Change search
Refine search result
1 - 15 of 15
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • harvard-cite-them-right
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Huč, Sabina
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Svensson, Staffan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Coupled two-dimensional modeling of viscoelastic creep of wood2018In: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 52, no 1, p. 29-43Article in journal (Refereed)
    Abstract [en]

    Three coupled two-dimensional viscoelastic creep models for orthotropic material are analyzed. The models of different complexity are mathematically formulated and implemented in a finite element software. Required viscoelastic material parameters are determined by calibration procedure, where numerical results are compared against experimentally obtained viscoelastic strains caused by tensile or shear loading. Finally, a comparison method is used to evaluate the accuracy of strain predictions of each particular model. The analysis shows that all the models are able to accurately predict viscoelastic creep simultaneously in two perpendicular directions for various periods of time and wood species. Calculated numerical values of the viscoelastic material parameters suitable for the three models and wood species, i.e., Douglas fir (Pseudotsuga menziesii), Norway spruce (Picea abies), Japanese cypress (Chamaecyparis obtusa), and European beech (Fagus sylvatica L.), under constant tensile loading are also given.

  • 2.
    Huč, Sabina
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Svensson, Staffan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Hozjan, Tomaž
    Faculty of Civil and Geodetic Engineering, University of Ljubljana.
    Hygro-mechanical analysis of wood subjected to constant mechanical load and varying relative humidity2018In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 72, no 10, p. 863-870Article in journal (Refereed)
    Abstract [en]

    A hygro-mechanical (H-M) analysis of a wooden specimen sustaining a mechanical load while subjected to varying relative humidity was performed to predict the long-term rheological behavior of wood. The numerical analysis was based on the experimental results of total strains, monitored in two orthotropic material directions on oak wood specimens under constant uniaxial compression and with moisture content (MC) variation. For the moisture analysis, a multi-Fickian moisture transport model (MFMTM) was used to obtain temporal and spatial MC fields, which were the input data in the mechanical analysis. The presented mechanical model assumed a decomposition of the total strains into the elastic, viscoelastic and mechanosorptive strains and the strains due to shrinkage and swelling. The moisture and mechanical analyses required material parameters, which were taken from the literature or were empirically obtained by a fitting procedure. The performed H-M analysis gave accurate numerical predictions of the experimentally obtained total strains in two orthotropic directions simultaneously. Thus, the analysis developed has a high potential for predicting the long-term rheological behavior of timber structures, assuming that the material parameters are determined previously, based on specific, extensive, multidimensional experimental analyses.

  • 3.
    Huč, Sabina
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Svensson, Staffan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Influence of grain direction on the time-dependent behavior of wood analyzed by a 3D rheological model. A mathematical consideration2018In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 72, no 10, p. 889-897Article in journal (Refereed)
    Abstract [en]

    A three-dimensional (3D) rheological model for an orthotropic material subjected to sustained load or deformation under constant climate has been mathematically formulated. The elastic and viscoelastic compliance matrices are symmetric, where the mathematical derivation of the latter is shown. The model is linear and requires constant numerical values for the elastic and viscoelastic material parameters. The model’s ability to predict the natural time-dependent response in three material directions simultaneously is demonstrated on a Douglas fir (Pseudotsuga menziesii) specimen subjected to a constant uniaxial tensile load. The material extends in a longitudinal direction and contracts in the transverse directions with time. The required material parameters are taken from the literature when possible, otherwise they are assumed. Furthermore, the influence of misalignment between the directions of observation and wood material directions on induced time-dependent strains is analyzed. The analyses show that the misalignment has a large effect on the material behavior. In some cases, the specimen under constant uniaxial tension even extends in the perpendicular transverse direction with time. The obtained results clearly demonstrate the high importance of considering the alignment of material directions precisely in order to be able to interpret the time-dependent behavior of wood correctly.

