稻谷与钉齿碰撞损伤的有限元分析

建立了稻谷3层椭球体结构CAD模型，在前处理软件HyperMesh中划分网格，设置单元、材料属性和接触碰撞参数，生成了稻谷的有限元模型。利用LS-DYNA软件仿真分析了稻谷与钉齿碰撞过程，仿真结果表明：碰撞接触区为椭圆，受压应力作用，区域中心处应力值最大。籽实皮和胚乳的Von Mises等效应力值随碰撞速度的增加逐步增大。稻谷与钉齿碰撞时，胚乳达到临界Von Mises等效应力值31.68?MPa对应的临界速度为24.2?m/s，而籽实皮碰撞损伤的临界速度要大得多。稻谷与钉齿碰撞形成宏观应力裂纹是从胚乳中心或近中心扩展而成的。

Finite element analysis on damage of rice kernel impacting on spike tooth

A computer-aided design model of a rice kernel comprising three layered ellipsoids was established. HyperMesh software was used to partition mesh cells and set material and contact parameters for each cell and thus construct a finite element model for analysis. Using LS-DYNA software, the impact process between the spike-tooth and the rice kernel was simulated and analyzed. The simulation showed that the contact zone between the spike-tooth and the rice kernel was elliptic, and the compressive stress was a maximum at the center of the contact zone. The von Mises stress value of rice seed skin and endosperm gradually increased with the increase of impact velocity. The critical damage velocity for the kernel corresponding to the endosperm critical von Mises stress was 24.2 m/s, while the critical damage velocity of the correspondent rice seed skin was much larger.