In order to elucidate the influences of the size of specimen, specific gravity, and moisture content on the work or the absorbed energy in impact bending, experiments were conducted for five species of Sugi (
Cryptomeria japonica), Akamatsu (
Pinus densiflora), Yachidamo (
Fraxinus mandshurica), Tochinoki (
Aesculus turbinata) and Makanba (
Betula maximowicziana).
The results obtained are as follows;
(1) The work during impact bending (
W) was expressed as a linear or exponential function of the breadth of specimen (
B) with the exponent not more than 1.0.
(2) The work was expressed as an exponential function of the height of specimen (
H) with the exponent more than 1.0.
(3) The work was given by the following equation:
W=aBmHn (
a: absorbed energy in impact bending,
m,
n: constant). So, it is necessary to reconsider the calculation method of the absorbed energy in impact bending which has been used in JIS, because the difference between the value (a) by JIS and that by eq. (6) becomes larger as the specimen size increases.
(4) The absorbed energy increased exponentially with specific gravity (γ) as expressed with the equation of
a=
kγ
n(
k,
n: constant). From this result it is thought that the equation for calculating dynamic specific strength by
a/γ
2 should inspected, because the exponent
n was less than 2.0.
(5) The relationship between the absorbed energy in impact bending and the moisture content was different for each species. There existed the minimum near 10% moisture content for Sugi and Akamatsu, and the maximum near 20% moisture content for Yachidamo. In Makanba the value of the absorbed energy decreased with moisture content above 10%, and in Tochinoki it showed a constant value regardless of moisture content.
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