  • 4.
    Huč, Sabina
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Hozjan, Tomaž
    University of Ljubljana.
    Svensson, Staffan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Rheological behavior of wood in stress relaxation under compression2018In: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225Article in journal (Refereed)
    Abstract [en]

    Rheological behavior of wood under uniaxial compression along and perpendicular to the grain in constant environment was examined. Tests with constant deformation rate until failure and stress relaxation tests with constant deformation applied stepwise were carried out. The experimental results of stress relaxation showed nonlinear material behavior over time that got more prominent under high deformation levels. Considerable amount of stress relaxed during applying the deformation. Wood experienced greater stress relaxation along the grain than perpendicular to it. Three rheological models for orthotropic material were calibrated to the experimentally determined stress–time curves in longitudinal and transverse directions simultaneously. Small deformation levels assuming linear strains were accounted for in the models. Required elastic material parameters were determined from the tests with constant deformation rate. A model including the highest number of viscoelastic material parameters was the most successful in predicting stress relaxation of wood under stepwise deformation. Modeling indicated that wood behavior was very close to linear viscoelastic in relaxation under small deformation. The obtained material parameters made the model suitable for predicting rheological behavior of wood comprehensively, under sustained deformation or load in constant conditions

  • 5.
    Svensson, Staffan
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Munch-Andersen, Jørgen
    Danish timber information.
    Accurate strength parameters for fasteners with examples for ring shank nails2016In: World Conference on Timber Engineering, 2016Conference paper (Refereed)
    Abstract [en]

    Strength parameters for fasteners determined in accordance with the methods prescribed for the European CE-marking leads quite different values for seemingly similar products from different manufactures. The results are hardly repeatable, to some extent due to difficulties in selecting representative timber samples for the testing. Beside this uncertainty, the declared values concerns only structural timber, so no values are available for e.g, LVL or plywood.

    This paper gives:

    • Examples of the variability of declared strength parameters for ring shank nails for almost similar products.
    • Results from withdrawal test for similar nails inserted in the same timber specimens (structural timber and LVL), which is used for investigating similarities and differences between nails and wood.
    • Discussion of statistical methods to compare the strength parameters of two nails.
    • A proposal for a method that enables to determine accurate strength parameters needed for structural design from comparative tests involving reference fasteners.
  • 6.
    Rorig-Dalgaard, I.
    et al.
    DTU.
    Svensson, Staffan
    University of Borås, Faculty of Textiles, Engineering and Business.
    High accuracy calibration of a dynamic vapor sorption instrument and determination of the equilibrium humidities using single salts2016In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 87, no 5Article in journal (Refereed)
    Abstract [en]

    We present a procedure for accurately calibrating a dynamic vapor sorption (DVS) instrument using single salts. The procedure accounts for and tailors distinct calibration tests according to the fundamental properties of each salt. Especially relevant properties influencing the calibration are the heat of solution, heat of condensation, and the kinetics connected to the salt phase transition, as these influence the microclimate surrounding the salts during calibration. All these issues were dealt with to obtain precise calibration results. The DVS instrument comprises two control modes to generate and measure the relative humidity (RH). Both control modes were separately examined and combined to overcome the shortcomings of each of the two control modes and thereby obtain the most accurate results. Repeated calibration testing with the single salts (LiCl, MgCl2, Mg(NO3)2, NaCl, and KNO3) enables five discrete sorption isotherm measurements within the range of 11%-93%RH. The equilibrium RH of the solution for LiCl, MgCl2, Mg(NO3)2, NaCl, and KNO3 was determined with a standard deviation of 0.06%-0.15% (0.45% for KNO3) RH. By comparing the measured calibration values with the well-known equilibrium RH of each salt solution, the presented method's results are both accurate with significant agreement and precise with small variation.

