仿生布利冈结构农机耐磨触土部件设计与试验

Design and experiments of the Bouligand structure inspired bionic wear resistant soil-engaging component for the agricultural machinery

针对农机触土部件易磨损失效这一难题,该研究设计了一种仿生布利冈结构件,并对其磨损特性进行评价,进一步探索耐磨机理。以布利冈结构的结构单元直径、层间螺旋角度、层间重叠间距3个因素设为自变量,以磨损量为响应值,在EDEM中进行仿真磨损试验,根据自变量与响应值之间的关系,优化布利冈结构的组成参数,得到最优的组成参数为:结构单元直径1.0mm、层间螺旋角度16°、层间重叠间距0.13mm,在此参数下经仿真磨损试验得到布利冈结构件的磨损量为2.13×10^(-6)g。对光滑件、单层棱纹件、布利冈结构件的耐磨效果,进行仿真磨损对比试验,结果表明,布利冈结构件较单层棱纹件磨损量减少了90.6%,较光滑件减少了92.2%。运用离散元法(digital elevation model,DEM)与有限单元法(finite element method,FEM)联合仿真,得到样件内部形变和应变,光滑件、单层棱纹件、布利冈结构件的平均变形量分别为1.62×10^(-9)、7.97×10^(-9)和1.82×10^(-8)mm;平均等效应力为1.16×10^(-6)、6.36×10^(-6)和1.01×10^(-5)MPa。布利冈结构件内部形变和所受应力较大,这一变化有助于吸收颗粒冲击能量,减小磨损。利用光固化打印技术加工样件,利用旋转式试验机和扫描电子显微镜分析3种样件的耐磨性能,结果表明,布利冈结构件的磨损量最小为0.12 g,且标准差最小,为0.012,耐磨性能较为稳定。研究结果可为农机具触土部件的耐磨增效提供设计依据和理论基础。

The impact of soil particles on the soil-engaging components can lead to wear and tear,even in the failure of agricultural machinery systems.The bionic Bouligand-type(twisted plywood)arrangement structure can be expected to provide new strategies in this case.This study aims to explore the wear-resistance performance of the bioinspired Bouligand structure for the soil-engaging components.A series of computational simulation experiments were also carried out on the abrasive wear using the EDEM platform.Three parameters of the geometric feature were first selected as the experimental independent variables,including the beam diameter,twist angle,and overlap distance of the Bouligand-type structure.By contrast,the abrasion loss was used as the response value.Multivariate quadratic polynomial regression models were then established for the optimization.The geometric feature parameters of the Bouligand-type structure were also optimized,according to the relationship between the independent variable and the response value.The optimization results showed that the favorable wear-resistance performance was achieved under the optimal combination of geometrical feature parameters,with a beam diameter of 1.0 mm,a twist angle of 16°,and an overlap distance of 0.13 mm.With the optimal parameters,the wear-resisting properties of the Bouligand-type structure were compared with the conventional solid ribbed surface and smooth surface.The computational results show that the abrasion losses were 2.13×10^(-6) g for the Bouligand-type structured surface,2.26×10^(-5) g for the conventional ribbed surface,and 2.73×10^(-5) g for the conventional smooth surface,respectively.The bouligand-type structured surface reduced the abrasion losses by 90.6%and 92.2%,respectively,compared with the conventional ribbed surface and smooth surface,respectively.Correspondingly,the Bouligand-type structure substantially reduced the abrasion loss from the abrasive wear,particularly for better wear-resistance performance.Furthermore,the EDM-FEM coupled simulation was used to evaluate the internal deformation and strain behavior of the samples,in order to further investigate the wear-resisting enhancement from the Bouligand-type structure.In addition,the averaged deformation of the Bouligand-type structured,conventional ribbed,and smooth surface were 1.82×10^(-8),7.97×10^(-9),and 1.62×10^(-9)mm,respectively,where the averaged equivalent stresses were 1.16×10^(-6),6.36×10^(-6),and 1.01×10^(-5) MPa,respectively.The results show that the Bouligand-type structure presented relatively higher internal deformation and strain,compared with the rest.The reason was that the Bouligand-type structure shared the better capability to absorb the impact energy from the abrasive particles for reduced abrasion loss.The rotary abrasive test bench was used to further validate the simulation.The minimum wear amount of Bouligand structural parts was 0.12 g,and the minimum standard deviation was 0.012,the wear resistance was stable compared with the conventional ribbed and smooth surface.Consequently,there were relatively stable variations in the abrasion loss of the Bouligand-type structure over the wear time.This research can also provide a new theoretical reference and technical basis for the development of promising wear-resistant materials.