The purpose of this study was to obtain the relationship between specific volume
v and compressive stress
P of tobacco shreds during compression and to disclose the influences of experimental factors, physical properties and compressive hysteresis of shreds upon the
v-P relation. Experiments were carried out with five experimental factors, that is, the variety of tobacco
V (Fluecured
V1 and Domestic
V2), the leaf position on a stalk
p (5 levels), the moisture content
w (7∼18% WB), the number of compression
N (1∼3) and the loosening of shreds after compression. The experimental data thus obtained were analyzed by means of a statistical method.
The important results obtained were as follows:
(1) The relationship between
v and
P of tobacco shreds during compression was able to be shown by the following formula,
ln P=K
0+K
1v.
(2) The sign of the direction coefficient
K1 was minus, and the absolute value of
K1 increased as
p decreased or
w increased. The absolute value of
K1 in
V1 was larger than that in
V2.
(3) The sign of the intercept
K0 was plus, and the absolute value of
K0 was nearly constant, independent of the condition of
V, p and
w.
(4) The physical properties, which affected the direction coefficient, were the elastic modulus, the specific volume of tobacco itself and the correlative specific volume between shreds after loose fill. Among these properties, the elastic modulus was the most influential one.
(5) The increase of
N caused stress relaxation and made the absolute values of
K0 and
K1, higher. The loosening of shreds after compression decreased the degree of stress relaxation.
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