الفهرس 
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Abstract
Spinning industries always deal with axially moving thread lines which are always subjected to lateral vibrations . The properties of the thread line and conditions of operation limit the spinning speed. The modern trend is to raise the production rate by increasing such speed. This requires the careful study of the vibration effect on the tension and strain in the thread lines especially those made from viscoelastic materials. In the vibration analysis the inclusion of hysteresis present in the mechanical characteristics of such materials is of prime importance .
The tension-strain relation has been recorded for a Nylon string. Mathematical relations has been obtained using optimization technique . Equations of motion of a moving string has been obtained taking into account the hysteresis effects, air drag and axial velocity . A numerical technique was used to solve the equations .
The effects of increasing the spinning speed , while considering realistic working condition, where air drag is always present , on the tension , strain and cross -sectional area variation in the thread line were examined. It is found that the increase in spinning speed always increase the tension , strain along the thread line but decreases the variation frequency of the cross - sectional area for the pulled string. The drag was seen to have a damping effect on the amplitude of oscillations and reduces the time averaged tension and strain.
The lateral vibration was examined for different end conditions at the outlet guide. This guide was assumed to undergo sinusoidal oscillations. It was found that for a specified velocity of pull there exit critical combinations of amplitudes and frequencies the guide should attain in order to avoid failure of the string. The guide frequency effect on the uniformity of the cross - sectional area for the string leaving that guide was examined and found to be small when the frequency number was kept below the limiting value causing failure.