含复杂管路的某机构模态参数识别研究

Identification of Modal Parameters for Certain Mechanism Containing Complicated Pipe Structures

目的获取复杂结构产品的模态参数及动态性能。方法采用基于冲击激励的试件自由模态分析试验,综合分析频响函数曲线幅值,确定局部结构模态频率点,利用半功率带宽法和专用分析软件分别计算模态阻尼比和模态振型。结果识别出影响某机构动态性能关键部件的模态参数。结论发现机构外壳模态频率远离冷却装置频率点,冷却管一阶横向模态由自身结构特性产生,二阶及纵向模态由减压阀模态引起。气体导管的动态特性主要受冷却装置模态的影响。

Objective To obtain the modal parameters and dynamic properties of products with complicated structures. Methods Using the free modal testing based on impact excitation, the modal frequencies of local structure were determined through comparing the amplitude of frequency-response function curves. By the method of half-power bandwidth and special analysis software, the damping-ratio and vibration mode were calculated respectively. Results The modal parameters of the key components for dynamic properties of a certain mechanism were identified. Conclusion The modal frequencies of the mechanism shell were away from that of the cooling device. The first transverse mode of the cooling tube was generated by its own structural property, but the second and vertical modes were arisen by the mode of decompression valve. The dynamic properties of the gas duct were mainly influenced by the mode of the cooling device.