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Publications (10 of 77) Show all publications
Huber, J. A., Ekevad, M., Girhammar, U. A. & Berg, S. (2018). A Review of Structural Robustness with Focus on Timber Buildings. In: : . Paper presented at 40th IABSE Symposium, Nantes 2018.
Open this publication in new window or tab >>A Review of Structural Robustness with Focus on Timber Buildings
2018 (English)Conference paper, Published paper (Refereed)
Abstract [en]

With an increasing number of storeys, timber buildings require closer attention to structuralrobustness. If a building can survive unforeseen events (e.g. accidents, terrorism), lives can be saved.The literature appears to be rather limited concerning robustness of timber buildings. This paperaims to give a brief review on robustness in general and design guidelines for timber in specific. Theresults indicate that connection design is a key aspect for robustness. Like in seismic design, by usingthe ductile capacity of connectors, the brittleness of timber can be controlled. For light timber-framebuildings, more guidelines exist than for posts and beams and cross-laminated timber, which bothseem to be similar to steel frames and precast concrete respectively regarding robustness.

Keywords
robustness, timber, disproportionate collapse, progressive collapse, alternative load path
National Category
Other Civil Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-70959 (URN)
Conference
40th IABSE Symposium, Nantes 2018
Funder
VINNOVA, Bioinnovation 4.4
Available from: 2018-09-24 Created: 2018-09-24 Last updated: 2018-09-24
Wei, H., Guo, X., Zhu, Z., Cao, P., Wang, B. & Ekevad, M. (2018). Analysis of Cutting Performance in High Density Fiberboard Milling by Ceramic Cutting Tools. Wood research, 63(3), 455-466
Open this publication in new window or tab >>Analysis of Cutting Performance in High Density Fiberboard Milling by Ceramic Cutting Tools
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2018 (English)In: Wood research, ISSN 1336-4561, Vol. 63, no 3, p. 455-466Article in journal (Refereed) Published
Abstract [en]

In order to study the cutting performance of TiC reinforced Al2O3 ceramic cutting tools in milling high density fiberboard, the effects of cutting parameter on the cutting forces, tool wear and cutting quality were investigated. Under the condition of same average chip thickness, feed per tooth and geometry angles, firstly, the change rate of maximum cutting forces were higher than that of average cutting forces at two different cutting speeds, and the cutting forces at high speed cutting was less than that at low speed cutting. Secondly, the flank wear at high speed cutting was more pronounced than that at low speed cutting, whose abnormal wear were pull-out of grain, cracking, chipping and flanking. Thirdly, the machining quality at high speed cutting was better than that at low speed cutting. Fourthly, the tendencies of cutting forces, tool wear and surface roughness relative to cutting length were similar, but the change rates were different, especially at the initial stage. Finally, high speed cuttingare plausible to use in HDF processing, which not only improves machining quality, but also promotes production efficiency.

Place, publisher, year, edition, pages
Slovak Forest Products Research, 2018
National Category
Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-70304 (URN)2-s2.0-85053086508 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-08-09 (andbra)

Available from: 2018-08-09 Created: 2018-08-09 Last updated: 2018-10-10Bibliographically approved
Huber, J. A., Ekevad, M., Berg, S. & Girhammar, U. A. (2018). Assessment of Connections In Cross-Laminated Timberbuildings Regarding Structural Robustness. In: : . Paper presented at 2018 World Conference on Timber Engineering, Seoul, Republic of Korea, August 20-23 2018.
Open this publication in new window or tab >>Assessment of Connections In Cross-Laminated Timberbuildings Regarding Structural Robustness
2018 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Cross-laminated timber makes timber buildings with an increasing number of storeys achievable. Withmore storeys, structural robustness needs more attention to make a building survive unforeseen events (e.g. accidents,terrorism) and save lives. For steel and concrete buildings, design methods for robustness focus on connection details.The assessment of joints in cross-laminated timber buildings regarding robustness is rather limited in the literature. Theobjective of this paper is to conduct an initial assessment of the connectors after the removal of a wall in a platformcross-laminated timber building. We used the finite element method and the component method for the analysis of acase building. The results indicate that the wall-to-wall and the floor-to-floor connectors may fail at low deflectionlevels leading to high shear loads in the floor panel above the removed wall, which might induce cracking. The removalanalysis was only partially completed, but we identified an indication of the deformation behaviour of the case building.Testing and refined modelling of the connections is needed in the future to verify the results. This study may facilitatefuture investigations regarding robustness of multi-storey cross-laminated timber buildings.

