复杂复合结构脱棉转子数值分析方法与振动特性分析

Numerical analysis method and vibration characteristics analysis of complex composite structure de cotton rotor

为揭示采棉机脱棉用复杂复合结构(Complex Composed Structure,CCS)脱棉转子的振动特性,对CCS脱棉转子的毛刷条部分建立了计入尼龙纤维的三维微结构纤维模型。同时对毛刷条进行简化并建立了计入复合材料特性的各向异性微结构复合模型。通过改变复合模型的弹性模量比分别进行了有限元模态分析,并对比分析了纤维模型和复合模型的振动特性,获得了接近实际毛刷条模型的弹性模量比并确定了复合模型的复合材料属性。同时也对单元类型和尺寸的影响进行了对比研究,从而验证了本建模方法和数值算法的有效性。建立了带毛刷条和无毛刷条的CCS脱棉转子数值模型并进行了模态分析,得到其固有频率和振型。分析结果表明:毛刷条对CCS脱棉转子振动特性的影响较大,前六阶固有频率范围为52.63~249.00 Hz,但第一阶固有频率高于CCS脱棉转子的实际工作频率25 Hz,故避免了产生共振。利用转子测试平台和激光多普勒测振仪得到了脱棉转子的固有频率,该结果可以正确地反映CCS脱棉转子的振动特性,从而验证了CCS除棉转子建模方法和相关算法的有效性。这为CCS脱棉转子设计与优化提供了有效手段和参考方法。

In order to reveal vibration characteristics of complex composite structure(CCS)de cotton rotor of a cotton picker,firstly,a 3-D microstructure fiber model including nylon fiber was established for brush strip part of CCS de cotton rotor.At the same time,the brush strip was simplified and an anisotropic microstructural composite model was established considering characteristics of composite material.Elastic modulus ratio of composite model was changed,and modal analyses were performed with finite element method.Vibration characteristics of the fiber model and the composite model were contrastively analyzed to obtain elastic modulus ratio of the model close to the actual brush strip,and determine composite material properties of composite model.At the same time,influences of element type and size were studied contrastively to verify the effectiveness of the proposed modeling method and numerical algorithm.Secondly,numerical models of CCS de cotton rotor with and without brush strip were established and modal analyses were performed to obtain the rotor natural frequencies and modal shapes.Results showed that the brush strip has a larger influence on vibration characteristics of the CCS de cotton rotor,the first six natural frequencies range is 52.63~249.00 Hz,but the rotor’s first natural frequency is higher than the rotor’s actual working frequency of 25 Hz to avoid the resonance.Finally,the rotor’s natural frequencies were obtained with a rotor test platform and Laser Doppler vibrometer.It was shown that both the numerical results and test ones agree well with each other,and can correctly reflect vibration characteristics of the CCS de cotton rotor to verify the effectiveness of the proposed modeling method and related algorithms;the results can provide a reference for design and optimization of CCS de cotton rotor.