decay by rot fungi if it is exposed to high-moisture contents during long periods of time and it is therefore important to limit the duration of such periods. Critical points in outdoor wood structures are, for example, end grain surfaces in joints where water can get trapped after a rain. It is therefore of interest to study both absorption and redistribution of moisture in wood. This paper presents moisture content profiles during end grain water absorption and redistribution in Norway spruce (Picea abies (L.) Karst.) measured by computed tomography with the specimens in individual climate boxes. Heartwood and sapwood of two provenances (slow-grown and fast-grown wood) were included. No major differences were seen between the water uptake of the slow-grown and the fast-grown wood since the densities were similar despite of the large difference in growth ring width. However, for the sapwood specimens, the moisture content was higher further into the specimens than for the heartwood specimens in agreement with previous studies. For the slow-grown wood, the redistribution was also generally more rapid for the sapwood specimens than for the heartwood specimens.

National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-11988 (URN)10.1080/17480272.2013.847492 (DOI)2-s2.0-84887136112 (Scopus ID)b0b40f27-beb3-493f-b356-c7c27b4a536b (Local ID)b0b40f27-beb3-493f-b356-c7c27b4a536b (Archive number)b0b40f27-beb3-493f-b356-c7c27b4a536b (OAI)
Note
Validerad; 2013; 20131030 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Vaziri, M., Lindgren, O. & Pizzi, A. (2012). Influence of machine setting and wood parameters on crack formation in Scots pine joints produced by linear friction welding (ed.). Paper presented at . Journal of Adhesion Science and Technology, 26(18-19), 2189-2197
Open this publication in new window or tab >>Influence of machine setting and wood parameters on crack formation in Scots pine joints produced by linear friction welding
2012 (English)In: Journal of Adhesion Science and Technology, ISSN 0169-4243, E-ISSN 1568-5616, Vol. 26, no 18-19, p. 2189-2197Article in journal (Refereed) Published
Abstract [en]

Previous investigations on linear welded woods have shown that the connections are not sufficiently resistant to water for use in outdoor conditions. Therefore, they are utilized mainly for non-structural use, with only short time exposure to varying humidity. Influences of some welding and wood parameters such as welding pressure, welding time and heartwood or sapwood on crack formation in the weldline of Scots pine (Pinus sylvestris) were investigated. Axial samples measuring 200 mm×20 mm×20 mm from Scots pine were welded, placed vertically in 5-mm-deep tap water and were taken out of the water one at a time after each 10 min of water absorption. Then they were scanned and put back into water until the first crack appeared in the weldline. An X-ray Computer Tomography (CT-) scanner was used to monitor water movement and density change in the weldlines during water absorption–desorption. CT-scanning enabled to detect the cracks as they formed in the weldline and could be used in wood welding studies. Data evaluation showed that all the three studied parameters had significant effects on crack formation and that crack occurrence could be postponed by using heartwood samples with 1.3 MPa welding pressure and 1.5 s welding time.

National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-11459 (URN)10.1163/156856111X610126 (DOI)000307933200001 ()2-s2.0-84865475125 (Scopus ID)a6c72c10-08f7-11e0-b767-000ea68e967b (Local ID)a6c72c10-08f7-11e0-b767-000ea68e967b (Archive number)a6c72c10-08f7-11e0-b767-000ea68e967b (OAI)
Note
Validerad; 2012; 20101216 (owelin)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Vaziri, M., Lindgren, O. & Pizzi, A. (2012). Optimization of tensile-shear strength for linear welded Scots pine (ed.). Paper presented at . Journal of Adhesion Science and Technology, 26(1-3), 109-119
Open this publication in new window or tab >>Optimization of tensile-shear strength for linear welded Scots pine
2012 (English)In: Journal of Adhesion Science and Technology, ISSN 0169-4243, E-ISSN 1568-5616, Vol. 26, no 1-3, p. 109-119Article in journal (Refereed) Published
Abstract [en]

The mechanical performance of welded wood has a decisive role in its applications. This study was performed to determine the welding conditions that optimized the tensile-shear strength of welded Scots pine (Pinus sylvestris). Tensile-shear strength as a function of welding pressure, welding time and holding time1 was measured according to European standard EN 205. Maximum tensile-shear strength of welded sample was 9.3 MPa that was obtained using 1.3 MPa welding pressure, 2.8 s welding time and 70 s holding time. This tensile-shear strength was about two times that of PVAc-glued samples. According to data evaluation tensile-shear strength could be optimized to 9.7 MPa by increasing the welding time to 3.5 s and decreasing the holding time to 60 s.