Keywords
Robustness, Connection, Component method, Cross-laminated timber, Finite element method, Disproportionate collapse
National Category
Other Civil Engineering Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-70599 (URN)
Conference
2018 World Conference on Timber Engineering, Seoul, Republic of Korea, August 20-23 2018
Projects
Bioinnovation 4.4
Funder
VINNOVA
Available from: 2018-08-27 Created: 2018-08-27 Last updated: 2018-08-31Bibliographically approved
Zhaolong, Z., Buck, D., Ekevad, M., Marklund, B., Guo, X., Cao, P. & Zhu, N. (2018). Cutting forces and chip formation revisited basedon orthogonal cutting of Scots pine. Holzforschung
Open this publication in new window or tab >>Cutting forces and chip formation revisited basedon orthogonal cutting of Scots pine
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2018 (English)In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434XArticle in journal (Refereed) Epub ahead of print
Abstract [en]

The objective of this study was to understandbetter the cutting forces and chip formation of Scots pine(Pinus sylvestris L.) with different moisture contents (MCs)and machined in different cutting directions. To thatend, an orthogonal cutting experiment was designed,in which Scots pine was intermittently machined usinga tungsten carbide tool to produce chips. The cuttingforces were measured and the chip shapes were quantitativelydescribed. Four conclusions can be drawn: (1)with increasing MC, the average cutting forces initiallydecreased and then stabilized, while the angle betweenthe direction of the main and the resultant force continuouslydecreased. (2) The average cutting forces in the 90°–0° cutting direction were lower than the same forces inthe 90°–90° cutting direction. (3) During machining, thedynamic cutting forces fluctuated less in the 90°–0° case.However, the dynamic feeding forces showed a decreasingtrend in both the 90°–0° and the 90°–90° cases. (4) Theprocess applied produced granule chips and flow chips,while less curly flow chips with a higher radius of curvaturewere more easily produced from samples with highMCs in the 90°–0° cutting direction.

Place, publisher, year, edition, pages
De Gruyter Open, 2018
Keywords
chip formation, cutting direction, cutting forces, moisture content, tungsten carbide cutting tools, wood machining
National Category
Engineering and Technology Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-70662 (URN)10.1515/hf-2018-0037 (DOI)
Available from: 2018-08-30 Created: 2018-08-30 Last updated: 2018-09-03
Li, R., Cao, P., Xu, W., Ekevad, M. & Wang, A. (2018). Experimental and Numerical Study of Moisture-induced Stress Formation in Hexagonal Glulam Using X-ray Computed Tomography and Finite-element Analysis. BioResources, 13(4), 7395-7403
Open this publication in new window or tab >>Experimental and Numerical Study of Moisture-induced Stress Formation in Hexagonal Glulam Using X-ray Computed Tomography and Finite-element Analysis
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2018 (English)In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 13, no 4, p. 7395-7403Article in journal (Refereed) Published
Abstract [en]

Hexagonal glue-laminated timber with large cross-sections, made from small diameter logs, was studied. Effects of relative humidity variations on the moisture-induced stresses were investigated to evaluate how the prediction model compared to a real outcome. The test samples were exposed to an environment with relative humidity variations from 80% to 30%. The moisture content inside the samples was measured via X-ray computed tomography scanning. A moisture transport and a hygromechanical finite element simulation model was used for the prediction of moisture content and resulting stress distribution. The results from both the test and simulation showed that the moisture content in the edge angles of the samples dropped rapidly due to a large moisture diffusion rate. The moisture gradient was generated via a different moisture transfer rate at the inner and external parts of the samples. The maximum stress perpendicular to the grain in the simulation was 8 MPa and was located at the surface near the corners. This stress peak caused cracking according to the model, which was also seen in the test samples. The results for the measured moisture content agreed with the simulated results and this indicated that the moisture transfer model was adequate for simulation.

