葵花籽仁力学特性的有限元分析

Finite element analysis on mechanical properties of sunflower seed

为减少葵花籽仁在收获、储运过程中的机械损伤,并为相关机械的设计提供理论依据,根据测量得到的几何尺寸与试验得到的力学参数,建立了葵花籽仁的物理模型及有限元计算模型。通过有限元分析的方法,分析了葵花籽仁在不同载荷和作用方式下的破坏形式以及变形与应力的分布规律,并将有限元仿真结果与试验结果进行对比,验证了模型的可行性。结果表明:葵花籽仁的抗挤压能力具有各向异性,其沿X、Y、Z3个方向的弹性模量分别为E_X=64.01 MPa,E_Y=23.63 MPa,E_Z=101.8 MPa。相同压力下,葵花籽仁受到水平方向挤压时破碎的可能性最大,而竖直方向破碎的可能性最小;加载方向的不同使得籽粒的破坏形式不同,竖直方向加载时易产生局部裂纹破裂,而水平和垂直两向加载时籽粒会沿子叶夹缝开裂,其中垂直向加载时有失稳的可能。

In order to reduce the mechanical damage of sunflower seed during its harvest and storage,and provide the theoretical foundation for the design of related mechanical devices,was studied the mechanical properties of sunflower seed.According to the geometrical dimensions and the mechanical parameters,which obtained from the experiment,we established the physical model and the finite element calculation model of sunflower seed.By the method of finite element analysis,not only analyzed the failure modes of sunflower seed under different compression loads and compress methods,but also the regularity of distribution of its stress and strain.By comparing the results of experiment and finite element simulation,we confirmed the feasibility of the model.The results showed that the antiextrusion capacity of sunflower seed is anisotropic,along the directions of X,Yand Z,its elastic modulus are EX =64.01 MPa,EY=23.63 MPa,EZ=101.8 MPa,respectively.Under the same pressure,sunflower seed is most likely to rupture in horizontal direction and least likely to rupture in the perpendicular direction.Different loading directions lead to different failure modes,the perpendicular loading tends to cause local cracks and rupture,while the horizontal and transversal loading lead to the seed cracks along the crevice of the cotyledons.Besides,instability failure might happen under the transversal loading.