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An analysis of variation in moduli of elasticity and rupture in young Douglas fir

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dc.contributor.author Littleford, Thomas William
dc.date.accessioned 2012-02-18T00:46:14Z
dc.date.available 2012-02-18T00:46:14Z
dc.date.copyright 1957
dc.date.issued 2012-02-17
dc.identifier.uri http://hdl.handle.net/2429/40794
dc.description.abstract The results of two hundred and fifty-eight static bending tests on young Douglas fir were obtained from the Vancouver Laboratory of the Forest Products Laboratories of Canada. Twenty-two trees had been sampled; seven of approximately sixty years of age from Port Moody, eight of about seventy years of age from Coombs (on Vancouver Island), and seven of approximately ninety years of age from Stave Lake. Stand site quality in each locality was similar and above average for second-growth fir from the coastal region of British Columbia. The laboratory's results were separated into two classes. Ninety-seven tests represented wood formed within the first five inches of radial growth in the tree. The remaining one hundred and sixty-one tests typified the older wood lying between the inner zone and the bark. Analyses of variance revealed highly significant differences in properties between zones. Wood from the inner zone had a faster growth rate, lower density (though wider bands of summerwood) and less strength and less stiffness in bending than wood from the outer zone. The influence of ring width, summerwood width and specific gravity on the moduli of elasticity and rupture was assessed for each zone by regression analyses. Ring width and summerwood width accounted for a significant amount of variation in modulus of elasticity and modulus of rupture in the two zones. Their influence on both moduli, however, was completely due to their association with specific gravity. Specific gravity, alone, accounted for almost twice as much of the variation in elasticity and bending strength as did ring width and summerwood width combined. The presence of compression wood in a few specimens from the outer growth zone weakened the relationship between modulus of elasticity and specific gravity in this zone but had no effect on the modulus of rupture — specific gravity relationship. In consequence, the influence of growth zone on modulus of elasticity could not be determined. The difference in average values of specific gravity between zones did not fully explain the similar difference between zones for average modulus of rupture values; an indication that radial growth zone in the tree had some influence on the bending strength independent to that exerted by density. en_US
dc.language.iso eng en_US
dc.publisher University of British Columbia en
dc.relation.ispartofseries UBC Retrospective Theses Digitization Project [http://www.library.ubc.ca/archives/retro_theses/] en
dc.subject Wood -- Testing en_US
dc.subject Douglas fir en_US
dc.title An analysis of variation in moduli of elasticity and rupture in young Douglas fir en_US
dc.type Electronic Thesis or Dissertation en
dc.degree.name Master of Forestry - MF en_US
dc.degree.discipline Forestry en_US
dc.degree.grantor University of British Columbia en
dc.degree.campus UBCV en_US
dc.description.scholarlevel Graduate en


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