繊維系の撚り構造と弾性的性質

Abstract

In this paper the correspondence of the induced pressure in twisted sliver with the compressed paessure in loaded wad was measured under such equilibrium condition that both of frictional forces at the two ends of metal wire inserted partly in the wool wad and partly in the twisted wool sliver were balanced (see fig. 1). At the balanced frictional state (see fig. 2), the experimental relations between the twist angle θ (deg/cm) of sliver having fullness (1-ε)s and the applied load R (g/cm2) of wad having fullness (1-ε)w are shown in fig. 4. On the other hand, the effect of R on the withdrawal force Fw (g/cm) of single fibre from this wad was described by inverse sigmosoidal curve in fig. 5, and the dependence of Fw on R/(1-ε)w was obtained linearly as shown in fig. 7. Thus, frictional coefficient of wool fibre was estimated to μ0=0.26 by Postle-Ingham's method23). And then, the dependence of average frictional force Ft (g/cm) of a fibre in wool sliver on its twist number n (cm-1) was estimated from the load-elongation curves of twisted wool sliver. In fig. 10, this relation of Ft and n was plotted exponentially.From these experimental results, detailed assignments of the mechanical state of a fibre in twisted sliver have been made as follows:(1) In fig. 12 it is shown that the value of radial pressure Pw (g/cm) produced on the unit length of axial centre line of twisted sliver increases quadratically as twist number n increases.(2) Inter-fibre frictional force Ft of twisted sliver increases with two sets of factors: one is bulk density increment of sliver by twisting, and another the curvature increment of fibre arrangement. The observed values of the former efiects on the frictional force of single fibre are given as Fw/4 in fig. 10, and those of the latter effect as (Ft-(Fw/4)) in fig. 10.(3) The tortional behavior of wool sliver as a whole is similar to the spongy material, for the orientation of fibre in a twisted sliver was not arranged to regular spiral configuration, but intercected mutually as the results of fibre migrations. This makes possible to suggest that the value of inter-fiber frictional cofficient μ in twisted sliver is larger than that of μ0 in untwisted wool wad. Actually, inserting the observed values of Ft/(Fw/4), the average ratio of frictional force along the generating line of unit length, into eqs. (6), (7), calculated value of μ was about 1.