  • 7.
    Pecenko, R.
    et al.
    Univ. Ljubljana.
    Svensson, Staffan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Hozjan, T.
    Univ. Ljubljana.
    Model evaluation of heat and mass transfer in wood exposed to fire2016In: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 50, no 4, p. 727-737Article in journal (Refereed)
    Abstract [en]

    The paper presents sensitivity analysis of coupled heat and moisture transfer model for timber exposed to fire. The objective of the analysis is to discover the non-influential model parameters and the model simplification accordingly. To achieve this, the standardized regression coefficient (SRC) method is introduced to determine the impact of specific permeability of dry timber K, bound water diffusion coefficient , vapour diffusion coefficient and heat of sorption on the two model outcomes, charring depth and total moisture content . The SRC method revealed that the least influential parameter is specific permeability of dry timber K. Therefore the model was adequately simplified by a more simple description of the energy equation, while preserving the accuracy of the results. Thus, the efficiency of the present coupled heat and moisture transfer model was increased.

  • 8.
    Svensson, Staffan
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Munch-Andersen, Jørgen
    Danish timber information.
    Theory of timber connections with slender dowel type fasteners2016In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, p. 1-9Article in journal (Refereed)
    Abstract [en]

    A theory on the lateral load-carrying capacity of timber connections with slender fasteners is presented. The base of the theory is the coupled mechanical phenomena acting in the connection, while the wood and the slender fastener deform and yield prior to failure. The objective is to derive a sufficient description of actions and responses which have determining influence on the load-carrying capacity of timber connections with slender fasteners. Model assumptions are discussed and made, but simplifications are left out. Even so, simple mathematical equations describing the lateral capacity are derived from mechanical equilibrium of the deformed fastener. The herein proposed theory is verified against tests. The tests were designed to vary the influence of isolated mechanical phenomenon as much as possible. The theory shows a very high accuracy and precision when predicting the load-carrying capacity of the tested connections.

  • 9.
    Pecenko, R.
    et al.
    University of Ljubljana.
    Svensson, Staffan
    Hozjan, T.
    University of Ljubljana.
    Modelling heat and moisture transfer in timber exposed to fire2015In: International Journal of Heat and Mass Transfer, ISSN 0017-9310, E-ISSN 1879-2189, Vol. 87, p. 598-605Article in journal (Refereed)
  • 10.
    Engelund, Emil Tang
    et al.
    Copenhagen University.
    Thygesen, Lisbeth Garbrecht
    Copenhagen University.
    Svensson, Staffan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Hill, Callum A. S.
    Napier University.
    A critical discussion of the physics of wood-water interactions2013In: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 47, no 1, p. 141-161Article in journal (Refereed)
  • 11.
    Munch-Andersen, J.
    et al.
    Danish Timber Information.
    Svensson, Staffan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Fasteners and connections in the next Eurocode 52013In: Proceedings of the Cib - W18: Working Commission W18 - Timber Structures, ISSN 1864-1784, p. 399-401Article in journal (Refereed)
  • 12.
    Svensson, Staffan
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Turk, Goran
    University of Ljubljana.
    Hozjan, Tomaz
    University of Ljubljana.
    Predicting moisture state of timber members in a continuously varying climate2011In: Engineering structures, ISSN 0141-0296, E-ISSN 1873-7323, Vol. 33, no 11, p. 3064-3070Article in journal (Refereed)
  • 13.
    Svensson, Staffan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Duration of load effects of solid wood: A review of methods and models2009In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 4, no 3-4, p. 115-124Article in journal (Refereed)
  • 14.
    Sørensen, John Dalsgaard
    et al.
    Aalborg University.
    Svensson, Staffan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Reliability-Based Modeling of Moisture and Load-Duration Effects2005In: Probabilistic Models in Timber Engineering, Test, Models, Applications, p. 79-86Article in journal (Refereed)
  • 15.
    Huč, Sabina
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Svensson, Staffan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Hozjan, Tomaž
    Faculty of Civil and Geodetic Engineering, University of Ljubljana.
    Numerical analysis of moisture-induced strains and stresses in glued-laminated timberIn: Article in journal (Refereed)
1 - 15 of 15
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • harvard-cite-them-right
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf