DIGITALNA ARHIVA ŠUMARSKOG LISTA
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ŠUMARSKI LIST 9-10/1957 str. 42     <-- 42 -->        PDF

3. The correlation between specific gravity and annual-ring width of Slavonian
oak wood is positive. The correlation coefficient for Pedunculate oak is r = + 0.338
± 0.042 and for Sessile oak r = + 0.418 ± 0.069 (see Tab. 20 and Fig. 5).
4. The radial shrinkage varies from 2.53 to 7.55°/o (mean 4.84°/o); the tangential
shrinkage from 4.50 to 13.99°/o (mean 9.31°/o); the volume shrinkage from 8.75 to
20.67°/o (mean 14.10°/o) (see Tabs. 2, 7, and Fig. 6). The radial, tangential and volume
shrinkage in wood of Pedunculate oak (4.87, 9.39 and 14.20°/o) is a little higher than
in wood Sessile oak wood (4.78, 9.28 and 13.86*/o respectively).
5. The shrinkage from fresh to air-dry state of wood vareies: radial from 1.41
to 6.13°/o (mean 3.00°/o); tangential from 2.73 to 11.54°/o (mean 6.56); in volume from
4.73 to 16,82%>) (mean 9.72°/o) (see Tabs. 2 and 8).
6. The correlation between shrinkage and specific gravity of wood is positive.
The correlation coefficients between shrinkage and nominal specific gravity are:
for radial shrinkage of Pedunculate oak wood r = + 0.625 + 0.029, and for radial
shrinkage of Sessile oak wood r = + 0.670 + 0.046; for tangential shrinkage of
Pedunculate oak wood r = + 0.647 + 0.028 and for tangential shrinkage of Sessile
oak wood r = + 0.762 + 0.035. The relationships between shrinkage and nominal
specific gravity of Oak wood are a = 25.4 t„, a. = 16.8 t , a = 8.7 t (see Fig. 7).
7. As to the mechanical properties of Slavonian oak wood, the following results
were obtained: the compressive strength varies from 246 to 720 kg./sq. cm (mean
494 kg./sq. cm.) (see Tab. 9 and Fig. 8) ; static bending strength from 466 to 1785
kg./sq. cm. (mean 1257 kg./sq. cm) (see Tab. 10 and Fig. 9); the impact bending strength
varies from 0.116 to 1.260 m. kg./sq. cm, (mean 0.740 m. kg./sq. cm) (see Tab. 11 and
Fig. 10). The compressive and impact bending strengths of Pedunculate oak wood
are lower than the same properties of Sessile oak wood. The static bending strength
of Pedunculate and Sessile oak wood are the same.
8. Between the specific gravity and strength of Sessile oak wood the following
relationships were established: for compressive strength y = 893,1 x i,299569; static
bending strength y = 2061,2 x 1.236049, and impact bending strength y = 2,0554
x 2,734537 (see Figs. 11, 12 and 13).
9. The annual-ring width, specific gravity, shrinkage and strength of old Slavonian
oak wood are lower than the same properties of young Slavonian oak wood
(see Tabs. 12, 13, 14 and Figs. 14 and 15).
10. The wood of Pedanculate oak from eastern Slavonian forest districts possess
a lower specific gravity, static bending strength and impact bending strength than
the wood of Pedunculate oak from western Slavonian forest districts (see Tabs. 15,
16 and 17).
11. The following differences exist between the wood of Pedunculate and Sessile
oak: the annual-ring width and late-wood %> of Pedunculate and Sessile oak wood
are roughly the same; the specific gravity of Pedunculate oak is lower than that
of Sessile oak; the shrinkage of Pedunculate and Sessile oak wood is roughly the
same; the compressive strength and impact bending strength are lower in wood of
Pedunculate oak than in wood of Sessile oak; the static bending strength of Pedunculate
and Sessile oak wood are the same (see Tab. 19).
12. The wood of Oaks from Yugoslav forests is lighter and milder than the wood
of Oaks from some other European countries (see Tabs. 21 and 22).
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