抄録
Compress-release behaviour of cotton assemblies over lower pressure range 0 to 3.5gr/cm2 was investigated by means of the oscillating method of pendulum type under the frequency of 0.6 to 1 cps. (see Fig. 1). Specimens are cut into square with a side of 5cm length from carded cotton lap, then they are immersed in ligroin solution of paraffin and dried. Each of them wighed 3.0g before oil treatment. The amount of paraffin added to specimens are four kinds of 0, 0.4, 1.7 and 2.3gr.
Observed values of displacement x on the surface of the specimen against time are represented by the damping oscillation curve with a constant reduction factor k (mm/cycle). (see Fig. 2).
(1) The displacement x is represented by the relation; where A0 is x at time t=0, coefficient α a constant determined by k, and T the period of oscillation.
(2) On the other hand the equation of motion containing unkown function f (t), which is the difference between the force fl(t) acting on the surface of right-hand side specimen and f2 (t) of left hand-side specimen, is obtained as follow; where I: moment of inertia of oscillational parts of the equipment, θ: angles between the horizontal level and the arm, Q: constant determined only by the equipment, g: gravitational constant, R: length of the arm (see Fig. 1).
(3) From eqs. (1) and (2), f (t) is given by; The first term on the right handside of the above equation represents conservative force and the second term is non-conservative force, where; T0: period of free oscillation.
(4) By integrating f (t) under assumption that the surface of the specimen regains initial position after one cycle, energy loss factor l is derived, that is: where Δ=K/A.
(5) Experimentally estimated values of l for cotton assemblies are increased by addition of paraffin, and the 0.4gr paraffin specimen has the maximum value of l.
