基于变密度法的油菜割晒机割台机架拓扑优化与试验
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作者单位:

1.华中农业大学工学院,武汉 430070;2.农业农村部长江中下游农业装备重点实验室,武汉 430070

作者简介:

樊伟,E-mail:1258678169@qq.com

通讯作者:

舒彩霞,E-mail:shucaixia@mail.hzau.edu.cn

中图分类号:

S225.2+1

基金项目:

国家现代农业产业技术体系油菜耕种机械化岗位(CASR-12);中国博士后科学基金项目(2020M682438)


Topology optimization and test of the header frame of rapeseed windrower based on the variable density method
Author:
Affiliation:

1.College of Engineering, Huazhong Agricultural University, Wuhan 430070,China;2.Ministry of Agriculture and Rural Affairs Key Laboratory of Agricultural Equipment in Mid-Lower Yangtze River,Wuhan 430070,China

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    摘要:

    为减少履带式油菜割晒机割台在不同工况下的振动,应用Hypermesh软件建立割台拓扑优化空间,利用多体动力学方法建立基于RecurDyn的油菜割晒机虚拟样机模型,获得部件调试工况、转运工况和田间作业工况下割台运动副的动态载荷;采用折衷规划法构建割台静态刚度和动态频率的综合目标函数,根据层次分析法确定各子目标的权重;以体积分数、运动副极大值载荷为约束条件,得到割台空间结构的理想材料密度分布,综合考虑实际工程应用,对优化得到的割台机架进行规则化处理;建立优化后割台机架的有限元模型并开展有限元静力分析与模态分析,对比分析优化前、后割台测点处的振动幅值。结果显示:优化后最大应力值由107.99 MPa下降到65.45 MPa,最大变形量由0.82 mm下降到0.36 mm;前三阶固有频率有不同程度提高,第一阶固有频率提高到24.187 Hz。实际振动测试结果表明,优化后割台各测点振动幅值下降,割台整体振动减小,其中纵向切割器支架振幅值由4.83 m/s2下降到1.49 m/s2

    Abstract:

    The truss structure of header in the caterpillar type rapeseed windrower is complex and changeable,which leads to the problem of large vibration of the header.Based on the variable density method,the multi-objective topology optimization of frame structure of the header was carried out to reduce the vibration of the header under different working conditions. The topology optimization model of header was established by using Hypermesh software. The virtual prototype model of rapeseed windrower based on RecurDyn was established by using multi-body dynamics method. The dynamic loads of the moving pair of the header under parts debugging conditions,transport conditions and field operation conditions were obtained. The comprehensive objective function of static stiffness and dynamic frequency of the header was constructed with the compromise programming method. The weight of each sub- object was determined according to the analytic hierarchy process (AHP). Taking the volume fraction and maximum load of moving pair as constraints,the ideal material density distribution of the header spatial structure was obtained. Considering the practical engineering application,the optimized frame of header was normalized. The finite element model of the optimized frame of header was established and the finite element static analysis and modal analysis were carried out. The vibration amplitudes at the measuring points of the header before and after optimization were compared and analyzed. The results showed that the maximum stress value decreased from 107.99 MPa to 65.45 MPa after optimization. The maximum deformation decreased from 0.82 mm to 0.36 mm. The natural frequencies of the first three orders were increased to varying degrees,and the natural frequency of the first order was increased to 24.187 Hz. The results of actual vibration test showed that the vibration amplitude of each measuring point of the header decreases after optimization. The overall vibration of the header decreased,in which the amplitude of the longitudinal cutter support decreased from 4.83 m/s2 to 1.49 m/s2. It will provide reference for the structure improvement and optimization of rapeseed windrower.

    表 1 油菜割晒机主要技术参数Table 1 Main technical parameters of rapeseed windrower
    表 5 各测点振动总量的加速度均方根值Table 5 Root mean square of acceleration of the total vibration of the measurement point
    表 3 优化前后模态分析结果比较Table 3 Comparison optimization result of model
    图1 油菜割晒机示意图Fig.1 Structure of rapeseed windrower
    图2 油菜割晒机工作过程示意图Fig.2 Schematic diagram of operation of rapeseed windrower
    图3 割晒机割台机架拓扑优化模型Fig.3 Topology optimization model of header
    图4 油菜割晒机虚拟样机Fig.4 Virtual prototype model of rape windrower
    图5 割台运动副受载极值Fig.5 Maximum load of moving pair
    图6 割台受力分析图Fig.6 Force analysis of header
    图7 3种工况下割台机架单目标优化结果Fig.7 Single-objective optimization result of header frame under three working conditions
    图8 多目标优化结果Fig.8 Multi-objective optimization results
    图9 割台拓扑优化结果Fig.9 Topology optimization results of header
    图10 优化后的割台三维模型Fig.10 3D model of optimized header
    图11 油菜割晒机转运工况振动测试Fig.11 Vibration test of rapeseed windrower
    表 2 综合目标函数中各级指标权重Table 2 Weights of all indicators in the integrated objective function
    表 4 油菜割晒机割台振动试验工况Table 4 Vibration test condition of header
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樊伟,舒彩霞,万星宇,廖宜涛,廖庆喜,杨佳.基于变密度法的油菜割晒机割台机架拓扑优化与试验[J].华中农业大学学报,2023,42(1):227-236

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  • 收稿日期:2022-02-25
  • 在线发布日期: 2023-02-22
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