Place, publisher, year, edition, pages
University of North Carolina Press, 2018
National Category
Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-70605 (URN)10.15376/biores.13.4.7395-7403 (DOI)
Note

Validerad;2018;Nivå 2;2018-08-27 (andbra)

Available from: 2018-08-27 Created: 2018-08-27 Last updated: 2018-08-27Bibliographically approved
Zhu, Z. (2018). Machinability investigation in turning of high density fiberboard. PLoS ONE, 13(9), 1-13, Article ID e0203838.
Open this publication in new window or tab >>Machinability investigation in turning of high density fiberboard
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2018 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 13, no 9, p. 1-13, article id e0203838Article in journal (Refereed) Published
Abstract [en]

A series of experiments were conducted to assess the machinability of high density fiberboardusing cemented carbide cutting tools. The objective of this work was to investigate theinfluence of two cutting parameters, spindle speed and feed per turn, on cutting forces, chipformation and cutting quality. The results are as follows: cutting forces and chip-breakinglength decrease with increasing spindle speed and decreasing feed per turn. In contrast,surface roughness increases with decrease of spindle speed and increase in feed perturn. Chips were divided into four categories based on their shape: dust, particle, splinter,and semicontinuous chips. Chip-breaking length had a similar tendency to the varianceof cutting forces with respect to average roughness and mean peak-to-valley height: anincrease in the variance of cutting forces resulted in increased average roughness andmean peak-to-valley height. Thus, high cutting speed and low feed rate are parameters suitablefor high-quality HDF processing and will improve not only machining quality, but productionefficiency.

Place, publisher, year, edition, pages
Public Library Science, 2018
National Category
Engineering and Technology Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-70870 (URN)10.1371/journal.pone.0203838 (DOI)000444545800088 ()30212578 (PubMedID)2-s2.0-85053234275 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-09-18 (svasva)

Available from: 2018-09-17 Created: 2018-09-17 Last updated: 2018-10-10Bibliographically approved
Huber, J. A., Ekevad, M., Girhammar, U. A. & Berg, S. (2018). Structural Robustness of Timber Buildings. In: : . Paper presented at 2018 World Conference on Timber Engineering, Seoul, Republic of Korea, August 20-23 2018.
Open this publication in new window or tab >>Structural Robustness of Timber Buildings
2018 (English)Conference paper, Published paper (Refereed)
Abstract [en]

The number of storeys in timber buildings are increasing. With more storeys, structural robustness needsmore attention, to make a building survive unforeseen events (e.g. accidents, terrorism) and save lives. The state of theart regarding robustness of concrete and steel buildings seems to be rather refined, but for timber buildings, theliterature appears to be quite limited. This study aims to review the design methods for robustness of timber buildings.First, the terminology and definitions are introduced. Then, the state of the art for design methods for robustness ingeneral are presented. Finally, the design methods for timber buildings are discussed and compared to those from otherbuilding materials. The results indicate that the guidelines for light timber-frame buildings are more refined than thosefor post and beam and cross-laminated timber buildings. Regarding robustness, the latter two construction types exhibitcertain similarities to steel frames and precast concrete buildings respectively. For timber, ductile connections can beused to avoid brittle timber failure after local damages, which resembles the approach of seismic design. Future researchin robustness should focus on the connection details in multi-storey timber buildings.

Keywords
Robustness, Timber buildings, Disproportionate collapse, Progressive collapse, Alternative load paths
National Category
Other Civil Engineering Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-70593 (URN)
Conference
2018 World Conference on Timber Engineering, Seoul, Republic of Korea, August 20-23 2018
Projects
Bioinnovation 4.4
Funder
VINNOVA
Available from: 2018-08-27 Created: 2018-08-27 Last updated: 2018-08-31Bibliographically approved
Huang, L., Wang, H., Guo, X., Jiang, Z., Xing, F. & Ekevad, M. (2018). Study on continuous cold-pressing technology of engineered wood flooring with EPI adhesive. Wood research, 63(2), 335-342
Open this publication in new window or tab >>Study on continuous cold-pressing technology of engineered wood flooring with EPI adhesive
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2018 (English)In: Wood research, ISSN 1336-4561, Vol. 63, no 2, p. 335-342Article in journal (Refereed) Published
Abstract [en]

