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Matti Kärkkäinen, Jukka Pietilä, Raili Vihola

Suomalaisten puulajien iskutaivutuslujuus tuoreena.

Kärkkäinen M., Pietilä J., Vihola R. (1985). Suomalaisten puulajien iskutaivutuslujuus tuoreena. Silva Fennica vol. 19 no. 4 article id 5255. https://doi.org/10.14214/sf.a15434

English title: Impact bending strength of Finnish tree species in green condition.

Abstract

There are great impact forces in mechanized harvesting and wood yard in the mills which can cause breaks in timber. The impact strength of timber in green condition was tested in temperatures of +18°C and -18°C using sawn pieces (20 x 20 x 300 mm) of Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) H. Karst.), birch (Betula pendula Roth and B. pubescens Ehrh.), grey alder (Alnus incana L.) and aspen (Populus tremula L.). In addition, unbarked naturally round sticks (length 300 mm, diameter 15 and 35 mm) of the same species were tested.

The impact strength of round sticks was 1.5–4.4 times as great as that of sawn pieces. The reasons are possibly the avoidance of cell breaks at the surface as well as growth stresses. The frozen samples were clearly weaker than the unfrozen ones. As a rule, the impact bending strength increased with increased density of the species. However, the correlation varied greatly between species. If density was kept constant, an increase in the growth ring width decreased the impact strength. The reason may lie in the fracture mechanism.

The PDF includes a summary in English.

Original keywords
taivutuslujuus; mänty; kuusi; rauduskoivu; hieskoivu; haapa; harmaaleppä; iskutaivutuslujuus

English keywords
impact bending strength; Pinus sylvestris; Picea abies; Betula pendula; Betula pubescens; Populus tremula; Alnus incana

Published in 1985

Available at https://doi.org/10.14214/sf.a15434 | Download PDF

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