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Vaziri, Mojgan
Publications (10 of 17) Show all publications
Vaziri, M., Abrahamsson, L., Hagman, O. & Sandberg, D. (2020). Welding of wood in the presence of wollastonite. BioResources, 15(1), 1617-1628
Open this publication in new window or tab >>Welding of wood in the presence of wollastonite
2020 (English)In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 15, no 1, p. 1617-1628Article in journal (Refereed) Published
Abstract [en]

The use of wollastonite as a natural additive for the welding of Scots pine improved the water resistance and shear strength of the welded joint. The X-ray computed tomography images revealed that the welding of Scots pine with wollastonite could postpone crack formation in the welded joints. The specimens welded for a longer time (5 s) had a more uniform distribution of wollastonite particles in welded joints. The microstructure of the wood and the thickness of the wood cell walls also had a great influence on the thickness and strength of the welded joints. Water immersion tests showed that the use of wollastonite in wood joints was able to meet the requirement of resistance to frequent short-term and long-term exposure to water.

Place, publisher, year, edition, pages
NC State University, 2020
National Category
Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-78020 (URN)10.15376/biores.15.1.1617-1628 (DOI)000511129100112 ()
Note

Validerad;2020;Nivå 2;2020-03-10 (johcin)

Available from: 2020-03-10 Created: 2020-03-10 Last updated: 2020-03-10Bibliographically approved
Berg, S., Sandberg, D., Ekevad, M. & Vaziri, M. (2015). Crack influence on load-bearing capacity of glued laminated timber using extended finite element modelling (ed.). Wood Material Science & Engineering, 10(4), 335-343
Open this publication in new window or tab >>Crack influence on load-bearing capacity of glued laminated timber using extended finite element modelling
2015 (English)In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 10, no 4, p. 335-343Article in journal (Refereed) Published
Abstract [en]

Most of the cracks are caused by changes in temperature and relative humidity which lead to shrinkage and swelling of the wood and thereby induce stresses in the structure. How these cracks influence the strength of the wooden structure, especially the shear strength, is not well understood. However, it is reasonable to expect that cracks have an impact on the shear strength as they preferably run along the beams in the direction of grain and bond lines. The purpose of this study was to investigate the load-bearing capacity of cracked glulam beams and to find a model that could predict the failure load of the beams due to the cracks. Three-point bending tests were used on glulam beams of different sizes with pre-manufactured cracks. An orthotropic elastic model and extended finite element method was used to model the behaviour of the cracked beams and to estimate the load-bearing capacity. The conclusions were validated by numerical simulations of the mechanical behaviour of three-point bending of glulam beams with different crack locations. The crack initiation load was recorded as the failure load and compared to the experimental failure load. The results of the compaction simulations agree well with the experimental results

Keywords
Forestry, agricultural sciences and landscape planning - Wood fibre and forest products, Skogs- och jordbruksvetenskap samt landskapsplanering - Träfiber- och virkeslära
National Category
Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-7608 (URN)10.1080/17480272.2015.1027268 (DOI)000368718400003 ()2-s2.0-84945452586 (Scopus ID)5ff81246-b07d-4875-b725-2b03c5e2df47 (Local ID)5ff81246-b07d-4875-b725-2b03c5e2df47 (Archive number)5ff81246-b07d-4875-b725-2b03c5e2df47 (OAI)
Note

Validerad; 2015; Nivå 1; 20150417 (andbra)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2020-01-28Bibliographically approved
Vaziri, M., Plessis, A. d., Sandberg, D. & Berg, S. (2015). Nano X-ray tomography analysis of the cell-wall density of welded beech joints. (ed.). Wood Material Science & Engineering, 10(4), 368-372
Open this publication in new window or tab >>Nano X-ray tomography analysis of the cell-wall density of welded beech joints.
2015 (English)In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 10, no 4, p. 368-372Article in journal (Refereed) Published
Abstract [en]

