摘要
针对喷雾机喷杆结构动力学特性原始设计缺陷,该文提出了一种基于遗传算法的多变量优化方法。以平面十八杆桁架单元为基础结构,在Abaqus平台中建立了单侧喷杆参数化有限元模型。基于Isight多学科多目标优化平台提取模型设计变量组及优化目标,采用多岛遗传算法(multi-island genetic algorithm,MIGA)对喷杆桁架结构形状及杆件截面尺寸进行优化,得到了一阶固有频率为10.87 Hz,质量为35.82 kg,幅宽为5 m的单侧喷杆结构模型。根据优化后模型的结构参数制造喷杆样品,通过对其进行模态试验验证了数值模型的准确性。针对优化前、后喷杆模型进行了以位移功率谱密度(power spectrum density,PSD)函数为激励的随机振动仿真,结果表明,优化后喷杆模型的质量下降并没有明显增加其在竖直方向上振动位移响应量。该文研究结果可为进一步研究喷雾机喷杆结构的动力学性能优化提供依据。
During the boom sprayer spraying, the vibration of the boom excited by field ground roughness not only influences homogeneity of spray distribution, but also reduces the life of the sprayer. To improve the structure dynamic behavior of the original boom design, a multi-variable optimization approach by genetic algorithms was presented. A parametric finite element model of the 18 bar plane truss element was built by the finite element software Abaqus. Then the mass of spray boom is taken as optimization goal. The first mode frequency of spray boom is taken as constraint condition. The element node coordinate and section dimension of spray boom are taken as design variables. All the design variables are transformed to dimensionless variables based on the unified design variable method to avoid optimization analysis failing to converge. The design variables and the optimization goal of the model were set on the Isight multidisciplinary multi-objective optimization platform, the shape of the boom structure and bar section dimension were optimized by using Multi-Island Genetic Algorithm （ MIGA） method to obtain a single lance structure with 10.87 Hz first mode frequency, 35.82 kg mass and 5 m width. According to the technological requirements, the optimized structural dimensions were adjusted to manufacture an actual sample. In order to ensure the reliability and accuracy of the finite element model, the modal test in impact method was done to validate the finite element model and its modal parameters. In the test, the boom was fixed on the concrete column to make the actual model consistent with the finite element model. Single-point excitation and multi-point acquisition method was used. The exciting signal was generated by an impulse hammer and the response signal was measured by acceleration sensors. Then the modal parameters were identified in the computer. After the test, a comparison between test and simulation was made. The result showed that the difference of first 6 modes frequency between finite element
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2015年第9期50-56,共7页
Transactions of the Chinese Society of Agricultural Engineering
基金
国家公益性行业(农业)科研专项资助项目(201203025)
关键词
模态分析
有限元分析
优化
喷杆
遗传算法
随机振动
路面不平度
modal analysis
finite element analysis
optimization
spray boom
genetic algorithms
stochastic vibration
road roughness
