饲用苜蓿茎秆拉伸试验力学特性及仿真分析

Simulation and experimental study on mechanical properties of alfalfa stalk during stretching process

针对当前饲用苜蓿茎秆力学性能测试存在数据差异大、结果重复性差问题,通过对茎秆不同部位进行拉伸试验并建立本构方程,建立了茎秆抗拉强度和断面截面积的函数关系。对苜蓿茎秆拉伸过程进行了数值仿真模拟及试验验证,结果表明,苜蓿茎秆上部和中部的抗拉强度和断面截面积满足三次项函数关系,下部更近似于幂指数关系。对苜蓿茎秆拉伸过程仿真模拟结果进行试验验证,结果表明,饲用模型茎秆拉伸应力-应变曲线与模拟结果相吻合,茎秆抗拉强度的模拟结果31.76MPa,与试验误差约4.09%,仿真模拟结果具有较高可靠性。研究结果可以解决茎秆切割机制造研究过程中复杂的非线性动力学问题,为饲草收获机关键部件设计制造提供了数据及理论支撑,还可为其他农作物茎秆力学性能研究提供新的思路和方法。

In response to problems of large data differences and poor repeatability in mechanical performance testing of forage alfalfa stems,tensile tests were conducted on different parts of stem and constitutive equations were established.Functional relationship between stem tensile strength and cross-sectional area was established,and numerical simulation and experimental verification were carried out on stretching process of alfalfa stems.Results showed that tensile strength and cross-sectional area of upper and middle parts of alfalfa stems satisfied a cubic function relationship,while lower part was more similar to a power exponential relationship.Simulation results of alfalfa stem stretching process were experimentally verified,and results showed that stress-strain curve of feed model stem stretching was consistent with simulation results.Simulation result of stem tensile strength was 31.76 MPa,with an error of about 4.09%compared to the experiment.Simulation results had high reliability.Research results could solve complex nonlinear dynamic problems in manufacturing process of stem cutting machines,provide data and theoretical support for design and manufacturing of key components of forage harvesters,and also provide new ideas and methods for study of mechanical properties of other crop stems.