稻谷吸湿性应力裂纹分形模型的动力学分析

Dynamic Analysis of Fractal Model in Rice Moisture-adorption Crack

将稻谷裂纹的生成看作籽粒内微缺陷扩展而成,建立了裂纹扩展分形模型,给出了分形模型背景下裂纹扩展的判据,推导出吸湿情况下断裂面的表面能,分析了分形模型的动力学特性。结果表明:吸湿性裂纹扩展路径通过淀粉颗粒,且宏观扩展方向受分形效应影响;分形效应降低了微裂纹扩展不规则程度;在吸湿膨胀情况下,淀粉对稻谷抗裂能力影响的本质是淀粉平均相对分子质量Mr存在差异,由于淀粉颗粒的Mr与直链淀粉含量的非线性关系的存在,使得裂纹率与直链淀粉的线性相关性并不显著。

In this paper, the potential of resistance to rice cracks was studied by the fractal theory. Four types of propagating models of stress cracks were established. Under moisture - adsorption condition, criterion for fissure propagation was given and surface energy of fractures was also deduced. The propagating kinetics of stress cracks was inves- tigated as well. The results showed the propagating movement of rice moisture - adsorption crack was influenced by fractal effect and the potential of resistance to cracks depends on M, of starch. The results also showed that, under moisture - adsorption condition, the more the content of amylose was, the greater the cracking rate became. However, the reverse was also possible due to the non - linear relationship between the content of amylase and Mr of starch.