紫花苜蓿圆捆机卷压过程的应力松弛特性与模型建立  

Stress relaxation behavior and modeling of alfalfa during rotary compression

作　　者：房佳佳 张永[1] 杨明韶[1] 王砹敏 王健 刘德环 高津 李海军[1] Fang Jiajia;Zhang Yong;Yang Mingshao;Wang Aimin;Wang Jian;Liu Dehuan;Gao Jin;Li Haijun(College of Mechanical&Electrical Engineering,Inner Mongolia Agricultural University,Huhhot 010018,China)

机构地区：[1]内蒙古农业大学机电工程学院,呼和浩特010018

出　　处：《农业工程学报》2018年第16期50-56,共7页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家自然科学基金资助项目(11262015)

摘　　要：牧草属于粘弹性物料,研究其应力松弛特性对降低圆捆机功耗、提高草捆质量具有重要意义。该文通过搭建圆捆机试验平台,结合各钢辊对草捆径向作用力分析,进行了紫花苜蓿应力松弛试验。采用无线电阻应变仪与ANSYS模拟相结合的方法,获取了卷压过程中捆室上半部分钢辊对草捆的径向作用力。在对应力松弛试验曲线和模型原理分析的基础上,确定了牧草应力松弛行为可采用2个Maxwell元件和1个弹簧元件并联组成的广义麦克斯韦尔模型模拟。利用残数法求得模型中应力松弛时间和平衡应力流变参数,分别为76.92、23.25 s和3.65 k Pa。该研究可为进一步探索喂入量、压缩频率、含水率与物料流变特性等参数间的关系,为节能圆捆机的设计提供理论依据及技术支持。Grass used as a high-quality animal feed has been grown in large scale in China.It is very important to study its stress relaxation characteristics to reduce the power consumption of round bales and improve the quality of bales.In order to understand the stress relaxation characteristics of alfalfa in course of rotary compression,a rotary compression test platform was designed using a steel-roll round baler.The radial forces of steel rolls to the bale during rotary compression were analyzed.Because of the different location of the steel roller of the baling chamber,the radial force of the steel roller to the bale is also different.The radial stress of the steel roll of the upper part of the baling chamber to the bale during rotary compression was obtained through the combination of the wireless resistance strain gauge and the ANSYS simulation.On the basis of the analysis of the stress relaxation test curve and the model principle,it is determined that the stress relaxation behavior of herbage can be simulated by a generalized Maxwell model composed of 2 Maxwell elements and 1 spring element in parallel.Residual stress method is used to get stress relaxation time and equilibrium stress rheological parameters in the model,which were 76.92 s,23.25 s and 3.65 kPa respectively.The coefficient of determination(R2)was used to evaluate the model fit to the experimental data.The parameters of stress relaxation were analyzed.The moduli of the 2 Maxwell elements were E1=1.88/ε1 and E2=6.1/ε2.The modulus of the material was not changed during the relaxation process.The stress relaxation times were T1=η1/E1=76.92 s and T2=η2/E2=23.25 s.It reflected the relaxation speed of the material and the stress relaxation time of each Maxwell element is independent of each other.The initial stress for stress relaxation was 11.63 kPa(σ=σ1+σ2+3.65),and the equilibrium stress was 3.65 kPa.This study provides a theoretical basis and technical support for the further exploration of the relationship between feed volume,compression frequ

关 键 词：应力 模型 试验 牧草 卷压过程 

分 类 号：S226.71[农业科学—农业机械化工程]