Current issue: 53(3)

Under compilation: 53(4)

Impact factor 1.683
5-year impact factor 1.950
Silva Fennica 1926-1997
1990-1997
1980-1989
1970-1979
1960-1969
Acta Forestalia Fennica
1953-1968
1933-1952
1913-1932

Articles containing the keyword 'taivutuslujuus'.

Category: Article

article id 7291, category Article
Paul Wallden. (1934). Tutkimuksia koivupuun anatoomisen rakenteen ja teknillisten ominaisuuksien keskinäisestä riippuvuudesta solumittauksien perusteella. Acta Forestalia Fennica vol. 40 no. 14 article id 7291. https://doi.org/10.14214/aff.7291
English title: Studies on relationship between anatomical structure and technical properties of birch wood.

Birch wood is used widely in wooden structures where mechanical strength is needed. The aim of the research was to study the influence of the relative share of mechanically weak tracheids, and length of the wood fibers on specific gravity and bending strength of downy birch (Betula pubescens Ehrh.) wood. According to the results, the strength of wood is strongly dependent on the relative share of tracheids, and length of the libriform cells. The strength of the wood increases when the share of tracheids decreases and the length of libriform cells increases. The specific gravity can be used as an indication of the strength of wood, especially if it is possible to analyze the structure of the wood.

The PDF includes a summary in German.

  • Wallden, ORCID ID:E-mail:
article id 7276, category Article
Paul Walldén. (1933). Eräs puun laadun tunnus. Acta Forestalia Fennica vol. 39 no. 5 article id 7276. https://doi.org/10.14214/aff.7276
English title: Bending strength of birch wood.

According to earlier studies, the weight of the wood may be a useful quality when aim is to create such wooden structures where small weight is combined with maximum mechanical strength. Of the northern tree species, Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) H. Karst.) and birch (Betula sp.), birch has the highest bending strength. The main focus of this study was to find out if there is correlation between the specific gravity of cell wall substance and bending strength of the birch wood, and if the specific gravity of cell wall substance could be used as indication of the quality of the wood.

Dominant trees from 55 years old birch (Betula sp.) stand was selected for bending tests. The bending strength did not vary in birch as much as in many other tree species. The highest bending strength was achieved near the specific gravity class s=0,65, and it can be concluded that when the specific gravity falls below S=0,57, the wood’s technical quality is not sufficient. The article includes a literature review on the subject.

The PDF includes a summary in German
  • Walldén, ORCID ID:E-mail:
article id 5277, category Article
Kirsi Maasalo. (1986). Pihlajan puuaineen ominaisuuksia. Silva Fennica vol. 20 no. 3 article id 5277. https://doi.org/10.14214/sf.a15456
English title: Properties of the wood of the rowan tree (Sorbus aucuparia).

The basic density of the wood of the rowan tree (Sorbus aucuparia L.) is almost the same along the stem but that of the bark is increasing along the stem. The moisture content of the wood and of the bark is increasing along the stem. Its strength in the bending and in the compression is high. The volume shrinkage is high.

The PDF includes an abstract in Finnish

  • Maasalo, ORCID ID:E-mail:
article id 5255, category Article
Matti Kärkkäinen, Jukka Pietilä, Raili Vihola. (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.

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.

  • Kärkkäinen, ORCID ID:E-mail:
  • Pietilä, ORCID ID:E-mail:
  • Vihola, ORCID ID:E-mail:
article id 5255, category Article
Matti Kärkkäinen, Jukka Pietilä, Raili Vihola. (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.

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.

  • Kärkkäinen, ORCID ID:E-mail:
  • Pietilä, ORCID ID:E-mail:
  • Vihola, ORCID ID:E-mail:
article id 5199, category Article
Pekka Saranpää. (1983). Puuaineen tiheyden ja vuosiluston leveyden vaikutus kuusen iskutaivutuslujuuteen Etelä- ja Pohjois-Suomessa. Silva Fennica vol. 17 no. 4 article id 5199. https://doi.org/10.14214/sf.a15182
English title: The influence of basic density and growth ring width on the impact strength of Norway spruce wood from Southern and Northern Finland.

Basic density and absorbed energy in impact bending were measured for 500 Norway spruce (Picea abies (L.) H. Karst.) samples from Northern and Southern Finland. Statistical analysis showed that the relationship between impact strength and basic density was significant and regression analysis showed that it was linear.

Furthermore, with constant density, the impact strength was higher in Northern than in Southern Finland. This was due to growth ring width: i.e. when density was kept constant the impact strength increased with decreasing growth ring width. In addition, when the growth ring width was kept constant, the basic density of wood was higher in Southern Finland than in Northern Finland.

The PDF includes a summary in English.

  • Saranpää, ORCID ID:E-mail:
article id 5182, category Article
Matti Kärkkäinen, Herman Hakala. (1983). Kuusitukin koon vaikutus sivulautojen taivutus- ja puristuslujuuteen. Silva Fennica vol. 17 no. 2 article id 5182. https://doi.org/10.14214/sf.a15098
English title: Effect of log size on the bending and compression strength of side boards in Norway spruce.

In order to evaluate the strength properties of boards made from small and large Norway spruce (Picea abies) butt logs, 15 small (top end diameter 13 cm) and 15 large (top end diameter 25 cm) logs were sampled from a sawmill in Finland. From each log two test pieces were made in order to measure the bending and compression strength, dry density and average ring width.

The boards from small logs were stronger and their density higher. When the differences between groups were analysed it was found that the strength was determined by the density and ring width. When the density was kept constant, the increase in ring width had a decreasing effect on the strength properties. Because there was a negative correlation between ring width and density, ring width alone had a great effect on the strength properties.

The PDF includes a summary in English.

  • Kärkkäinen, ORCID ID:E-mail:
  • Hakala, ORCID ID:E-mail:
article id 5181, category Article
Matti Kärkkäinen, Olle Dumell. (1983). Kuusipuun taivutuslujuuden riippuvuus tiheydestä ja vuosiluston leveydestä Etelä- ja Pohjois-Suomessa. Silva Fennica vol. 17 no. 2 article id 5181. https://doi.org/10.14214/sf.a15097
English title: Effect of basic density and growth ring width on the bending strength of Norway spruce wood from southern and northern Finland.

A population consisting of 450 Norway spruce (Picea abies (L.) H. Karst.) samples was gathered from northern and southern Finnish wood. The static bending strength was affected greatly by the density of the wood. However, keeping the density constant, the bending strength was higher in northern than in southern Finnish wood. The reason was the effect of the growth ring width.

The basic density was affected by the growth rate. Keeping the growth ring width constant, the basic density was over 5 kg/m3 lower in northern than in southern Finnish wood. This result supports the earlier findings on the effect of latitude.

The PDF includes a summary in English.

  • Kärkkäinen, ORCID ID:E-mail:
  • Dumell, ORCID ID:E-mail:

Register
Click this link to register for Silva Fennica submission and tracking system.
Log in
If you are a registered user, log in to save your selected articles for later access.
Contents alert
Sign up to receive alerts of new content
Your selected articles

Committee on Publication Ethics A Trusted Community-Governed Archive