关键词: 青核桃, 青皮厚度, 压力, 裂纹, 青皮破裂

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