基于ANSYS/LS-DYNA的螺旋刀辊土壤切削有限元模拟

Finite element simulation of soil cutting with rotary knife roller based on ANSYS/LS-DYNA software

为揭示秸秆还田耕整机的螺旋刀辊与土壤之间的关系特性,根据螺旋刀辊切削土壤的工作特点,利用ANSYS/LS-DYNA971软件对螺旋刀辊土壤切削过程进行模拟,得出了螺旋刀辊切削土壤的功率消耗、切削阻力的大小以及土壤等效应力的变化规律。模拟结果表明,螺旋刀辊转速为300r/min,机组行进速度为1.1m/s时,单组螺旋刀辊切削土壤的最大功耗为6.4kW,最大切削阻力为2820.7N,且土壤最大等效应力发生在横刀刚入土时的内侧面,所得功耗值与经验推导值相符。研究结果为双轴型水田高茬秸秆还田耕整机的系统参数优化设计提供参考。

The straw returning and tillage machine with double roller for high stubble in paddy field had several advantages, such as wide working range, crushing earth evenly, good coverage rate, high working efficiency and so on. The rotary knife roller was the main working part of the machine. The interactions between rotary knife roller and soil included shear, friction and extrusion of knife roller for soil, deformation and failure of the soil and so on. In order to study the interaction characteristics, the soil cutting process of the rotary knife roller was analyzed by Finite Element Method （FEM） software ANSYS/LS-DYNA971 according to the operating feature of the rotary knife roller. The power consumption and cutting resistance of the rotary knife roller were measured by simulation, and the variation rules of equivalent stress of the soil was revealed during the soil cutting process of the rotary knife roller. The maximum values of power consumption and cutting resistance were obtained when the rotational speed was 300r/min and the forward speed was 1.1 m/s, and the values were 6.4 kW and 2820.7 N respectively. The value of power consumption acquired by simulation were accorded with derived value by empiric formulas, which showed that the proposed modeling method was practical and reasonable Furthermore, the maximum equivalent stress of the soil appeared at the inner side surface of the cross knife when lateral blade just cut the soil. Finally, the lateral blade had a lateral push effect on soil in the practical field test, and the adjacent lateral blade had an overlapping time of soil cutting, which could make the machine work more smoothly. The study would provide a theoretical basis for the system parameter’s optimal design of the straw returning and tillage machine with double roller for high stubble in a paddy field.