tailieunhanh - Báo cáo lâm nghiệp: "Variability of spruce (Picea abies [L.] Karst.) compression strength with present reaction wood"

Tuyển tập những bài báo cáo nghiên cứu khoa học hay nhất được đăng trên tạp chí JOURNAL OF FOREST SCIENCE đề tài: Variability of spruce (Picea abies [L.] Karst.) compression strength with present reaction wood. | JOURNAL OF FOREST SCIENCE 55 2009 9 415-422 Variability of spruce Picea abies L. Karst. compression strength with present reaction wood V. Gryc H. Vavrcik Faculty of Forestry and Wood Technology Mendel University of Agriculture and Forestry in Brno Brno Czech Republic ABSTRACT The aim of research was to find out the variability of spruce Picea abies L. Karst. wood compression strength limits in the direction parallel to grain. The wood strength was examined using samples from a tree with present reaction compression wood. The strength was found out for individual stem zones CW OW SWL and SWR . The zone with present compression wood CW demonstrated slightly higher values of wood strength limits. The differences in the limits of compression strength parallel to grain in individual zones were not statistically significant. All the data acquired by measuring were used to create 3D models for each zone. The models describe the strength along the radius and along the stem height. The change of strength along the stem radius was statistically highly significant. There was an obvious tendency towards an increase in the strength limit in the first 40 years. With the increased stem height there is a slight decrease in wood strength. Keywords strength parallel to grain spruce compression wood reaction wood As we use wood as a construction material we have to consider several vital factors to evaluate its quality and these are not only its physical properties and imperfections but also its strength properties wood strength and modules of elasticity . The evaluation of wood is much more complicated than the evaluation of metal because wood is an inhomogeneous anisotropic material. From the practical point of view wood compression strength parallel to grain is one of the most important wood properties. When a force is applied deformation occurs. This deformation is manifested as the shortening of the object in the direction of the applied force. The wood strength parallel to .