多级叶盘结构随机失谐响应特性分析

Mistuned forced response characteristics analysis of mistuned multi-stages bladed disks

为研究多级叶盘结构最大失谐强迫响应幅值及最坏失谐模式,通过设置失谐变量为优化变量,提出了运用遗传算法和序列二次规划混合方法确定最大的失谐强迫响应幅值及最坏失谐模式的通用方法。针对典型三自由度扇区单级和耦合两级叶盘结构集中参数模型计算了相应谐调系统叶片刚度失谐时的最大失谐幅值放大系数及最坏失谐模式,揭示了失谐跳变-局部化现象,通过算例说明在失谐跳变的叶片位置,叶片出现了强烈的振动响应局部化,构建了与振动响应局部化直接关联的表达因素。运用提出的方法分析了三自由度扇区单级叶盘集中参数模型谐调系统叶片刚度失谐时的敏感度特性,研究表明,随着失谐强度的增加,最大幅值放大系数逐渐增大,并在失谐强度上界处取得极值,并没有所谓的失谐"阈值"现象。

The worst mistuning pattern and robust maximum mistuned forced response of a mistuned multi-stages bladed rotor were studied as an optimization problem.Simulations were carried out on both a lumped parameter model and a disk model with blades simplified as three-degrees-of-freedom substructures.The results of the optimum search of the worst-case mistuning patterns for the lumped parameter model were analyzed,which reveals that the maximum forced response of blade in a mistuned bladed disk is associated with mistuning jump which causes strong localization of the vibration response on a particular blade.The three-degrees-of-freedom per blade disk model was also used for calculation of the maximum forced resonant response of mistuned assemblies and for determination of its sensitivity coefficients with respect to mistuning variation.The studies show that there is no threshold of mistuning beyond which the maximum forced response levels off,or even drops,as the degree of mistuning is increased further.The maximum amplitude magnification of forced response tends to increase with the increase of blade mistuning.The influence of the multi-stages coupling is revealed by com-paring the results of single stage analysis with those in the multi-stages case.