National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-3975 (URN)10.1163/016942411X569327 (DOI)000300037400008 ()2-s2.0-84863184830 (Scopus ID)1d3dcaf0-08fa-11e0-b767-000ea68e967b (Local ID)1d3dcaf0-08fa-11e0-b767-000ea68e967b (Archive number)1d3dcaf0-08fa-11e0-b767-000ea68e967b (OAI)
Note
Validerad; 2012; 20101216 (owelin)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Mansouri, H., Pizzi, A., Leban, J.-M., Delmotte, L., Lindgren, O. & Vaziri, M. (2011). Causes for the improved water resistance in pine wood linear welded joints (ed.). Paper presented at . Journal of Adhesion Science and Technology, 25(16), 1987-1995
Open this publication in new window or tab >>Causes for the improved water resistance in pine wood linear welded joints
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2011 (English)In: Journal of Adhesion Science and Technology, ISSN 0169-4243, E-ISSN 1568-5616, Vol. 25, no 16, p. 1987-1995Article in journal (Refereed) Published
Abstract [en]

Linear vibration welding of good quality pine (Pinus sylvestris) wood from Sweden containing a small proportion of a native mixture of terpenoic acids, known under the collective name of rosin, has been shown to yield joints of much upgraded water resistance. This has been shown to be due to the protecting influence the molten rosin from the wood itself has on the welded interphase, because of the water repellency of rosin. Joints of unusually high percentage wood failure but modest strength were obtained, rosin apparently reinforcing the welded interphase to yield weldline strengths always much higher than the strength of the surrounding wood.

National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-13098 (URN)10.1163/016942410X544794 (DOI)2-s2.0-80052322942 (Scopus ID)c4370060-08fa-11e0-b767-000ea68e967b (Local ID)c4370060-08fa-11e0-b767-000ea68e967b (Archive number)c4370060-08fa-11e0-b767-000ea68e967b (OAI)
Note
Validerad; 2011; 20101216 (owelin)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Vaziri, M., Lindgren, O. & Pizzi, A. (2011). Influence of welding parameters and wood properties on the water absorption in Scots pine joints induced by linear welding (ed.). Paper presented at . Journal of Adhesion Science and Technology, 25(15), 1839-1847
Open this publication in new window or tab >>Influence of welding parameters and wood properties on the water absorption in Scots pine joints induced by linear welding
2011 (English)In: Journal of Adhesion Science and Technology, ISSN 0169-4243, E-ISSN 1568-5616, Vol. 25, no 15, p. 1839-1847Article in journal (Refereed) Published
Abstract [en]

Wood welding is an environmentally-friendly and very quick technique to yield wood joints in just a few minutes and without using any adhesives. The only limitation of welded wood is that the joint is suitable only for interior use. Exterior use, or use in an environment with varying humidity requires water resistance of the welded joints. An investigation was performed to determine the effects of welding parameters and wood properties on water absorption in the weldline and how to reduce it through controlling the production parameters. The influences of welding pressure, welding time, and heartwood/sapwood on water absorption in the weldline of Scots pine (Pinus sylvestris) joints were investigated. Specimens composed of two pieces of heartwood or sapwood, each of dimensions 200 mm × 20 mm × 20 mm, were welded together to form specimens of dimensions 200 mm × 20 mm × 40 mm. The specimens were allowed to stand in 5-mm-deep tap water and then they were taken out of the water one at a time and scanned in 10-min intervals until the first crack appeared in the weldline. An X-ray Computerized Tomography scanner was employed to monitor water movement and density change in weldlines during water absorption-desorption. All three evaluated parameters showed significant effect on water absorption. Samples of heartwood welded by 1.3 MPa welding pressure and 1.5 s welding time showed the lowest water absorption

National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-15902 (URN)10.1163/016942410X525731 (DOI)000295376400005 ()2-s2.0-80052326754 (Scopus ID)f78f987c-ea0b-4b72-b2e6-ac685b0364ae (Local ID)f78f987c-ea0b-4b72-b2e6-ac685b0364ae (Archive number)f78f987c-ea0b-4b72-b2e6-ac685b0364ae (OAI)
Note
Validerad; 2011; 20110927 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Vaziri, M., Lindgren, O. & Pizzi, A. (2011). Influence of weldling parameters on weldline density and its relation to crack formation in welded Scots pine joints (ed.). Paper presented at . Journal of Adhesion Science and Technology, 25(15), 1819-1828
Open this publication in new window or tab >>Influence of weldling parameters on weldline density and its relation to crack formation in welded Scots pine joints
2011 (English)In: Journal of Adhesion Science and Technology, ISSN 0169-4243, E-ISSN 1568-5616, Vol. 25, no 15, p. 1819-1828Article in journal (Refereed) Published
Abstract [en]

Exterior use of welded wood laminates without further treatment is not recommended. Frictional welded joints have poor resistance to moisture variation, especially to drying. Therefore, application of welded woods is limited to interior use without exposure to highly variable air humidity. Influences of some welding and wood parameters such as welding pressure, welding time and heartwood/sapwood on weldline density of Scots pine (Pinus sylvestris) joints were investigated. Interdependence between density and water resistance of weldline (in terms of crack time) was also studied by comparing the results of this investigation with those of the earlier studies. Specimens composed of two wood pieces, each measuring 20 mm x 20 mm x 200 mm, were welded together to form a specimen measuring 40 mm x 20 mm x 200 mm by a vibration movement of one wood surface against another at a frequency of 150 Hz. An X-ray Computerized Tomography scanner was used to measure weldline density. Weldlines of sapwood produced by 1.3 MPa welding pressure and 1.5 s welding time showed the highest density. No correlation between weldline density and crack time was evident.