This paper reports the results of a novel approach using nano X-ray computed tomography (CT) for the non-invasive determination of the weld-line density profile of welded wood joints. As a case study, wood samples with a dimension of 2 mm × 2 mm × 20 mm were cut from a board of welded beech (Fagus sylvatica L.). The spatial resolution of the X-ray scan was 500 nm. Densitometry results showed that welding was accompanied by a considerable increase in the bulk density and a decrease in the cell-wall density at the weld-line. The cell-wall density in the weld-line was almost 33% less than that of the unaffected wood. As an additional application of nano computed tomography, the 3D imaging also revealed details of the internal structure of the welded sample. This study showed that nano-CT is a powerful tool for the descriptive and quantitative study of welded wood

Keywords
Forestry, agricultural sciences and landscape planning - Wood fibre and forest products, Skogs- och jordbruksvetenskap samt landskapsplanering - Träfiber- och virkeslära
National Category
Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-2537 (URN)10.1080/17480272.2015.1062418 (DOI)000368718400006 ()2-s2.0-84945483187 (Scopus ID)02917556-811c-4f26-8993-c177f6298f2d (Local ID)02917556-811c-4f26-8993-c177f6298f2d (Archive number)02917556-811c-4f26-8993-c177f6298f2d (OAI)
Note

Validerad; 2015; Nivå 1; 20150614 (dicsan)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2020-01-28Bibliographically approved
Vaziri, M., Rogaume, C., Masson, E., Pizzi, A. & Sandberg, D. (2015). VOC emissions from linear vibration (ed.). In: (Ed.), A. Kutnar; M. Burnard; M. Schwarzkopf ; A. Simmons (Ed.), Proceedings of the 1st COST Action FP1407 Conference: Life Cycle Assessment, EPDs and Modified Wood, Koper, Slovenia, August 25-26. Paper presented at COST Action FP1407 : Life Cycle Assessment, EPDs and Modified Wood 25/08/2015 - 26/08/2015 (pp. 26-27). Koper, Slovenia: University of Primorska, Scence and Research Centre of Koper
Open this publication in new window or tab >>VOC emissions from linear vibration
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2015 (English)In: Proceedings of the 1st COST Action FP1407 Conference: Life Cycle Assessment, EPDs and Modified Wood, Koper, Slovenia, August 25-26 / [ed] A. Kutnar; M. Burnard; M. Schwarzkopf ; A. Simmons, Koper, Slovenia: University of Primorska, Scence and Research Centre of Koper , 2015, p. 26-27Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Koper, Slovenia: University of Primorska, Scence and Research Centre of Koper, 2015
Keywords
Forestry, agricultural sciences and landscape planning - Wood fibre and forest products, Skogs- och jordbruksvetenskap samt landskapsplanering - Träfiber- och virkeslära
National Category
Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-29538 (URN)30c107c9-1940-4ae6-b2f7-54427ac31eeb (Local ID)978-961-6963-89-3 (ISBN)30c107c9-1940-4ae6-b2f7-54427ac31eeb (Archive number)30c107c9-1940-4ae6-b2f7-54427ac31eeb (OAI)
Conference
COST Action FP1407 : Life Cycle Assessment, EPDs and Modified Wood 25/08/2015 - 26/08/2015
Note

Godkänd; 2015; 20150831 (dicsan)

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2020-01-28Bibliographically approved
(2014). Final Cost Action FP0904 Conference: “Recent Advances in the Field of TH and THM Wood Treatment” : May 19-21, 2014, Skellefteå, Sweden : book of abstracts (ed.). Paper presented at . Skellefteå: Luleå tekniska universitet
Open this publication in new window or tab >>Final Cost Action FP0904 Conference: “Recent Advances in the Field of TH and THM Wood Treatment” : May 19-21, 2014, Skellefteå, Sweden : book of abstracts
2014 (English)Report (Refereed)
Place, publisher, year, edition, pages
Skellefteå: Luleå tekniska universitet, 2014. p. 90
Keywords
Forestry, agricultural sciences and landscape planning - Wood fibre and forest products, Skogs- och jordbruksvetenskap samt landskapsplanering - Träfiber- och virkeslära
National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-24726 (URN)c35f7ee1-a6ce-4c73-bbb9-73215f765250 (Local ID)978-91-7439-937-0 (ISBN)978-91-7439-938-7 (ISBN)c35f7ee1-a6ce-4c73-bbb9-73215f765250 (Archive number)c35f7ee1-a6ce-4c73-bbb9-73215f765250 (OAI)
Note

