基于临界滑脱长度的短纤纱断裂强力计算

为得到一种更加合理的短纤纱断裂强力的近似计算方法，根据短纤纱结构的理想化假设和临界滑脱长度的概念，推导出短纤纱断裂过程中纤维临界滑脱长度的近似计算表达式以及发生断裂和滑脱的纤维对短纤纱断裂强力的实际贡献。鉴于短纤纱截面纤维根数的不匀，根据计算得到的临界滑脱长度采用纤维在短纤纱中随机排列的模拟对短纤纱断裂强力进行计算。通过纺制不同线密度下具有不同捻系数的粘胶纱与涤纶纱并测试其断裂强力对该计算方法进行验证。计算和验证结果表明：临界滑脱长度的计算值随着捻系数的增加而减小，且当捻系数增加时，短纤纱断裂强力的计算值随着捻系数的增加升高至最高值而后发生下降，这是与实测短纤纱强力值的变化趋势是一致的。

Calculation of staple yarn strength based on critical slipping length

In order to obtain a morereasonable approach to estimate staple yarn strength, based on idealized assumptions of yarn structure and definition of critical slipping length, the expression of fiber critical slipping length during yarn breaking process was deduced, as well as the actual contributions that breaking and slipping fibers made to yarn strength. Considering variation of fiber number in each yarn cross section, yarn strength was then calculated by simulating fiber random arrangement in the yarn based on the calculated critical slipping length. Viscose and polyester yarns of various yarn counts and twist multipliers were spun and their strengths were tested for calculation and verification. It could be seen from calculated results that the critical slipping lengths declines with the increase of theyarn twist multiplier. Meanwhile, as the twist multiplier increases, the calculated yarn strengthincreases to the highest point and thendecreases, which is in good agreement with tested results.