National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-3856 (URN)10.1163/016942410X525713 (DOI)000295376400003 ()2-s2.0-80052337085 (Scopus ID)1b46dec2-eb12-47fd-88c7-c51d9da04161 (Local ID)1b46dec2-eb12-47fd-88c7-c51d9da04161 (Archive number)1b46dec2-eb12-47fd-88c7-c51d9da04161 (OAI)
Note
Validerad; 2011; 20111028 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Vaziri, M., Orädd, G., Lindgren, O. & Pizzi, A. (2011). Magnetic resonance imaging of water distribution in welded woods (ed.). Paper presented at . Journal of Adhesion Science and Technology, 25(16), 1997-2003
Open this publication in new window or tab >>Magnetic resonance imaging of water distribution in welded woods
2011 (English)In: Journal of Adhesion Science and Technology, ISSN 0169-4243, E-ISSN 1568-5616, Vol. 25, no 16, p. 1997-2003Article in journal (Refereed) Published
Abstract [en]

This study was performed for a better understanding of water effect on welded wood and improving its water resistance. In this article, we have also attempted to demonstrate the feasibility of using Magnetic Resonance Imaging technology to study water movement in welded woods. Water distribution in welded woods of Scots pine (Pinus sylvestris) and beech (Fagus sylvatica) was investigated by Magnetic Resonance Imaging. Axial specimens were cut from beech and sapwood of Scots pine in longitudinal direction of wood grain. Two pieces of each wood species were welded together by a linear vibration machine. Sub-samples measuring 30 mm × 20 mm × 100 mm were cut from the welded specimens for Magnetic Resonance Imaging. The results showed that weldline of Scots pine was more resistant to water than weldline of beech. Pine joint was still holding after 40 h immersion in water, while a rapid wetting of the beech joint resulted in breakage of the joint in even less than an hour. This preliminary study also showed that MRI is a powerful tool to measure water distribution in welded woods and highlighted the potential of this technique to enhance understanding of wood welding

National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-14075 (URN)10.1163/016942410X544802 (DOI)000295888000003 ()2-s2.0-80052327302 (Scopus ID)d63807b0-08f9-11e0-b767-000ea68e967b (Local ID)d63807b0-08f9-11e0-b767-000ea68e967b (Archive number)d63807b0-08f9-11e0-b767-000ea68e967b (OAI)
Note
Validerad; 2011; 20101216 (owelin)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Vaziri, M., Lindgren, O., Pizzi, A. & Mansouri, H. (2010). Moisture sensitivity of Scots pine joints produced by linear frictional welding (ed.). Paper presented at . Journal of Adhesion Science and Technology, 24(8), 1515-1527
Open this publication in new window or tab >>Moisture sensitivity of Scots pine joints produced by linear frictional welding
2010 (English)In: Journal of Adhesion Science and Technology, ISSN 0169-4243, E-ISSN 1568-5616, Vol. 24, no 8, p. 1515-1527Article in journal (Refereed) Published
Abstract [en]

The industrial application range of welded wood so far has been limited to interior use because of its poor moisture resistance. Influences of some welding and wood parameters such as welding pressure, welding time, and heartwood/sapwood on water resistance of Scots pine (Pinus sylvestris) were investigated. An X-ray Computed Tomography scanner was used to monitor density change in weldlines during water absorption-desorption. Axial samples measuring 200 mm × 20 mm × 20 mm from Scots pine were welded and placed standing in 5-mm-deep tap water. Then they were taken out of the water one at a time and scanned at 10-min intervals until the first crack appeared in the weldline where the two parts of each specimen made connection. Results showed that the X-ray Computed Tomography can be used as an effective tool to study welded wood. Welding pressure, welding time, and heartwood/sapwood showed significant effect on length and location of the crack in the welded zone. Data evaluation showed that combination of 1.3 MPa welding pressure, 1.5 s welding time and using heartwood led to highest moisture resistance, which produced only a very short crack in the beginning of the weldline

National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-11553 (URN)10.1163/016942410X501098 (DOI)000283762800012 ()2-s2.0-77954604022 (Scopus ID)a8e56ba0-98be-11df-8806-000ea68e967b (Local ID)a8e56ba0-98be-11df-8806-000ea68e967b (Archive number)a8e56ba0-98be-11df-8806-000ea68e967b (OAI)
Note
Validerad; 2010; 20100726 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
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