荔枝挤压损伤有限元预测分析

Finite Element Analytic Prediction of Compression Injury of Litchi

为减小荔枝的挤压损伤,通过试验测定了荔枝果壳和果肉的极限应力,建立了根据荔枝结构所对应的有限元模型,模拟了外力沿不同方向挤压荔枝的过程,得到荔枝内部组织的等效应力云图。结果显示:挤压过程中,荔枝果壳的应力大于果肉,果肉的损伤先于果壳;相同挤压力下,果壳的纵向挤压应力小于横向,但果肉的纵向挤压应力却大于横向;荔枝的挤压损伤具有各向异性,试验范围内,果肉出现机械损伤的纵向和横向挤压力分别为10 N和20 N,果壳出现机械损伤的纵向和横向挤压力为35 N和25 N。

In order to reduce the compression injumy of litchi,the limit stress of litchi hull and litchi flesh was measured by experiment,a finite element model was established based on the structure of litchi, the process of compressing litchi by the force in different directions was simulated, and the equivalent stress nephograms of the inner organization of litchi were made. The results indicated that during compressing, the stress of the hull was greater than that of the flesh and the injury of the flesh was ahead of the hull. Under the same extrusion force, the vertical extrusion stress was less than the landscape extrusion stress for the hull, but opposite for the flesh. Because the compression injury of litchi was anisotropic ,in the experimental scope, the extrusion forces（ vertical and landscape） were 10 N and 20 N when the mechanical injury of litchi flesh occurred, and the extrusion forces （ vertical and landscape） were 35 N and 25 N when the mechanical injury of litchi hull occurred.