基于微动滑移摩擦模型的失谐叶盘系统振动分析

Vibration analysis of mistuned bladed disk system based on microslip friction model

在航空发动机叶-盘系统中,由于叶片失谐导致严重的振动局部化,造成局部叶片的高周疲劳,拟采用增加叶根干摩擦的方法降低失谐叶-盘系统振动幅值,减轻其振动局部化程度。基于微动滑移摩擦模型建立叶根阻尼器干摩擦力本构关系,采用等效椭圆代替阻尼器力与位移函数关系的迟滞回线,获得阻尼器的等效阻尼、等效刚度;将等效阻尼、等效刚度作用于叶-盘系统集中参数模型上,建立单个扇区三自由度整周失谐叶-盘系统动力学方程;采用谐波平衡法对其进行振动特性分析,讨论了叶根干摩擦对失谐叶盘系统振动特性的影响。结果表明:叶根摩擦能显著降低系统共振幅值;有叶根摩擦系统较无叶根摩擦系统的共振峰在频率上延后;增加叶根摩擦可有效降低失谐叶-盘系统的振动局部化程度。

The vibration localization is caused by blade mistuning,and then it will develop high cycle fatigue in local blade of the aero-engine bladed disk system.The method of increasing friction existed in blade root is used,which decreases the vibration amplitude and its localization degree of bladed disk system.Based on a microslip friction model the constitutive relation of dry friction force for blade root damper is formulated.The hysteresis loop expressing force and displacement relationship of damper is replaced by an equivalent oval.And the equivalent damping and stiffness are calculated,they can be used in lumped mass model of bladed disk system,thus dynamics equation for mistuned bladed disk system is established in single sector with 3-DOF.The harmonic balance method is applied to analyze vibration characteristics,and the effect of dry friction on vibration performances of mistuned bladed disk system is discussed.The results show that resonance peak value can be decreased remarkably by the friction existed in the blade roots.Meanwhile,comparing to no blade root friction system the frequency of resonance peak for the system with friction gets higher.The degree of vibration localization can be decreased effectively by increasing blade root friction.