面向采摘机械手的蒜薹力学特性试验研究

为确定蒜薹的机械化采摘参数,以收获期蒜薹为对象,进行不同部位蒜薹的拉伸和压缩试验,以及整根蒜薹的拉伸试验。结果表明:拉伸初期,拉应力与应变近似线性增长,表现出弹性材料的特征;当应变增大到一定值时,拉应力随着应变缓慢增大,表现出弹塑性材料的特征。从顶部到根部,蒜薹的最大拉应力单调递减,最大压力总体呈现减小的趋势,蒜薹的弹性性能逐渐减弱,相同压力下的压缩变形量依次减小。当拉伸速度为20mm/min时,90%的蒜薹在根部断裂,此时最大拉应力为(1.2±0.1)MPa,最大应变为0.15±0.04。采摘机械手夹持蒜薹的最佳部位为蒜薹中部以上,夹持载荷应4.1N/mm。可用对数函数和多项式函数分别表达蒜薹的拉应力与应变及压力与压缩变形量的关系。

Experimental study on mechanical properties of garlic-stem for harvesting manipulator

To provide basic data for designing harvesting manipulator, tensile and compression tests on different parts of garlic-stem, and tensile tests for whole garlic-stem were conducted on ripe garlic-stem.The results showed that the tensile stress increased almost linearly with strain at the initial tensile stage, presenting the characteristics of elastic materials.After the strain reached to certain values, the tensile stress increased slowly with the increase of strain, presenting the characteristics of elastic-plastic materials.From top to root of the garlic-stem, the maximum tensile stress decreased monotonously, the maximum compression force almost decreased gradually, the elastic property gradually decreased, and the compression deformation gradually decreased at same compressive force.When the tensile speed was 20 mm/min, 90% garlic-stems broke at the root part, with the maximum tensile stress of (1.2±0.1) MPa and the maximum strain of 0.15±0.04.The best part for clipping the garlic-stems is above the middle part, and the clip load should be less than 4.1 N/mm.Logarithmic functions and polynomial functions can be used to express the relationship between tensile stress and strain, and compressive force and compression deformation, respectively.