| 1. |
- Bader, Thomas K., 1980-, et al.
(författare)
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Modeling the Mechanical Behavior of Wood Materials and Timber Structures
- 2023
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Ingår i: Springer Handbook of Wood Science and Technology. - : Springer. - 9783030813147 - 9783030813154 ; , s. 507-568
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Bokkapitel (refereegranskat)abstract
- This chapter aims at highlighting the benefit of numerical methods and their broad application in the field of wood, engineered wood-based products (EWPs), structural elements including glued-laminated and cross-laminated timber, and engineered timber structures. It focuses on the hygrothermo- viscoelastic material behavior of these elements and structures as a consequence of the behavior of wood materials. After motivating the need for models of wood, different types of numerical models and their application for determination of mechanical properties and dimensional stability of wooden boards, strand- and veneer-based engineered woodbased products, including glued-laminated and crosslaminated timber, as well as of connections in EWPs are reviewed and application examples are given. Methods and application examples are furthermore provided for moisturerelated stresses and deformations in timber structures, the influence of connections on the structural response, instability of structural systems, and modeling of prefabricated frame structures, before modeling of historical structures of wood is discussed. The chapter ends with discussing bottlenecks in modeling of wood materials and timber structures, which might be a starting point for further improvements and novel modeling strategies. © Springer Nature Switzerland AG 2023.
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| 3. |
- Blomqvist, Lars, 1962-, et al.
(författare)
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Stress distribution in veneers under lamination and simultaneously bending : an experimental and numerical investigation
- 2023
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Ingår i: Wood Material Science & Engineering. - : Taylor & Francis Group. - 1748-0272 .- 1748-0280. ; 18:3, s. 995-1002
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Tidskriftsartikel (refereegranskat)abstract
- Laminated veneer products (LVPs) are veneers glued together into a predetermined shape. Experimental and numerical investigations were performed under lamination and simultaneously bending of veneer laminate to study the stress distribution in the laminate. Laminates of different thicknesses were made of peeled veneers of European beech. The veneers were coated with adhesive, inserted in a mould which had the shape of a semicircle, and finally pressed at 20 degrees C to a laminate. Two Teflon-polymer films including sensors for measurement of the contact pressure were placed on both sides of the laminate to measure the local contact pressure (contact stress) between the laminate and the mould. At the beginning of the bending process, the contact stresses were locally distributed over the laminate in a similar pattern as in a three-point bending; after the laminate was further bent, the stress distribution rearranged to be as in four-point bending. In the end of the moulding, the local contact stresses increased over the entire laminate and reached a 'peak-value' over bent area in the middle part of the mould. A finite-element model was created to study the bending process. Regarding the overall development of the contact stress variations, the experimental and the numerical results agreed.
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| 4. |
- Bolmsvik, Åsa, 1975-, et al.
(författare)
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Vibration Distribution Due to Continous, Intermittent or Half Embedded Elastomer Connections in Wooden Constructions
- 2016
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Ingår i: Proceeding of the 2016 World Conference on Timber Engineering (WCTE), August 22-25, 2016 Vienna. - Vienna : TU-MV Media Verlag. - 9783903039001 - 9783903024359 ; , s. 2912-2920
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Konferensbidrag (refereegranskat)abstract
- Elastomers are commonly used to decrease the sound transmission between apartments in timber framed houses. In previous studies, different types of elastomers have been evaluated experimentally. The wooden assemblies, in which elastomers were used in the connections, showed that elastomers cause the vibrations to increase in the direction perpendicular to the applied load within the low frequency span.In this study, the effects on acceleration, depending on how the elastomers are placed are studied. The cases having the elastomer continuous, placed as intermittent pieces or positioned half embedded in the junctions are evaluated.The frequency dependent properties of the elastomers are needed in order to model the dynamic behaviour and thereby be able to predict sound- and vibration transmission in wooden houses. Here, the properties of a wooden construction having different elastomers connections are studied to enable simulations of the behaviour of the elastomers in a FE model in the future.
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| 5. |
- Carlsson, Peter, et al.
(författare)
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Optimization, a tool with which to create an effective drying schedule
- 1998
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Ingår i: Holzforschung. - : Walter de Gruyter. - 0018-3830 .- 1437-434X. ; 52:5, s. 530-540
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Tidskriftsartikel (refereegranskat)abstract
- A method for defining effective schedules for kiln drying of wood is presented. The method is designed in such a way that it proposes an optimized variation of temperature and humidity which yields the minimum total drying time, with the condition that the moisture content and the deformation not exceed specified limits after the drying and that the stress not exceeds a specified level at any time during the drying process in order to avoid crack development. To demonstrate the capability of the optimization method numerical results are presented. It should be noted that ill this first approach, drying starts from moisture content corresponding to the fibre-saturation point, i.e. approximate to 30%).
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| 7. |
- Crocetti, Roberto, et al.
(författare)
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Experimental and numerical investigation on the shear strength of glulam
- 2010
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Ingår i: International Council for Research and Innovation in Building and Construction: Working Commission W18 ‑ Timber Structures — 2010. - Nelson : University of Canterbury.
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Konferensbidrag (refereegranskat)abstract
- According to EC5, the shear resistance of a structural timber element should be determined on the basis of the characteristic shear strength of the material, along with classical beam theory. For glulam, the characteristic strength values are given by the European standard EN 1194 [3], which assumes a direct relationship between tensile strength and shear strength of the lamination. As an example, the characteristic shear strength of glulam class GL28c, consisting of inner laminations with characteristic tensile strength ft,0,k = 14.5 MPa, would be fv,k = 0.32·(14.5)^0.8 = 2.9 MPa. However, recent investigations both on glulam members [4] and on timber members [5] have shown that the shear strength of spruce is higher than the shear strength obtained by means of the model proposed by EN1194. Moreover, the studies show that the shear strength is nearly constant, regardless the strength class of the timber material.
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