Godkänd; 2014; 20140509 (andbra)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2020-01-28Bibliographically approved
Sandberg, D., Vaziri, M., Trischler, J. & Öhman, M. (2014). The role of the wood mechanical industry in the Swedish forest industry cluster (ed.). Paper presented at . Scandinavian Journal of Forest Research, 29(4), 352-359
Open this publication in new window or tab >>The role of the wood mechanical industry in the Swedish forest industry cluster
2014 (English)In: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 29, no 4, p. 352-359Article in journal (Refereed) Published
Abstract [en]

The forest and forest products form one of the most important basis for the transfer to a biobased economy in Sweden. About 75% of the area covered by forest in Sweden is used industrially to produce raw material for the wood-refining industries. Every year, this cluster uses 75 million m3 of roundwood and has an export value of € 12 billion. This review paper is devoted to the wood mechanical industry, i.e. the industry which turns the forest into sawn timber, packaging, construction wood, furniture and interior fittings. The sawmills consume about half of the volume of softwood which is felled, and about two thirds of the sawn timber goes to export without any further refining within the country. Nevertheless, in spite of the relatively low degree of refinement in the sawmill and the fact that the sawmills in general over time have a very low profitability, they are responsible for 70–80% of the forest owners' profits on the sale of timber. An increased upgrading of the sawn timber within the country is desirable from a national economic viewpoint – increased employment opportunities, increased export income etc. It should then in the first place be for products with a higher added value, such as furniture and fittings. Today, the refinement value is 15–20 times higher for products from joinery and furniture industries compared that of the sawn timber and the added value of the wood within the building industry is only about 1.5 times.

National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-4701 (URN)10.1080/02827581.2014.932005 (DOI)000339920100007 ()2-s2.0-84904765271 (Scopus ID)2af2d770-5d8d-43c8-8ebd-d2d04c5615a0 (Local ID)2af2d770-5d8d-43c8-8ebd-d2d04c5615a0 (Archive number)2af2d770-5d8d-43c8-8ebd-d2d04c5615a0 (OAI)
Note
Validerad; 2014; 20140619 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2020-01-28Bibliographically approved
Vaziri, M., Berg, S., Sandberg, D. & Gheinani, I. T. (2014). Three-dimensional finite element modelling of heat transfer for linear friction welding of Scots pine (ed.). Paper presented at . Wood Material Science & Engineering, 9(2), 102-109
Open this publication in new window or tab >>Three-dimensional finite element modelling of heat transfer for linear friction welding of Scots pine
2014 (English)In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 9, no 2, p. 102-109Article in journal (Refereed) Published
Abstract [en]

Finite element numerical analyses were performed to determine three-dimensional heat flux generated by friction to wood pieces during linear friction welding. The objective was to develop a computational model to explain the thermal behaviour of welded wood material rather than experimental methods, which are usually expensive and time consuming. This model serves as a prediction tool for welding parameters, leading to optimal thermo-mechanical performance of welded joints. The energy produced by the friction welding of small wood specimens of Scots pine (Pinus sylvestris L.) was determined by thermocouples and used as input data in the model. The model is based on anisotropic elasticity and the thermal properties were modelled as isotropic. This numerical simulation gave information on the distribution of the temperature in the welding interface during the entire welding process. A good agreement between the simulation and experimental results showed the appropriateness of the model for planning welded wood manufacture and prediction of thermal behaviour of wood during other mechanically induced vibration processes. The specimens presented in this model required a heat flux of 11 kW/m2 to achieve a satisfactory welding joint

Keywords
Forestry, agricultural sciences and landscape planning - Wood fibre and forest products, Skogs- och jordbruksvetenskap samt landskapsplanering - Träfiber- och virkeslära
National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-10807 (URN)10.1080/17480272.2014.903297 (DOI)2-s2.0-84901232077 (Scopus ID)9ab6c462-4726-4d0b-9354-697f34784bbc (Local ID)9ab6c462-4726-4d0b-9354-697f34784bbc (Archive number)9ab6c462-4726-4d0b-9354-697f34784bbc (OAI)
Note
Validerad; 2014; 20140415 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2020-01-28Bibliographically approved
Vaziri, M., Berg, S. & Sandberg, D. (2014). Three-dimensional finite element modelling of heat transfer for linear friction welding of Scots pine (ed.). In: (Ed.), Mojgan Vaziri; Dick Sandberg (Ed.), Final Cost Action FP0904 Conference: “Recent Advances in the Field of TH and THM Wood Treatment” : May 19-21, 2014, Skellefteå, Sweden : book of abstracts. Paper presented at Cost action FP0904 Conference : 19/05/2014 - 21/05/2014 (pp. 45-46). Skellefteå: Luleå tekniska universitet
Open this publication in new window or tab >>Three-dimensional finite element modelling of heat transfer for linear friction welding of Scots pine
2014 (English)In: Final Cost Action FP0904 Conference: “Recent Advances in the Field of TH and THM Wood Treatment” : May 19-21, 2014, Skellefteå, Sweden : book of abstracts / [ed] Mojgan Vaziri; Dick Sandberg, Skellefteå: Luleå tekniska universitet, 2014, p. 45-46Conference paper, Oral presentation with published abstract (Refereed)
Place, publisher, year, edition, pages
Skellefteå: Luleå tekniska universitet, 2014
Keywords
FEM, thermo-hydro-mechanical wood processing
National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-27014 (URN)05183ac5-a8e7-4b15-a61f-a86553af9ff8 (Local ID)978-91-7439-937-0 (ISBN)978-91-7439-938-7 (ISBN)05183ac5-a8e7-4b15-a61f-a86553af9ff8 (Archive number)05183ac5-a8e7-4b15-a61f-a86553af9ff8 (OAI)
Conference
Cost action FP0904 Conference : 19/05/2014 - 21/05/2014
Note

Godkänd; 2014; 20140516 (andbra)

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2020-01-28Bibliographically approved
Vaziri, M., Berg, S., Sandberg, D. & Gheinani, I. T. (2014). Wood modification through mechanically induced wood fusion welding: 3-D finite element modelling of heat transfer. (ed.). In: (Ed.), Lina Nunes; Dennis Jones; Callum Hill; Holger Militz (Ed.), The seventh European Conference on Wood Modification (ECWM7: Book of Abstracts. Paper presented at European Conference on Wood Modification : 10/03/2014 - 11/03/2014 (pp. 43-44). Lissabon
Open this publication in new window or tab >>Wood modification through mechanically induced wood fusion welding: 3-D finite element modelling of heat transfer.
2014 (English)In: The seventh European Conference on Wood Modification (ECWM7: Book of Abstracts / [ed] Lina Nunes; Dennis Jones; Callum Hill; Holger Militz, Lissabon, 2014, p. 43-44Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Lissabon: , 2014
Keywords
Forestry, agricultural sciences and landscape planning - Wood fibre and forest products, Skogs- och jordbruksvetenskap samt landskapsplanering - Träfiber- och virkeslära
National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-37647 (URN)bb9c5f5a-3876-4319-a3f0-2670bc4867c2 (Local ID)978-972-49-2267-6 (ISBN)bb9c5f5a-3876-4319-a3f0-2670bc4867c2 (Archive number)bb9c5f5a-3876-4319-a3f0-2670bc4867c2 (OAI)
Conference
European Conference on Wood Modification : 10/03/2014 - 11/03/2014
Note
Godkänd; 2014; 20140320 (dicsan)Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2020-01-28Bibliographically 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
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