随机失谐叶盘结构失谐特性分析

为研究失谐叶盘结构最大的强迫响应幅值及最坏失谐模式,提出了运用遗传算法和序列二次规划混合优化方法确定失谐叶片最大的幅值放大系数及相应最坏失谐模式的通用方法.揭示了失谐跳变-局部化现象,构建了与振动响应局部化直接关联的表达因素.失谐敏感度分析表明,失谐叶片最大的幅值放大系数随失谐强度的增加而增大,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. 

Mistuning characteristics analysis of mistuned bladed disk assemblies

The problem of determining the worst mistuning pattern and robust maximum mistuned forced response of turbine engine bladed disks is formulated and solved as an optimization problem. Maximum resonant amplitudes searched across all the degrees of a mistuned bladed disk and across all the excitation frequencies in a given range are combined into an objective function. Individual blade mistuning is controlled by varying mistuning parameters. This approach is exemplified on a lumped-parametric model with two-degree-of-freedom per blade disk sector. Results of the optimum search of the worst-case mistuning patterns for the lumped parameter model are analyzed and reveals that maximum blade forced response in a mistuned bladed disk associated with mistuning jump which causing strong localization of the vibration response in a particular blade. Detailed two-degree-of-freedom per blade disk model are also used for calculation of the maximum forced resonant response of mistuned assemblies and for determination of its sensitivity coefficients with re-spect to mistuning variation. Studies have shown that there is not a threshold of frequency mistuning beyond which the maximum forced response levels off, or even drops, as the degree of mistuning is increased further, the tendency of the forced response amplification factor to increase with blade mistuning.