玉米收获机车架应力及模态数值模拟焊点模型优选  

Optimum seeking of spot weld model on numerical simulation of stress and modal analysis for corn combine harvester frame

作　　者：姚艳春[1] 宋正河[1] 杜岳峰[1] 毛恩荣[1] 赵雪彦[1] 张万昊 Yao Yanchun Song Zhenghe Du Yuefeng Mao Enrong Zhao Xueyan Zhang Wanhao(Beijing Key Laboratory of Optimized Design for Modern Agricultural Equipment, China Agricultural University, Beo＇ing 100083, China)

机构地区：[1]中国农业大学现代农业装备优化设计北京市重点实验室,北京100083

出　　处：《农业工程学报》2016年第24期50-58,共9页Transactions of the Chinese Society of Agricultural Engineering

基　　金：北京市科技创新基地培育与发展专项项目(Z151100001615017);现代农业装备与技术协同创新资助项目(NZXT01201601);教育部博士学科点专项科研基金资助项目(20130008110043)

摘　　要：玉米收获机车架作为一种典型的薄壁焊合结构,各结构件主要通过焊接关系连接,该文针对车架有限元建模分析中焊点连接关系复杂、不同焊点模型引起数值模拟精度差异的问题,以提高车架有限元建模准确性与计算精度为目标,研究不同焊点模型对收获机械车架有限元计算精度的影响。首先,研究了有限元建模中常用4种不同焊点模型的构造机理与数学描述,并分别建立了4种焊点的车架有限元分析模型,计算静态加载下不同焊点模型车架的应力分布;其次,设计了玉米收获机车架应变试验,得到不同测点的应力分布规律。通过对比分析仿真与试验数据得出:采用RBAR(rigid-bar)焊点模型计算结果与试验结果吻合,相关系数为0.993 2,较适合模拟计算应力-应变模式的静态工况。通过Block Lanzcos算法计算不同焊点模型的车架模态振动频率与振型,获取不同焊点模型对车架频率和振型的影响规律,得出采用ACM2(area contact model 2)焊点模型的计算结果与二阶四面体单元计算结果相关性较高,相关系数为0.995 9。综合考虑不同焊点模型的适用性与建模效率得出:对于应力-应变模式的静态分析,建议采用RBAR焊点模型;对于模态分析模式的车架动态振动特性分析,建议采用ACM2焊点模型。研究结果为收获机械焊接结构件的有限元建模方法、焊点模型的选用以及提高数值模拟精度和建模效率等问题提供依据。More and more spot weld have been used extensively to joint different components in industry,thus many finite element models of spot weld have been developed for various types of analysis,for example,static analysis,modal analysis,fatigue analysis and optimization analysis.Currently,there are already plenty spot weld models,but few comprehensive study and guidance are available for how to evaluate performance of different kinds of spot weld models,such as,which model with a proper mesh refinement can represent adequately behavior of spot weld joint and perform properly in the process of structural analysis.For frame structure of corn combine harvester,which can be considered as a typical thin-wall structure and its components are mainly connected by welding,spot weld model are always neglected and replaced by treating frame structure as a whole unit or considering the connection as contact relation.However,spot weld connection model will affect accuracy of finite element model and numerical simulation,especially when there are a lot of welding relationships in the frame structure of corn combine harvester machine.At present,finite element modeling and seeking optimization of different spot weld models are seldom considered and no guideline exists in static analysis and model analysis.The purpose of this paper is to seek optimal spot weld model on numerical simulation of static analysis and modal analysis for combine harvester frame.Influence of different welding spot models on the accuracy of the finite element calculation of the harvesting machine frame was investigated,and accuracy of finite element modeling and precision of numerical simulation was improved.Firstly,schematic mechanism and mathematical descriptions of four different kinds of spot weld models,including Rbe2（rigid bar element 2）,RBAR（rigid-bar）,CWELD and ACM2（area contact model 2） models were studied and corresponding finite element models were established to conduct two kinds of numerical simulation mode including static analysis and

关 键 词：模型 有限元分析 应变 焊点 数值模拟 应力 模态振动频率 车架 

分 类 号：S225.3[农业科学—农业机械化工程] TB533.1[农业科学—农业工程]