Bending and shearing characteristics of cotton seedling stem

摘要

In order to analyze and evaluate the resist ability of cotton seedling to wind and sandstorm damage in Xinjiang,China,the bending resistance strength and shearing resistance strength were determined by experiments for cotton stem in its seedling stage rather than maturity period.The bending force and shearing force were measured by using a universal testing machine TMS-PRO with a specialized three-point fixture,and the bending resistance strength and shearing resistance strength were calculated from these data.The experiments were conducted at different stage of cotton seedlings life.The shearing force and bending force of cotton seedling stem increases with the age,but it is not obvious in the first five weeks.The results show that the five weeks old cotton seedlings are still weak against external damage,the maximum bending force that a cotton seedling stem can be suffered is 1.98 N and the maximum shearing force is 101.93N.After five weeks,these values climb rapidly,and they reach to 68.27 and 622.77 N respectively in the ninth week.%为评估分析新疆地区棉花幼苗茎杆对风沙破坏的抵抗能力,该文通过试验测定了棉花幼苗茎杆的弯曲强度和剪切强度.采用TMS-PRO质构仪进行了棉花幼苗的剪切试验和弯曲试验,分析了典型剪切过程和弯曲过程中作用力随位移变化的特性.测定了不同苗龄棉花幼苗的最大剪切力和最大弯折力,结果表明,棉花幼苗能够承受的最大剪切力和折弯力随着苗龄增加呈指数关系增长,苗龄小于5周幼苗抵抗外力破坏能力较弱,能够承受的最大剪切力为101.93 N,最大折弯力为1.98 N,5周后棉苗抵抗外力破坏的能力明显增强,9周时二者分别达到68.27和622.77N.