关键词: 核桃, 尺寸效应, 物理特性, 损伤断裂, 农产品加工

Abstract: In order to clarify the influence of impact load on damage and fracture characteristics of walnut during primary processing, in this paper, based on the continuum damage theory, the existence of damage was first proved by uniaxial compression test. Then, the damage and fracture models of walnut were established by single impact and repeated impact loading tests using the drop hammer impact test bench. Finally, the influence of walnut size between 30mm and 44mm on model characteristic parameters was discussed. The results showed that the damage accumulation coefficient was the minimum value 3.89 when the walnut size was 35mm, when the walnut size was 30mm, the threshold energy required for cracking was 4.74J/kg. The walnut fracture was caused by the damage of walnut. The energy threshold is the judgment standard for walnut crack generation, and the damage accumulation coefficient quantifies the damage resistance ability of walnut. The threshold energy is linearly with the increase in the walnut size. The relationship between the walnut size and damage accumulation coefficient conforms to polynomial function. The results are helpful to control walnut fracture during primary processing.

Key words: walnut, size effect, physical characteristics, damage fracture, agricutural product processing