Extrusion mechanical properties of fresh litchi

In order to reduce the mechanical damage of litchi in harvesting, storage and transportation, and provide the design basis for operation equipment, the geometric characteristics of fresh litchi were determined in this paper, the extrusion tests were conducted for litchi under different loading conditions. Moreover, tensile tests were carried out for the hulls of fresh litchi. The rupture force of cultivar Feizixiao and Guiwei were 76.46-112.90?N and 38.67-53.83?N under five loading rates and two loading directions, while the relative deformation were 27.93%-32.57% and 18.87%-21.27%, and the elastic modulus were 2.52-4.69×105?Pa and 4.26-5.93×105?Pa. The results of tests showed that the anti-extrusion capacity of litchi fruit was anisotropic and was stronger in the vertical direction than in horizontal direction. The anisotropy of cultivar Feizixiao was more significant than Guiwei, and its anti-extrusion capacity was also greater than Guiwei. The loading rate in this experiment had no significant anti-extrusion capacity. Therefore, litchi fruit can be simplified as uniform thickness shell sphere, and its stone was elongated ellipsoid. According to simplified structure and anisotropy of hulls, the mechanical principle of extrusion properties and cracking characteristics were analyzed. The results can provide a theoretical basis for litchi harvesting, processing and transporting.