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Holz als Roh- und Werkstoff

, Volume 65, Issue 1, pp 7–16 | Cite as

Fracture mechanics models applied to delayed failure of LVL beams

  • Myriam ChaplainEmail author
  • Gerard Valentin
ORIGINALARBEITEN ORIGINALS

Abstract

Several theories for modelling fracture and slow growth of a crack in wood have been developed. The various models may be differentiated by the specifically regarded stress levels, failure mechanisms and averaging procedures. This paper deals with the application of viscoelastic fracture mechanics models to predict delayed failure of a timber element in bending. Simulations are compared to experimental results of bending tests carried out on LVL (Laminated Veneer Lumber) notched beams. This analysis emphasizes the influence of the geometry and of the size of the beam as well as of the damage area on the delayed failure.

Keywords

Stress Intensity Factor Crack Length Crack Velocity Creep Compliance Calibration Function 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Bruchmechanische Modelle zur Beschreibung des Rissfortschritts bei Furnierschichtholz-Balken

Zusammenfassung

Zur Modellierung des Bruchverhaltens und Rissfortschritts in Holz wurden bereits viele Theorien entwickelt. Die verschiedenen Modelle lassen sich anhand der jeweils betrachteten Spannungsniveaus, Bruchmechanismen und Mittelungsverfahren unterscheiden. Diese Arbeit beschäftigt sich mit der Anwendung viskoelastischer Bruchmechanikmodelle zur Beschreibung des Rissfortschritts in einem biegebeanspruchten Holzbauteil. Simulationsergebnisse werden mit den Ergebnissen aus Biegeversuchen an ausgeklinkten Furnierschichtholz-Balken verglichen. Dabei wird der Einfluss der Geometrie und der Größe der Balken sowie des Schädigungsbereichs an der Rissspitze auf den Rissfortschritt deutlich.

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References

  1. 1.
    Aicher S, Dill-Langer G (1999) Long term strength of spruce solid wood at transverse tension loading. Holz Roh- Werkst 56(5):295–305CrossRefGoogle Scholar
  2. 2.
    Aicher S, Gustafsson PJ, Haller P, Petersson H (2002) Fracture mechanics models for strength analysis of timber beams with a hole or a notch. Report of RILEM TC-133. Lund University report TVSM 02/7134Google Scholar
  3. 3.
    Barrett JD, Foschi RO (1978) Duration of load probability of failure in wood. Part I. Modelling creep rupture. Can J Eng 5:505–514Google Scholar
  4. 4.
    Boyancé P (1999) Modélisation de la rupture différée d’un matériau orthotrope viscoélastique en environnement naturel. Application à un composite à base de bois: le LVL. Thèse no 2145, Université de BordeauxGoogle Scholar
  5. 5.
    Brockway GS, Schapery RA (1978) Some viscoelastic crack growth relations for orthotropic and prestrained media. Eng Fract Mech 10:453–468CrossRefGoogle Scholar
  6. 6.
    Chaplain M, Valentin G (2000) Fracture mechanics analysis of delayed failure of notched beam. In: Proceeding of cost action E8, wood and wood fiber composite, Stuttgart, Germany, pp 159–170Google Scholar
  7. 7.
    Chaplain M, Valentin G (2002) Modélisation de la durée de vie. Application à des poutres entaillées. Ann GC Bois 6:41–49Google Scholar
  8. 8.
    Chaplain M, Bouadjel R, Valentin G (2003) Cracking and rupture of notched LVL beams. In: Proceedings of the second international Conference of the European Society for Wood Mechanics, Stockholm, Sweden, pp 143–148Google Scholar
  9. 9.
    Gerhards CC, Link CL (1987) A cumulative damage model to predict load duration characteristics of lumber. Wood Fiber Sci 19(2):147–164Google Scholar
  10. 10.
    Gustafsson PJ, Hoffmeyer P, Valentin G (1998) DOL behaviour of end-notched beams. Holz Roh- Werkst 56(4):307–317CrossRefGoogle Scholar
  11. 11.
    Hanhijärvi A, Galimard P, Hoffmeyer P (1998) Duration of load behaviour of different sized straight timber beams subjected to bending in variable climate. Holz Roh- Werkst 56(5):285–293CrossRefGoogle Scholar
  12. 12.
    Johns K, Madsen B (1982) Duration of load effects in lumber. Part I: A fracture mechanics approach. Can J Civil Eng 9:502–514CrossRefGoogle Scholar
  13. 13.
    Larricq, P (1992) Une méthode d’estimation des caractéristiques de rupture différée d’un matériau viscoélastique orthotrope. Application au bois. Thèse no 738, Université de BordeauxGoogle Scholar
  14. 14.
    Madsen B, Barret JD (1976) Time-strength relationship for lumber. University of British Colombia, Civil Engineering Structural Research Series, Report no 13Google Scholar
  15. 15.
    Mindess S, Nadeau JS, Barret JD (1975) Slow crack growth in Douglas-fir. Wood Sci 7(1):389–396Google Scholar
  16. 16.
    Morlier P, Ranta-Maunus A (1998) DOL effect of different sized timber beams. Holz Roh- Werkst 56(4):279–284CrossRefGoogle Scholar
  17. 17.
    Morlier P, Valentin G, Toratti T (1994) Review of the theories on long term strength and time to failure. Cost 508 Wood mechanics, 18–19 May 1994, Espoo Finland, pp 3–27Google Scholar
  18. 18.
    Nielsen LF (1996) Lifetime and residual strength of wood subjected to static and variable load. Department of Structural Engineering an Materials, Technical University of Denmark, series R, 6Google Scholar
  19. 19.
    Nielsen LF (1985) Wood as a cracked viscoelastic material, Part I: theory and applications. In: Proc. International Workshop on Duration of Load in Lumber and Wood Products, Richmond, Canada, pp. 67–78Google Scholar
  20. 20.
    Nielsen LF (1978) Crack propagation in Linear-Viscoelastic Materials. Bygningsstatiske Meddelelser 49:1Google Scholar
  21. 21.
    Schapery RA (1975a) A theory of crack initiation and growth in viscoelastic media: I. Theoritical development. Int J Fract 11:141–159CrossRefGoogle Scholar
  22. 22.
    Schapery RA (1975b) A theory of crack initiation and growth in viscoelastic media: II. Approximate methods of analysis. Int J Fract 11:369–388Google Scholar
  23. 23.
    Valentin G, Chaplain M (2001) Effects of relative humidity on crack growth and fracture of Laminated Veneer Lumber. In: Proceeding of the first international Conference of the European Society for Wood Mechanics, Lausanne, EPFL, pp. 243–253Google Scholar
  24. 24.
    Valentin G, Bostrom L, Gustafsson PJ, Ranta-Maunus A, Gowda S (1991) Application of fracture mechanics to timber structures. RILEM state-of-the-art. Research notes 1262, VTTGoogle Scholar

Copyright information

© Springer-Verlag 2006

Authors and Affiliations

  1. 1.Laboratoire de Rhéologie du Bois de Bordeaux, UMR 5103CNRS/INRA/Université Bordeaux ICestas CedexFrance

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