Thursday, 3 November 2016

A new assessment of internal stress within kiln-dried lumber using a restoring force technique on a half-split specimen

Published Date

Original
DOI: 10.1007/s00226-016-0852-y

Cite this article as: 
Jantawee, S., Leelatanon, S., Diawanich, P. et al. Wood Sci Technol (2016) 50: 1277. doi:10.1007/s00226-016-0852-y

Author
  • Sataporn Jantawee
  • Satjapan Leelatanon
  • Prawate Diawanich
  • Nirundorn Matan
Abstract

Due to difficulties in determining modulus of elasticity of wood, only strain or deflection profiles caused by relaxation of internal stress are normally evaluated for industrial kiln-dried lumber. To directly assess the level of internal stress within the lumber, a new technique of measuring the restoring force on a half-split specimen has been presented and the corresponding device has been designed and constructed. Kiln-dried rubberwood specimens with dimensions of 30 or 50 mm (thickness), 130 mm (width) and 50 mm (length) were used in the study. The measured restoring force appears to vary with half-split length and specimen thickness. A mathematical model based on an elastic cantilever beam theory has been successfully developed to describe the restoring force behavior in a flexural response regime. The magnitude of the maximum linearly averaged internal stress σm can be derived without prior knowledge of the modulus of elasticity of wood. For the 30-mm-thick lumber, the derived values of σm are in general agreement with the ones obtained from the conventional McMillen slice test. Very close agreement is observed when the internal stress is at a relatively low level and its profile is approximately linear. But for the 50-mm-thick lumber, the determination of σm is less appropriate because of its relatively short flexural range. A restoring force–internal stress chart has been proposed for practical use in the lumber industry. This assessment was performed to investigate the evolution of internal stress during the conditioning and storage stages of kiln-dried rubberwood lumber.

References

  1. Bodig J, Jayne BA (1982) Mechanics of wood and wood composites. Van Nostrand Reinhold Company, New YorkGoogle Scholar
  2. Diawanich P, Matan N, Kyokong B (2010) Evolution of internal stress during drying, cooling and conditioning of rubberwood lumber. Eur J Wood Prod 68(1):1–12CrossRefGoogle Scholar
  3. Diawanich P, Tomad S, Matan N, Kyokong B (2012) Novel assessment of casehardening in kiln-dried lumber. Wood Sci Technol 46:101–114CrossRefGoogle Scholar
  4. European Committee for Standardization (2010) Sawn timber-method for assessment of case-hardening. CEN standard ENV 14464
  5. Fuller J (1995) Conditioning stress development and factors that influence the prong test. Res. Pap. FPL–RP–537. Department of Agriculture, Forest Service, Forest Products Laboratory, Madison
  6. Fuller J, Hart CA (1994) Factors that influence the prong test. In: Proceedings of the 4th IUFRO international wood drying conference, Rotorua, pp 313–320
  7. Hibbeler RC (2012) Structural analysis. Prentice Hall, New JerseyGoogle Scholar
  8. Lados DA, Apelian D (2006) The effect of residual stress on the fatigue crack growth behavior of Al–Si–Mg cast alloys—mechanisms and corrective mathematical models. Metall Mater Trans A 37:133–145CrossRefGoogle Scholar
  9. Matan N, Kyokong B (2003) Effect of moisture content on some physical and mechanical properties of juvenile rubberwood. Songklanakarin J Sci Technol 25(3):327–340Google Scholar
  10. McMillen JM (1958) Stresses in wood during drying (Report 1652). Department of Agriculture, Forest Service, Forest Products Laboratory, MadisonGoogle Scholar
  11. Perré P, Passard J (2007) Stress development. In: Perré P (ed) Fundamentals of wood drying. European COST A.R.B.O.LOR, Nancy, pp 243–271Google Scholar
  12. Rossini NS, Dassisti M, Benyounis KY, Olabi AG (2012) Methods of measuring residual stresses in components. Mater Des 35:572–588CrossRefGoogle Scholar
  13. Schajer GS, Ruud CO (2013) Overview of residual stresses and their measurement. In: Schajer GS (ed) Practical residual stress measurement methods. Wiley, West Sussex, pp 1–27CrossRefGoogle Scholar
  14. Simpson WT (1991) Dry kiln operator’s manual. In: Agriculture Handbook AH-188. Department of Agriculture, Forest Service, Forest Products Laboratory, Madison
  15. Simpson WT (1999) Drying and control of moisture content and dimensional changes. In: Wood handbook (Wood as an Engineering Material). Department of Agriculture, Forest Service, Forest Products Laboratory, Madison
  16. Sonderegger W, Martienssen A, Nitsche C, Ozyhar T, Kaliske M, Niemz P (2013) Investigations on the physical and mechanical behavior of sycamore maple (Acer pseudoplatanus L.). Eur J Wood Prod 71:91–99CrossRefGoogle Scholar
  17. Tomad S, Matan N, Diawanich P, Kyokong B (2012) Internal stress measurement during drying of rubberwood lumber: effects of wet-bulb temperature in various drying strategies. Holzforschung 66:645–654CrossRefGoogle Scholar
  18. Walton HW (2002) Deflection methods to estimate residual stress. In: Totten G, Howes M, Inoue T (eds) Handbook of residual stress and deformation of steel. ASM International, Ohio, pp 89–98Google Scholar
  19. Wengert E (1992) Techniques for equalizing and conditioning lumber. Cooperative extension programs No. 65. Department of Forest and Wildlife Ecology, University of Wisconsin, Madison

For further details log on website :
http://dx.doi.org/10.1007/s00226-016-0847-8

No comments:

Post a Comment