Abstract: With the continuous expansion of walnut planting area and yield in China, the processing scale of green walnut is fairly large, but the efficiency of artificial peeling is still low. Mechanized peeling is an important way to improve walnut appearance quality and realize walnut commercialization. However, the mechanical properties of peeling directly affect the performance of green walnut peeling equipment. This study determined the sphericity and green peel thickness of Zha 343. Quasi-static compression test was carried out on Zha 343 by microcomputer controlled electronic universal testing machine. The effect of extrusion direction, extrusion speed, size, pretreatment, etc. factors on green peel split were  explored. The results showed that cracks of walnut green peel had certain direction. Walnut green peel could be taken as isotropic material. There was a linear relationship between extrusion pressure and displacement during the extrusion process. The displacement decreased with the increase of extrusion speed. The displacement of peel during fracture grew with the increasing of green walnut size. The rupture pressure decreased if there was a cut on green peel. This result  provided a reliable basis for the structure design of walnut peeling equipment.

Key words: green walnuts, peel thickness, pressure, crack, peel rupture

摘要： 随着我国核桃种植面积和产量不断增大，青核桃加工规模大，人工脱皮效率低。机械化脱皮是提高核桃外观品质、实现核桃商品化的重要途径，而青核桃脱皮力学特性直接影响青核桃脱皮设备性能。测定了扎343青核桃的球度及青皮厚度。在微机控制电子万能实验机上，对扎343青核桃进行准静态压缩实验。探索出青核桃挤压方向、挤压速率、尺寸大小，预处理等因素对青皮破裂力的影响。结果表明：核桃青皮破裂具有方向性；挤压青核桃时核桃青皮可看作各向同性材料；青核桃在挤压过程中压力与位移呈线性关系；不同挤压速率下,青皮破裂时的位移量随着挤压速率的增加而减少；青皮破裂时的位移量随着青核桃尺寸的增加而增大；增加对核桃青皮划口预处理,可以减小青皮破裂时的压力，这为核桃脱皮机械的结构设计提供可靠依据。

关键词: 青核桃, 青皮厚度, 压力, 裂纹, 青皮破裂