Study on Static Characteristics Prediction of Porous Hydrostatic Bearing
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摘要: 在多孔质静压轴承设计中,轴承设计参数是影响其静动态特性的关键因素之一,通常情况下,要得到合适的轴承设计参数,需要多次重复建模和仿真,且由于轴承结构复杂,建模难度大,仿真时间长,严重影响了轴承的设计效率。本文构建了一种基于遗传算法(Genetic algorithm,GA)优化反向传播(Back propagation, BP)神经网络的轴承静态特性预测模型,采用拉丁超立方抽样方法在轴承参数设计空间内采样,并进行Fluent流体仿真,将仿真数据用于GA-BP神经网络模型的训练与测试,实现了对设计空间内任意设计参数下的多孔质静压轴承静态特性的预测。研究结果表明,训练出的GA-BP神经网络模型能够准确预测多孔质静压轴承的静态特性,预测精度在95%以上,对多孔质静压轴承的快速设计和参数优化具有重要意义。Abstract: In the design of porous hydrostatic bearings, bearing's design parameter is one of the key factors affecting its static and dynamic characteristics. Normally, several repetitions of modeling and simulation are required to obtain suitable bearing design parameters, and due to the complex bearing structure makes modeling difficult and simulation time long, which seriously affects the efficiency of bearing design. In this paper, a bearing static characteristic prediction model based on genetic algorithm (GA) optimized BP (Back Propagation) neural network is constructed, Latin hypercube sampling method is used to sample the bearing parameter design space, and perform Fluent fluid simulation. The data is used for the training and testing of the GA-BP neural network model to realize the prediction of static characteristics of porous hydrostatic bearing under any design parameters in the design space. The research results show that the trained GA-BP neural network model can accurately predict the static characteristics of porous hydrostatic bearings with a prediction accuracy of over 95%, which is great significance for the rapid design and parameter optimization of porous hydrostatic bearings.
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表 1 多孔质静压止推轴承设计参数
Table 1. Design parameters of porous hydrostatic thrust bearing
参数名称 最小值 最大值 多孔质长度L/mm 20.0 80.0 多孔质宽度W/mm 10.0 50.0 多孔质厚度H/mm 3.0 15.0 气膜厚度h/μm 5 20 供气压力Ps/bar 5.0 8.0 多孔质渗透率α/m2 1.0×10−13 1.0×10−13 表 2 部分样本数据
Table 2. Partial sample data
样本编号 多孔质长度L/mm 多孔质宽度W/mm 多孔质厚度H/mm 气膜厚度h/μm 供气压力Ps/bar 渗透率α/10−13 m2 静态承载力Wb/N 耗气量Q/(L·min−1) 静刚度K/(N·μm−1) 1 23.2 43.3 11.1 18 5.9 1.0 122.5 13.3 11.5 2 39.0 19.5 14.7 14 7.0 1.0 105.8 9.1 12.0 3 51.4 23.3 4.7 15 6.4 1.0 398.7 24.6 22.5 4 43.2 35.3 8.4 20 6.3 1.0 310.3 24.4 20.6 5 31.0 38.3 12.4 10 6.1 1.0 324.4 10.0 28.2 6 68.8 31.9 3.3 16 7.7 1.0 1174.8 49.1 36.5 $\vdots $ $\vdots $ $\vdots $ $\vdots $ $\vdots $ $\vdots $ $\vdots $ $\vdots $ $\vdots $ $\vdots $ 200 78.4 16.7 3.4 7 5.5 1.0 569.7 13.9 27.1 表 3 BP神经网络参数设置
Table 3. BP neural network parameters settings
参数 取值/方法 输入层神经元数 5 隐含层神经元数 11 输出层神经元数 3 激活函数 Tansig、Purelin 训练函数 Trainlm 最大训练次数 150 学习速率 0.01 训练精度 1.0 × 10−4 表 4 GA-BP神经网络模型预测精度
Table 4. Prediction accuracy of GA-BP neural network model
静态特性 EMR/% R2 预测精度/% 静态承载力 3.32 0.991 96.68 静刚度 2.99 0.996 97.01 耗气量 4.65 0.988 95.35 -
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