The effects of process parameters (adhesive spread, press time, and applied pressure) on the gluing performance of engineered wood flooring bonded with emulsion-polymer-isocyanate (EPI) adhesive were studied. The results showed (shear strength and aging test) that the major factors were adhesive spread and press time. The optimized parameters for best gluing performance of engineered wood flooring were 160 g.m-2, 14 s, and 60 s for adhesive spread, heat time, and press time, respectively, within certain ranges

Place, publisher, year, edition, pages
Statny Drevarsky Vyskumny Ustav, 2018
National Category
Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-68853 (URN)000432579000014 ()2-s2.0-85046712217 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-05-22 (andbra)

Available from: 2018-05-22 Created: 2018-05-22 Last updated: 2018-06-08Bibliographically approved
Guo, X., Zhaolong, Z., Ekevad, M., Xu, B. & Pingxiang, C. (2018). The cutting performance of Al2O3 and Si3N4ceramic cutting tools in the milling plywood. Advances in Applied Ceramics: Structural, Functional and Bioceramics, 117(1), 16-22
Open this publication in new window or tab >>The cutting performance of Al2O3 and Si3N4ceramic cutting tools in the milling plywood
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2018 (English)In: Advances in Applied Ceramics: Structural, Functional and Bioceramics, ISSN 1743-6753, E-ISSN 1743-6761, Vol. 117, no 1, p. 16-22Article in journal (Refereed) Published
Abstract [en]

This research focuses on the cutting performance of Al2O3 and Si3N4 ceramic cutting tools in upmillingplywood, the results of which are as follows. First, whether the tool material is Al2O3 orSi3N4 ceramic, the cutting forces at low-speed cutting were less than those at high-speedcutting, and the machining quality at low-speed cutting was greater than that at high-speedcutting. Then, whether at low- or high-speed cutting, the cutting forces of Al2O3 cutting toolswere higher than those of Si3N4 cutting tools, and the machining quality of plywood milledby Al2O3 ceramic cutting tools was poorer than that milled by Si3N4 ceramic cutting tools.Finally, Si3N4 ceramic cutting tools were more suitable to machine the wooden productionswith much glue content than Al2O3 ceramic cutting tools for the better machined quality.

Place, publisher, year, edition, pages
Taylor & Francis Group, 2018
Keywords
Al2O3 ceramic cutting tools; Si3N4 ceramic cutting tools; plywood; cutting forces; machining quality
National Category
Engineering and Technology Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-65723 (URN)10.1080/17436753.2017.1368946 (DOI)000418673200003 ()2-s2.0-85029516061 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-11-14 (andbra)

Available from: 2017-09-19 Created: 2017-09-19 Last updated: 2018-01-16Bibliographically approved
Turesson, J., Ekevad, M. & Berg, S. (2017). Comparison of Cross- and Stress-Laminated Timber Bridge Decks. In: : . Paper presented at 3rd International conference on timber bridges 2017, ICTB2017, June 26-29 2017 in Skellefteå, Sweden..
Open this publication in new window or tab >>Comparison of Cross- and Stress-Laminated Timber Bridge Decks
2017 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Simply supported bridge decks made of cross-laminated timber (CLT) and stress-laminated timber (SLT) are compared. The decks have a constant axle load and varying span and thickness. CLT in the form of a plate is built up from an uneven number of layers of boards with crosswise varying fibre directions. SLT is built up from glulam beams with the same fibre direction placed side by side to form a plate. Both CLT and SLT have homogenised mechanical and physical properties and can be produced as large elements. This study was conducted by comparing results from finite element simulations of bridge decks made up from SLT and CLT for various bridge spans. The ratio of timber volume needed to fulfil deflection limits for CLT and SLT increased as the bridge span increased. The ratio was 1.3 for 24 m span and width 3.2 m. The transverse displacement curve was flatter for CLT compared to SLT. Longitudinal displacement curves were similar for CLT and SLT.

Keywords
stress-laminated, cross-laminated, timber bridge deck, FEM, finite element method
National Category
Engineering and Technology Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-63066 (URN)
Conference
3rd International conference on timber bridges 2017, ICTB2017, June 26-29 2017 in Skellefteå, Sweden.
Available from: 2017-04-19 Created: 2017-04-19 Last updated: 2017-11-24Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-0145-080x

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